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1. name NMTOKEN REQUIRED data type CDATA IMPLIED is abstract true false false is readonly true false false is vector true false false vector size CDATA IMPLIED enum name NMTOKEN IMPLIED default value CDATA TMPLIED gt ae unknown is used internally to represent elements not in this NED DTD gt lt ELEMENT unknown ANY gt lt ATTLIST unknown element CDATA REQUIRED gt 20 Appendix NED Functions The functions that can be used in NED expressions and ini files are the following The question mark as in rng marks optional arguments Category conversion e double double double any x http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Converts x to double and returns the result A boolean argument becomes 0 or 1 a string is interpreted as number an XML argument causes an error e int Long int any x Converts x to long and returns the result A boolean argument becomes 0 or 1 a double is converted using floor a string is interpreted as number an XML argument causes an error e string string string any x Converts x to string and returns the result Category math e acos double acos double Trigonometric function see standard C function of the same name e asin double asin double Trigonometric function see standard C functi
2. lt ELEMENT namespace comment gt lt ATTLIST namespace name CDATA REQUIRED gt lt note not NMTOKEN because it May contain si gt lt ELEMENT cplusplus comment gt lt ATTLIST cplusplus body CDATA REQUIRED gt lt C type announcements gt lt ELEMENT struct decl comment gt lt JATTEGST struct d cl name NMTOKEN REQUIRED gt lt ELEMENT class decl comment gt lt ATTLIST class decl name NMTOKEN REQUIRED is cobject true false false xtends nam NMTOKEN IT MPLIED gt lt ELEMENT message decl comment gt lt ATTLIST message decl name NMTOKEN REQUIRED gt lt ELEMENT packet decl comment gt lt ATTLIST packet decl name NMTOKEN REQUIRED gt lt ELEMENT enum decl comment gt lt ATTLIST enum decl name NMTOKEN REQUIRED gt lt Enums gt lt ELEMENT enum comment enum fields gt lt ATTLIST enum name NMTOKEN REQUIRED http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual xtends nam NMTOKEN IMPL source code CDAT
3. beginning of a call to another module ME ModuleMethodEndEntry end of a call to another module MC ModuleCreatedEntry creating a module id int moduleltd id of the new module c string moduleClassName C class name of the module t string nedTypeName fully qualified NED type name pid int parentModuleId id of the parent module n string fullName full dotted hierarchic module name cm bool compoundModule false simple or compound module Module DeletedEntry deleting a module id 1nt ModuleReparentedEntry reparenting moduleId id of the module being deleted a module id int modulelId Lf Ud of the module being reparented new parent module module in which the gate was create 1 otherwise module in which the gate was created p int newParentModulelId id of the GC GateCreatedEntry gate created m int modulelId Hee g int gateld id of the new gate n string name gate name i int index 1 gate index if vector o bool isOutput input or output gate GD GateDeletedEntry gate deleted m int moduleld g int gateld id of the deleted gate ConnectionCreatedEntry creating a connection sm int sourceModuleId id of the source module identifying the connection sg int sourceGatelId id of the gate at the so
4. lt ELEMENT property decl comment property key property gt lt ATTLIST property decl name NMTOKEN REQUI RED is array true false lt ELEMENT extends comment gt lt ATTLIST extends false gt name CDATA RE QU lt ELEMENT interface nam comment gt http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual interfac parameters interfac types name parameters gates gt name submodules parameters gt lt ATTLIST interface nam name CDATA REQUIRED gt lt ELEMENT simple module comment extends gt lt ATTLIST simple module name NMTOKEN REQUIRED gt lt ELEMENT modul interfac comment extends lt ATTLIST modul interfac name NMTOKEN REQUIRED gt lt ELEMENT compound module comment extends parameters gates gt lt ATTLIST compound module name NMTOKEN REQUIRED gt lt ELEMENT chann interfac comment extends lt ATTLIST chann interfac name NMTOKEN REQUIRED gt lt ELEMENT channel comment extends inte
5. void Sink handleMessage cMessage msg endToEndDelayVec setName End to End Delay simtime_t eed simTime msg gt getCreationTime endToEndDelayVec record eed delete msg There is also a recordWithTimestamp method to make it possible to record values into output vectors with a timestamp other than simTime Increasing timestamp order is still enforced though All cOut Vector objects write to a single output vector file named omnetpp vec by default You can configure output vectors from omnetpp ini you can disable writing to the file or limit it to a certain simulation time interval for recording section 8 6 2 The format and processing of output vector files is described in section 11 1 2 If the output vector object is disabled or the simulation time is outside the specified interval record doesn t write anything to the output file However if you have a Tkenv inspector window open for the output vector object the values will be displayed there regardless of the state of the output vector object 6 8 2 Output scalars While output vectors are to record time series data and thus they typically record a large volume of data during a simulation run output scalars are supposed to record a single value per simulation run You can use output scalars e to record summary data at the end of the simulation run e to do several runs with different parameter settin
6. CE CancelEventEntry canceling an event caused by self messag id long messagelId id of the message being removed from the FES pe long previousEventNumber 1 event number from which the message being cancelled was sent or 1 if the message was sent from initialize BS BeginSendEntry beginning to send a message id long messagelId being sent tid long messageTreeld eid long messageEncapsulationlId encapsulation life time unique id of the message as etid long messageEncapsulationTreelId 1 id of the message inherited by both ee id of the message inherited by dup id of the message inherited by dup and encapsulation c string messageClassName n string messageFullName message nam pe long previousEventNumber 1 event number from which the message being sent was processed or 1 if the message has not yet been processed befor C class name of the message k short messageKind 0 message kind p short messagePriority 0 message priority l int64 messageLength 0 message length in bits er bool hasBitError false true indicates the message has bit errors d string detail NULL detailed information of message content when recording message data is turned on ES EndSendEntry prediction of the arrival of a message t simtime_t arrivalTime wh
7. The calliInitialize function performs the full multi stage initialization for that module and all its submodules If you do not redefine the multi stage initialization functions the default behavior is single stage initialization the default numInitStages returns 1 and the default initialize int stage simply calls initialize End of Simulation event The task of finish is solved in several simulators by introducing a special end of simulation event This is nota very good practice because the simulation programmer has to code the models often represented as FSMs so that they can always properly respond to end of simulation events in whichever state they are This often makes program code unnecessarily complicated This can also be witnessed in the design of the PARSEC simulation language UCLA Its predecessor Maisie used end of simulation events but as documented in the PARSEC manual this has led to awkward programming in many cases so for PARSEC end of simulation events were dropped in favour of finish called finalize in PARSEC 4 3 4 handleParameterChange http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The handleParameterChange method was added in OMNeT 3 2 and it gets called by the simulation kernel when a module parameter changes The method signature is the following void handleParameterChange const char parname The user can redefin
8. fifo u Cmdenv c Fifol OMNeT Discrete Event Simulation C 1992 2008 Andras Varga OpenSim Ltd Version 4 0 edition Academic Public License NOT FOR COMMERCIAL USE S the license for distribution terms and warranty disclaimer Setting up Cmdenv Loading NED files from 5 Preparing for running configuration Fitel sun 0 Scenario repetition 0 Assigned runID Fifol 0 20090104 12 23 25 5792 Setting up network FifoNet Ena ala zing Initializing modu FifoNet stage 0 Initializing modu Initializing modul FifoNet gen stage 0 FifoNet fifo stage 0 Initializing modul ooo oO FifoNet sink stage 0 Running simulation k k Event 1 T 0 Elapsed 0 000s Om 00s 0 completed Speed ev sec 0 simsec sec 0 v simsec 0 Messages created 2 present 2 in EES kk Event 232448 P O 05 10T4922336 Elapsed 2 003s Om 02s 3 completed Speed ev sec 116050 simsec sec 5850 75 ev simsec 19 8351 Messages created 58114 present 3 In BEES 2 x Event 7206882 T 360000 52066583684 Elapsed 78 282s 1m 18s 100 completed Speed ev sec 118860 simsec sec 5911 9 ev simsec 20 1053 Messages created 1801723 present 3 angie RES 2 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual lt gt Simulation time limit rea
9. The above calls write into the output scalar file which is named omnetpp sca by default The output scalar file is preserved across simulation runs unlike the output vector file which gets deleted at the beginning of every simulation run Data are always appended at the end of the file and output from different simulation runs are separated by special lines The format and processing of output vector files is described in section 6 8 3 Precision Output scalar and output vector files are text files and floating point values doubles are recorded into it using fprintf s g format The number of significant digits can be configured using the output scalar precision and output vector precision configuration entries see The default precision is 12 digits The following has to be considered when changing the default value IEEE 754 doubles are 64 bit numbers The mantissa is 52 bits which is roughly equivalent to 16 decimal places 52 log 2 log 10 However due to rounding errors usually only 12 14 digits are correct and the rest is pretty much random garbage which should be ignored However when you convert the decimal representation back into an IEEE 754 double as in Plove and Scalars an additional small error will occurs because 0 1 0 01 etc cannot be accurately represented in binary This conversion error is usually smaller than the one that the double variable already had before recording into the file however if
10. a gt gate out gt connectTo b gt gate in B gt gate outi SCommEecie lo a Searce Gimni connectTo also accepts a channel object as an additional optional argument Channels are subclassed from cChanne1l Almost always you ll want use an instance of cDatarateChannel as Channel this is the one that supports delay bit error rate and data rate The channel object will be owned by the source gate of the connection and you cannot reuse the same channel object with several connections cDatarateChannel has setDelay setBitErrorRate and setDatarate methods to set up the channel attributes An example that sets up a channel with a delay cDatarateChannel channel new cDatarateChannel Channel channel gt setDelay 0 001 a gt gate out gt connectTo b gt gate in channel a b are modules 4 11 7 Removing connections The disconnect method of cGate can be used to remove connections This method has to be invoked on the source side of the connection It also destroys the channel object associated with the connection if one has been set srcGate gt disconnect 5 Messages http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 5 1 Messages and packets 5 1 1 The cMessage class cMessage is acentral class in OMNeT Objects of cMessage and subclasses may model a number of things events messages packets frames c
11. probability 1 p lon m gt 3 P w They are the same functions that can be used in NED files intuniform generates integers including both the lower and upper limit so for example the outcome of tossing a coin could be written as intuniform 1 2 truncnormal is the normal distribution truncated to nonnegative values its implementation generates a number jo fe fa n a O 3 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual with normal distribution and if the result is negative it Keeps generating other numbers until the outcome is nonnegative If the above distributions do not suffice you can write your own functions If you register your functions with the Register_Function macro you can use them in NED files and ini files too 6 4 5 Random numbers from histograms You can also specify your distribution as a histogram The cLongHistogram cDoubleHistogram cVarHistogram cKSplit or cPSquare classes are there to generate random numbers from equidistant cell or equiprobable cell histograms This feature is documented later with the statistical classes 6 5 Container classes 6 5 1 Queue class cQueue Basic usage cQueue is a container class that acts as a queue cQueue can hold objects of type derived from cOwnedObject almost all classes from the OMNeT library such as cMessage cPar etc Internally cQueue uses a double linked list to store
12. urement label lt string gt default S iterationvars per run setting Identifies the measurement within the experiment This string gets recorded into result files and may be referred to during result analysis ect full path gt module eventlog recording lt bool gt default true per object ing Enables recording events on a per module basis This is meaningful for simple modules only Example xx router 10 20 module eventlog recording true xx module eventlog recording false path lt path gt global setting A semicolon separated list of directories The directories will be regarded as roots of the NED package hierarchy and all NED files will be loaded from their subdirectory trees This option is normally left empty as the opp IDE sets the NED path automatically and for simulations started outside the IDE it is more convenient to specify it via a command line option or the NEDPATH environment variable A ork lt string gt per run setting The name of the network to be simulated The package name can be omitted if the ini file is in the same directory as the NED file that contains the network rngs lt int gt default 1 per run setting The number of random number generators T ut scalar file lt filename gt d nnumber sca per run setting Na
13. virtual void processMsgFromHigherLayer cMessage packet virtual void processMsgFromLowerLayer FooPacket packet virtual void processTimer cMessage timer virtual void initialize virtual void handleMessage cMessage msg I void FooProtocol handleMessage cMessage msg if msg gt isSelfMessage processTimer msg else if msg gt arrivedOn fromNetw processMsgFromLowerLayer check_and_cast lt FooPacket gt msg else processMsgFromHigherLayer msg The functions processMsgFromHigherLayer processMsgFromLowerLayer and processTimer are then usually split further there are separate methods to process separate packet types and separate timers Example 2 Simple traffic generators and sinks The code for simple packet generators and sinks programmed with handleMessage might be as simple as the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual following pseoudocode PacketGenerator handleMessage msg create and send out a new packet schedule msg again to trigger next call to handleMessage PacketSink handleMessage msg delete msg Note that PacketGenerator will need to redefine initialize to create m and schedule the first event The following simple module generates packets with exponential inter arrival time Some details in the source haven t bee
14. Ident is either a parameter reference or an identifier for sizeof operator format is name or module name or module n name If there s a child that s the module index n gt lt ELEMENT ident comment operator function ident literal gt lt ATTLIST ident module CDATA IMPLIED http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual name NMTOKEN REQUIRED gt lt ELEMENT literal comment gt lt Note value is in fact REQUIRED but empty attr value should also be accepted because that represents the string literal spec is for properties to store the null value and the antivalue Unit can only be present with double gt lt IATTLIST literal type double int string bool spec REQUIRED unit CDATA IMPLIED text CDATA IMPLIED value CDATA IMPLIED gt lt 1 AHA KKK KKK KKK KK KK KK KK KK KK KKK KK KK KK KKK KK KKK KKK KK KK KK KK KK KK KK KKK KK KK KKK KK KKK D gt Sl k k OMNeT OMNEST Message Definitions MSG k gt lt ELEMENT msg file comment namespace property decl property cplusplus struct decl class decl message decl packet decl enum decl struct class message packet enum gt lt ATTLIST msg file filename CDATA TMPLIED version CDATA T
15. http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Setting a module s position icon and status icon eDisplayscring CliisoSere CecDuisjollaySieieimeE h y dispStr gt parse p 40 20 i device cellphone i2 status disconnect NOTE The connection display string is stored in the channel object but it can also be accessed via the source gate of the connection Id Betting an outgoing connection s color to red cDisplayString gateDispStr gate out gt getDisplayString dispStr gt parse l1s red NOTE In OMNeT 3 x to manipulate the appearance of a compound module you had to use the backgroundDisplayString method This method is no longer supported in OMNeT 4 0 because there is no separate background display string Use the getDisplayString method instead with the background specific tags i e those starting with bg Setting module background and grid with background display string tags cDisplayString parentDispStr getParentModule gt getDisplayString parentDispStr gt parse bgi maps europe bgg 100 2 As far aS cDisplayString is concerned a display string e g p 100 125 i cloud is a string that consist of several tags separated by semicolons and each tag has a name and after an equal sign zero or more arguments separated by commas The class facilitates tasks such as finding out what tags a display str
16. lt object full path gt rng lt int gt per object setting Maps a module local RNG to one of the global RNGs Example gen rng 1 3 maps the local RNG 1 of modules matching gen to the global RNG 3 The default is one to one mapping rng class lt string gt default cMersenneTwister per run setting The random number generator class to be used It can be cMersenneTwister cLCG32 cAkaroaRNG or you can use your own RNG class it must be subclassed from cCRNG runnumber width lt int gt default 0 per run setting Setting a nonzero value will cause the Srunnumber variable to get padded http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual with leading zeroes to the given length lt object full path gt scalar recording lt bool gt default true per object setting Whether the matching output scalars should be recorded Syntax lt module full path gt lt scalar name gt scalar recording true false Example queue packetsDropped scalar recording true scheduler class lt string gt default cSequentialScheduler global setting Part of the Envir plugin mechanism selects the scheduler class This plugin interface allows for implementing real time hardware in the loop distributed and distributed parallel simulation The class has to implement the cScheduler interface seed lcg32 lt int gt per run set
17. removeOb ject methods use the object name as the key to the array An example cLongHistogram pklenDistr new cLongHistogram pklenDistr msg gt addObject pklenDistr fe if msg gt hasObject pklenDistr cLongHistogram pklenDistr cLongHistogram msg gt getObject pklenDistr You should take care that names of the attached objects do not clash with each other or with cMsgPar parameter names see next section If you do not attach anything to the message and do not call the getParList function the internal cArray object will not be created This saves both storage and execution time You can attach non object types or non cOwnedOb ject objects to the message by using cMsgPar s void pointer P type see later in the description of cMsgPar An example Struc Commis ecoimin new Commits COMME 1S a Stuer msg gt addPar conn voici Gomis mso par conn configPointer NULL NULL sizeof struct conn_t Attaching parameters The preferred way of extending messages with new data fields is to use message definitions See section 5 2 The old deprecated way of adding new fields to messages is via attaching cMsgPar objects There are several downsides of this approach the worst being large memory and execution time overhead cMsgPar s are heavy weight and fairly complex objects themselves It has been reported that using cMsgPar mes
18. 24 10 Statistics Object Represents a statistics object Syntax statistic moduleName statisticName Example Sceciscile Alona server Wecollisiomn mileciplieity A statistic line may be followed by field and attribute lines and a series of bin lines that represent histogram data OMNeT uses the following attributes unit measurement unit e g s for seconds e isDiscrete boolean 0 or 1 meaning whether observations are integers A full example with fields attributes and histogram bins Siceciscile Aloing seiver Ve lilasiem imullesjoiliemey ciellel coume 1S SOs field mean 6 8510209951107 field stddev 5 2385484477843 field sum 95284 field sqrsum 1034434 ialSilel min 2 Lele meaz 65 attr isDiscrete 1 arti wale packers OLM INF 0 bin 0 5 0 bin 0 5 0 bin IRS 2254 bin 2s 5 2047 bin 35 1586 bin Al 5 1428 bin 575 LLO DLM 6 5 952 bin 75 785 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual bin 51 5 2 24 11 Field Represents a field in a statistics object Syntax field fieldName value Example field sum 95284 Fields e count observation count mean mean of the observations e stddev standard deviation e sum sum of the observations e sqrsum sum of the squared observations e min minimum of the observations e max maximum of the observations For weighted statistics additionally the foll
19. The getName method of cGate returns the name of the gate or gate vector If you need a string that contains the gate index as well getFullName is what you want If you also want to include the hierarchical name of the owner module call getFullPath The getType method of cGate returns the gate type either cGate INPUT or cGate OUTPUT It cannot return cGate INOUT because an inout gate is represented by a pair of cGates The isVector get Index getVectorSize getId method names speak for themselves size is an alias to getVectorSize The getOwnerModule method returns the module the gate object belongs to To illustrate these methods we expand the gate iterator example to print some information about each gate for cModule GatelIterator i this i end it cGate gate i ey lt lt Gace SoecrullNneme lt lt Ws W ev lt lt id lt lt gate gt getId lt lt if gate gt isVector ev lt lt scalar gate gt else ev lt lt gate lt lt gate gt getIndex lt lt in vector lt lt gate gt getName lt lt A Oh SA Se Se hbl Tae xe 10h Touro h aren iy A m 0 Gr ev lt lt type lt lt cGate getTypeName gate gt getType ew lt lt Tnt There are further cGate methods to access and manipulate the connection s attached to the gate they will be covered in the following sections
20. amp UMIN Pe ee dal 3 enumvalue INTCONSTANT INTCONSTANT NAME J quantity quantity INTCONSTANT NAME quantity REALCONSTANT NAME INTCONSTANT NAME http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual REALCONSTANT NAME pi property property_namevalue J property_namevalue property_name property_name opt_property_keys 3 property name NAME NAME T NAME J opt_property_keys property_keys J property_keys property_keys property_key property_key J property_key NAME property_values property_values J property_values property_values property_value property_value 3 property_value NAME NAME STRINGCONSTANT TRUE FALSE INTCONSTANT REALCONSTANT quantity http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual J opt_fieldsblock_old FIELDS opt_fields_old J opt_fields_old fields old 3 fields old fields_old field field J opt_propertiesblock_old PROPERTIES opt_properties_old 3 opt_properties_old properties_old 3 properties_old properties old property_old property_old H property_old NAME property_value 3 opt_semicolon http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 22 Appendix Display St
21. delete sim deletes env as well The function accepts a network type name which must be fully qualified i e with package name and a simulation time limit In the first few lines we look up the network name among the modules that have been loaded from NED files and print an error message if not found Then we need to create and activate a simulation manager object cSimulation The simulation manager needs an environment object to take the configuration from write simulation results to and so on The environment object CustomSimulationEnv in the above code has to be provided by the programmer this is discussed in detail ina later section NOTE Before the 4 0 version simulation and ev were global variables now they are macros that resolve to cSimulation getActiveSimulation and cSimulation getActiveSimulation gt getEnvir Then we set up the network in the simulation manager The sim gt setupNetwork method creates the system module and recursively all modules and their interconnections module parameters are also read from the configuration where needed and assigned If there is an error e g module type not found an exception will be thrown The exception object is some kind of std exception usually a cRuntimeError If network setup was successful we call sim gt startRun one side effect of which is that the initialize methods of modules and channels get invoked This step als
22. host generationInterval exponential 0 2 0 4 0 6 s The syntax specifies an iteration It is sort of a macro at each run the whole string gets textually replaced with the current iteration value The values to iterate over do not need to be numbers unless you want to use the a b or a b step c syntax and the substitution takes place even inside string constants So the following examples are all valid note that textual substitution is used x param 1 1 677 37 Sin 0 5 gt param le 6 param 1 3 param L sian 0 5 greeting We will simulate 1 2 5 host s gt greeting We will simulate 1 host s greeting We will simulate 2 host s greeting We will simulate 5 host s To write a literal inside a string constant quote with a backslash and write 8 5 2 Named iteration variables You can assign names to iteration variables which has the advantage that you ll see meaningful names instead of 0 and 1 in the Cmdenv output and also lets you refer to the variables at more than one place in the ini file The http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual syntax is lt varname gt lt iteration gt and variables can be referred to simply as lt varname gt Config Aloha x numHosts S N i 2 Shes Osteo 10 host generationInterval
23. http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Messages are described in detail in chapter 5 At this point all we need to know about them is that they are referred to as cMessage pointers Message objects can be given descriptive names a const char string that often helps in debugging the simulation The message name string can be specified in the constructor so it should not surprise you if you see something like new cMessage token in the examples below 4 6 1 Sending messages Once created a message object can be sent through an output gate using one of the following functions send cMessage msg const char gateName int index 0 send cMessage msg int gateld send cMessage msg cGate gate In the first function the argument gateName is the name of the gate the message has to be sent through If this gate is a vector gate index determines though which particular output gate this has to be done otherwise the index argument is not needed The second and third functions use the gate Id and the pointer to the gate object They are faster than the first one because they don t have to search through the gate array Examples send msg outGate send msg outGates i send via outGates i The following code example creates and sends messages every 5 simulated seconds int outGateId findGate outGate while true send new cMessage job outGat
24. lt multicol gt lt ol gt lt p gt lt small gt lt span gt lt strong gt lt sub gt lt sup gt lt table gt lt td gt lt th gt lt tr gt lt tt gt lt kbd gt lt ul gt lt var gt Any tags not in the above list will not be interpreted as formatting commands but will be printed verbatim for example lt what gt bar lt what gt will be rendered literally as lt what gt bar lt what gt unlike HTML where unknown tags are simply ignored i e HTML would display bar If you insert links to external pages web sites its useful to add the target _blank attribute to ensure pages come up in a new browser window and not just in the current frame which looks awkward Alternatively you can use the target _top attribute which replaces all frames in the current browser Examples For more info on Ethernet and other LAN standards see the lt a href http www ieee802 org target _blank gt IEEE 802 Committee s site lt a gt Jd You can also use the lt a href gt tag to create links within the page See the lt a href resources gt resources lt a gt in this page lt a name resources gt lt b gt Resournces lt b gt lt a gt SS SS SESS SSS SS You can use the lt pre gt lt pre gt HTML tag to insert source code examples into the documentation Line breaks and indentation will be preserved but HTML tags continue to be interpreted or you c
25. yes topo extractByParameter includeInTopo amp yes The third form allows you to pass a function which can determine for each module whether it should or should not http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual be included You can have cTopology pass supplemental data to the function through a void pointer An example which selects all top level modules and does not use the void pointer int selectFunction cModule mod void return mod gt getParentModule simulation getSystemModule topo extractFromNetwork selectFunction NULL A cTopology object uses two types cTopology Node for nodes and cTopology Link for edges sTopoLinkIn and cTopology LinkOut are aliases for cTopology Link we ll talk about them later Once you have the topology extracted you can start exploring it Consider the following code we ll explain it shortly for int i 0 i lt topo getNumNodes i cTopology Node node topo getNode i ev lt lt Node i lt lt i lt lt is lt lt node gt getModule gt getFullPath lt lt endl ey lt lt It mas T lt lt node getNumOutLinks lt lt T conns to other mocles in 5 ev lt lt and lt lt node gt getNumInLinks lt lt conns from other nodes n ev lt lt Connections to other modules are n for int j 0 j lt node gt getNumOutLinks
26. Returns a random number from the Geometric distribution e intuniform long intuniform long a long b long rng Returns a random number from the Intuniform distribution e negbinomial long negbinomial long n double p long rng Returns a random number from the Negbinomial distribution e poisson long poisson double lambda long rng Returns a random number from the Poisson distribution Category strings e choose string choose long index string list Interprets list as a space separated list and returns the item at the given index Negative and out of bounds indices http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Cause an error e contains bool contains string s string substr Returns true if string s contains substr as substring e endsWith bool endsWith string s string substr Returns true if s ends with the substring substr e indexOf Long indexOf string s string substr Returns the position of the first occurrence of substring substr in s or 1 if s does not contain substr e length Long length string s Returns the length of the string e replace string replace string s string substr string repl long startPos Replaces all occurrences of substr in s with the string repl If startPos is given search begins from position startPos ins e replaceFirst string replaceFirst string s string substr string repl long startPos Repla
27. The simulator as well as user interfaces and tools are highly portable They are tested on the most common operating systems Linux Mac OS X Windows and they can be compiled out of the box or after trivial modifications on most Unix like operating systems OMNeT also supports parallel distributed simulation OMNeT can use several mechanisms for communication between partitions of a parallel distributed simulation for example MPI or named pipes The parallel simulation algorithm can easily be extended or new ones plugged in Models do not need any special instrumentation to be run in parallel it is just a matter of configuration OMNeT can even be used for classroom presentation of parallel simulation algorithms because simulations can be run in parallel even under the GUI which provides detailed feedback on what is going on OMNEST is the commercially supported version of OMNeT OMNeT is only free for academic and non profit use for commercial purposes one needs to obtain OMNEST licenses from Simulcraft Inc 1 2 Organization of this manual The manual is organized the following way e The chapters 1 and 2 contain introductory material e The second group of chapters 3 4 and 6 are the programming guide They present the NED language the simulation concepts and their implementation in OMNeT explain how to write simple modules and describe the class library e The chapters 10 and 13 elaborate the topic furth
28. e Normal non express mode is for debugging detailed information will be written to the standard output event banners module output etc Express mode can be used for long simulation runs only periodical status update is displayed about the progress of the simulation cmdenv performance display affects express mode only it controls whether to print performance information Turning it on results in a 3 line entry printed on each update containing ev sec simsec sec ev simsec number of messages created still present currently scheduled in FES For a full list of options see the ones beginning with cmdenv in Appendix 23 9 2 4 Interpreting Cmdenv output When the simulation is running in express mode with detailed performance display enabled Cmdenv periodically outputs a three line status info about the progress of the simulation The output looks like this xx Event 250000 T 123 74354 2m 3s Elapsed Om 12s Speed ev sec 19731 6 simsec sec 9 80713 ev simsec 2011 97 Messages created 55532 present 6553 in FES 8 xx Event 300000 T 148 55496 2m 28s Elapsed Om 15s Speed ev sec 19584 8 simsec sec 9 64698 ev simsec 2030 15 Messages created 66605 present 7815 im EFES 7 The first line of the status display beginning with contains e how many events have been processed so far http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual e the cur
29. exponential mean 0 2 0 4 0 6 s xx greeting There are N hosts The scope of the variable name is the section that defines it plus sections based on that section via extends There are also a number of predefined variables configname and runnumber with the obvious meanings network is the name of the network that is simulated processid and datetime expand to the OS process id of the simulation and the time it was started and there are some more runid iterationvars and repetition runid holds the Run ID When a simulation is run it gets assigned a Run ID which uniquely identifies that instance of running the simulation if you run the same thing again it will get a different Run ID Run ID isa concatenation of several variables like configname runnumber datetime and processid This yields an identifier that is unique enough for all practical purposes yet it is meaningful for humans The Run ID is recorded into result files written during the simulation and can be used to match vectors and scalars written by the same simulation run In cases when not all combinations of the iteration variables make sense or need to be simulated it is possible to specify an additional constraint expression This expression is interpreted as a conditional an if statement within the innermost loop and it must evaluate to true for the variable combination to generate a run The expression sho
30. omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The unit property of a parameter cannot be added or overridden in subclasses or in submodule declarations XML parameters Sometimes modules need more complex input than simple module parameters can describe Then you d put these parameters into an external config file and let the modules read and process the file You d pass the file name to the modules in a string parameter These days XML is increasingly becoming a standard format for configuration files as well so you might as well describe your configuration in XML From the 3 0 version OMNeT contains built in support for XML config files OMNeT wraps the XML parser LioXML Expat etc reads and DTD validates the file if the XML document contains a DOCTYPE caches the file so that if you refer to it from several modules it ll still be loaded only once lets you pick parts of the document via an XPath subset notation and presents the contents to you in a DOM like object tree This machinery can be accessed via the NED parameter type xm1 and the xmldoc operator You can point xm1 type module parameters to a specific XML file or to an element inside an XML file via the xmldoc operator You can assign xml parameters both from NED and from omnetpp ini The following example declares an xm1 parameter and assigns an XML file to it simple TrafGen parameters xml profile gatesi QUlcjo
31. stack kb amount for Cmdenv Tkenv which makes about 16K with Cmdenv and about 48K when using Tkenv Unfortunately the CreateFiber Win32 API doesn t allow the RSS to be specified The more advanced CreateFiberEx API which accepts RSS as parameter is unfortunately only available from Windows XP The alternative is the stacksize parameter stored in the EXE header which can be set via the STACKSIZE def file parameter via the stack linker option or on an existing executable using the editbin stack utility This parameter specifies a common RSS for the main program stack fiber and thread stacks 64K should be enough This is the way simulation executable should be created linked with the stack 65536 option or the stack 65536 parameter applied using editbin later For example after applying the editbin stacksize 65536 command to dyna exe was able to successfully run the Dyna sample with 8000 Client modules on my Win2K PC with 256M RAM that means about 12000 modules at runtime including about 4000 dynamically created modules Segmentation fault On Unix if you set the total stack size higher you may get a segmentation fault during network setup or during execution if you use dynamically created modules for exceeding the operating system limit for maximum stack size For example in Linux 2 4 x the default stack limit is 8192K that is 8MB The ulimit shell command can be used to modify the resource limits and you can raise
32. where various problems with the simulation model can manifest as exceptions void simulate const char networkName simtime_t limit look up network type cModuleType networkType cModuleType find networkName if networkType NULL printf No such network s n networkName TETEA create a simulation manager and an environment for the simulation cEnvir env new CustomSimulationEnv argc argv new EmptyConfig cSimulation sim new cSimulation Simulation env cSimulation setActiveSimulation sim set up network and prepare for running it sim gt setupNetwork networkType E sim gt startRun E Il ron the Saimuleeaom bool ok true tey while sim gt getSimTime lt limit cSimpleModule mod sim gt selectNextModule E iLic limm e break sim gt doOneEvent mod MIATA printi rinished time limit reachedin catch cTerminationException amp e printi Finished s n e what catch std exception e ok false printi TERROR Ss in Sa winatc iit Ol http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual simulation callFinish ye finish the simulation and clean up the network sim gt endRun Vint sim gt deleteNetwork V7 ta Cl cSimulation setActiveSimulation NULL
33. 3 2 3 The App Routing and Queue simple modules Simple modules are the basic building blocks for other compound modules All active behavior in the model is encapsulated in simple modules Behavior is defined with a C class NED files only declare the externally visible interface of the module gates parameters In our example we could define Node as a simple module However its functionality is quite complex traffic generation routing etc so it is better to implement it with several smaller simple module types which we are going to assemble into a compound module We ll have one simple module for traffic generation App one for routing Routing and one for queueing up packets to be sent out Queue For brevity we omit the bodies of the latter two in the code below simple App i http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual paromet ensk int destAddress display i block browser gatesi Loote Line QUE OUE oie simple Routing simple Queue i By convention the above simple module declarations go into the App ned Routing ned and Queue ned files NOTE Note that module type names App Routing Queue begin with a capital letter and parameter and gate names begin with lowercase this is the recommended naming convention Capitalization matters because the language is case sensitive Let us see the first simple module type declaration Ap
34. 36ms Src 4 Dest 3 O gt 1 cMessage Tarr 0 0370745702 37ms Src 4 Dest 3 Q gt 2 cMessage Tarr 0 0387984129 38ms Src 4 Dest 3 0 gt 1 cMessage Tarr 0 0457462493 45ms Src 4 Dest 3 0 gt 2 cMessage Tarr 0 0487308918 48ms Src 4 Dest 3 0 gt 2 cMessage Tarr 0 0514466766 5lms Src 4 Dest 3 end cMessage token comp 0 mac local objects send queue 0 gt 1 begin 4 gt 3 sent 0 OL5EL05774 15m arnrriyecls 0 0L156105774 15m8 length 33536 kind 0 prioriltys 0 error FALSE time stamp 0 0000000 0 008 parameter list dest egens I il source Ge Baltes Ome Gln gentime SP alia 0 01561L106 D end laso It is possible that the format of the snapshot file will change to XML in future OMNeT releases 6 9 6 Getting coroutine stack usage It is important to choose the correct stack size for modules If the stack is too large it unnecessarily consumes memory if it is too small stack violation occurs From the Feb99 release OMNeT contains a mechanism that detects stack overflows It checks the intactness of a predefined byte pattern 0xdeadbeef at the stack boundary and reports stack violation if it was overwritten The mechanism usually works fine but occasionally it can be fooled by large and not fully used local variables e g char buffer 256 if the byte pattern happens to fall in the middle of such a local variable it may be preserved intact and OMNeT does not dete
35. 4 5 2 Connections Simple module gates have normally one connection attached Compound module gates however need to be connected both inside and outside of the module to be useful A series of connections joined with compound http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual module gates is called a path A path is directed and it normally starts at an output gate of a simple module ends at an input gate of a simple module and passes through several compound module gates Every cGate object contains pointers to the previous gate and the next gate in the path returned by the getPreviousGate and getNextGate methods so a path can be thought of as a double linked list The use of the previous gate next gate pointers with various gate types is illustrated on figure below next prev next a b meee next prev c d Figure a simple module output gate b compound module output gate c simple module input gate d compound module input gate The start and end gates of the path can be found with the getPathStartGate and getPathEndGate methods which simply follow the previous gate next gate pointers until they return NULL The isConnectedOutside and isConnectedInside methods return whether a gate is connected on the outside or on the inside They examine either the from or the to pointer depending on the gate type input or output Again see figure be
36. So suffix and returns the same number The hasGate method may be used both with and without an index and they mean two different things without an index it tells the existence of a gate vector with the given name regardless of its size it returns t rue for an existing vector even if its size is currently zero with an index it also examines whether the index is within the bounds Gate IDs A gate can also be accessed by its ID A very important property of gate IDs is that the D of gate k in a gate vector equals the ID of gate 0 plus the index This allows you to efficiently access any gate in a gate vector because retrieving a gate by ID is more efficient than by name and index The index of the first gate can be obtained with gate out 0 gt getId but it is better to use a dedicated method gateBaselId which also works if the gate size is zero Two further important properties of gate IDs they are stable and unique within the module By stable we mean that the ID of a gate never changes and by unique we not only mean that at any given time no two gates have the same IDs but also that IDs of deleted gates do not get reused later so gate IDs are unique in the lifetime of a simulation run NOTE Earlier versions of OMNeT did not have these guarantees resizing a gate vector could cause its ID range to be relocated if it would have overlapped with the ID range of other gate vectors OMNeT 4 0 solves
37. The OMNeT simulation kernel is not reentrant so it must be protected against concurrent access S fddi h opp Discrete Event Simulation C 1992 2004 Andras Varga Available networks DI1 al FD NRI TU TU ilable modules DDI_MAC DDI_MAC4Ring Available channels End run of opp Define Module FIFO o o9 static cModule FIFO_create const char name cModule parentmod return new FIFO name parentmod BXECUTE_ON_STARTUP FIFO__mod modtypes getInstance gt add new cModul leType FIFO FIFO ModuleCreateFunc FIFO__create cEnvir ev 17 Appendix NED Reference o o9 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 17 1 Syntax 17 1 1 NED file extension NED files have the ned file name suffix This is mandatory and cannot be overridden 17 1 2 NED file encoding NED files are read as 8 bit clean ASCII This permits NED files saved in UTF 8 or any character set compatible with ASCII 8859 1 etc NOTE There is no official way to determine the encoding of a NED file It is up to the user to configure the correct encoding in text editors and other tools that are used to edit or process NED files Keywords and other syntactic elements in NED are ASCII and identifiers must be ASCII as well Comments and string literals may contain characters above 127 String literals e g in param
38. and activity implement different event processing strategies for each simple module the user has to redefine exactly one of these functions handleMessage is a method that is called by the simulation kernel when the module receives a message http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual activity is a coroutine based solution which implements the process interaction approach coroutines are non preemptive i e cooperative threads Generally it is recommended that you prefer handleMessage to activity mainly because activity doesn t scale well Later in this chapter we ll discuss both methods including their advantages and disadvantages Modules written with activity and handleMessage can be freely mixed within a simulation model The finish functions are called when the simulation terminates successfully The most typical use of finish is the recording of statistics collected during simulation 4 1 4 Events in OMNeT OMNeT uses messages to represent events Each event is represented by an instance of the cMessage class or one its subclasses there is no separate event class Messages are sent from one module to another this means that the place where the event will occur is the message s destination module and the model time when the event occurs is the arrival time of the message Events like timeout expired are implemented by the module sending a message
39. but they are normally of little interest for users 4 4 4 Emulating parameter arrays As of version 4 0 OMNeT does not support parameter arrays but in practice they can be emulated using string parameters One can assign the parameter a string which contains all values in a textual form for example 0 1 234 3 95 5 467 then parse this string in the simple module The cStringTokenizer Class can be quite useful for this purpose The constructor accepts a string which it regards as a sequence of tokens words separated by delimiter characters by default spaces Then you can either enumerate the tokens and process them one by one hasMoreTokens next Token or use one of the cStringTokenizer convenience methods to convert them into a vector of strings asVector integers asIntVector Or doubles asDoubleVector The latter methods can be used like this const char vstr par v stringValue S g aa bO co std e vector lt stak string v cStringTokenizer vstr asVector and Const ehar sii W3d dz is 486 72 sive std SWSCEOr lt iliMe gt W CSG lOKkemizSr aASslimc Vee Cie 2 Const Ces sci YO 4311 0 7402 O 71345 std vector lt double gt v cStringTokenizer asDoubleVector The following example processes the string by enumerating the tokens const char str 3 25 1 83 34 x 19 607 imput std vector lt double gt result cStringTokenizer tokeniz
40. i block queue red 60 network SimpleQueue submodules submod Derived daspllay 1 yellow p 273 101 r 70 77 gt i block queue yellow p 273 101 r 70 10 1 4 Display string tags used in submodule context The following tags define how a module appears on the Tkenv user interface if it is used as a submodule b shapes colors i icon is icon size http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual i2 alternate status icon placed at the upper right corner of the main icon e p positioning and layouting e r range indicator e q queue information text e t text e tt tooltip Icons By default modules are represented by simple icons Using images for the modules is possible with the i tag See the images subfolder of your OMNeT installation for possible icons The stock images installed with OMNeT have several size variants Most of them have very small vs small s large I and very large vl variants You can specify which variant you want to use with the is tag adisplay 1i block source is 1 a large source icon from the block icons group Sometimes you want to have similar icons for modules but would like to make them look a little different to create groups or to reflect status information about the module You can easily change the color of an already existing image The following example colorizes
41. iclailis 5 module gt buildiInside create activation message modul gt scheduleStart simTime If you want to set up parameter values or gate vector sizes Step 3 the code goes between the create and buildInside calls create cModuleType moduleType cModuleType get WirelessNode cModule module moduleTyp Sereace Vinoce tlaals 5 set up parameters and gate sizes before we set up its submodules module gt par address lastAddress modul SserGacteSize Vain 3 module Sseteate Sue7es VO mia S n ld create internals and schedule it module gt buildiInside modul gt scheduleStart simTime 4 11 4 Deleting modules To delete a module dynamically module gt deleteModule If the module was a compound module this involves recursively destroying all its submodules A simple module can also delete itself in this case the deleteModule call does not return to the caller Currently you cannot safely delete a compound module from a simple module in it you must delegate the job to a module outside the compound module 4 11 5 Module deletion and finish When you delete a module during simulation its finish function is not called automatically delet eModule doesn t do it How the module was created doesn t play any role here finish gets called for all modules at the end of the simulation If a module doesn t li
42. ie to all connected modules For example the send and scheduleAt functions check that the message being sent scheduled must is owned by the module If it is not then it signals a programming error the message is probably owned by another module already sent earlier or currently scheduled or inside a queue a message or some other object in either case the module does not have any authority over it When you get the error message not owner of object you need to carefully examine the error message which object has the ownership of the message why s that and then probably you ll need to fix the logic somewhere in your program The above errors are easy to make in the code and if not detected automatically they could cause random crashes which are usually very difficult to track down Of course some errors of the same kind still cannot be detected automatically like calling member functions of a message object which has been sent to and so currently kept by another module 6 11 2 Managing ownership Ownership is managed transparently for the user but this mechanism has to be supported by the participating classes themselves It will be useful to look inside cQueue and cArray because they might give you a hint what behavior you need to implement when you want to use non OMNeT container classes to store messages or other cOwnedOb ject based objects Insertion cArray and cQueue have internal data structures array a
43. loadNedSourceFolder bardir cSimulation doneLoadingNedFiles cun two simulations simulate FooNetwork 1000 Simi lece UiBeieNeicwworclk lt 2000 5 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual return O The first few lines of the code initialize the simulation library The purpose of cStaticFlag is to set a global variable to t rue for the duration of the main function to help the simulation library handle exceptions correctly in extreme cases ExecuteOnStartup executeAll does various startup tasks such as building registration tables out of the Define_Module Register_Class and similar entries throughout the code SimTime setScaleExp 12 sets simulation time resolution to picoseconds other values can be used as well but it is mandatory to choose one NOTE It is not allowed to change the simulation time exponent later because as the exponent is a global variable existing simt ime_t instances would change their values The code then loads the NED files from the foodir and bardir subdirectories of the working directory as if the NED path was foodir bardir and goes on to run two simulations 16 2 2 The simulate function A minimalistic version of the simulate function is shown below For conciseness we omitted exception handling code try catch blocks except for the event loop but marked every line with E
44. lt string gt per object setting Specifies type for submodules and channels declared with like lt gt user interface lt string gt global setting Selects the user interface to be started Possible values are Cmdenv and Tkenv This option is normally left empty as it is more convenient to specify the user interface via a command line option or the IDE s Run and Debug dialogs lt object full path gt vector max buffered values lt int gt per object setting For output vectors the maximum number of values to buffer per vector before writing out a block into the output vector file The default is no per vector limit ise only the total memory limit is an CL eece lt object full path gt vector record eventnumbers lt bool gt default true per object setting Whether to record event numbers for an output vector Simulation time and value are always recorded Event numbers are needed by the Sequence Chart Tool for example ie lt object full path gt vector recording lt bool gt default true per object setting Whether data written into an output vector should be recorded lt object full path gt vector recording interval lt custom gt per object setting Recording interval s for an output vector Syntax lt from gt lt to gt That is both start and end of an interval are optional and int
45. so they can be referred to during result analysis WARNING If an iteration variable has non numeric value it will not be recorded automatically and cannot be used during analysis This can happen unintentionally if you specify units inside an iteration variable list NEVER USE host generationInterval exponential S mean 0 2s 0 4s 0 6s INSTEAD Specify the unit outside of the variable host generationInterval exponential S mean 0 2 0 4 0 6 s Module parameters can also be saved but this has to be requested by the user by configuring save as scalar true for the parameters in question The configuration key is a pattern that identifies the parameter plus save as scalar An example AMNS e ene vork ioaad Siav e Salsa Scalia Ere This looks simple enough However there are three pitfalls non numeric parameters too many matching parameters and random valued volatile parameters First the scalar file only holds numeric results so non numeric parameters cannot be recorded that will result in a runtime error Second if wildcards in the pattern match too many parameters that might unnecessarily increase the size of the scalar file For example if the host module vector size is 1000 in the example below then the same value 3 will be saved 1000 times into the scalar file once for each host x host startlame 3 host startTime save as scalar true sav
46. 17 5 4 The sizeof operator 17 5 5 The xmldoc operator 17 5 6 Functions 17 5 7 Units of measurement 18 Appendix NED Language Grammar 19 Appendix NED XML Binding 20 Appendix NED Functions 21 Appendix Message Definitions Grammar 22 Appendix Display String Tags 22 1 Module and connection display string tags 22 2 Message display string tags 23 Appendix Configuration Options 23 1 Configuration Options 23 2 Predefined Configuration Variables 24 Appendix Result File Formats 24 1 Version 24 2 Run Declaration 24 3 Attributes 24 4 Module Parameters 24 5 Scalar Data 24 6 Vector Declaration 24 7 Vector Data 24 8 Index Header 24 9 Index Data 24 10 Statistics Object 24 11 Field 24 12 Histogram Bin 25 Appendix Eventlog File Format 1 Introduction 1 1 What is OMNeT OMNeT is an object oriented modular discrete event network simulation framework It has a generic architecture so it can be and has been used in various problem domains e modeling of wired and wireless communication networks e protocol modeling e modeling of queueing networks e modeling of multiprocessors and other distributed hardware systems http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual e validating of hardware architectures e evaluating performance aspects of complex software systems e and in general it can be used for the modeling and simulation of any system where the discrete event
47. 2 3 Recording Modules 12 2 4 Recording Message Data 12 3 Eventlog Tool 12 3 1 Filter 12 3 2 Echo 13 Documenting NED and Messages 13 1 Overview 13 2 Documentation comments 13 2 1 Private comments 13 2 2 More on comment placement 13 3 Text layout and formatting 13 3 1 Paragraphs and lists 13 3 2 Special tags 13 3 3 Text formatting using HTML 13 3 4 Escaping HTML tags 13 4 Customizing and adding pages 13 4 1 Adding a custom title page 13 4 2 Adding extra pages 13 4 3 Incorporating externally created pages 14 Parallel Distributed Simulation 14 1 Introduction to Parallel Discrete Event Simulation 14 2 Assessing available parallelism in a simulation model 14 3 Parallel distributed simulation support in OMNeT 14 3 1 Overview 14 3 2 Parallel Simulation Example 14 3 3 Placeholder modules proxy gates 14 3 4 Configuration 14 3 5 Design of PDES Support in OMNeT 15 Plug in Extensions 15 1 Overview 15 2 Plug in descriptions 15 2 1 Defining a new random number generator 15 2 2 Defining a new scheduler 15 2 3 Defining a new configuration provider 15 2 4 Defining a new output scalar manager 15 2 5 Defining a new output vector manager 15 2 6 Defining a new snapshot manager 15 3 Accessing the configuration 15 3 1 Defining new configuration options 15 3 2 Reading values from the configuration 15 4 Implementing a new user interface http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 16 Embedding the S
48. 20 20 32 29 OMNeT Manual This code looks up the the parameter by name every time This lookup can be spared by storing the parameter object s pointer in a class variable resulting in the following code class Source public cSimpleModule protected Raie silimee iewvel las virec al yore wimslicaallaZe hs virtual void handleMessage cMessage msg WOLGl SOUTOSSs mmie Laila ZS intervalp amp par interval void Source handleMessage cMessage msg scheduleAt SimTime intervalp gt doubleValue timerMsg 4 4 2 Changing a parameter s value Parameter values can be changed from the program during execution This is rarely needed but may be useful for some scenarios NOTE The parameter s type cannot be changed at runtime it must remain the type declared in the NED file It is also not possible to add or remove module parameters at runtime The methods to set the parameter value are setBoolValue setLongValue setStringValue setDoubleValue setXMLValue There are also overloaded assignment operators for various types including bool int long double const char and cXMLElement To let a module get notified about parameter changes override its handleParameterChange method see 4 4 3 Further cPar methods The parameter s name and type are returned by the getName and getType methods The latter returns a
49. 2009 4 20 20 32 29 OMNeT Manual The cMessage constructor accepts further arguments too ength priority bit error flag but for readability of the code it is best to set them explicitly via the set methods described below Length and priority are integers and the bit error flag is boolean Once a message has been created its data members can be changed by the following functions msg gt setKind kind msg gt setBitLength length MSEC SSSciaycSelemeicin Ieincelalmsyces 5 MSC SSOQUCPIILOWLiey rewO wey msg gt setBitError err msg gt setTimestamp msg gt setTimestamp simtime F With these functions the user can set the message kind the message length the priority the error flag and the time stamp The setTimeStamp function without any argument sets the time stamp to the current simulation time setByteLength sets the same length field as setBitLength only the parameters gets internally multiplied by 8 The values can be obtained by the following functions lae ik msg gt getKind aime 7S mSsq ScqecrerLoricy 5 Lat IL msg gt getBitLength aime lis msg gt getByteLength BOOL Is mMSsg gt hasBithrror Ssimtime_t t msg gt getTimestamp getByteLength also reads the length field as length but the result gets divided by 8 and rounded up Duplicating message
50. 32 29 OMNeT Manual The OMNeT design places a big emphasis on separation of models from experiments The main rationale is that usually a large number of simulation experiments need to be done on a single model before a conclusion can be drawn about the real system Experiments tend to be ad hoc and change much faster than simulation models thus it is a natural requirement to be able to carry out experiments without disturbing the simulation model itself Following the above principle OMNeT allows simulation models to be executed in parallel without modification No special instrumentation of the source code or the topology description is needed as partitioning and other PDES configuration is entirely described in the configuration files OMNeT supports the Null Message Algorithm with static topologies using link delays as lookahead The laziness of null message sending can be tuned Also supported is the Ideal Simulation Protocol ISP introduced by Bagrodia in 2000 bagrodia00 ISP is a powerful research vehicle to measure the efficiency of PDES algorithms both optimistic and conservative more precisely it helps determine the maximum speedup achievable by any PDES algorithm for a particular model and simulation environment In OMNeT ISP can be used for benchmarking the performance of the Null Message Algorithm Additionally models can be executed without any synchronization which can be useful for educational purposes to demon
51. Appendix 22 about display string tags 10 1 7 Message display strings Message display string affects how messages are shown during animation By default they are displayed as a small filled circle in one of 8 basic colors the color is determined as message kind modulo 8 and with the message class and or name displayed under it The latter is configurable in the Tkenv Options dialog and message kind dependent coloring can also be turned off there Specifying message display strings Message objects do not store a display string by default but you can redefine the cMessage s getDisplayString method and make it return one Example of using an icon to represent a message const char CustomPacket getDisplayString const return i msg packet is vs Or better If you add the field displayString to your message definition msg file the message compiler will automatically generate the set getDisplayString methods for you message Job string displayString i msg package_s kind Message display string tags The following tags can be used in message display strings http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual e b shapes colors e i icon e is icon size Using a small red box icon to represent the messages display i msd box red is s Messages will be represented by a 15x15 rectangle with white background Their border color will depend on th
52. Generation Gap pattern Sometimes you need the generated code to do something more or do something differently than the version generated by the message compiler For example when setting a integer field named payloadLength you might also need to adjust the packet length That is the following default generated version of the setPayloadLength method is not suitable void FooPacket setPayloadLength int payloadLength this gt payloadLength payloadLength Instead it should look something like this void FooPacket setPayloadLength int payloadLength int diff payloadLength this gt payloadLength this gt payloadLength payloadLength setBitLength length diff According to common belief the largest drawback of generated code is that it is difficult or impossible to fulfill such wishes Hand editing of the generated files is worthless because they will be overwritten and changes will be lost in the code generation cycle http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual However object oriented programming offers a solution A generated class can simply be customized by subclassing from it and redefining whichever methods need to be different from their generated versions This practice is known as the Generation Gap design pattern It is enabled with the customize property set on the message message FooPacket customize true int pa
53. If the connection with a data rate is not directly connected to the simple module s output gate but is the second one in the path you have to check the second gate s busy condition You could use the following code if gate out gt getNextGate gt isBusy Beers Note that if data rates change during the simulation the changes will affect only the messages that are sent after the change 4 6 4 Broadcasts and retransmissions When you implement broadcasts or retransmissions two frequently occurring tasks in protocol simulation you might feel tempted to use the same message in multiple send operations Do not do it you cannot send the same message object multiple times The solution in such cases is duplicating the message Broadcasting messages In your model you may need to broadcast a message to several destinations Broadcast can be implemented in a simple module by sending out copies of the same message for example on every gate of a gate vector As described above you cannot use the same message pointer for in all send calls what you have to do instead is create copies duplicates of the message object and send them Example foie iliac a 0e a lt mg iar CMES Sial iS mua COPE te Cer pO sendi CoOL AROUCA eeee delete msg http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual You might have noticed that copying the message for the last gate is redund
54. Watches and snapshots 6 9 1 Basic watches It would be nice but variables of type int long double do not show up by default in Tkenv neither do STL classes std string std vector etc or your own structs and classes This is because the simulation kernel being a library knows nothing about types and variables in your source code OMNeT provides WATCH and set of other macros to come to your rescue and make variable to be inspectable in Tkenv and to be output into the snapshot file WATCH macros are usually placed into initialize to watch instance variables or to the top of the activity function to watch its local variables the point being that they should only be executed once RomGmOceleciastse miter double idleTime WATCH packetsSent WATCH idleTime Of course members of classes and structs can also be watched WATCH config maxRetries When you open an inspector for the simple module in Tkenv and click the Objects Watches tab in it you ll see your watched variables and their values there Tkenv also lets you change the value of a watched variable The WATCH macro can be used with any type that has a stream output operator operator lt lt defined By default this includes all primitive types and std string but since you can write operator lt lt for your classes structs and basically any type WATCH can be used with anything The only limitation is that since the output should more o
55. a C header file with a generated class FooPacket FooPacket will be a subclass of cMessage For each field in the above description the generated class will have a protected data member a getter and a setter method The names of the methods will begin with get and set followed by the field name with its first letter converted to uppercase Thus FooPacket will contain the following methods virtual int getSourceAddress const virtual void setSourceAddress int sourceAddress virtual int getDestAddress const virtual void setDestAddress int destAddress virtual bool getHasPayload const virtual void setHasPayload bool hasPayload Note that the methods are all declared virtual to give you the possibility of overriding them in subclasses Two constructors will be generated one that optionally accepts object name and for cMessage subclasses message kind and a copy constructor FooPacket const char name NULL int kind 0 FooPacket const FooPacket amp other Appropriate assignment operator operator and dup methods will also be generated Data types for fields are not limited to int and bool You can use the following primitive types i e primitive types as defined in the C language e bool e char unsigned char e short unsigned short e int unsigned int http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual e long unsigned long double Fi
56. a pointer to the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual transmission channel once and then call isBusy and getTransmissionFinishTime on the cached channel pointer An incomplete code example to illustrate the above process simtime_t txfinishTime gate out gt getTransmissionFinishTime if txfinishTime lt simTime send pkt out else scheduleAt txFinishTime timerMsg also remember pkt and ensure that when timerMsg expires it will get sent out Receiving a packet Normally the packet object gets delivered to the destination module at the simulation time that corresponds to finishing the reception of the message ie the arrival of its last bit However the receiver module may change this by reprogramming the receiver gate with the setDeliverOnReceptionStart method gate in gt setDeliverOnReceptionStart true This method may only be called on simple module input gates and it instructs the simulation kernel to give arriving packets to the receiver module when reception begins not ends that is on arrival of the first bit of the message getDeliverOnReceptionStart only needs to be called once so it is usually done in the initialize method of the module When a packet gets delivered to the module the packet s isReceptionStart method can be called to determine whether it correspo
57. and Packet Error Rate and allow basic error modelling They expect a double in the 0 1 range When the channel decides based on random numbers that an error occurred during transmission a packet it sets an error flag in the packet object The receiver module is expected to check the flag and discard the packet as corrupted if it is set The default ber and per are zero NOTE There is no channel parameter that would decide whether the channel delivers the message object to the destination module at the end or at the start of the reception that is decided by the C code of the target simple module See the setDeliverOnReceptionStart method of cGate The following example shows how to create a new channel type by specializing DatarateChannelL channel C extends ned DatarateChannel datarate 100Mbps delay 100us ber le 10 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual NOTE The three built in channel types are also used for connections where the channel type not explicitly specified You may add parameters and properties to channels via subclassing and modify existing ones In the following example we introduce length based calculation of the propagation delay channel DatarateChannel2 extends ned DatarateChannel double length unit m delay this length 200000km 1s Parameters are primarily useful as input to the underlying C class b
58. and use a C debugger to look at the stack trace and examine variables Enabling the debug on errors ini file entry lets you do that check it in section If you detect an error condition in your code you can stop the simulation with an error message using the opp_error function opp_error s argument list works like printf the first argument is a format string which can contain ss Sd etc filled in using subsequent arguments An example if msg gt getControlinfo NULL opp_error message s s has no control info attached msg gt getClassName msg gt getName 6 2 Logging from modules The logging feature will be used extensively in the code examples we introduce it here The ev object represents the user interface of the simulation You can send debugging output to ev with the C style output operators ev lt lt packet received sequence number is lt lt seqNum lt lt endl ev lt lt queue full discarding packet n An alternative solution is ev printf ev printf packet received sequence number is d n seqNum The exact way messages are displayed to the user depends on the user interface In the command line user interface Cmdenv it is simply dumped to the standard output This output can also be disabled from omnetpp ini so that it doesn t slow down simulation when it is not needed In Tkenv the runtime GUI you can open a text output window for every
59. approach is suitable and which can be conveniently mapped into entities communicating by exchanging messages OMNeT itself is not a simulator of anything concrete but it rather provides infrastructure and tools for writing simulations One of the fundamental ingredients of this infrastructure is a component architecture for simulation models Models are assembled from reusable components termed modules Well written modules are truly reusable and can be combined in various ways like LEGO blocks Modules can be connected with each other via gates other systems would call them ports and combined to form compound modules The depth of module nesting is not limited Modules communicate through message passing where messages may carry arbitrary data structures Modules can may messages along predefined paths via gates and connections or directly to their destination the latter is useful for wireless simulations for example Modules may have parameters which can be used to customize module behaviour and or to parameterize the model s topology Modules at the lowest level of the module hierarchy are called simple modules and they encapsulate behaviour Simple modules are programmed in C and make use of the simulation library OMNeT simulations can be run under various user interfaces Graphical animating user interfaces are highly useful for demonstration and debugging purposes and command line user interfaces are best for batch execution
60. arbitrary non equidistant cells It can operate in two modes e manual where you specify cell boundaries explicitly before starting collecting e automatic where transform will set up the cells after collecting a certain number of initial observations The cells will be set up so that as far as possible an equal number of observations fall into each cell equi probable cells Modes are selected with a transform type parameter e HIST_TR_NO_TRANSFORM no transformation uses bin boundaries previously defined by addBinBound IST_TR_AUTO_EPC_DBL automatically creates equiprobable cells IST_TR_AUTO_EPC_INT like the above but for integers oo Creating an object cVarHistogram const char s NULL int numcells 11 int transformtype HIST_TR_AUTO_EPC_DBL Manually adding a cell boundary void addBinBound double x Rangemin and rangemax is chosen after collecting the numFirstVals initial observations One cannot add cell boundaries when the histogram has already been transformed 6 7 3 The k split algorithm Purpose The k split algorithm is an on line distribution estimation method It was designed for on line result collection in simulation programs The method was proposed by Varga and Fakhamzadeh in 1997 The primary advantage of k split is that without having to store the observations it gives a good estimate without requiring a priori
61. be an error Interactive mode is typically disabled for batch executions where it would do more harm than good It is also possible to explicitly apply the default this can sometimes be useful x sendilaTime default Finally one can explicitly ask the simulator to prompt the user interactively for the value again provided that interactivity is enabled otherwise this will result in an error xx sendlaTime ask NOTE How do you decide whether to assign a parameter from NED or from an ini file The point of ini files is a cleaner separation of the model and experiments NED files together with C code are considered to be part of the model and to be more or less constant Ini files on the other hand are for experimenting with the model by running it several times with different parameters Thus parameters that are expected to change or make sense to be changed during experimentation should be put into ini files Expressions Parameter values may be given with expressions NED language expressions have a C like syntax with some variations on operator names binary and logical XOR are and while has been reassigned to power of instead The operator does string concatenation as well as numeric addition Expressions can use various numeric string stochastic and other functions fabs toUpper uniform erlang_k etc http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manu
62. by calling their enable or disable member functions Disabled nodes or edges are ignored by the shortest paths calculation algorithm The isEnabled member function returns the state of a node or edge in the topology graph One usage of disable is when you want to determine in how many hops the target node can be reached from our node through a particular output gate To calculate this you calculate the shortest paths to the target from the neighbor node but you must disable the current node to prevent the shortest paths from going through it cTopology Node thisnode topo getNodeFor this thisnode gt disable topo calculateUnweightedSingleShortestPathsTo targetnode thisnode gt enable http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual for int j 0 j lt thisnode gt getNumOutLinks cTopology LinkOut link thisnode gt getLinkOut 1 j ev lt lt Through gate lt lt link gt getLocalGate gt getFullName lt lt lt lt 1 link gt getRemoteNode gt get In the future other shortest path algorithms will also be implemented unweightedMultiShortestPathsTo cTopology Node target weightedSingleShortestPathsTo cTopology Node target weightedMultiShortestPathsTo cTopology Node target 6 7 Statistics and distribution estimation 6 7 1 cStatistic and descendants DistanceToTarget lt lt hops lt
63. by step focusing on the behavior instead of the statistical results of your model The eventlog file is created automatically during a simulation run upon explicit request configurable in the ini file The resulting file can be viewed in the OMNeT IDE using the Sequence Chart and the Eventlog Table or can be http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual processed by the command line Eventlog Tool These tools support filtering the collected data to show you only the relevant parts focusing on what you are looking for They allow examining causality relationships and provide filtering based on simulation times event numbers modules and messages The simulation kernel records into the eventlog among others user level messages creation and deletion of modules gates and connections scheduling of self messages sending of messages to other modules either through gates or directly and processing of messages that is events Optionally detailed message data can also be automatically recorded based on a message filter The result is an eventlog file which contains detailed information of the simulation run and later can be used for various purposes NOTE The eventlog file may become quite large for long running simulations often hundreds of megabytes but occasionally several gigabytes because it contains a lot of information about the run especially when message detail recording is turned on 12
64. cTopology Link is returned either as cTopology LinkIn or aS cTopology LinkOut so that remote and local can be correctly interpreted for edges of both directions 6 6 3 Shortest paths The real power of cTopology is in finding shortest paths in the network to support optimal routing cTopology http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual finds shortest paths from all nodes to a target node The algorithm is computationally inexpensive In the simplest case all edges are assumed to have the same weight A real life example when we have the target module pointer finding the shortest path looks like this cModule targetmodulep cTopology Node targetnode topo getNodeFor targetmodulep topo calculateUnweightedSingleShortestPathsTo targetnode This performs the Dijkstra algorithm and stores the result in the cTopology object The result can then be extracted using cTopology and cTopology Node methods Naturally each call to calculateUnweightedSingleShortestPathsTo overwrites the results of the previous call Walking along the path from our module to the target node cTopology Node node topo getNodeFor this if node NULL else if node gt getNumPaths 0 ey lt We 7 lt lt getFullPath lt lt T are noe included in tche topology n ey lt lt No path Lo destina lion nT else whi
65. components when the simulation model is set up at the beginning of the simulation run It also refers to the component library when dynamic module creation is used The machinery for registering and looking up components in the model component library is implemented as part of Sim Executing Model lt gt Envir The ev object logically part of Envir is the facade of the user interface towards the executing model The model uses ev to write debug logs ev lt lt ev printf Sim lt gt Envir Envir is in full command of what happens in the simulation program Envir contains the main function where execution begins Envir determines which models should be set up for simulation and instructs Sim to do so Envir contains the main simulation loop determine next event execute event sequence and invokes the simulation kernel for the necessary functionality event scheduling and event execution are implemented in Sim Envir catches and handles errors and exceptions that occur in the simulation kernel or in the library classes during execution Envir presents a single facade object ev that represents the environment user interface toward Sim no Envir internals are visible to Sim or the executing model During simulation model setup Envir supplies parameter values for Sim when Sim asks for them Sim writes output vectors via Envir so one can redefine the output vector storing mechanism by changing Envir Sim and its classes use Envir to prin
66. compound module 3 2 5 Putting it together 3 3 Simple modules 3 4 Compound modules 3 5 Channels 3 6 Parameters 3 7 Gates 3 8 Submodules 3 9 Connections 3 10 Multiple connections 3 10 1 Connection patterns 3 11 Submodule type as parameter 3 12 Properties metadata annotations 3 13 Inheritance 3 14 Packages 4 Simple Modules 4 1 Simulation concepts 4 1 1 Discrete Event Simulation 4 1 2 The event loop 4 1 3 Simple modules in OMNeT 4 1 4 Events in OMNeT 4 1 5 Simulation time 4 1 6 FES implementation 4 2 Defining simple module types 4 2 1 Overview 4 2 2 Constructor 4 2 3 Constructor and destructor vs initialize and finish 4 2 4 An example 4 2 5 Using global variables 4 3 Adding functionality to cSimpleModule 4 3 1 handleMessage 4 3 2 activity 4 3 3 initialize and finish 4 3 4 handleParameterChange 4 3 5 Reusing module code via subclassing 4 4 Accessing module parameters 4 4 1 Volatile and non volatile parameters http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 4 4 2 Changing a parameter s value 4 4 3 Further cPar methods 4 4 4 Emulating parameter arrays 4 5 Accessing gates and connections 4 5 1 Gate objects 4 5 2 Connections 4 5 3 The connection s channel 4 6 Sending and receiving messages 4 6 1 Sending messages 4 6 2 Packet transmissions 4 6 3 Delay data rate bit error rate packet error rate 4 6 4 Broadcasts and retransmissions 4 6 5 Delayed sending 4 6 6 Direct
67. concrete scheduler class whether selectNextModule may return NULL The default cSequentialScheduler never returns NULL Execution may terminate in various ways Runtime errors cause a cRuntimeError or other kind of std exception to be thrown cTerminationException is thrown on normal termination conditions such as when the simulation runs out of events to process You may customize the loop to exit on other termination conditions as well such as on a simulation time limit see above on CPU time limit or when results reach a required accuracy It is relatively straightforward to build in progress reporting and interactivity start stop as well Animation can be hooked up to the appropriate callback methods of cEnvir beginSend sendHop endSend and others 16 2 10 Multiple coexisting simulations It is possible for several instances of cSimulation to coexist and also to set up and simulate a network in each instance However this requires frequent use of cSimulation setActiveSimulation before invoking any cSimulation method or module method the corresponding cSimulation instance needs to be designated as the active simulation manager This is necessary because several models and simulation kernel methods refer to the active simulation manager instance via the simulation macro and it is similar with the ev macro NOTE Before the 4 0 version simulation and ev were global variables now they are macros that
68. delivered to the module simtime_t getSendingTime simtime_t getCreationTime f simtime_t getArrivalTime Context pointer cMessage contains a void pointer which is set returned by the setContextPointer and getContextPointer functions volc COMCEE Soos msg Sone ore ace Sa eee vondi Context mscj SCj Eom oot Pod ES s It can be used for any purpose by the simulation programmer It is not used by the simulation kernel and it is treated as a mere pointer no memory management is done on it Intended purpose a module which schedules several self messages timers will need to identify a self message when it arrives back to the module ie the module will have to determine which timer went off and what to do then The context pointer can be made to point at a data structure kept by the module which can carry enough context information about the event 5 1 3 Modelling packets Arrival gate and time The following methods can tell where the message came from and where it arrived or will arrive if it is currently scheduled or under way int getSenderModulel int getSenderGateld int getArrivalModule int getArrivalGateld The following methods are just convenience functions which build on the ones above eModule getsSenderModulle cGate getSenderGate cGate getArrivalGate And there are further convenience functions to tell whether the message arrive
69. described briefly here because several details and examples have been already presented in previous sections http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual In NED a type may only extend extends keyword an element of the same component type a simple module may only extend a simple module compound module may only extend a compound module and so on Single inheritance is supported for modules and channels and multiple inheritance is supported for module interfaces and channel interfaces A network is a shorthand for a compound module with the isNetwork property set so the same rules apply to it as to compound modules However a simple or compound module type may implement like keyword several module interfaces likewise a channel type may implement several channel interfaces IMPORTANT When you extend a simple module type both in NED and in C you must use the class property to tell NED to use the new C class otherwise your new module type inherits the C class of the base Inheritance may e add new properties parameters gates inner types submodules connections as long as names do not conflict with inherited names modify inherited properties and properties of inherited parameters and gates e it may not modify inherited submodules connections and inner types For details and examples see the corresponding sections of this chapter simple modules 3 3 compound modu
70. directory where lt root gt gets listed in NEDPATH then the package name is a b c The package name has to be explicitly declared at the top of the NED files as well like this package a b c The package name that follows from the directory name and the declared package must match it is an error if they don t The only exception is the root package ned file as described below By convention package names are all lowercase and begin with either the project name myproject or the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual reversed domain name plus the project name org example myproject The latter convention would cause the directory tree to begin with a few levels of empty directories but this can be eliminated with a toplevel package ned NED files called package ned have a special role as they are meant to represent the whole package For example comments in package ned are treated as documentation of the package Also a namespace property in a package ned file affects all NED files in that directory and all directories below The toplevel package ned file can be used to designate the root package which is useful for eliminating a few levels of empty directories resulting from the package naming convention That is if you have a package ned file in your lt root gt directory whose package declaration says org example myproject then the lt root gt a b c directory will be
71. eliminate the bias introduced by the particular random number stream used for the simulation several replications of every measurement are run with different random number seeds and the results are averaged OMNeT result analysis tools can take advantage of experiment measurement replication labels recorded into result files and organize simulation runs and recorded output scalars and vectors accordingly on the user interface These labels can be explicitly specified in the ini file using the experiment measurement and replication config keys If they are missing the default is the following xperiment S configname measurement Sfiterationvars replication S repetition seed set lt seedset gt That is the default experiment label is the configuration name the measurement label is concatenated from the iteration variables and the replication label contains the repeat loop variable and for the seed set Thus for our first example the experiment measurement replication tree would look like this PureAloha Unknown LaTeX command textrm experiment SN 1 Smean 0 2 Unknown LaTeX command textrm measurement 0 seed set 0 Unknown LaTeX command textrm replication 1 seed set 1 2 seed set 2 3 seed set 3 4 seed set 4 SN 1 Smean 0 4 0 seed set 5 1 seed set 6 He 4 seed set 9 SN 1 mean 0 6 0 seed set 10 1 seed set 11 4 seed set 14 SN 2 Smean 0
72. fast computers it is easy to exhaust all random numbers and the structure of the generated random points is too regular The Hellekalek98 paper provides a broader overview of issues associated with RNGs used for simulation and it is well worth reading It also contains useful links and references on the topic The Akaroa RNG When you execute simulations under Akaroa control See section 9 5 you can also select Akaroa s RNG as the RNG underlying for the OMNeT random number functions The Akaroa RNG also has to be selected from omnetpp ini section 8 7 Other RNGs OMNeT allows plugging in your own RNGs as well This mechanism based on the cRNG interface is described in section For example one candidate to include could be L Ecuyer s CMRG LEcuyer02 which has a period of about 2191 and can provide a large number of guaranteed independent streams 6 4 2 Random number streams RNG mapping Simulation programs may consume random numbers from several streams that is from several independent RNG instances For example if a network simulation uses random numbers for generating packets and for simulating bit errors in the transmission it might be a good idea to use different random streams for both Since the seeds for each stream can be configured independently this arrangement would allow you to perform several simulation runs with the same traffic but with bit errors occurring in different places A simulation technique
73. for improvements came from the user community of OMNeT It would be impossible to mention everyone here and the list is constantly growing instead the README and ChangeLog files contain acknowledgements Between summer 2001 and fall 2004 the OMNeT CVS was hosted at the University of Karlsruhe Credit for setting up and maintaining the CVS server goes to Ulrich Kaage Ulrich can also be credited with converting the User Manual from Microsoft Word format to LaTeX which was a huge undertaking and great help 2 Overview 2 1 Modeling concepts An OMNeT model consists of modules that communicate with message passing The active modules are termed simple modules they are written in C using the simulation class library Simple modules can be grouped into compound modules and so forth the number of hierarchy levels is not limited The whole model called network in OMNeT is itself a compound module Messages can be sent either via connections that span between modules or directly to other modules The concept of simple and compound modules is similar to DEVS atomic and coupled models In Fig below boxes represent simple modules gray background and compound modules Arrows connecting small boxes represent connections and gates http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Network Simple modules Compound module Figure Simple and compound modules Modules communicate with messa
74. generators 6 4 2 Random number streams RNG mapping 6 4 3 Accessing the RNGs 6 4 4 Random variates 6 4 5 Random numbers from histograms 6 5 Container classes 6 5 1 Queue class cQueue 6 5 2 Expandable array cArray 6 6 Routing support cTopology 6 6 1 Overview 6 6 2 Basic usage 6 6 3 Shortest paths 6 7 Statistics and distribution estimation 6 7 1 cStatistic and descendants 6 7 2 Distribution estimation 6 7 3 The k split algorithm 6 7 4 Transient detection and result accuracy 6 8 Recording simulation results 6 8 1 Output vectors cOutVector 6 8 2 Output scalars 6 8 3 Precision 6 9 Watches and snapshots 6 9 1 Basic watches 6 9 2 Read write watches 6 9 3 Structured watches 6 9 4 STL watches 6 9 5 Snapshots 6 9 6 Getting coroutine stack usage 6 10 Deriving new classes 6 10 1 cOwnedObject or not 6 10 2 cOwnedObject virtual methods 6 10 3 Class registration 6 10 4 Details 6 11 Object ownership management 6 11 1 The ownership tree 6 11 2 Managing ownership 7 Building Simulation Programs 7 1 Overview 7 2 Using gcc 7 2 1 The opp_makemake tool 7 2 2 Basic use 7 2 3 Debug and release builds http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 7 2 4 Using external C C libraries 7 2 5 Building directory trees 7 2 6 Automatic include dirs 7 2 7 Dependency handling 7 2 8 Out of directory build 7 2 9 Building shared and static libraries 7 2 10 Recursive builds 7 2 11 Customizing the Make
75. getClassName method returns RadioMsg So when you inspect a RadioMsg in your simulation Tkenv can use RadioMsgDescriptor to extract and display the values of the freq and power variables The actual implementation is somewhat more complicated than this but not much 6 The Simulation Library OMNeT has an extensive C class library which you can use when implementing simple modules Parts of the class library have already been covered in the previous chapters e the message class cMessage chapter 5 e sending and receiving messages scheduling and canceling events terminating the module or the simulation section e access to module gates and parameters via cModule member functions sections and e accessing other modules in the network section e dynamic module creation section This chapter discusses the rest of the simulation library e random number generation normal exponential etc e module parameters cPar class e storing data in containers the cArray and cQueue Classes e routing support and discovery of network topology cTopology class e recording statistics into files cout Vector class e collecting simple statistics cStdDev and cWeightedStddev classes e distribution estimation cLongHistogram cDoubleHistogram cVarHistogram cPSquare cKSplit classes e making variables inspectable in the graphical user interface Tkenv the WATCH macros e sending debug output to and prompting for
76. int minw 4 double wind 1 3 double acc 0 3 Accuracy detection Currently one accuracy detection algorithm is implemented i e there s one class derived from cAccuracyDetection The algorithm implemented in the cADByStddev class is divide the standard deviation by the square of the number of values and check if this is small enough void setParameters double acc 0 1 int reps 3 6 8 Recording simulation results 6 8 1 Output vectors cOutVector Objects of type cOut Vector are responsible for writing time series data referred to as output vectors to a file The record method is used to output a value or a value pair with a timestamp The object name will serve as the name of the output vector The vector name can be passed in the constructor cOutVector responseTimeVec response time but in the usual arrangement you d make the cOut Vector a member of the module class and set the name in initialize You d record values from handleMessage or from a function called from handleMessage The following example is a Sink module which records the lifetime of every message that arrives to it class Sink public cSimpleModule protected cout vec rormenCoEndI IEMNME E virtual void initialize virtual void handl ssage cMessage msg http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Define Module Sink volel Siak lt amlciLalive
77. into logical units fixed and varying part etc An example omnetpp ini include parameters ini imeludelper nun pars ni You can also include files from other directories If the included ini file further includes others their path names will be understood as relative to the location of the file which contains the reference rather than relative to the current working directory of the simulation This rule also applies to other file names occurring in ini files such as the 1oad libs output vector file output scalar file etc options and xmldoc module parameter values 8 3 Sections 8 3 1 The General section The most commonly used options of the General section are the following e The network option selects the model to be set up and run e The length of the simulation can be set with the sim time limit and the cpu time limit options the usual time units such as ms s m h etc can be used It is important to note that the loaded NED files may contain any number of modules channel and any number of networks as well It does not matter whether you use all or just some of them in the simulations You will be able to select any of the networks that occur in the loaded NED files using the net work omnetpp ini entry and as long as every module channel etc for it has been loaded network setup will be successful 8 3 2 Named configurations Named configurations are sections of the form Config lt configname
78. is often called hold Internally the wait function is implemented by a scheduleAt followed by a receive The wait function is very convenient in modules that do not need to be prepared for arriving messages for example message generators An example for pp wait for a potentially random amount of time specified in the interArrivalTime volatile module parameter wait par interArrivalTime doubleValue generate and send messag It is a runtime error if a message arrives during the wait interval If you expect messages to arrive during the wait period you can use the waitAndEnqueue function It takes a pointer to a queue object of class cQueue described in chapter 6 in addition to the wait interval Messages that arrive during the wait interval will be accumulated in the queue so you can process them after the waitAndEnqueue Call returned cQueue queue queue waitAndEnqueue waitTime amp queue if queue empty process messages arrived during wait interval 4 6 9 Modeling events using self messages In most simulation models it is necessary to implement timers or schedule events that occur at some point in the future For example when a packet is sent by a communications protocol model it has to schedule an event that would occur when a timeout expires because it will have to resent the packet then As another example suppose you want to wri
79. it is important you can eliminate it by setting gt 16 digits precision for the file but again be aware that the last digits are garbage The practical upper limit is 17 digits setting it higher doesn t make any difference in fprintf s output Errors coming from converting to from decimal representation can be eliminated by choosing an output vector output scalar manager class which stores doubles in their native binary form The appropriate configuration entries are outputvectormanager class and outputvectormanager class see For example cMySQLOutputScalarManager and cMySQLOutputScalarManager provided in samples database fulfill this requirement However before worrying too much about rounding and conversion errors it is worth considering what is the real accuracy of your results Some things to consider e in real life it is very hard to measure quantities weight distance even time with more than a few digits of precision What precision are your input data For example if you approximate inter arrival time as exponential 0 153 when the mean is really 0 752607 and the distribution is not even exactly exponential you are already starting out with a bigger error than rounding can cause e the simulation model is itself an approximation of real life How much error do the known and unknown http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual simplifications cause in the results 6 9
80. j cTopology Node neighbour node gt getLinkOut j gt getRemoteNode cGate gate node gt getLinkOut j gt getLocalGate ev lt lt lt lt neighbour gt getModule gt getFullPath lt lt through gate lt lt gate gt getFullName lt lt endl The getNumNodes member function 1st line returns the number of nodes in the graph and getNode i returns a pointer to the ith node an cTopology Node structure The correspondence between a graph node and a module can be obtained by cTopology Node node topo getNodeFor module cModule module node gt getModule The getNodeFor member function returns a pointer to the graph node for a given module If the module is not in the graph it returns NULL getNodeFor uses binary search within the cTopology object so it is fast enough cTopology Node s other member functions let you determine the connections of this node getNumInLinks getNumOut Links return the number of connections in i and out i return pointers to graph edge objects By calling member functions of the graph edge object you can determine the modules and gates involved The getRemoteNode function returns the other end of the connection and getLocalGate getRemoteGate getLocalGateId and getRemoteGateId return the gate pointers and ids of the gates involved Actually the implementation is a bit tricky here the same graph edge object
81. little fluctuations in time They are also intuitive and easy to measure The OMNeT displays these values on the GUI while the simulation is running see Figure below Cmdenv can also be configured to display these values Figure Performance bar in OMNeT showing P R and E Ev sec 114356 Simsec sec 53336 2 Ev simsec 2 14407 After having approximate values of P E L and 7 calculate the A coupling factor as the ratio of LE and r P A LE tT P Without going into the details if the resulting A value is at minimum larger than one but rather in the range 10 100 there is a good change that the simulation will perform well when run in parallel With A lt 1 poor performance is guaranteed For details see the paper ParsimCrit03 14 3 Parallel distributed simulation support in OMNeT 14 3 1 Overview This chapter presents the parallel simulation architecture of OMNeT The design allows simulation models to be run in parallel without code modification it only requires configuration The implementation relies on the approach of placeholder modules and proxy gates to instantiate the model on different LPs the placeholder approach allows simulation techniques such as topology discovery and direct message sending to work unmodified with PDES The architecture is modular and extensible so it can serve as a framework for research on parallel simulation http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20
82. members and expose them via public methods Other modules can then call these public methods to get or set the values Calling methods of other modules will be discussed in section Examples of such modules are the Blackboard in the Mobility Framework and InterfaceTable and RoutingTable in the INET Framework 4 3 Adding functionality to cSimpleModule This section discusses cSimp1leModul1e s four previously mentioned member functions intended to be redefined by the user initialize handleMessage activity and finish plus a fifth less frequently used one handleParameterChange 4 3 1 handleMessage Function called for each event The idea is that at each event message arrival we simply call a user defined function This function handleMessage cMessage msg is a virtual member function of cSimpleModule which does nothing by http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual default the user has to redefine it in subclasses and add the message processing code The handleMessage function will be called for every message that arrives at the module The function should process the message and return immediately after that The simulation time is potentially different in each call No simulation time elapses within a call to handleMessage The event loop inside the simulator handles both activity and handleMessage simple modules and it corresponds to the following ps
83. message sending 4 6 7 Receiving messages 4 6 8 The wait function 4 6 9 Modeling events using self messages 4 7 Stopping the simulation 4 7 1 Normal termination 4 7 2 Raising errors 4 8 Finite State Machines in OMNeT 4 9 Walking the module hierarchy 4 10 Direct method calls between modules 4 11 Dynamic module creation 4 11 1 When do you need dynamic module creation 4 11 2 Overview 4 11 3 Creating modules 4 11 4 Deleting modules 4 11 5 Module deletion and finish 4 11 6 Creating connections 4 11 7 Removing connections 5 Messages 5 1 Messages and packets 5 1 1 The cMessage class 5 1 2 Self messages 5 1 3 Modelling packets 5 1 4 Encapsulation 5 1 5 Attaching parameters and objects 5 2 Message definitions 5 2 1 Introduction 5 2 2 Declaring enums 5 2 3 Message declarations 5 2 4 Inheritance composition 5 2 5 Using existing C types 5 2 6 Customizing the generated class 5 2 7 Using STL in message classes 5 2 8 Summary 5 2 9 What else is there in the generated code 6 The Simulation Library 6 1 Class library conventions 6 1 1 Base class http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 6 1 2 Setting and getting attributes 6 1 3 getClassName 6 1 4 Name attribute 6 1 5 getFullName and getFullPath 6 1 6 Copying and duplicating objects 6 1 7 Iterators 6 1 8 Error handling 6 2 Logging from modules 6 3 Simulation time conversion 6 4 Generating random numbers 6 4 1 Random number
84. method ever being called then the reference count of the encapsulated message simply gets decremented The encapsulated message is deleted when its reference count reaches zero Reference counting can significantly improve performance especially in LAN and wireless scenarios For example in the simulation of a broadcast LAN or WLAN the IP TCP and higher layer packets won t get duplicated and then discarded without being used if the MAC address doesn t match in the first place The reference counting mechanism works transparently However there is one implication one must not change anything in a message that is encapsulated into another That is getEncapsulatedMsg should be viewed as if it returned a pointer to a read only object it returns a const pointer indeed for quite obvious reasons the encapsulated message may be shared between several messages and any change would affect those other messages as well Encapsulating several messages The cMessage Class doesn t directly support adding more than one messages to a message object but you can subclass cMessage and add the necessary functionality It is recommended that you use the message definition syntax 5 2 and customized messages 5 2 6 to be described later on in this chapter it can spare you some work You can store the messages in a fixed size or a dynamically allocated array or you can use STL classes like std vector or std list There is one additional tr
85. module It is not recommended that you use printf or cout to print messages ev output can be controlled much better from omnetpp ini and it is more convenient to view using Tkenv One can save CPU cycles by making logging statements conditional on whether the output actually gets displayed or recorded anywhere The ev isDisabled call returns true when ev lt lt output is disabled such as in Tkenv or Cmdenv express mode Thus one can write code like this if ev isDisabled ev lt lt Packet lt lt msg gt getName lt lt received n A more sophisticated implementation of the same idea is to the EV macro which can be used in logging statements instead of ev One would simply write EV lt lt instead of ev lt lt EV lt lt Packet lt lt msg gt getName lt lt received n EV s implementation makes use of the fact that the lt lt operator binds looser than the conditional operator 6 3 Simulation time conversion Simulation time is represented by the type simt ime_t which is a typedef to double OMNeT provides utility http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual functions which convert simtime_t to a printable string 3s 130ms 230us and vica versa The simtimeToStr function converts a simt ime_t passed in the first argument to textual form The result is placed into the char array pointed to by the second argument If th
86. more and more statistics The size of output vector files can easily reach a magnitude of several ten or hundred megabytes but very often only some of the recorded statistics are interesting to the analyst In OMNeT you can control how cOut Vector objects record data to disk You can turn output vectors on off or you can assign a result collection interval By default all output vectors are turned on NOTE The way of configuring output vectors has changed In OMNeT 3 x the keys for enabling disabling a vector and specifying recording interval were lt module and vectorname pattern gt enabled and lt module and vectorname pattern gt interval The enabled and interval words changed to vector recording and vector recording interval The reason for this change is that per object configuration keys are now required to have a hyphen in their names to make it possible to tell them apart from module parameter assignments This allows the simulator to catch mistyped config keys in ini files The syntax for specifying the recording interval has also been extended in a backward compatible way to accept multiple intervals separated by comma Output vectors can be configured with the following syntax dS module pathname objectname vector recording true false module pathname objectname vector recording interval startl stopl stant maS EOP Either start or stop can be omitted to mean the beginning and the end o
87. omitted or adjust your shared library path according to your OS On Windows set the PATH on Unix set LD_LIBRARY_PATH and on Mac OS X set the DYLD_LIBRARY_PATH as needed 9 1 2 Running a shared library Shared libraries can be run using the opp_run program Both opp_run and simulation executables are capable of loading additional shared libraries actually opp_run is nothing else than an empty simulation executable Example opp_run 1 mymodel The above example will load the model found in 1ibmymodel so and execute it 9 1 3 Controlling the run There are several useful configuration options that control how a simulation is run e cmdenv express mode Provides only minimal status updates on the console cmdenv interactive Allows asking interactively for missing parameter values e cmdenv status frequency How often the status is written to the console e cpu time limit Limit how long the simulation should run in wall clock time e sim time limit Limit how long the simulation should run in simulation time e debug on errors If the runtime detects any error it will generate a breakpoint so you will be able to check the location and the context of the problem in your debugger e fingerprint The simulation kernel computes a checksum while running the simulation It is calculated http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual from the module id and from the current
88. omnetpp global setting When cNamedPipeCommunications is selected as parsim communications class selects the name prefix for Windows named pipes created parsim nullmessageprotocol laziness lt double gt default 0 5 global setting When cNullMessageProtocol is selected as parsim synchronization class specifies the laziness of sending null messages Values in the range 0 1 are accepted Laziness 0 causes null messages to be sent out immediately as a new EOT is learned which may result in excessive null message traffic parsim nullmessageprotocol lookahead class lt string gt default cLinkDelayLookahead global setting When cNullMessageProtocol is selected as parsim synchronization class specifies the C class that calculates lookahead The class should subclass from cNMPLookahead parsim synchronization class lt string gt default cNullMessageProtocol global setting If parallel simulation true it selects the parallel simulation algorithm The class must implement the cParsimSynchronizer interface lt object full path gt partition id lt string gt per object setting With parallel simulation in which partition the module should be instantiated Specify numeric partition ID or a comma separated list of partition IDs for compound modules that span across multiple partitions Ranges 5 9 and all are accepted too pri
89. operator lt lt for the pointer type itself Examples SECIS SWECTOR lt KiMe gt sLIMNE Wee s WATCH_VECTOR intvec std map lt std string Command gt commandMap WATCH_PTRMAP commandMap 6 9 5 Snapshots http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The snapshot function outputs textual information about all or selected objects of the simulation including the objects created in module functions by the user into the snapshot file const char label NULL bool snapshot cOwnedObject obj amp simulation The function can be called from module functions like this dump the whole network dump this simple module and all its objects dump future events snapshot snapshot this snapshot amp simulation msgQueue This will append snapshot information to the end of the snapshot file The snapshot file name has an extension of sna default is omnetpp sna Actual file name can be set in the config file The snapshot file output is detailed enough to be used for debugging the simulation by regularly calling snapshot one can trace how the values of variables objects changed over the simulation The arguments label is a string that will appear in the output file obj is the object whose inside is of interest By default the whole simulation all modules etc will be written out If you run the simulation with Tkenv you can also create a s
90. or re sent e Other attributes and data members make simulation programming easier they will be discussed later parameter list encapsulated message control info and context pointer e A number of read only attributes store information about the message s last sending scheduling source destination module and gate sending scheduling and arrival time They are mostly used by the simulation kernel while the message is in the FES but the information is still in the message object when a module receives the message Basic usage The cMessage constructor accepts several arguments Most commonly you would create a message using an object name a const char string and a message kind int cMessage msg new cMessage MessageName msgKind Both arguments are optional and initialize to the null string and O so the following statements are also valid cMessage msg new cMessage cMessage msg new cMessage MessageName It is a good idea to always use message names they can be extremely useful when debugging or demonstrating your simulation Message kind is usually initialized with a symbolic constant e g an enum value which signals what the message object represents in the simulation i e a data packet a jam signal a job etc Please use positive values or zero only as message kind negative values are reserved for use by the simulation kernel http omnetpp org doc omnetpp40 manual usman html
91. package org example myproject a b c and NED files in them must contain that as package declaration Only the root package ned has this property other package ned s cannot change the package Let s look at the INET Framework as example which contains hundreds of NED files in several dozen packages The directory structure looks like this NET sre base transport ECO udp networklayer linklayer examples adhoc ethernet The src and examples subdirectories are denoted as NED source folders so NEDPATH is the following provided INET was unpacked in home joe nome joe INET src home joe INET examples Both src and examples contain package ned files to define the root package INET src package ned package inet INET examples package ned package inet examples And other NED files follow the package defined in package ned INET sre transport tcep TCP ned package inet transport tcp Name resolution imports We already mentioned that packages can be used to distinguish similarly named NED types The name that includes the package name a b c Queue for a Queue module in the a b c package is called fully qualified name without the package name Queue it is called simple name Simple names alone are not enough to unambiguously identify a type Here is how you can refer to an existing http omnetpp org doc omnetpp40 manual usm
92. places from NED code from the configuration omnetpp ini or even interactively from the user The following example shows how parameters of an App module from the previous example may be assigned when App gets used as a submodule http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual module Node submodules app App sendiaTime 3s packetLength 1024B B byte After the above definition the app submodule s parameters cannot be changed from omnetpp ini any more IMPORTANT A value assigned in NED cannot be overwritten from ini files they count as hardcoded as far as ini files are concerned Provided that the value isn t set in the NED file a parameter can be assigned in the configuration in the following way xx sendlaTime 100ms The above line applies to all parameters called sendIaTime whichever module they belong to it is possible to write more selective assignments by replacing with more specific patterns Parameter assignments in the configuration are described in section 8 4 One can also write expressions including stochastic expressions in the ini file 2s endi anmime 2s 4 xponential 100ms If there is no assignment in the ini file the default value given with default in NED is applied implicitly If there is no default value the user will be asked provided the simulation program is allowed to do that otherwise there will
93. radioIn gate is marked with directIn simple WirelessNode Gases input radiolIn directIn In the following example we define TreeNode as having gates to connect any number of children then subclass it to get a BinaryTreeNode to set the gate size to two http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Simple TreeNode gameri inout parent taote Claas Ikekeein i simple BinaryTreeNod xtends TreeNode gatesi chnisldrenil2li An example for setting the gate vector size in a submodule using the same TreeNode module type as above module BinaryTree submodules nodes 31 TreeNode gatesi echinikdrenil 2k connections 3 8 Submodules Modules that a compound module is composed of are called its submodules A submodule has a name and it is an instance of a compound or simple module type In the NED definition of a submodule this module type may be given explicitly but as we ll see later it is also possible to specify the type with a string expression see section 3 11 NED supports submodule arrays vectors as well Submodule vector size unlike gate vector size must always be specified and cannot be left open as with gates The basic syntax of submodules is shown below module Node submodules FOEN INO sLiave yy a submodule queue sizeof port Queue submodule vector A submodule vector may a
94. read the parameter every time a value is needed at runtime so the parameter can be used a source of random numbers NOTE This does not mean that a non volatile parameter cannot be assigned a value like uniform 0 5s 1 5s It can but that has a totally different effect Had we omitted the volatile keyword from the serviceTime parameter for example the effect would be that every job had the same constant service time say 1 2975367s chosen randomly at the beginning of the simulation Units One can declare a parameter to have an associated unit of measurement by adding the unit property An example simple App Wekeemewicrass volatile double sendIaTime unit s default exponential 350ms volatile int packetLength unit byte default 4KB The unit s and unit byte bits declare the measurement unit for the parameter Values assigned to parameters must have the same or compatible unit i e unit s accepts milliseconds nanoseconds minutes hours etc and unit byte accepts kilobytes megabytes etc as well NOTE The list of units accepted by OMNeT is listed in the Appendix see 17 5 7 Unknown units bogomips etc can also be used but there are no conversions for them i e decimal prefixes will not be recognized The OMNeT runtime does a full and rigorous unit check on parameters to ensure unit safety of models Constants should always include the measurement unit http
95. router 10 20 module eventlog recording true xx module eventlog recording false 12 2 4 Recording Message Data http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Since recording message data dramatically increases the size of the eventlog file and additionally slows down the simulation therefore it is turned off by default even if writing the eventlog is enabled To turn on message data recording enter a value for the following configuration key in the ini file eventlog message detail pattern An example configuration for an IEEE 80211 model that records the field encapsulationMsg and all other fields which name ends with Address from messages which class name ends with Frame looks like this eventlog message detail pattern Frame encapsulatedMsg Address An example configuration for a TCP IP model that records the port and address fields in all network packets looks like the following eventlog message detail pattern PPPFrame encapsulatedMsg IPDatagram encapsulatedMsg Address TCPSegment Port NOTE Take care about long running simulations because they might output eventlog files of several Gbytes and thus fail due to insufficient disk space 12 3 Eventlog Tool The Eventlog Tool is a command line tool to process eventlog files Invoking it without parameters will display usage information such as available commands and options The following are the most useful
96. runtime environment is present in your executable but you can override this with the user interface Cmdenv in your ini file or by specifying u Cmdenv on the command line If both the config option and the command line option are present the command line option takes precedence Selecting a configuration and run number Configurations can be selected with the c lt configname gt command line option If you do not specify the configuration and you are running under e Tkenv the runtime environment will prompt you to choose one e Cmdenv the General configuration will be executed User interfaces may support the r runnumber option to select runs either one or more depending on the type of the user interface There are several command line options to get information about the iteration variables and the number of runs in the configurations e a Prints all configuration names and the number of runs in them e x lt configname gt Prints the number of runs available in the given configuration e g Prints the unrolled configuration together with the x option and expands the iteration variables http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual G Prints even more details than g Loading extra libraries OMNeT allows you to load shared libraries at runtime This means that you can create simulation models as a shared library and load the model later into a different executab
97. see Chapter 15 For example an omnetpp ini entry such as rng class cMersenneTwister would result in something like the following code to be executed for creating the RNG objects CRNG rng check_and_cast lt cRNG gt createOne cMersenneTwister But for that to work we needed to have the following line somewhere in the code Register_Class cMersenneTwister createOne is also needed by the parallel distributed simulation feature Chapter 14 to create blank objects to unmarshal into on the receiving side 6 10 4 Details We ll go through the details using an example We create a new class NewClass redefine all above mentioned cOwnedOb ject member functions and explain the conventions rules and tips associated with them To demonstrate as much as possible the class will contain an int data member dynamically allocated non cOwnedOb ject data an array of doubles an OMNeT object as data member a cQueue anda dynamically allocated OMNeT object a cMessage The class declaration is the following It contains the declarations of all methods discussed in the previous section Ud M ae ioe Nene lass in Ui include lt omnetpp h gt class NewClass public cOwnedObject protected int data double array COvete Guette cMessage msg http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual pubike NewClass const char name NULL int d 0 NewClass const
98. simulation with an error message if this function is called The assignment operator copies contents of the other object to this one except the name string It should always return this First we should make sure we re not trying to copy the object to itself because it might be disastrous If so that is amp other this we return immediately without doing anything The base class part is copied via invoking the assignment operator of the base class New data members are copied in the normal C way If the class contains pointers you ll most probably want to make a deep copy of the data where they point and not just copy the pointer values If the class contains pointers to OMNeT objects you need to take ownership into account If the contained object is not owned then we assume it is a pointer to an external object consequently we only copy the pointer If it is owned we duplicate it and become the owner of the new object Details of ownership management will be covered in section 6 11 void NewClass forEachChild cVisitor v v gt visit queue if msg We SVILSALIC MSc The forEachChild function should call v gt visit obj for each obj member of the class See the API http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Reference for more information of forEachChild std string NewClass info stel sstrilngstr rean OWT out lt lt d
99. submodules submodules submodule submodule J submodule submoduleheader submoduleheader opt_paramblock opt_gateblock opt_semicolon 3 submoduleheader submodulename dottedname submodulename likeparam LIKE dottedname 3 submodulename NAME NAME vector 3 likeparam lt 2 lt gt http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual lt expression gt J opt_connblock connblock J connblock CONNECTIONS ALLOWUNCONNECTED opt_connections CONNECTIONS opt_connections J opt_connections connections 3 connections connections connectionsitem connectionsitem 3 connectionsitem connectiongroup connection opt_loops_and_conditions J connectiongroup opt_loops_and_conditions connections opt_semicolon J opt_loops_and_conditions loops_and_conditions 3 loops_and_conditions loops _and_conditions loop_or_condition loop_or_condition J http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual loop_or_condition loop condition J loop FOR NAME expression expression connection leftgatespec gt rightgatespec leftgatespec gt channelspec gt rightgatespec leftgatespec lt rightgatespec leftgatespec lt channelspec lt rightgatespec leftgatespec lt gt rightgat
100. supports parallel execution of large simulations The following paragraphs provide a brief picture of the problems and methods of parallel discrete event simulation PDES Interested readers are strongly encouraged to look into the literature For parallel execution the model is to be partitioned into several LPs logical processes that will be simulated independently on different hosts or processors Each LP will have its own local Future Event Set thus they will maintain their own local simulation times The main issue with parallel simulations is keeping LPs synchronized in order to avoid violating the causality of events Without synchronization a message sent by one LP could arrive in another LP when the simulation time in the receiving LP has already passed the timestamp arrival time of the message This would break causality of events in the receiving LP There are two broad categories of parallel simulation algorithms that differ in the way they handle causality problems outlined above 000 Conservative algorithms prevents incausalities from happening The Null Message Algorithm exploits knowledge of the time when LPs send messages to other LPs and uses null messages to propagate this information to other LPs If an LP knows it won t receive any messages from other LPs until A t simulation time it may advance until t A t without the need for external synchronization Conservative simulation tends to converge to sequential simulati
101. the allowed maximum stack size up to 64M ulimit s 65500 ulimit s 65500 Further increase is only possible if you re root Resource limits are inherited by child processes The following sequence can be used under Linux to get a shell with 256M stack limit S su root Password ulimit s 262144 su andras ulimit s 262144 If you do not want to go through the above process at each login you can change the limit in the PAM configuration files In Redhat Linux maybe other systems too add the following line to etc pam d login session required lib security pam_limits so and the following line to etc security limits conf ms hard stack 65536 A more drastic solution is to recompile the kernel with a larger stack limit Edit usr src linux include linux sched h and increase _STK_LIM from 8 1024 1024 to 64 1024 1024 Finally it you re tight with memory you can switch to Cmdenv Tkenv increases the stack size of each module by about 32K so that user interface code that is called from a simple module s context can be safely executed Cmdenv does not need that much extra stack Eventually http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Once you get to the point where you have to adjust the total stack size to get your program running you should probably consider transforming some of your activity simple modules to handleMessage activity does no
102. the block source icon 20 red display i block source red 20 gen If you want to show state information about your module you can use the i2 tag to add a small status icon to your main icon This icon is displayed in the upper right corner of your main icon In most cases the i2 tag is specified at runtime using the setDisplayString method so the icon can be changed dynamically based on the module s internal state display i block queue i2 status busy fii server Shapes If you want to have simple but resizable representation for your module you can use the b tag to create geometric shapes Currently oval and rectangle is supported an oval shape with 70x30 size red background black 4 pixel border display b 70 30 oval red black 4 source Positioning coordinates http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual To define the position of a module inside an other one use the p tag If you do not specify a p tag for your module the parent module will automatically choose a position based on a layouting algorithm The following example will place the module at the given position adiisp kay GPE 30F nOr NOTE The coordinates specified in the p b or r tags are not necessarily integers and measured in pixels You can use the parent module s bgs pix2unitratio unit tag to set the scaling parameter and the unit of measurement for your mod
103. the index in brackets That is for a module node 3 in the submodule vector node 10 getName http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual returns node and getFullName returns node 3 For other objects getFullName is the same as getName getFullPath returns getFullName prepended with the parent or owner object s getFullPath and separated by a dot That is if the node 3 module above is in the compound module net subnet1 its getFullPath method will return net subnet1 node 3 hf Sais hode gt node 3 Md Wneic Silomerc l inocke 3 ev lt lt this gt getName ev lt lt this gt getFullName ev lt lt this gt getFullPath getClassName getFullName and getFullPath are extensively used on the graphical runtime environment Tkenv and also appear in error messages getName and getFullName return const char pointers and getFullPath returns std string This makes no difference with ev lt lt but when getFullPath is used as a s argument to sprintf you have to write getFullPath c_str chorten IL 00 5 sprinti mag as 17803 msg getrullPath c str note c str 6 1 6 Copying and duplicating objects The dup member function creates an exact copy of the object duplicating contained objects also if necessary This is especially useful in the case
104. the target color is missing Brightness of icon is also affected to keep the original brightness specify a color with about 50 brightness e g 808080 mid grey 008000 mid http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual green Examples e i device server gold creates a gold server icon e i misc globe 808080 100 makes the icon greyscale e i block queue white 100 yields a burnt in black and white icon Colorization works with both submodule and message icons 10 4 The icons 10 4 1 The image path In the current OMNeT version module icons are PNG or GIF files The icons shipped with OMNeT are in the images subdirectory Both the graphical NED editor and Tkenv need the exact location of this directory to load the icons Icons are loaded from all directories in the image path a semicolon separated list of directories The default image path is compiled into Tkenv with the value omnetpp dir images images bitmaps which will work fine as long as you don t move the directory and you ll also be able to load more icons from the images subdirectory of the current directory As people usually run simulation models from the model s directory this practically means that custom icons placed in the images subdirectory of the model s directory are automatically loaded The compiled in image path can be overridden with the OMNETPP_IMAGE_PATH environment variable The way o
105. to filters that were active during simulation so the file can later be used to reproduce the history of the simulation on a sequence chart or in some other form The file is line oriented text file Blank lines and lines beginning with comments will get ignored Other lines begin with an entry identifier like amp for Event or BS for BeginSend followed by attribute identifier and value pairs One exception is debug output recorded from ev lt lt statements which are represented by lines that begin with a hypen and continue with the actual text lt file gt lt line gt lt line gt lt empty line gt lt user log message gt lt event log entry gt lt empty line gt CR LF lt user log message gt SPACE lt text gt CR LE lt event log entry gt lt event log entry Eype gt SPACE lt parameters gt CR LF lt event log entry type gt SB SE BU MB ME MC MD MR GC GD CC CD ES MS I CE BS ES I SD SH DMI E lt parameters gt lt parameter gt lt parameter gt lt name gt SPACE lt value gt lt name gt 23 gt lt Text gt lt value gt lt boolean gt lt integer gt lt text gt lt quoted text gt Here is a fragment of an existing eventlog file as an example E 14 t 1 018454036455 m 8 ce 9 msg 6 id 6 tid 6 c cMessa
106. to itself Events are consumed from the FES in arrival time order to maintain causality More precisely given two messages the following rules apply the message with earlier arrival time is executed first If arrival times are equal the one with smaller priority value is executed first If priorities are the same the one scheduled or sent earlier is executed first Priority is a user assigned integer attribute of messages 4 1 5 Simulation time The current simulation time can be obtained with the simTime function Simulation time in OMNeT is represented by the C type simtime_t which is by default a typedef to the SimTime class SimTime class stores simulation time in a 64 bit integer using decimal fixed point representation The resolution is controlled by the scale exponent global configuration variable that is SimTime instances have the same resolution The exponent can be between chosen between 18 attosecond resolution and 0 seconds Some exponents with the ranges they provide are shown in the following table 10 185 1as 9 228 10 15s 11s 153 72 minutes 12 s 1ps 106 75 days 10 95 ns 292 27 years Ea 10 8s 1us 292271 years 10 35 1ms 2 9227e8 years ai 2 9227e11 years Note that although simulation time cannot be negative it is still useful to be able to represent negative numbers because they often arise during the evaluation of
107. to redefine certain virtual functions and adhere to conventions and your class will be a bit more heavy weight However if you need to store your objects in OMNeT objects like cQueue or you ll want to store OMNeT classes in your object then you must subclass from cOwnedOb ject For simplicity in the these sections OMNeT object should be understood as object of a class subclassed from cOwnedOb ject The most significant features cOwnedOb ject has is the name string which has to be stored somewhere so it has its overhead and ownership management see section 6 11 which also has the advantages but also some costs As a general rule small struct like classes like IPAddress MACAddress RoutingTableEntry TCPConnectionDescriptor etc are better not sublassed from cOwnedOb ject If your class has at least one virtual member function consider subclassing from cOb ject which does not impose any extra cost because it doesn t have data members at all only virtual functions 6 10 2 cOWwnedObject virtual methods Most classes in the simulation class library are descendants of cOwnedOb ject If you want to derive a new class from cOwnedObject ora cOwnedObject descendant you must redefine some member functions so that objects of the new type can fully co operate with other parts of the simulation system A more or less complete list of these functions is presented here You do not need to worry about the length of the list
108. to use handleMessage instead Other simulators http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Coroutines are used by a number of other simulation packages e All simulation software which inherits from SIMULA e g C SIM is based on coroutines although all in all the programming model is quite different e The simulation parallel programming language Maisie and its successor PARSEC from UCLA also use coroutines although implemented with normal preemptive threads The philosophy is quite similar to OMNeT PARSEC being just a programming language it has a more elegant syntax but far fewer features than OMNeT e Many Java based simulation libraries are based on Java threads 4 3 3 initialize and finish Purpose initialize to provide place for any user setup code finish to provide place where the user can record statistics after the simulation has completed When and how they are called The initialize functions of the modules are invoked before the first event is processed but after the initial events starter messages have been placed into the FES by the simulation kernel Both simple and compound modules have initialize functions A compound module s initialize function runs before that of its submodules The finish functions are called when the event loop has terminated and only if it terminated normally i e not with a runtime error The callin
109. tools and the suggested porting produre are described in the Migration Guide 6 1 3 getClassName For each class the getClassName member function returns the class name as a string const char classname msg gt getClassName returns cMessage 6 1 4 Name attribute An object can be assigned a name a character string The name string is the first argument to the constructor of every Class and it defaults to NULL no name string An example cMessage timeoutMsg new cMessage timeout You can also set the name after the object has been created timeoutMsg gt setName timeout You can get a pointer to the internally stored copy of the name string like this const char name timeoutMsg gt getName gt timeout For convenience and efficiency reasons the empty string and NULL are treated as equivalent by library objects That is is stored as NULL but returned as If you create a message object with either NULL or as name string it will be stored as NULL and getName will return a pointer to a static cMessage msg new cMessage NULL lt additional args gt const char str msq SqecNeme s gt returns 6 1 5 getFullName and getFullPath Objects have two more member functions which return strings based on object names get FullName and getFullPath For gates and modules which are part of gate or module vectors getFullName returns the name with
110. tooltip etc compound modules networks display string can specify background color border color border thickness background image scaling grid unit of measurement etc e connections display string can specify positioning color line thickness line style text and tooltip e messages display string can specify icon icon color etc 10 1 1 Display string syntax The display string syntax is a semicolon separated list of tags Each tag consists of a key an equal sign and a comma separated list of arguments display p 100 100 b 60 10 rect blue black 2 Tag arguments may be omitted both at the end and inside the parameter list display p 100 100 b rect blue 10 1 2 Display string placement The following NED sample shows where to place display strings in the code simple Queue parame Censi display i block queue network SimpleQueue parameters display bgi maps europe submodules Simke Saemikes http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual adiis pilay WETA Or ORDE connections source out gt display ls red 3 gt queue int 10 1 3 Display string inheritance Every module and channel object has one single display string object which controls its appearance in various contexts The initial value of this display string object comes from merging the display properties occurring at various places in NED
111. try to use Tkenv for debugging While cMsgPar based message parameters can be viewed in message inspector windows fields added via subclassing do not appear there The reason is that Tkenv being just another C library in your simulation program doesn t know about your C instance variables The problem cannot be solved entirely within Tkenv because C does not support reflection extracting class information at runtime like for example Java does There is a solution however one can supply Tkenv with missing reflection information about the new class Reflection info might take the form of a separate C class whose methods return information about the RadioMsg fields This descriptor class might look like this class RadioMsgDescriptor public Descriptor jOWISIL ILE virtual int getFieldCount return 2 virtual const char getFieldName int k const char fieldname freq power if k lt O k gt 2 return NULL return fieldname k I virtual double getFieldAsDouble RadioMsg msg int k if k 0 return msg gt freq if k 1 return msg gt power return 0 0 not found http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual ee Then you have to inform Tkenv that a RadioMsgDescriptor exists and that it should be used whenever Tkenv finds messages of type RadioMsg as it is currently implemented whenever the object s
112. urstLength par burstLength eSiCoumesic lobieSic lysine ins schedule first packet of first burst scheduleAt simTime new cMessage or for void BurstyGenerator handleMessage cMessage msg generate amp send packet cMessage pkt new cMessage senci ERE ounce if this was the last packet of the burst if burstCounter 0 schedule next burst SUisS ECOuUMEC ae Me OUa Selim eite it scheduleAt SsimTime exponential 5 0 msg else schedule next sending within burst scheduleAt simTime exponential 1 0 msg Pros and Cons of using handleMessage Pros e consumes less memory no separate stack needed for simple modules e fast function call is faster than switching between coroutines Cons e local variables cannot be used to store state information e need to redefine initialize Usually handleMessage should be preferred to activity Other simulators Many simulation packages use a similar approach often topped with something like a state machine FSM which hides the underlying function calls Such systems are e OPNET which uses FSM s designed using a graphical editor e NetSim clones OPNET s approach e SMURPH University of Alberta defines a Somewhat eclectic language to describe FSMs and uses a precompiler to turn it into C code Ptolemy UC Berkeley uses a similar method OMNeT s FSM s
113. user input in the graphical user interface Tkenv the ev object cEnvir Class 6 1 Class library conventions 6 1 1 Base class Classes in the OMNeT simulation library are derived from cOwnedOb ject Functionality and conventions that come from cOwnedOb ject e name attribute e getClassName member and other member functions giving textual information about the object e conventions for assignment copying duplicating the object ownership control for containers derived from cOwnedOb ject e support for traversing the object tree e support for inspecting the object in graphical user interfaces Tkenv http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Classes inherit and redefine several cOwnedOb ject member functions in the following we ll discuss some of the practically important ones 6 1 2 Setting and getting attributes Member functions that set and query object attributes follow a naming convention the setter member function begins with set and the getter begins with get or in the case of boolean attributes with is or has whichever is more appropriate For example the ength attribute of the cPacket class can be set and read like this pk gt setBitLength 1024 length pk gt getBitLength NOTE OMNeT 3 x and earlier versions did not have the get verb in the name of getter methods There are scripts to port old source code to OMNeT 4 0 these
114. value from an enum which can be converted to a readable string with the get TypeName static method The enum values are BOOL DOUBLE LONG STRING and XML and since the enum is an inner type they usually have to be qualified with cPar isVolatile returns whether the parameter was declared volatile in the NED file isNumeric returns true if the parameter type is double or long The str method returns the parameter s value in a string form If the parameter contains an expression then the string representation of the expression gets returned An example usage of the above methods int n getNumParams for inte i 0 sy i Ceart par i http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual ev lt lt parameter lt lt p getName lt lt n ey lt lt type lt lt cPar getTypeName p getType lt lt T n ey lt lt T contains lt lt p st lt Tin The NED properties of a parameter can be accessed with the getProperties method that returns a pointer to the cProperties object that stores the properties of this parameter Specifically getUnit returns the unit of measurement associated with the parameter unit property in NED Further cPar methods and related classes like cExpression and cDynamicExpression are used by the NED infrastructure to set up and assign parameters They are documented in the API Reference
115. void HelloModule initialize ev lt MHEN NOr Ialn void HelloModule handleMessage cMessage msg delete msg just discard everything we receive In order to be able to refer to this simple module type in NED files we also need an associated NED declaration which might look like this file HelloModule ned simple HelloModule gates Wapu Liy 4 2 2 Constructor Simple modules are never instantiated by the user directly but rather by the simulation kernel This implies that one cannot write arbitrary constructors the signature must be what is expected by the simulation kernel Luckily this contract is very simple the constructor must be public and must take no arguments pubike HelloModule constructor takes no arguments cSimpleModule itself has two constructors cSimpleModule one without arguments cSimpleModule size_t stacksize one that accepts the coroutine stack size The first version should be used with handleMessage simple modules and the second one with activity modules With the latter the activity method of the module class runs as a coroutine which needs a separate CPU stack usually of 16 32K This will be discussed in detail later Passing zero stack size to the latter http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual constructor also selects handleMessage Thus the followin
116. void forEachChild cVisitor v The implementation should call the function passed for each object it contains via pointer or as data member see the API Reference on cOwnedOb ject on how to implement forBachChild forEachChild makes it possible for Tkenv to display the object http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual tree to you to perform searches on it etc It is also used by snapshot and some other library functions The following methods are recommended to implement e Object info std string info The info function should return a one line string describing the object s contents or state info is displayed at several places in Tkenv Detailed object info std string detailedInfo This method may potentially be implemented in addition to info it can return a multi line description detailedInfo is also displayed by Tkenv in the object s inspector e Serialization parsimPack and parsimUnpack methods These methods are needed for parallel simulation if you want objects of this type to be transmitted across partitions 6 10 3 Class registration You should also use the Register_Class macro to register the new class It is used by the createOne factory function which can create any object given the class name as a string createOne is used by the Envir library to implement omnetpp ini options such as rng class or scheduler class
117. while n _ are integers m__ and thus _ are typically real numbers The histogram estimate calculated from k split is not exact because the frequency counts calculated in the above manner contain a degree of estimation themselves This introduces a certain cell division error the A parameter should be selected so that it minimizes that error It has been shown that the cell division error can be reduced to a more than acceptable small value Strictly speaking the k split algorithm is semi online because its needs some observations to set up the initial histogram range Because of the range extension and cell split capabilities the algorithm is not very sensitive to the choice of the initial range so very few observations are sufficient for range estimation say Npre 10 Thus we can http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual regard k split as an on line method K split can also be used in semi online mode when the algorithm is only used to create an optimal partition from a larger number of Nore observations When the partition has been created the observation counts are cleared and the Nore observations are fed into k split once again This way all mother non leaf observation counts will be zero and the cell division error is eliminated It has been shown that the partition created by k split can be better than both the equi distant and the equal frequency partition OMNeT contains an
118. 0 20 32 29 OMNeT Manual the gate name plus an index in square brackets or gatename The gatename notation causes the first unconnected gate index to be used If all gates of the given gate vector are connected the behavior is different for submodules and for the enclosing compound module For submodules the gate vector expands by one For a compound module after the last gate is connected will stop with on error NOTE Why is it not possible to expand a gate vector of the compound module The model structure is built in top down order so new gates would be left unconnected on the outside as there is no way in NED to go back and connect them afterwards When the operator is used with i or So e g gSi or gSo see later it will actually add a gate pair input output to maintain equal gate size for the two directions Channel specification A channel specification gt channelspec gt inside a connection are similar to submodules in many respect Let s see some examples K gt i cllay limes gt lt gt delay 10ms datarate le 8 lt gt el Oe lt gt BBone cost 100 length 52km datarate le 8 lt gt lt gt display XXX lt gt lt e PLONG 4 Cdalsp lay Oo lt Wa When a channel type is missing one of the built in channel types will be used based on the parameters assigned in the connection If datarate ber or
119. 0 manual usman html 2009 4 20 20 32 29 OMNeT Manual virtual void initialize virtual void handleMessage cMessage msg Define_Module BurstyGenerator void BurstyGenerator initialize fsm setName fsm sleepTimeMean par sleepTimeMean burstTimeMean par burstTimeMean sendIATime par sendIATime msgLength amp par msgLength aL Oe WATCH i always put watches in initialize startStopBurst new cMessage StartStopBurst sendMessage new cMessage SendMessage scheduleAt 0 0 startStopBurst void BurstyGenerator handl ssage cMessage msg FSM_Switch fsm Case ISM lac INIT 3 transition to SLEEP state FSM_Goto fsm SLEEP break case FSM Enter SLEEP schedule end of sleep period start of next burst scheduleAt SsimTime exponential sleepTimeMean SCALMTSCLOOSUKSIt F break case FSM_Exit SLEEP Il echecule enci Of this burst scheduleAt simTime exponential burstTimeMean Starto tTopBuUr Sti transition to ACTIVE state Lit MEG T SEACCSCOMBUESic 1 erron slave llicl Swen ain Sicaice ACTIN FSM_Goto fsm ACTIVE break case FSM Enter ACTIVE schedule next sending scheduleAt simTime exponential sendIATime sendMessage break case FSM_Exit ACTIVE transition to either SEND or SLEEP i
120. 2 N 2 mean 0 4 The experiment measurement replication labels should be enough to reproduce the same simulation results given of course that the ini files and the model NED files and C code haven t changed Every instance of running the simulation gets a unique run ID We can illustrate this by listing the corresponding run IDs under each repetition in the tree For example PureAloha SN 1 mean 0 2 0 seed set 0 PureAloha 0 20070704 11 38 21 3241 PureAloha 0 20070704 11 53 47 3884 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual PureAloha 0O 20070704 16 50 44 4612 1 seed set 1 PureAloha 1 20070704 16 50 55 4613 2 seed set 2 PureAloha 2 20070704 11 55 23 3892 PureAloha 2 20070704 16 51 17 4615 The tree shows that PureAloha N 1 mean 0 2 0 seed set 0 was run three times The results produced by these three executions should be identical unless for example some parameter was modified in the ini file or a bug got fixed in the C code We believe that the default way of generating experiment measurement replication labels will be useful and sufficient in the majority of the simulation studies However you can customize it if needed For example here is a way to join two configurations into one experiment he on Con xperi g PureAloha_Part1 ment PureAloha Config PureAloha_Part2 xperiment PureAloha Measure
121. 2 Configuration To record an eventlog file during the simulation simply insert the following line into the ini file record eventlog true NOTE Since writing an eventlog file might significantly decrease overall simulation performance therefore eventlog recording is turned off by default 12 2 1 File Name The simulation kernel will write the eventlog file during the simulation into the file specified by the following ini file configuration entry showing the default file name pattern here eventlog file S resultdir configname runnumber elog 12 2 2 Recording Intervals The size of an eventlog file is approximately proportional to the number of events it contains To reduce the file size and speed up the simulation it might be useful to record only certain events The following ini file configuration entry instructs the kernel to record events with simulation time less than 10 2 between 22 2 and 100 and greater than 233 3 event log recording sinieciavells pollO 2 22a 00an 12 2 3 Recording Modules Another factor that affects the size of an eventlog file is the number of modules for which the simulation kernel records events during the simulation The following ini file configuration entry instructs the kernel to record only the events that occurred in any of the routers having index between 10 and 20 while turns off recording for all other modules This configuration key makes sense only for simple modules x
122. 9 5 2 What is Akaroa 9 5 3 Using Akaroa with OMNeT 9 6 Troubleshooting 9 6 1 Unrecognized configuration option 9 6 2 Stack problems 9 6 3 Memory leaks and crashes 9 6 4 Simulation executes slowly 10 Network Graphics And Animation 10 1 Display strings 10 1 1 Display string syntax 10 1 2 Display string placement 10 1 3 Display string inheritance 10 1 4 Display string tags used in submodule context 10 1 5 Display string tags used in module background context 10 1 6 Connection display strings 10 1 7 Message display strings 10 2 Parameter substitution 10 3 Colors 10 3 1 Color names 10 3 2 Icon colorization 10 4 The icons 10 4 1 The image path 10 4 2 Categorized icons 10 4 3 Icon size 10 5 Layouting 10 6 Enhancing animation 10 6 1 Changing display strings at runtime 10 6 2 Bubbles 11 Analyzing Simulation Results 11 1 Result files 11 1 1 Results 11 1 2 Output vectors 11 1 3 Format of output vector files 11 1 4 Scalar results 11 2 The Analysis Tool in the Simulation IDE 11 3 Scave Tool 11 3 1 Filter command 11 3 2 Index command 11 3 3 Summary command 11 4 Alternative statistical analysis and plotting tools 11 4 1 Spreadsheet programs 11 4 2 GNU R 11 4 3 MATLAB or Octave 11 4 4 NumPy and MatPlotLib 11 4 5 ROOT 11 4 6 Gnuplot http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 11 4 7 Grace 12 Eventlog 12 1 Introduction 12 2 Configuration 12 2 1 File Name 12 2 2 Recording Intervals 12
123. A IMPLI z T iD gt lt ELEMENT enum fields comment enum field gt c lt ELEMENT enum field comment gt lt ATTLIST enum field name NMTOKEN REQUIRED value CDATA IMPLIED gt lt Message class struct gt lt ELEMENT message comment property field gt lt ATTLIST message name NMTOKEN REQUIRED xtends nam NMTOKEN IMPLIED source code CDATA TMPLIED gt lt ELEMENT packet comment property field gt lt ATTLIST packet name NMTOKEN REQUIRED xtends nam NMTOKEN IMPLIED source code CDATA IMPLIED gt lt ELEMENT class comment property field gt lt ATTLIST class name NMTOKEN REQUIRED xtends nam NMTOKEN IMPLIED source code CDATA TMPLIED gt lt ELEMENT struct comment property field gt lt ATTLIST struct name NMTOKEN REQUIRED xtends nam NMTOKEN IMPLIED source code CDATA IMPLIED gt lt ELEMENT field comment gt lt ATTLIST field
124. BidirectionalChannel gawek TOOLE als LAOLE 97 moduleinterface IUnidirectionalChannel gatesi Loote Le out puto http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 17 3 Packages NED supports hierarchical namespaces called packages The solution is roughly modelled after Java s packages with minor changes 17 3 1 Package declaration The package of the declarations in a NED file is determined by the package declaration in the file package keyword A NED file may contain at most one package declaration If there is no package declaration the file s contents is in the default package Component type names must be unique within their package 17 3 2 Directory structure package ned Like in Java the directory of a NED file must match the package declaration However it is possible to omit directories at the top which do not contain any NED files like the typical org lt projectname gt directories in Java The top of a directory tree containing NED files is named a NED source folder The package ned file directly ina NED source folder plays a special role If there is no toplevel package ned or it contains no package declaration the declared package of a NED file in the folder lt srcfolder gt x y z mustbe x y z lf there is a toplevel package ned and it declares to be in package a b then any NED file in the folder lt srcfolder gt x y z must have the declared package a
125. CE NAME opt_interfaceinheritance opt_interfaceinheritance EXTENDS extendsnames http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual extendsnames extendsnames extendsname extendsname J simplemoduledefinition simplemoduleheader opt_paramblock opt_gateblock y J simplemoduleheader SIMPLE NAME opt_inheritance J compoundmoduledefinition compoundmoduleheader opt_paramblock opt_gateblock opt_typeblock opt_submodblock opt_connblock y 3 compoundmoduleheader MODULE NAME opt_inheritance J networkdefinition networkheader opt_paramblock opt_gateblock opt_typeblock opt_submodblock opt_connblock y J networkheader NETWORK NAME http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual opt_inheritance J moduleinterfacedefinition moduleinterfaceheader opt_paramblock opt_gateblock y J moduleinterfaceheader MODULEINTERFACE NAME opt_interfaceinheritance opt_paramblock opt_params PARAMETERS opt_params p opt_params params 3 params params paramsitem paramsitem 3 paramsitem param property H param param_typenamevalue pattern_value J param_typenamevalue param_typename opt_inline_properties param_typename opt_inline_properties paramvalue opt_inline_properties J http omnetpp org doc omnetpp40 manual usm
126. Caveats e f the full graph is too big after layouting it is scaled back so that it fits on the screen unless it contains any fixed position module For obvious reasons if there s a module with manually specified position we don t want to move that one To prevent rescaling you can specify a sufficiently large bounding box in the background display string e g b 2000 3000 e Size is ignored by the present layouter so longish modules such as an Ethernet segment may produce funny results e The algorithm is prone to produce erratic results especially when the number of submodules is small or when using predefined matrix row ring etc layouts The Re layout toobar button can then be very useful Larger networks usually produce satisfactory results e The algorithm is starting from random positions To get the best results you may experiment with different seeds by specifying them using the bgl seed display string tag 10 6 Enhancing animation 10 6 1 Changing display strings at runtime Often it is useful to manipulate the display string at runtime Changing colors icon or text may convey status change and changing a module s position is useful when simulating mobile networks Display strings are stored in cDisplayString objects inside channels modules and gates cDisplayString also lets you manipulate the string To get a pointer to the cDisplayString object you can call the components s getDisplayString method
127. D features The NED language has an equivalent tree representation which can be serialized to XML that is NED files can be converted to XML and back without loss of data including comments This lowers the barrier for programmatic manipulation of NED files for example extracting information refactoring and transforming NED generating NED from information stored in other system like SQL databases and so on NOTE This chapter is going to explain the NED language gradually via examples If you are looking for a more formal and concise treatment see Appendix 18 3 2 Warmup In this section we introduce the NED language via a complete and reasonably real life example a communication network Our hypothetical network consists of nodes One each node there s an application running which generates packets at random intervals The nodes are routers themselves as well We assume that the application uses datagram based communication so that we can leave out the transport layer from the model 3 2 1 The network First we ll define the network then in the next sections we ll continue to define the network nodes Let the network topology be as in Figure below http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual rte 8 Figure The network The corresponding NED description would look like this BR network M network Network submodules nodel Node node2 Node node3 N
128. ELD PATTERN FIELD PATTERN MATCH EXPRESSION Examples enter them without quotes x captures all fields of all messages xFrame Address Id captures all fields named somethingAddress and somethingId from messages of any class named somethingFrame MyMessage declaredOn MyMessage captures instances of MyMessage recording the fields declared on the MyMessage class not declaredOn cMessage and not declaredOn cNamedObject and not declaredOn cObject records user defined fields from all messages eventlog recording intervals lt custom gt per run setting Simulation time interval s when events should be recorded Syntax lt treom gt i ci lt Go gt That 1s both start and end of an Interval are optional and intervals are separated by comma Example 10 2 22 2 100 DO Saou xperiment label lt string gt default configname per run setting Identifies the simulation experiment which consists of several potentially repeated measurements This string gets recorded into result cS files and may be referred to during result analysis http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual exte fing nds lt string gt per run setting Name of the configuration this section is based on Entries from that section will be inherited and can be overridden In other words configuration lookups will fall back to the b
129. LCG32 at all cMersenneTwister is superior in every respect 8 7 5 Manual seed configuration In some cases you may want manually configure seed values Reasons for doing that may be that you want to use variance reduction techniques or you may want to use the same seeds for several simulation runs http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual To manually set seeds for the Mersenne Twister RNG use the seed kA mt option where k is the RNG index An example General mum rags 3 seed 0 mt 12 seed 1 mt 9 seed 2 mt 7 For the now obsolete cLCG32 RNG the name of the corresponding option is seed k 1cg32 and OMNeT provides a standalone program called opp_lcg32_seedtool to generate good seed values that are sufficiently apart in the RNG s sequence 9 Running Simulations 9 1 Introduction This chapter describes how to run simulations It covers basic usage user interfaces batch runs how to use Akaroa and also explains how to solve the most common errors 9 1 1 Running a simulation executable By default the output of an opp_makemake generated makefile is a simulation executable that can be run directly In simple cases this executable can be run without command line arguments but usually one will need to specify options to specify what ini file to use which user interface to activate where to load NED files from and so on Getting help The following sections d
130. LIME JOECLEOC OIL Wels value for SSAP DSAP in Ethernet frame double waitMean unit s mean for exponential interarrival times Gaels output out to Ethernet LLC You can also place comments above parameters and gates This is useful if they need long explanations Example Deletes packets and optionally keeps statistics aL mple Sink AS SSS parame tensi You can t rn statistics generation on and off This is a very long comment because it has to be described what Stacustives are collected or Nor book coimMleeeS ce atstsit es aerau ENE cUe gates Lagat alin 13 2 1 Private comments If you want a comment line not to appear in the documentation begin it with Those lines will be ignored by the documentation tool and can be used to make private comments like FIXME or TODO or to comment out unused code http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual An ad hoc traffic generator to test the Ethernet models TODO above description needs to be refined aL mple Gen aS 6 SS SSS akaaine ores string destAddress destination MAC address LINE jORCGEC Ce OL ucls value for SSAP DSAP in Ethernet frame double burstiness not yet supported double waitMean unit s mean for exponential interarrival times gates Output Othe TO Bthernet Lhe 13 2 2 More o
131. MNeT PDES implementation The parallel simulation subsytem is an optional component itself which can be removed from the simulation kernel if not needed It consists of three layers from the bottom up Communications Layer Partitioning Layer and Synchronization Layer The Communications Layer The purpose of the Communications Layer is to provide elementary messaging services between partitions for the upper layer The services include send blocking receive nonblocking receive and broadcast The send receive operations work with buffers which encapsulate packing and unpacking operations for primitive C types The message class and other classes in the simulation library can pack and unpack themselves into such buffers The Communications layer API is defined in the cParsimCommunications interface abstract class specific implementations like the MPI one cMPICommunications subclass from this and encapsulate MPI send receive calls The matching buffer class cMPICommBuf fer encapsulates MPI pack unpack operations The Partitioning Layer The Partitioning Layer is responsible for instantiating modules on different LPs according to the partitioning specified in the configuration for configuring proxy gates During the simulation this layer also ensures that cross partition simulation messages reach their destinations It intercepts messages that arrive at proxy gates and transmits them to the destination LP using the servi
132. Manual finishes If the first match is a lt parameter fullpath gt ask line the parameter will be asked from the user interactively UI dependent If there was no match and the parameter has a default value it is applied and the process finishes Otherwise the parameter is declared unassigned and handled accordingly by the user interface It may be reported as an error or may be asked from the user interactively 8 5 Parameter studies 8 5 1 Basic use It is quite common in simulation studies that the simulation model is run several times with different parameter settings and the results are analyzed in relation to the input parameters OMNeT 3 x had no direct support for batch runs and users had to resort to writing shell or Python Ruby etc scripts that iterated over the required parameter space and generated a partial ini file and run the simulation program in each iteration OMNeT 4 0 largely automates this process and eliminates the need for writing batch execution scripts It is the ini file where the user can specify iterations over various parameter settings Here s an example Config AlohaStudy SoiMimlloscs Stil 2 57r 10 50 step 10 x h host generationInterval exponential 0 2 0 4 O 6 s This parameter study expands to 8 3 24 simulation runs where the number of hosts iterates over the numbers 1 2 5 10 20 30 40 50 and for each host count three simulation runs will
133. Message msg double delay int gatelId sendDelayed cMessage msg double delay cGate gate The arguments are the same as for send except for the extra delay parameter The effect of the function is the same as if the module had kept the message for the delay interval and sent it afterwards That is the sending time of the message will be the current simulation time time at the sendDelayed call plus the delay The delay value must be non negative Example sendDelayed msg 0 005 outGate 4 6 6 Direct message sending Sometimes it is necessary or convenient to ignore gates connections and send a message directly to a remote destination module The sendDirect function does that sendDirect cMessage msg double delay cModule mod int gatelId sendDirect cMessage msg double delay cModule mod const char gateName int index 1 sendDirect cMessage msg double delay cGate gate In addition to the message and a delay it also takes the destination module and gate The gate should be an input gate and should not be connected In other words the module needs dedicated gates for receiving via sendDirect Note For leaving a gate unconnected in a compound module you ll need to specify connections nocheck instead of plain connections in the NED file An example cModule destinationModule getParentModule gt getSubmodule node2 doub
134. Module ModifiedTransportProtocol void ModifiedTransportProtocol recalculateTimeout fl aa 4 4 Accessing module parameters Module parameters declared in NED files are represented with the cPar class at runtime and be accessed by calling the par member function of cModule cPar amp delayPar par delay http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual cPar s value can be read with methods that correspond to the parameter s NED type boolValue longValue doubleValue stringValue stdstringValue xmlValue There are also overloaded type cast operators for the corresponding types boo1 integer types including int long etc double const char cXMLElement long numJobs par numJobs longValue double processingDelay par processingDelay using operator double Note that cPar has two methods for returning string value stringValue which returns const char and stdstringValue which returns std string For volatile parameters only stdstringValue may be used but otherwise the two are interchangeable If you use the par foo parameter in expressions Such as 4 par foo 2 the C compiler may be unable to decide between overloaded operators and report ambiguity In that case you have to clarify by adding either an explicit cast double par foo or long par foo or use the doubleValue or longValue metho
135. NewClass amp other virtual NewClass virtual NewClass dup const NewClass amp operator const NewClass amp other Wwiirtual yoi rortachCaile evisicoc ys yiectual srel sSewilime Laro l e We ll discuss the implementation method by method Here s the top of the cc file take New lasis ec Uff lm culbtGlem lt s t Galen M gt include lt string h gt imelude lt iostream h gt include newclass h Register_Class NewClass NewClass NewClass const char name int d cOwnedObject name Claica cls array new double 10 take amp queue MSE INUILUls The constructor above calls the base class constructor with the name of the object then initializes its own data members You need to call take for cOwnedObject based data members NewClass NewClass const NewClass amp other cOwnedObject other getName array new double 10 MSC NULLA take amp queue operator other The copy constructor relies on the assignment operator Because by convention the assignment operator does not copy the name member it is passed here to the base class constructor Alternatively we could have written setName other getName into the function body Note that pointer members have to be initialized to NULL or to an allocated object memory before calling the assignment operator to avoid crashes You need to call take for cOwnedObject based da
136. OGEwINnee OEOrOCOMSE NeE WOR lO Rom lai INMMOOIEIE Laer jOEOCOCOLS 5 5 Lj 5 import inet RoutingTable One asterisk stands for any character sequence not containing period two asterisks mean any character sequence which may contain period No other wildcards are recognized An import not containing wildcard MUST match an existing NED type However it is legal for an import that does contain wildcards not to match any NED type although that might generate a warning Inner types may not be referenced outside their enclosing types Base types and submodules Fully qualified names and simple names are accepted Simple names are looked up among the inner types of the enclosing type compound module then using imports then in the same package Parametric module types like submodules Lookup of the actual module type for like submodules differs from normal lookups This lookup ignores the imports in the file altogether Instead it collects all modules that support the given interface and match the given type name string i e end in the same simple name or have the same fully qualified name The result must be exactly one module type The algorithm for parametric channel types works in the same way Network name in the ini file The network name in the ini file may be given as fully qualified name or as simple unqualified name Simple unqualified names are tried with the same package as the ini file is in pr
137. OMNeT Manual OMNeT User Manual OMNeT version 4 0 Chapters 1 Introduction 2 Overview 3 The NED Language 4 Simple Modules 5 Messages 6 The Simulation Library 7 Building Simulation Programs 8 Configuring Simulations 9 Running Simulations 10 Network Graphics And Animation 11 Analyzing Simulation Results 12 Eventlog 13 Documenting NED and Messages 14 Parallel Distributed Simulation 15 Plug in Extensions 16 Embedding the Simulation Kernel 17 Appendix NED Reference 18 Appendix NED Language Grammar 19 Appendix NED XML Binding 20 Appendix NED Functions 21 Appendix Message Definitions Grammar 22 Appendix Display String Tags 23 Appendix Configuration Options 24 Appendix Result File Formats 25 Appendix Eventlog File Format Table of Contents 1 Introduction 1 1 What is OMNeT 1 2 Organization of this manual 1 3 Credits 2 Overview 2 1 Modeling concepts 2 1 1 Hierarchical modules 2 1 2 Module types http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 2 1 3 Messages gates links 2 1 4 Modeling of packet transmissions 2 1 5 Parameters 2 1 6 Topology description method 2 2 Programming the algorithms 2 3 Using OMNeT 2 3 1 Building and running simulations 2 3 2 What is in the distribution 3 The NED Language 3 1 NED overview 3 2 Warmup 3 2 1 The network 3 2 2 Introducing a channel 3 2 3 The App Routing and Queue simple modules 3 2 4 The Node
138. OMNeT Manual connections Modules contained in a compound module are called submodules and they are listed in the submodules section One can create arrays of submodules i e submodule vectors and the submodule type may come from a parameter Connections are listed under the connections section of the declaration One can create connections using simple programming constructs loop conditional Connection behaviour can be defined by associating a channel with the connection the channel type may also come from a parameter Module and channel types only used locally can be defined in the types section as inner types so that they don t pollute the namespace Compound modules may be extended via subclassing Inheritance may add new submodules and new connections as well not only parameters and gates also one may refer to inherited submodules to inherited types etc What is not possible is to de inherit submodules or connections or to modify inherited ones In the following example we show how one can assemble common protocols into a stub for wireless hosts and add user agents via subclassing Module types gate names etc used in the example are fictional not based on an actual OMNeT based model framework module WirelessHostBase gares Loput LaACHLOLN submodules ces TCR Hos IPs wlan Ieee80211 connections Ceppu pE epN Cao ciprn lt iD iccpOulcs ij ima COUNE gt wla
139. OMNeT into applications can be achieved by implementing a new user interface in addition to Cmdenv and Tkenv or by replacing Envir with another implementation of ev see sections 15 4 and 16 2 e Cmdenv and Tkenv are specific user interface implementations A simulation is linked with Cmdenv Tkenv or both The Model Component Library consists of simple module definitions and their C implementations compound module types channels networks message types and in general everything that belongs to models and has been linked into the simulation program A simulation program is able to run any model that has all necessary components linked in e The Executing Model is the model that has been set up for simulation It contains objects modules channels etc that are all instances of components in the model component library The arrows in the figure show how components interact with each other Executing Model lt gt Sim The simulation kernel manages the future events and invokes modules in the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual executing model as events occur The modules of the executing model are stored in the main object of Sim simulation of class cSimulation In turn the executing model calls functions in the simulation kernel and uses classes in the Sim library Sim lt gt Model Component Library The simulation kernel instantiates simple modules and other
140. RRGGBB or HHSSBB Default black is 0 icon size The size of the image Values very small vs small s normal n large l very large vl i r 3 range border width Border width of the range indicator Default 1 aueue ode oren elec pio pty bgb 0 bg width Width of the module background rectangle http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual bgb 1 bg height Height of the module background rectangle bgb 2 bg fill color Background fill color colorname or RRGGBB or HHSSBB Default grey82 bgb 3 bg border color Border color of the module background rectangle colorname or RRGGBB or HHSSBB Default black bgb 4 bg border width Border width of the module background rectangle Default 2 bgtt 0 bg tooltip Tooltip to be displayed over the module s background bgi 0 bg image An image to be displayed as a module background bgi 1 bg image mode How to arrange the module s background image Values fix f tile t stretch s center c Default fixed bgg 2 grid color Color of the grid lines colorname or RRGGBB or HHSSBB Default grey Is 0 line color Connection color colorname or RRGGBB or HHSSBB Default black Is 1 line width Connection line width Default 1 Is 2 line style Connection line style Values solid s dotted d dashed da Default solid 22 2 Message display string tags To customize the app
141. SIMTIME preprocessor macro during compiling OMNeT and the simulation models There are several macros that can be used in simulation models to make them compile with both double and SimTime simulation time SIMTIME_STR converts simulation time to a const char can be used in printf argument lists SIMTIME_DBL t converts simulation time to double SIMTIME_RAW t returns the underlying int64 or double STR_SIMTIME s converts string to simulation time and SIMTIME_TTOA buf t converts simulation time to string and places the result into the given buffer MAXTIME is also defined correctly for both simtime_t types NOTE Why did OMNeT switch to int 64 based simulation time double s mantissa is only 52 bits long and this caused problems in long simulations that relied on fine grained timing for example MAC protocols Other problems were the accumulation of rounding errors and non associativity often x y z x y z see Goldberg91what which meant that two double simulation times could not be reliably compared for equality 4 1 6 FES implementation The implementation of the FES is a crucial factor in the performance of a discrete event simulator In OMNeT the FES is implemented with binary heap the most widely used data structure for this purpose Heap is also the best algorithm we know although exotic data structur
142. T NAME EXTENDS NAME 3 class header CLASS NAME CLASS NAME EXTENDS NAME f b struct_ header STRUCT NAME STRUCT NAME EXTENDS NAME J body opt_fields_and_properties opt_propertiesblock_old opt_fieldsblock_old http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual opt_semicolon 3 opt_fields_and_properties fields_and_properties J fields_and_properties fields_and_properties field fields_and_properties property field property 3 field fieldmodifiers fielddatatype NAME opt_fieldvector opt_fieldenum opt_fieldvalue fieldmodifiers NAME opt_fieldvector opt_fieldenum opt_fieldvalue fieldmodifiers ABSTRACT READONLY ABSTRACT READONLY READONLY ABSTRACT J fielddatatype NAME NAME CHAR SHORT INT LONG UNSIGNED CHAR UNSIGNED SHORT UNSIGNED INT UNSIGNED LONG DOUBLE STRING BOOL J http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual opt_fieldvector T INTCONSTANT J T NAME T ITT H opt_fieldenum ENUM NAME J opt_fieldvalue fieldvalue J fieldvalue fieldvalue fieldvalueitem fieldvalueitem J fieldvalueitem STRINGCONSTANT CHARCONSTANT INTCONSTANT REALCONSTANT TRUE FALSE NAME EERE I HAF gt gt lt lt peT lt lt gt gt Pe P ZEA
143. a boot time configuration object The boot time configuration is always a SectionBasedConfiguration with InifileReader 10 Shared libraries get loaded see the 1 command line option and the load 1ibs configuration option This allows configuration classes to come from shared libraries 0O00 The configuration class configuration option is examined If it is present a configuration object of the given class is instantiated and replaces the boot time configuration The new configuration object is initialized from the boot time configuration so that it can read parameters e g database connection parameters XML file name etc from it Then the boot time configuration object is deallocated q0 The load 1ibs option from the new configuration object is processed 10 Then everything goes on as normally using the new configuration object Providing a custom configuration class http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual To replace the configuration object with your custom implementation you would write the class include cconfiguration h Class CUSICOMCOMIIgGUKaAcLOMm s joulolace CCOMEIG Use LOTE Register_Class CustomConfiguration and then activate it in the boot time configuration General cont igurat ion class CUS wom onf iguricion Providing a custom reader for SectionBasedConfiguration As said already writing a configu
144. age is turned off here with the allowunconnected modifier Consequently it is the simple modules responsibility not to send on a gate which is not leading anywhere Random graph Conditional connections can be used to generate random topologies for example The following code generates a random subgraph of a full graph module RandomGraph parameters iLiMic CGOUAE double connectedness 0 0 lt x lt 1 0 submodules node count Node gatesi alia eo uinic Oune eowliac connections allowunconnected tor I comume l Io count m MOCES la OU gt moade if i j amp amp uniform 0 1 lt connectedness Note the use of the allowunconnected modifier here too to turn off error messages given by the network setup code for unconnected gates 3 10 1 Connection patterns Several approaches can be used when you want to create complex topologies which have a regular structure three of them are described below Subgraph of a Full Graph This pattern takes a subset of the connections of a full graph A condition is used to carve out the necessary interconnection from the full graph http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual oie I OREN I J O0 NH 1 MOCKS a OUElsoo gt moOce 7 eao wit CGo mehicio m iL 3 p The RandomGraph compound module presented earlier is an example of this pattern but the pattern can generate any graph w
145. al NOTE The list of NED functions can be read in Appendix 20 The user can also extend NED with new functions this feature is described in XXX Expressions may refer to module parameters gate vector and module vector sizes using the sizeof operator and the index of the current module in a submodule vector index A Expressions may refer to parameters of the compound module being defined of the current module with the this prefix and to parameters of already defined submodules with the syntax submodule parametername or submodule index parametername volatile The volatile modifier causes the parameter s value expression to be evaluated every time the parameter is read This has significance if the expression is not constant for example it involves numbers drawn from a random number generator In contrast non volatile parameters are evaluated only once This practically means that they are evaluated and replaced with the resulting constant at the start of the simulation To better understand volatile let s suppose we have an ActiveQueue simple module that has a volatile double parameter named serviceTime The queue module s C implementation would re read the serviceTime parameter at runtime for every job serviced so if serviceTime Is assigned an expression like uniform 0 5s 1 5s every job would have a different random service time In practice a volatile parameter usually means that the underlying C code will re
146. al of the message is delayed by when it travels through the channel Bit error rate specifies the probability that a bit is incorrectly transmitted and allows for simple noisy channel modelling Data rate is specified in bits second and it is used for calculating transmission time of a packet http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual When data rates are in use the sending of the message in the model corresponds to the transmission of the first bit and the arrival of the message corresponds to the reception of the last bit This model is not always applicable for example protocols like Token Ring and FDDI do not wait for the frame to arrive in its entirety but rather start repeating its first bits soon after they arrive in other words frames flow through the stations being delayed only a few bits If you want to model such networks it is possible to change this default behaviour and deliver the message to the module when the first bit is received 2 1 5 Parameters Modules can have parameters Parameters can be assigned either in the NED files or the configuration file omnetpp ini Parameters may be used to customize simple module behaviour and for parameterizing the model topology Parameters can take string numeric or boolean values or can contain XML data trees Numeric values include expressions using other parameters and calling C functions random variables from differen
147. al usman html 2009 4 20 20 32 29 OMNeT Manual Several of the example simulations contain message definitions for example Tictoc Dyna Routing and Hypercube For example in Dyna you ll find this e dynapacket msg defines DynaPacket and DynaDataPacket e dynapacket_m h and dynapacket_m cc are produced by the message subclassing compiler from it and they contain the generated DynaPacket and DynaDataPacket C classes plus code for Tkenv inspectors e other model files client cc server cc use the generated message classes 5 2 9 What else is there in the generated code In addition to the message class and its implementation the message compiler also generates reflection code which makes it possible to inspect message contents in Tkenv To illustrate why this is necessary Suppose you manually subclass cMessage to get a new message class You could write the following Note that the code is only for illustration In real code freq and power should be private members and getter setter methods should exist to access them Also the above class definition misses several member functions constructor assignment operator etc that should be written class RadioMsg public cMessage pubike int freq double power hy Now it is possible to use RadioMsg in your simple modules RadioMsg msg new RadioMsg nsiG gt ineqg i msg gt power 10 0 You ll notice one drawback of this solution when you
148. alled when the simulations stops with an error message The destructor always gets called at the end no matter how the simulation stopped but at that time it is fair to assume that the simulation model has been halfway demolished already Based on the above the following conventions exist for these four methods e Constructor Set pointer members of the module class to NULL postpone all other initialization tasks to initialize e initialize Perform all initialization tasks read module parameters initialize class variables allocate dynamic data structures with new also allocate and initialize self messages timers if needed e finish Record statistics Do not delete anything or cancel timers all cleanup must be done in the destructor Destructor Delete everything which was allocated by new and is still held by the module class With self messages timers use the cancelAndDelete msg function It is almost always wrong to just delete a self message from the destructor because it might be in the scheduled events list The cancelAndDelete msg function checks for that first and cancels the message before deletion if necessary OMNeT prints the list of unreleased objects at the end of the simulation Simulation models that dump http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual undisposed object messages need to get their module destructors fixed As a temporary me
149. ally the t and tt tags are used at runtime with the setDisplayString method To see detailed descripton of the display string tags check Appendix 22 about display string tags 10 1 5 Display string tags used in module background context http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The following tags describe what a module looks like if opened in Tkenv They mostly deal with the module background e bgi background image e bgtt tooltip above the background e bgg background grid e bgl control child layouting e bgb background size color border e bgs scaling of background coordinates e bgp background coordinate offset In some cases it is required that the module s physical position should be modeled also in your model In this case you would set the submodule display strings with the setDisplayString method at run time but it would be also nice to customize the area in what the modules are moving It is possible to manipulate what a module s background looks like or whether we can use measurement units instead of pixels to set the position of the modules The following example demonstrates the use of module background tags The coordinates are given in km SI unit The bgs pixelsperunit unit specifies pixel unit ratio i e 1km is 0 075 pixel on the screen The whole area is 6000x4500km bgb and the map of Europe is used as a background and stretched to fill the mo
150. alues that do not fit the grammar notably those containing a comma or a semicolon need to be surrounded with double quotes When interpreting a property value one layer of quotes is removed automatically that is foo and foo are the same To add a value with quotation marks included enclose it in an extra layer of quotes foo Example prop marks the mark the mark the mark other marks Placement Properties may be added to NED files component types parameters gates submodules and connections For the exact syntax see Appendix 18 When a component type extends another component type s properties are merged This is described in section http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 17 4 17 Property declarations The property keyword is reserved for future use It is envisioned that accepted property names and property keys would need to be pre declared so that the NED infrastructure can warn the user about mistyped or unrecognized names 17 4 9 Parameters Parameters can be defined and assigned in the parameters section of component types In addition parameters can also be assigned in the parameters sections of submodule bodies and connection bodies but those places do not allow adding new parameters The parameters keyword is optional and can be omitted without change in the meaning A parameter is identified by a name and has a data type A param
151. an html 2009 4 20 20 32 29 OMNeT Manual param_typename opt_volatile paramtype NAME NAME J pattern_value 7 pattern paramvalue J paramtype DOUBLE INT STRING BOOL XML J opt_volatile VOLATILE 3 paramvalue expression DEFAULT expression DEFAULT ASK J opt_inline_properties inline_properties 3 inline_properties inline_properties property_namevalue property_namevalue J pattern pattern pattern_elem pattern_elem J http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual pattern_elem Wa pe NAME INTCONSTANT lees T pattern T T pattern IMPORT PACKAGE PROPERTY MODULE SIMPLE NETWORK CHANNEL MODULEINTERFACE CHANNELINTERFACE EXTENDS LIKE DOUBLE INT STRING BOOL XML VOLATILE INPUT OUTPUT INOUT IF FOR TYPES PARAMETERS GATES SUBMODULES CONNECTIONS ALLOWUNCONNECTED TRUE FALSE THIS DEFAULT CONST SIZEOF INDEX XMLDOC J property property_namevalue J property_namevalue property_name property_name opt_property_keys 3 property name NAME NAME T NAME 3 opt_property_keys property_keys 3 property_keys property_keys property _key property_key 3 property_key NAME property_values property_values J http omnetpp org doc omnetpp40
152. an html 2009 4 20 20 32 29 OMNeT Manual type By fully qualified name This is often cumbersome though as names tend to be too long IO Import the type then the simple name will be enough IO If the type is in the same package then it doesn t need to be imported it can be referred to by simple name Types can be imported with the import keyword by either fully qualified name or by a wildcard pattern In wildcard patterns one asterisk stands for any character sequence not containing period and two asterisks mean any character sequence which may contain period So any of the following lines can be used to import a type called inet protocols networklayer ip RoutingTable import inet protocols networklayer ip RoutingTable import inet protocols networklayer ip import inet protocols networklayer ip Ro Ta INMMOOIE GLINENE jOIeOICOCOLS 5 19 5 IMPON ERNE era ear ROUEN DIS If an import explicitly names a type with its exact fully qualified name then that type must exist otherwise it s an error Imports containing wildcards are more permissive it is allowed for them not to match any existing NED type although that might generate a warning Inner types may not be referred to outside their enclosing types so they cannot be imported either Name resolution with like The situation is a little different for submodule and connection channel specifications using the like keyw
153. an turn them off with lt nohtm1 gt see later Example http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual lt pre gt my preferred way of indentation in C C is this lt b gt for lt b gt lt b gt int lt b gt i 0 i lt 10 i i lt pre gt forealinteic i Taa a 31 6 SS SS SS SS SS S SSS SS SS SS ES SS will be rendered as my preferred way of indentation in C C is this for int i 0 i lt 10 itt pPrint 2a in a HTML is also the way to create tables The example below M Wi lt table border i gt Jl lt r gt lt r gt lt ra gt lt iclisimuinosiex lt clas lt tr gt H lt ces lt cd gt il lt eds lt ceSone lt ce gt Sf icie gt Va ees lt lt cds2 lt fed gt lt cechcwo lt ces gt STES Ui lt i gt lt C ee lt ceehtinree lt tcee lt tic gt lt table gt i if will be rendered approximately as gcc 13 3 4 Escaping HTML tags Sometimes may need to off interpreting HTML tags lt i gt lt b gt etc as formatting instructions and rather you want them to appear as literal lt i gt lt b gt texts in the documentation You can achieve this via surrounding the text with the lt nohtml1 gt lt nohtml1 gt tag For example Use the lt nohtml gt lt i gt lt nohtml gt tag like lt tt gt lt nohtml gt lt i gt this lt i gt lt nohtml gt lt tt gt Ji tO wreirce im lt iSitalie
154. andom number generators or PRNGs to highlight their deterministic nature There are real random numbers as well see e g http www random org http Awww comscire com or the Linux dev random device For non random numbers try www noentropy net Starting from the same seed RNGs always produce the same sequence of random numbers This is a useful property and of great importance because it makes simulation runs repeatable RNGs produce uniformly distributed integers in some range usually between 0 or 1 and 2 or so Mathematical transformations are used to produce random variates from them that correspond to specific distributions 6 4 1 Random number generators Mersenne Twister By default OMNeT uses the Mersenne Twister RNG MT by M Matsumoto and T Nishimura Matsumoto98 MT has a period of 219937 1 and 623 dimensional equidistribution property is assured MT is also very fast as fast or faster than ANSI C s rand The minimal standard RNG OMNeT releases prior to 3 0 used a linear congruential generator LCG with a cycle length of 231 2 described in Jain91 pp 441 444 455 This RNG is still available and can be selected from omnetpp ini Chapter 9 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual This RNG is only suitable for small scale simulation studies As shown by Karl Entacher et al in Entacher02 the cycle length of about 2 is too small on todays
155. ant we can just send out the original message there Also we can utilize gate IDs to spare looking up the gate by name for each send operation The optimized version of the code looks like this int outGateBaseId gateBaseld out Ose aimic a Op a lt ing arr send i n 1 msg msg gt dup outGateBaseldti Retransmissions Many communication protocols involve retransmissions of packets frames When implementing retransmissions you cannot just hold a pointer to the same message object and send it again and again you d get the not owner of message error on the first resend Instead whenever it comes to re transmission you should create and send copies of the message and retain the original When you are sure there will not be any more retransmission you can delete the original message Creating and sending a copy re transmit packet CMISSisalgems COO Oc el ket aO send copy out and finally when no more retransmissions will occur delete packet Why A message is like any real world object it cannot be at two places at the same time Once you ve sent it the message object no longer belongs to the module it is taken over by the simulation kernel and will eventually be delivered to the destination module The sender module should not even refer to its pointer any more Once the message arrived in the destination module that module will have full authority ov
156. anual usman html 2009 4 20 20 32 29 OMNeT Manual snapshot manager is cFileSnapshotManager defined in the Envir library The new class can be activated with the snapshotmanager class configuration option 15 3 Accessing the configuration config is the ini file plus ccc vvv options 15 3 1 Defining new configuration options New configuration options need to be declared with one of the appropriate registration macros These macros are Register_GlobalConfigOption ID NAME TYPE DEFAULTVALUE DESCRIPTION Register _PerRunConfigOption ID NAME TYPE DEFAULTVALUE DESCRIPTION Register_GlobalConfigOptionU ID Register_PerRunConfigOptionu ID U NAME UNIT DEFAULTVALUE DESCRIPTION NAME UNIT DEFAULTVALUE DESCRIPTION ID NAME TYPE DEFAULTVALUE DESCRIPTION ID NAME UNIT DEFAULTVALUE DESCRIPTION lt Register_PerObjectConfigOption Register_PerObjectConfigOption Config options come in three flavours as indicated by the macro names e Global options affect all configurations i e they are only accepted in the General section but not in Config lt name gt sections e Per Run options can be specified in any section i e both in General andin Config lt name gt sections e Per Object options The macro arguments are as follows e Di
157. arithmetic expressions http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The SimTime class performs additions and substractions as 64 bit integer operations Integer overflows are checked and will cause the simulation to stop with an error message Other operations multiplication division etc are performed in double then converted back to integer There is no implicit conversion from SimTime to double mostly because it would conflict with overloaded arithmetic operations of SimTime use the db1 method of Simtime to convert To reduce the need for db1 several functions and methods have overloaded variants that directly accept SimTime for example fabs fmod ceil floor uniform exponential and normal NOTE Converting a SimTime to double may lose precision because double only has a 52 bit mantissa Other useful methods of SimTime include str which returns the value as a string parse which converts a string to SimTime raw which returns the underlying int 64 value getScaleExp which returns the global scale exponent and getMaxTime which returns the maximum simulation time that can be represented at the current scale exponent Compatibility Earlier versions of OMNeT used double for simulation time To facilitate porting existing models to OMNeT 4 0 or later OMNeT can be compiled to use double for simt ime_t To enable this mode define the USE_DOUBLE_
158. ase section erprint lt string gt per run setting The expected fingerprint of the simulation When provided a fingerprint will be calculated from the simulation event times and other quantities during simulation and checked against the given one Fingerprints are Suitable for crude regression tests As fingerprints occasionally differ across platforms more than one fingerprint values can be specified here separated by spaces and a match with any of them will be accepted To calculate the initial fingerprint enter any dummy string such as none and run the simulation fname append host lt bool gt default false global setting load Turning it on will cause the host name and process Id to be appended to the names of output files e g omnetpp vec omnetpp sca This is especially useful with distributed simulation libs lt filenames gt global setting max A space separated list of dynamic libraries to be loaded on startup The libraries should be given without the ACH SO Sol sulfa x that will be automatically appended module nesting lt int gt default 50 per run setting The maximum allowed depth of submodule nesting This is used to catch accidental infinite recursions in NED meas lt obj sett ned netw num outp ru outp outp http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29
159. ases for entering and leaving each state FSM_Switch fsm case FSM Exit statel Mle break case FSM Enter statel ee break case FSM_Exit state2 MERE break case FSM Enter state2 anaes break see State transitions are done via calls to FSM_Goto which simply stores the new state in the cFSM object FSM Goto fsm textit newState The FSM starts from the state with the numeric code 0 this state is conventionally named INIT Debugging FSMs FSMs can log their state transitions ev with the output looking like this FSM GenState leaving state SLEEP FSM GenState entering state ACTIVE FSM GenState leaving state ACTIVE http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual FSM GenState entering state SEND FSM GenState leaving state SEND FSM GenState entering state ACTIVE FSM GenState leaving state ACTIVE FSM GenState entering state SLE AS W El 5 To enable the above output you have to define FSM_DEBUG before including omnetpp h define FSM_DEBUG enables debug output from FSMs include lt omnetpp h gt The actual logging is done via the FSM_Print macro It is currently defined as follows but you can change the output format by undefining FSM_Print after including omnetpp ini and providing a new definition instead d
160. asure these messages may be hidden by setting print undisposed false in the configuration NOTE The perform gc configuration option has been removed in OMNeT 4 0 Automatic garbage collection cannot be implemented reliably due to the limitations of the C language 4 2 4 An example The following code is a bit longer but actually useful simple module implementation It demonstrates several of the above concepts plus some others which will be explained in later sections IO constructor initialize and destructor conventions IODO using messages for timers IODO accessing module parameters IQ recording statistics at the end of the simulation 10 documenting the programmer s assumptions using ASSERT file EFGenerator h include lt omnetpp h gt Generates messages or jobs see NED file for more info aes class FFGenerator public cSimpleModule private cMessage sendMessageEvent long numSent PUDE FFGenerator virtual FFGenerator protected Wiecuall woe aLinsieaallawe virtual void handleMessage cMessage msg yircesal yore ciais r file EFEGenerator ce include FFGenerator cc register module class with opp Define Module FFGenerator FFGenerator FFGenerator sendMessageEvent NULL void FFGenerator initialize numSent 0 sendMessageEvent new cMessage sendMes
161. ata lt lt data lt lt array 0 lt lt array 0 return CViblic Sicie amp The info method should produce a concise one line string about the object You should try not to exceed 40 80 characters since the string will be shown in tooltips and listboxes See the virtual functions of cObject and cOwnedOb ject in the class library reference for more information The sources of the Sim library include src sim can serve as further examples 6 11 Object ownership management 6 11 1 The ownership tree OMNeT has a built in ownership management mechanism which is used for sanity checks and as part of the infrastructure supporting Tkenv inspectors Container classes like cQueue own the objects inserted into them But this is not limited to objects inserted into a container every cOwnedOb ject based object has an owner all the time From the user s point of view ownership is managed transparently For example when you create a new cMessage it will be owned by the simple module When you send it it will first be handed over to i e change ownership to the FES and upon arrival to the destination simple module When you encapsulate the message in another one the encapsulating message will become the owner When you decapsulate it again the currently active simple module becomes the owner The getOwner method defined in cOwnedOb ject returns the owner of the object cOwnedObject o msg gt getOwn
162. ate dependency info only files changed since you last compiled your project will be re compiled or linked opp_makemake automatically adds dependencies to the makefile You can regenerate the dependencies by typing make depend any time The warnings during the dependency generation process can be safely ignored You may generate and add dependencies to the makefile manually using the opp_makedep tool Use opp_makedep help to display the supported command line options NOTE The dependency generator does not handle conditional macros and includes Conditionally included header files are always added to the file s dependency list 7 2 8 Out of directory build http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The build system creates object and executable files in a separate directory called output directory The structure of the output folder will be the same as your sourcefolder structure except that it will be placed in the out configname directory The configname part will mirror your compiler toolchain and build mode settings i e The result of a debug build with gcc will be placed in out gcc debug The location of the generated output file is determined by the O option The default value is out relative to the project root directory opp_makemake 0 tmp obj NOTE The project directory is the first ancestor of the current directory which contains a project file NOTE Sou
163. ate properties The following properties are recognized on gates directIn and loose They have the same effect When either of them is present on a gate the gate is not required to be connected in the connections section of a compound module see 17 4 12 directiIn should be used when the gate is an input gate that is intended for being used as a target for the sendDirect method loose should be used in any other case when the gate is not required to be connected for some reason NOTE The reason directIn gates are not required to remain unconnected is that it is often useful to wrap such modules in a compound module where the compound module also has a directIn input gate that is internally connected to the submodule s corresponding gate Example gates input radioIn directIn 17 4 11 Submodules Submodules are defined in the submodules section of the compound module Submodules may be scalar or vector the vector size of the latter being specified with a numeric expression inside the square brackets Submodule type The simple or compound module type 17 4 1 17 4 2 that will be instantiated as the submodule may be specified in several ways e with a concrete module type name or e by astring valued expression that evaluates to the name of a module type or the type name may come from the configuration In the latter two cases the like keyword is used and a module interfa
164. ate shortest paths between nodes for you The mapping between the graph nodes edges and network model modules gates connections is preserved you can easily find the corresponding module for a cTopology node and vica versa 6 6 2 Basic usage You can extract the network topology into a cTopology object by a single function call You have several ways to select which modules you want to include in the topology e by module type e by a parameter s presence and its value e with a user supplied boolean function First you can specify which node types you want to include The following code extracts all modules of type Router or Host Router and Host can be either simple or compound module types CLCSOlOC yy LOOX topo extractByModuleType Router Host NULL Any number of module types can be supplied the list must be terminated by NULL A dynamically assembled list of module types can be passed as a NULL terminated array of const char pointers or in an STL string vector std vector lt std string gt An example for the former E KOPLO ITORO const char typeNames 3 typeNames 0 Router typeNames 1 Host typeNames 2 NULL topo extractByModuleType typeNames Second you can extract all modules which have a certain parameter topo extractByParameter ipAddress You can also specify that the parameter must have a certain value for the module to be included in the graph cMsgPar yes
165. ationvars2 Concatenation of all user defined iteration variables in name value form plus S repetition 24 Appendix Result File Formats The file format described here applies to both output vector and output scalar files Their formats are consistent only the types of entries occurring into them are different This unified format also means that they can be read with a common routine Result files are ine oriented A line consists of one or more tokens separated by whitespace Tokens either don t contain whitespace or whitespace is escaped using a backslash or are quoted using double quotes Escaping within quotes using backslashes is also permitted The first token of a line usually identifies the type of the entry A notable exception is an output vector data line which begins with a numeric identifier of the given output vector A line starting with as the first non whitespace character denotes a comment and is to be ignored during processing Result files are written from simulation runs A simulation run generates physically contiguous sets of lines into one or more result files That is lines from different runs do not arbitrarily mix in the files A run is identified by a unique textual runid which appears in all result files written during that run The runld may appear on the user interface so it should be somewhat meaningful to the user Nothing should be assumed about the particular format of r
166. ault cFileOutputScalarManager global setting Part of the Envir plugin mechanism selects the output scalar manager class to be used to record data passed to recordScalar The class has to implement the cOutputScalarManager interface outputvectormanager class lt string gt default cIndexedFileOutputVectorManager global setting Part of the Envir plugin mechanism selects the output vector manager class to be used to record data from output vectors The class has to implement the cOutputVectorManager interface parallel simulation lt bool gt default false global setting Enables parallel distributed simulation lt object full path gt param record as scalar lt bool gt default false per object setting Applicable to module parameters specifies whether the module parameter should be recorded into the output scalar file Set it for parameters whose ve value you ll need for result analysis parsim communications class lt string gt default cFileCommunications global setting If parallel simulation true it selects the class that implements communication between partitions The class must implement the eParsimCommunications interface parsim debug lt bool gt default true global setting With parallel simulation true turns on printing of log messages from the parallel simulation code parsim filecommunications prefix lt str
167. b x y z NOTE package ned files are allowed in other folders as well but they cannot be used to define the package they are in 17 4 Components Simple modules compound modules networks channels module interfaces and channel interfaces are called components 17 4 1 Simple modules Simple module types are declared with the simple keyword see the NED Grammar Appendix 18 for the syntax Simple modules may have properties 17 4 8 parameters 17 4 9 and gates 17 4 10 A simple module type may not have inner types 17 4 13 A simple module type may extend another simple module type and may implement one or more module interfaces 17 4 5 Inheritance rules are described in section 17 4 17 and interface implementation rules in section 17 4 16 Every simple module type has an associated C class which must be subclassed from cSimpleModule The way of associating the NED type with the C class is described in section 17 4 7 17 4 2 Compound modules http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Compound module types are declared with the module keyword see the NED Grammar Appendix 18 for the syntax Compound modules may have properties 17 4 8 parameters 17 4 9 and gates 17 4 10 its internal structure is defined by its submodules 17 4 11 and connections 17 4 12 and it may also have inner types 17 4 13 that can be used for submodule
168. ba on all computers in the cluster However because all OMNeT simulation processes run with the same settings they would overwrite each other s output files e g omnetpp vec omnetpp sca Your can prevent this from happening using the fname append host ini file entry General fname append host true When turned on it appends the host name to the names of the output files output vector output scalar snapshot files 9 6 Troubleshooting 9 6 1 Unrecognized configuration option If you receive an error message about unrecognized configuration options you may use h config or h configdetails options to display all possible configuration options and their descriptions 9 6 2 Stack problems Stack violation FooModule stack too small in module bar foo OMNeT detected that the module has used more stack space than it has allocated The solution is to increase the stack for that module type You can call the get StackUsage from finish to find out actually how much stack the module used Error Cannot allocate nn bytes stack for module foo bar The resolution depends on whether you are using OMNeT on Unix or on Windows Unix If you get the above message you have to increase the total stack size the sum of all coroutine stacks You can do so in omnetpp ini General total stack ko 20484 2MB There is no penalty if you set total stack kb too high recommend to set it to a few K less than the maxim
169. be done with the generation interval being exponential 0 2 exponential 0 4 and exponential 0 6 How does it get run First of all Cmdenv with the x option will tell you how many simulation runs a given section expands to You ll of course use Cmdenv for batch runs not Tkenv aloha u Cmdenv x AlohaStudy opp Discrete Event Simulation Config AlohaStudy Number of runs 24 If you add the g option the program will also print out the values of the iteration variables for each run Use G for even more info Note that the parameter study actually maps to nested loops with the last becoming the innermost loop The iteration variables are just named 0 and 1 we ll see that it is possible to give meaningful names to them Please ignore the repetition 0 part in the printout for now aloha u Cmdenv x AlohaStudy g opp Discrete Event Simulation Config AlohaStudy Number of runs 24 Run 0 0 1 1 0 2 Srepetition 0 Run 1 S 0 1 1 0 4 Srepetition 0 Rum 2 0 1 1 0 6 repetition 0 Run 3 0 2 1 0 2 Srepetition 0 Run 4 0 2 1 0 4 Srepetition 0 Run 5 0 2 1 0 6 Srepetition 0 Run 6 0 5 1 0 2 Srepetition 0 Run 7 0 5 1 0 4 Srepetition 0 Run 19 0 40 1 0 4 Srepetition 0 Run 20 0 40 1 0 6 Srepetition 0 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Run 21 S0 50 1 Ru
170. be used but one must explicitly choose one of them by providing a package name mobilityType inet adhoc RandomWalk The default package http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual It is not mandatory to make use of packages if all NED files are in a single directory listed on the NEDPATH then package declarations and imports can be omitted Those files are said to be in the default package 4 Simple Modules Simple modules are the active components in the model Simple modules are programmed in C using the OMNeT class library The following sections contain a short introduction to discrete event simulation in general explain how its concepts are implemented in OMNeT and give an overview and practical advice on how to design and code simple modules 4 1 Simulation concepts This section contains a very brief introduction into how Discrete Event Simulation DES works in order to introduce terms we ll use when explaining OMNeT concepts and implementation 4 1 1 Discrete Event Simulation A Discrete Event System is a system where state changes events happen at discrete instances in time and events take zero time to happen It is assumed that nothing i e nothing interesting happens between two consecutive events that is no state change takes place in the system between the events in contrast to continuous systems where state changes are continuous Those systems that ca
171. bed in the section 3 4 3 9 Connections Connections are defined in the connections section of compound modules Connections cannot span across hierarchy levels one can connect two submodule gates a submodule gate and the inside of the parent compound module s gates or two gates of the parent module though this is rarely useful It is not possible to connect to any gate outside the parent module or inside compound submodules Input and output gates are connected with a normal arrow and inout gates with a double headed arrow lt gt To connect the two gates with a channel use two arrows and put the channel specification in between The same syntax is used to add properties such as display to the connection Some examples have already been shown in the Warmup section 3 2 let s see some more It has been mentioned that an inout gate is basically an input and an output gate glued together These sub gates can also be addressed and connected individually if needed as port i and port o or for vector gates as port i k and port o k Gates are specified as modulespec gatespec to connect a submodule or as gatespec to connect the compound module modulespec is either a submodule name for scalar submodules or a submodule name plus an index in square brackets for submodule vectors For scalar gates gatespec is the gate name for gate vectors it is either http omnetpp org doc omnetpp40 manual usman html 2009 4 2
172. but also from your own message classes e use not only primitive types as fields but also structs classes or typedefs Sometimes you ll want to use a C type present in an already existing header file another time you ll want a struct or class to be generated by the message compiler so that you can benefit from Tkenv inspectors The following section describes how to do this Inheritance among message classes By default messages are subclassed from cMessage However you can explicitly specify the base class using the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual extends keyword message FooPacket extends FooBase For the example above the generated C code will look like class FooPacket public FooBase Inheritance also works for structs and classes see next sections for details Defining classes Until now we have used the message keyword to define classes which implies that the base class is cMessage either directly or indirectly But as part of complex messages you ll need structs and other classes rooted or not rooted in cOwnedOb ject as building blocks Classes can be created with the class class keyword structs we ll cover in the next section The syntax for defining classes is almost the same as defining messages only the class keyword is used instead of message Slightly different code is generated for classes that are rooted in cOwnedOb j
173. called variance reduction is also related to the use of different random number streams It is also important that different streams and also different simulation runs use non overlapping series of random numbers Overlap in the generated random number sequences can introduce unwanted correlation in your results The number of random number streams as well as seeds for the individual streams can be configured in omnetpp ini section 8 7 For the minimal standard RNG the seedtool program can be used for selecting good seeds section In OMNeT streams are identified with RNG numbers The RNG numbers used in simple modules may be arbitrarily mapped to the actual random number streams actual RNG instances from omnetpp ini section 8 7 The mapping allows for great flexibility in RNG usage and random number streams configuration even for simulation models which were not written with RNG awareness 6 4 3 Accessing the RNGs The intrand n function generates random integers in the range 0 n 1 and dblrand generates a random double on 0 1 These functions simply wrap the underlying RNG objects Examples int dice double p 1 intrand 6 result of intrand 6 is in the range 0 5 dblrand dblrand produces numbers in 0 1 They also have a counterparts that use generator k int dice 1 genk_intrand k 6 uses generator k double prob genk_dblrand k fp The underlying RNG objects are subclassed
174. ce type 17 4 5 needs to be specified as well which the concrete module type needs to implement to be eligible to be chosen In the second case the string expression is specified in angle braces lt gt in the third case an empty pair of angle braces is used lt gt See the NED Grammar Appendix 18 for the exact syntax NOTE When using the lt gt syntax the actual NED type should be provided with the type name configuration option host 0 3 type name MobileHost Parameters gates A submodule definition may or may not have a body a curly brace delimited block An empty submodule body is equivalent to a missing one A submodule body may contain parameters 17 4 9 and gates 17 4 5 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual A submodule body cannot define new parameters or gates It is only allowed to assign existing parameters and to set the vector size of existing gate vectors It is also allowed to add or modify properties and parameter gate properties 17 4 12 Connections Connections are defined in the connections section of the compound module Normally all gates must be connected including submodule gates and the gates of the compound module When the allowunconnected modifier is present after connections gates will be allowed to be left unconnected NOTE The directIn and loose gate properties are alternatives to the connections allo
175. ces of the Communications Layer The receiving LP unpacks the message and injects it at the gate the proxy gate points at The implementation basically encapsulates the cParsimSegment cPlaceholderModule cProxyGate Classes The Synchronization Layer The Synchronization Layer encapsulates the parallel simulation algorithm Parallel simulation algorithms are also represented by classes subclassed from the cParsimSynchronizer abstract class The parallel simulation algorithm is invoked on the following hooks event scheduling processing model messages outgoing from the LP and messages model messages or internal messages arriving from other LPs The first hook event scheduling is a function invoked by the simulation kernel to determine the next simulation event it also has full access to the future event set FES and can add remove events for its own use Conservative parallel simulation algorithms will use this hook to block the simulation if the next event is unsafe e g the null message algorithm implementation cNullMessageProtocol1 blocks the simulation if an EIT has been reached until a null message arrives see bagrodia00 for terminology also it uses this hook to periodically send null messages The second hook is invoked when a model message is sent to another LP the null message algorithm uses this hook to piggyback null messages on outgoing model messages The third hook is invoked when any message arrives from other LPs and it all
176. ces the first occurrence of substr in s with the string repl If startPos is given search begins from position startPos in s e startsWith bool startsWith string s string substr Returns true if s begins with the substring substr e substring string substring string s long pos long len Return the substring of s starting at the given position either to the end of the string or maximum len characters e substringAfter string substringAfter string s string substr Returns the substring of s after the first occurrence of substr or the empty string if s does not contain substr e substringAfterLast string substringAfterLast string s string substr Returns the substring of s after the last occurrence of substr or the empty string if s does not contain substr e substringBefore string substringBefore string s string substr Returns the substring of s before the first occurrence of substr or the empty string if s does not contain substr e substringBeforeLast string substringBeforeLast string s string substr Returns the substring of s before the last occurrence of substr or the empty string if s does not contain substr e tail string tail string s long len Returns the last len character of s or the full s if it is shorter than len characters toLower string toLower string s Converts s to all lowercase and returns the result e toUpper string toUpper string s Converts s to all uppercase and return
177. ched simulation stopped ce Calling finish at end of Run 0 End As Cmdenv runs the simulation periodically it prints the sequence number of the current event the simulation time the elapsed real time and the performance of the simulation how many events are processed per second the first two values are 0 because there wasn t enough data for it to calculate yet At the end of the simulation the finish methods of the simple modules are run and the output from them are displayed On my machine this run took 34 seconds This Cmdenv output can be customized via omnetpp ini entries The output file results Fifol 0 vec contains vector data recorded during simulation here queueing times and it can be processed using the IDE or other tools 9 2 2 Command line switches The command line environment allows you to specify more than one run by using the r 2 4 6 8 format See 9 4 for more information about running simulation batches 9 2 3 Cmdenv ini file options cmdenv runs to execute specifies which simulation runs should be executed It accepts a comma separated list of run numbers or run number ranges e g 1 3 4 7 9 If the value is missing Cmdenv executes all runs that have ini file sections if no runs are specified in the ini file Cmdenv does one run The r command line option overrides this ini file setting Cmdenv can be executed in two modes selected by the cmdenv express mode ini file option
178. commands for users 12 3 1 Filter The eventlog tool provides off line filtering that is usually applied to the eventlog file after the simulation has been finished and before actually opening it in the OMNeT IDE or processing it by any other means Use the filter command and its various options to specify what should be present in the result file 12 3 2 Echo Since the eventlog file format is text based and users are encouraged to implement their own filters therefore there needs to be a way to check whether an eventlog file is correct The echo command provides a way to check this and help users creating custom filters Anything not echoed back by the eventlog tool will not be taken into consideration by the other tools found in the OMNeT IDE NOTE Custom filter tools should filter out whole events only otherwise the consequences are undefined 13 Documenting NED and Messages 13 1 Overview OMNeT provides a tool which can generate HTML documentation from NED files and message definitions Like Javadoc and Doxygen the NED documentation tool makes use of source code comments The generated HTML documentation lists all modules channels messages etc and presents their details including description gates http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual parameters unassigned submodule parameters and syntax highlighted source code The documentation also includes clickable network diagram
179. contains no wait and it has only one receive call at the top of an infinite loop there s no point in using activity and the code should be written with handleMessage The body of the infinite loop would then become the body to handleMessage state variables inside activity would become data members in the module class and you d initialize them in initialize Example WOLGC Slak sae cawaley while true msg receive g delete msg should rather be programmed as void Sink handleMessage cMessage msg delete msg Activity is run as a coroutine activity is run in a coroutine Coroutines are a sort of threads which are scheduled non preemptively this is also called cooperative multitasking From one coroutine you can switch to another coroutine by a transferTo otherCoroutine call Then this coroutine is suspended and otherCoroutine will run Later when otherCoroutine does a transferTo firstCoroutine call execution of the first coroutine will resume from the point of the transferTo otherCoroutine Call The full state of the coroutine including local variables are preserved while the thread of execution is in other coroutines This implies that each coroutine must have its own processor stack and transferTo involves a switch from one processor stack to another Coroutines are at the heart of OMNeT and the simulation programmer doesn t ever need to call transferTo or oth
180. ct API expressed as a C class and registering the implementation after that the new communications mechanism can be selected for use in the configuration New PDES synchronization algorithms can be added in a similar way PDES algorithms are also represented by C classes that have to implement a very small API to integrate with the simulation kernel Setting up the model on various LPs as well as relaying model messages across LPs is already taken care of and not something the implementation of the synchronization algorithm needs to worry about although it can intervene if needed because the necessary hooks are provided The implementation of the Null Message Algorithm is also modular in itself in that the lookahead discovery can be plugged in via a defined API Currently implemented lookahead discovery uses link delays but it is possible to implement more sophisticated ones and select them in the configuration 14 3 2 Parallel Simulation Example We will use the Parallel CQN example simulation for demonstrating the PDES capabilities of OMNeT The model consists of N tandem queues where each tandem consists of a switch and k single server queues with exponential http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual service times Figure below The last queues are looped back to their switches Each switch randomly chooses the first queue of one of the tandems as destination using uniform distribut
181. ct the stack violation To be able to make a good guess about stack size you can use the get StackUsage Call which tells you how much stack the module actually uses It is most conveniently called from finish void FooModule finish ev lt lt getStackUsage lt lt bytes of stack used n The value includes the extra stack added by the user interface library see extraStackforEnvir in envir omnetapp h which is currently 8K for Cmdenv and at least 16K for Tkenv The actual value is platform dependent get StackUsage also works by checking the existence of predefined byte patterns in the stack area so it is also subject to the above effect with local variables 6 10 Deriving new classes http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 6 10 1 cOwnedObject or not If you plan to implement a completely new class as opposed to subclassing something already present in OMNeT you have to ask yourself whether you want the new class to be based on cOwnedOb ject or not Note that we are not saying you should always subclass from cOwnedOb ject Both solutions have advantages and disadvantages which you have to consider individually for each class cOwnedOb ject already carries or provides a framework for significant functionality that is either relevant to your particular purpose or not Subclassing cOwnedOb ject generally means you have more code to write as you have
182. ctor size CDATA IMPLIED gt lt ELEMENT types comment channel channel interfac lt ELEMENT submodules comment submodule gt lt ELEMENT submodule comment expression http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 compound module modul parameters simole module interface gt gates gt gates connections OMNeT Manual lt ATTLIST submodule name type like type like param vector size lt ELEMENT connection lt ATTLIST connection allow unconnect lt ELEMENT connection lt ATTLIST connection src module src module inde sre gate src gate pluspl src gate index src gate subg dest module dest module index dest gate dest gate plusp dest gate index dest gate subg arrow direction lt EL EM ENT channel spec NMTOKEN REQUIRED CDATA IMPLIED CDATA IMPLIED CDATA Pi LED CDATA IMPLIED gt s comment connection connection group gt S ed true false comment false gt expression channel spec Locoplcondition gt NMTOKEN PLIED x CDATA PLIED NMTOKEN REQUIRE us true false fal
183. ctorManager These lines cause the simulation to obtain random numbers from Akaroa and allows data written to selected output vectors to be passed to Akaroa s global data analyser For more details on the plugin mechanism these settings make use of see section Akaroa s RNG is a Combined Multiple Recursive pseudorandom number generator CMRG with a period of approximately 219 random numbers and provides a unique stream of random numbers for every simulation engine It is vital to obtain random numbers from Akaroa otherwise all simulation processes would run with the same RNG seeds and produce exactly the same results Then you need to specify which output vectors you want to be under Akaroa control By default all output vectors are under Akaroa control the lt modulename gt lt vectorname gt with akaroa false setting can be used to make Akaroa ignore specific vectors You can use the wildcards here see section 8 4 1 For example if you only want a few vectors be placed under Akaroa you can use the following trick true true lt modulename gt lt vectornamel gt with akaroa lt modulename gt lt vectorname2 gt with akaroa oll http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual xx x with akaroa false catches everything not matched above Using shared file systems It is usually practical to have the same physical disk mounted e g via NFS or Sam
184. d STLMessage const STLMessage amp other STLMessage_Base other getName operator other STLMessage amp operator const STLMessage amp other if amp xother this return this STLMessage_Base operator other foo other foo bar other bar ieee S EMS virtual STLMessage dup return new STLMessage this foo methods virtual void setFooArraySize unsigned int size virtual unsigned int getFooArraySize const return foo size virtual Item amp getFoo unsigned int k return foo k virtual void setFoo unsigned int k const Item amp afoo foo k afoo virtual void addToFoo const Item amp aroo foo push_back afoo bar methods virtual void setBarArraySize unsigned int size virtual unsigned int getBarArraySize const return bar size virtual Item amp getBar unsigned int k throw cRuntimeException sorry virtual void setBar unsigned int k const Item amp bar throw cRuntimeException sorry virtual void barPush const Item amp abar bar push abar yvirc al woslcl barropl Toar 009 p virtual Item amp barTop return bar top Register_Class STLMessage Some additional notes IO setFooArraySize setBarArraySize are redundant IOO getBar int k cannot be implemented in a straightforward way std stack
185. d cSocketRTScheduler which is part of the Sockets sample simulation 15 2 3 Defining a new configuration provider Overview The configuration provider plug in lets you replace ini files with some other storage implementation for example a database The configuration provider C class must implement the cConfigurationEx interface and can be activated with the configuration class configuration option The cConfigurationEx interface abstracts the inifile based data model a little It assumes that the configuration data consists of several named configurations Before every simulation run one of the named configurations get activated and from then on all queries into the configuration operate on the active named configuration only It practice you ll probably use the SectionBasedConfiguration Class in src envir or subclass from it because it already implements a lot of functionality that otherwise you would have to SectionBasedConfiguration does not assume ini files or any other particular storage format instead it accepts an object that implements the cConfigurationReader interface to provides the data in raw form to it The default implementation of cConfigurationReader IS InifileReader The startup sequence From the configuration plug in s point of view the startup sequence looks like the following see src sim bootenv cc in the source code First ini files specified on the command line are read into
186. d on a specific gate given with id or name index bool aAicwiweclOim alin uel gt bool arrivedOn const char gname int gindex 0 The following methods return message creation time and the last sending and arrival times simtime_t getSendingTime simtime_t getArrivalTime simtime_t getCreationTime 1 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Control info One of the main application areas of OMNeT is the simulation of telecommunication networks Here protocol layers are usually implemented as modules which exchange packets Packets themselves are represented by messages subclassed from cMessage However communication between protocol layers requires sending additional information to be attached to packets For example a TCP implementation sending down a TCP packet to IP will want to specify the destination IP address and possibly other parameters When IP passes up a packet to TCP after decapsulation from the IP header it ll want to let TCP know at least the source IP address This additional information is represented by control info objects in OMNeT Control info objects have to be subclassed from cObject a small footprint base class with no data members and attached to the messages representing packets cMessage has the following methods for this purpose void setControliInfo cObject controlinfo cObject getControlinfo cObject removeControlin
187. d with other tools like gnuplot see 11 4 6 When scavetool is invoked without arguments it prints usage information scavetool lt command gt options lt file gt 11 3 1 Filter command The result files can be filtered and processed by this command and the result can be written into files as vector files CSV files Matlab or Octave files The filter can be specified by the itshape p lt filter gt option The filter is one or more itshape lt fieldname gt lt pattern gt expression connected with AND OR and NOT operators The possible field names are e file full path of the result file e run run identifier e module module name e name vector name attr lt runAttribute gt value of an attribute of the run e g experiment param lt moduleParameters gt value of the parameter in the run Processing operations can be applied to vectors by the itshape a lt function gt lt parameterlist gt option You can list the available functions and their parameters by the itshape info command The name and format of the output file can be given by the itshape O lt file gt and itshape F lt formatname gt options where the formatname is one of e vec vector file default e csv CSV file e octave Octave text file e matlab Matlab script file Examples scavetool filter p queuing time a winavg 10 0 out vec in vec Writes the window averaged queuing times stored in in vec into out vec scav
188. dNedText The first one loads a whole subdirectory tree the second one loads a single NED file and the third takes a literal string containing NED code and parses that one NOTE One use of loadNedText is to parse NED sources previously converted to C string constants and linked into the executable This allows for creating executables that are self contained and do not need NED files to be distributed with them The above functions can be mixed as well but after the last call doneLoadingNedFiles must be invoked it checks for unresolved NED types Loading NED files has global effect and they cannot be unloaded 16 2 6 How to eliminate NED files It is possible to get rid of NED files altogether This would also remove the dependency on the oppnedxml1 library and the code in sim netbuilder as well albeit at the cost of additional coding NOTE When the only purpose is to get rid of NED files as external dependency of the program it is simpler to use loadNedText on NED files converted to C string constants instead The trick is to write cCModuleType and cChannelType objects for your simple module compound module and channel types and register them manually For example cModuleType has pure virtual methods called createModuleObject addParametersAndGatesTo module setupGateVectors module buildInside module which you need to implement The body of the buildInside method would be similar to C files genera
189. ded scalars for example in an std map where the main program can find them later Values from output vectors can be captured in a similar way A draft implementation class CustomSimulationEnv g public cNullEnvir private std map lt std string double gt results fololbiek virtual void recordScalar cComponent component const char name double value opp_string_map attributes NULL results component gt getFullPath name value const std map lt std string double gt amp getResults return results const std map lt std string double gt amp results env gt getResults int numRequestsSent results Network client 2 app numRequestsSent double avgReplyTime results Network client 2 app avgReplyTime A drawback is that compile time checking of statistics names is lost but definite advantages include that any simulation model can now be used without changes and that capturing additional statistics does not require code modification in the main program http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 16 2 9 The simulation loop To run the simulation the selectNextModule and doOneEvent methods of cSimulation must be called in a loop while sim gt getSimTime lt limit cSimpleModule mod sim gt selectNextModule sim gt doOneEvent mod It depends on the
190. del If the run number or the RNG number is different OMNeT does its best to choose different seeds which are also sufficiently apart in the RNG s sequence so that the generated sequences don t overlap The run number can be specified either in in omnetpp ini e g via the cmdenv runs to execute entry or on the command line mysim r 1 e my sim r 2 mysim r 3 For the cMersenneTwister random number generator selecting seeds so that the generated sequences don t overlap is easy due to the extremely long sequence of the RNG The RNG is initialized from the 32 bit seed value seed runNumber numRngs rngNumber This implies that simulation runs participating in the study should have the same number of RNGs set While to our knowledge no one has proven that the seeds 0 1 2 are well apart in the sequence this is probably true due to the extremely long sequence of MT The author would however be interested in papers published about seed selection for MT For the cLCG32 random number generator the situation is more difficult because the range of this RNG is rather short 291 1 about 2 billion For this RNG OMNeT uses a table of 256 pre generated seeds equally spaced in the RNG s sequence Index into the table is calculated with the runNumber numRngs rngNumber formula Care should be taken that one doesn t exceed 256 with the index or it will wrap and the same seeds will be used again It is best not to use the c
191. denotes the module whose gates are being enumerated it can be replaced by any cModule variable http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual NOTE In earlier OMNeT versions gate IDs used to be small integers so it made sense to iterate over all gates of a module by enumerating all IDs from zero to a maximum skipping the holes NULLS This is no longer the case with OMNeT 4 0 and later versions Moreover the gate method now throws an error when called with an invalid ID and not just returns NULL Adding and deleting gates Although rarely needed it is possible to add and remove gates during simulation You can add scalar gates and gate vectors change the size of gate vectors and remove scalar gates and whole gate vectors It is not possible to remove individual random gates from a gate vector to remove one half of an inout gate e g gate o or to set different gate vector sizes on the two halves of an inout gate vector The cModule methods for adding and removing gates are addGate name type isvector false and deleteGate name Gate vector size can be changed by using set GateSize name size None of these methods accept i So suffix in gate names NOTE When memory efficiency is of concern it is useful to know that in OMNeT 4 0 and later a gate vector will consume significantly less memory than the same number of individual scalar gates cGate methods
192. directly to C classes is no longer supported in OMNeT 4 0 NED files are always dynamically loaded File names for libraries differ for Unix Linux and for Windows and also different for static and shared libraries Let us suppose you have a library called Tkenv If you are compiling with gcc or mingw the file name for the static library would be something like Libopptkenv d a and the shared library would be called libopptkenv d so libopptkenvd so would be used for the debug version while libopptkenv so is for the release build NOTE On Windows shared libraries have the d11 extension instead of so On Mac OS X shared libraries have the dylib extension instead of so In OMNeT 4 0 we recommend to use shared libraries whenever it is possible You ll need to link with the following libraries e The simulation kernel and class library called oppsim file Liboppsim so dll dylib etc User interfaces The common part of all user interfaces is the oppenvir library file liboppenvir so d1l dylib etc and the specific user interfaces are opptkenv and oppcmdenv libopptkenv so dll dylib liboppcmdenv so d1l1 dylib etc You have to link with oppenvir plus opptkenv or oppcmdenv or both Luckily you do not have to worry about the above details because automatic tools like opp_makemake will take care of the hard part for you The following figure gives an overview of the process of building and running simulation pr
193. doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual ps picosecond 1e 12s Kbps 1e3bps Mbps 1e6bps Gbps 1e9bps Tbps 1e12bps 1024B 1 04858e6B 1 07374e9B 1 09951e12B meter 1e3Hz 1e6Hz 1e9Hz millivolt 1e 3V s oO oO x Q T c J KB GB B m km m mm W mW Hz kHz MHz GHz kg kJ MJ V kV mV A 18 Appendix NED Language Grammar This appendix contains the grammar for the NED language http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual In the NED language space horizontal tab and new line characters count as delimiters so one or more of them is required between two elements of the description which would otherwise be unseparable two slashes may be used to write comments that last to the end of the line The language is fully case sensitive Notation e rule syntax is that of bison yacc e uppercase words are terminals lowercase words are nonterminals e NAME STRINGCONSTANT INTCONSTANT REALCONSTANT represent identifier names and string integer and real number literals defined as in the C language e other terminals represent keywords in all lowercase nedfile definitions r definitions definitions definition definition 3 definition packagedeclaration import propertydecl fileproperty channeldefinition channelinterfacedefinition simplemoduledefinition compound
194. does not support accessing elements by index It could still be implemented in a less efficient way using STL iterators and efficiency does not seem to be major problem because only Tkenv is going to invoke this function 100 setBar int k const Item could not be implemented but this is not particularly a problem The exception will materialize in a Tkenv error dialog when you try to change the field value You may regret that the STL vector stack are not directly exposed Well you could expose them by adding a vector lt Item gt amp getFoo return foo method to the class but this is probably not a good idea STL itself was purposefully designed with a low level approach to provide nuts and bolts for C programming and STL is better used in other classes for internal representation of data 5 2 8 Summary This section attempts to summarize the possibilities You can generate e classes rooted in cOwnedObject http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual messages default base class is cMessage e classes not rooted in cOwnedObject e plain C structs The following data types are supported for fields e primitive types bool char short int long unsigned short unsigned int unsigned long double e string a dynamically allocated string presented as const char e fixed size arrays of the above types e structs classes both r
195. dropped here http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The Windows version of OMNeT contains a redistribution of the MinGW gcc compiler together with a copy of MSYS that provides Unix tools commonly used in Makefiles The MSYS directory also contains various 3rd party open source libraries needed to compile and run OMNeT mingw MinGW gcc port msys MSYS plus libraries Sample simulations are in the samples directory samples directories for sample simulations aloha models the Aloha protocol cqn Closed Queueing Network The contrib directory contains material from the OMNeT community contrib directory for contributed material octave Octave scripts for result processing emacs NED syntax highlight for Emacs 3 The NED Language 3 1 NED overview The user describes the structure of a simulation model in the NED language NED stands for Network Description NED lets the user declare simple modules and connect and assemble them into compound modules The user can label some compound modules as networks self contained simulation models Channels are another component type whose instances can also be used in compound modules The NED language has several features which let it scale well to large projects e Hierarchical The traditional way to deal with complexity is via introducing hierarchies In OMNeT any module which would be too comple
196. ds 4 4 1 Volatile and non volatile parameters A parameter can be declared volatile inthe NED file The volatile modifier indicates that a parameter is re read every time a value is needed during simulation Volatile parameters typically are used for things like random packet generation interval and get values like exponential 1 0 numbers drawn from the exponential distribution with mean 1 0 In contrast non volatile NED parameters are constants and reading their values multiple times is guaranteed to yield the same value When a non volatile parameter is assigned a random value like exponential 1 0 it gets evaluated once at the beginning of the simulation and replaced with the result so all reads will get same randomly generated value The typical usage for non volatile parameters is to read them in the initialize method of the module class and store the values in class variables for easy access later class Source public cSimpleModule protected long numJobs yva metel yole sinalje walla we F void Sourees initialize numJobs par numJobs volatile parameters need to be re read every time the value is needed For example a parameter that represents a random packet generation interval may be used like this void Source handleMessage cMessage msg scheduleAt simTime par interval doubleValue timerMsg http omnetpp org doc omnetpp40 manual usman html 2009 4
197. dule background A light grey grid is drawn with a 1000km distance between major ticks and 2 minor ticks per major tick ogg tickdistance minorpermajorticks color See Figure below network EuropePlayground display bgb 6000 4500 bgi maps europe s bgg 1000 2 grey95 bgs 0 075 km Figure Background grid scaling and image After specifying the above bgs tag all your submodule coordinates will be treated as if they were specified in km To see detailed descripton of the display string tags check Appendix 22 about display string tags 10 1 6 Connection display strings Connections may also have display strings Connections inherit the display string property of their channel in the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual same way submodules inherit their display string from their types If no channel is specified for a connection IdealChannel1 will be used implicitly by the simulation kernel Connections support the following tags e 1s line shape and colors e t text e tt tooltip e m used for hinting Tkenv how the connections should route to from the module Example of a thick red connection souiceeil louie gt Qdisplay ls roed 2 gt queuel intt i queuel sourcel NOTE If you want to hide a connection specify width 0 for the connection i e use 1s 0 To see detailed descripton of these tags check
198. e gt gt syntax the actual NED type to be used will depend on the parameters set in the connection When no parameters are set ned IdealChannel Is chosen When only ned DelayChannel parameters are used delay and disabled ned DelayChannel is chosen When only ned DatarateChannel parameters are used datarate delay ber per disabled the chosen channel type will be ned DatarateChannel Unnamed channels connections cannot use any other parameters 17 4 13 Inner types Inner types are defined in the types section of the component type Inner types are only visible inside the enclosing component type 17 4 14 Name uniqueness Identifier names within a component must be unique That is submodule or inner type cannot be named the same or the same as a gate or parameter of the parent module 17 4 15 Type name resolution Names from other NED files can be referred to either by fully qualified name inet networklayer ip RoutingTable or by short name Rout ingTable if the name is visible http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Visible names are e inner types e anything from the same package e imported names Imports Imports have a similar syntax to Java but they are more flexible with wildcards All of the following are legal import inet protocols network ip RoutingTable impone sALMISIE sj OCOCOILS 5 nS wOiwls 1D 7 IMP
199. e Illustration of the k split algorithm k 2 The numbers in boxes represent the observation count values For density estimation the total number of observations that fell into each cell of the partition has to be determined For this purpose mother observations in each internal node of the tree must be distributed among its child cells and propagated up to the leaves Let n _ be the mother observation count for a cell s__ be the total observation count in a cell n _ plus the observation counts in all its sub sub sub etc cells and m the mother observations propagated to the cell We are interested inthe n m__ estimated amount of observations in the tree nodes especially in the leaves P aa ig T a aa aia h a E a a aiaiai aor a ai a rna A S Two natural distribution methods are even distribution when M 1 M__j 2 M__ k and proportional distribution when mM i1 M i277 M ik S i1 7 S i27 7 S ik Even distribution is optimal when the Sjj values are very small and proportional distribution is good when the s j values are large compared to m j In practice a linear combination of them seems appropriate where A 0 means even and A 7 means proportional distribution m _ij 1 A f kK A iS 57 8 where A is in 0 1 Thoo 7 ry 01 6 Noo 4 IE 1 7 TEE 2 42 2 4 2 l 7 0 4 5 Figure Density estimation from the k split cell tree We assume A 0 i e we distribute mother observations evenly Note that
200. e cModule parentmod convenience function to get a module up and running in one step mod modtyp SCreac eS Glaechwile limite Yinocke ENS It does create buildInside scheduleStart now callInitialize This method can be used for both simple and compound modules Its applicability is somewhat limited however because it does everything in one step you do not have the chance to set parameters or gate sizes and to connect gates before initialize is called initialize expects all parameters and gates to be in place and the network fully built when it is called Because of the above limitation this function is mainly useful for creating basic simple modules Expanded form If the previous simple form cannot be used There are 5 steps find factory object create module http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual set up parameters and gate sizes if needed call function that builds out submodules and finalizes the module call function that creates activation message s for the new simple getModule s Each step except for Step 3 can be done with one line of code See the following example where Step 3 is omitted tind factory Ob jvect cModuleType moduleType cModuleType get WirelessNode create possibly compound module and build its submodules if any cModule module moduleTyp Sereace Vinocke
201. e messageKind property of the message claisjolany Mo 15 15 rect wiit Kaliacl 5 5 NOTE In message display strings you may use the word kind as a special color This virtual color depends on the mes sageKind field in the message 10 2 Parameter substitution Parameters of the module or channel containing the display string can be substituted into the display string with the SparameterName notation Example simple MobileNode paramet ernsk double xpos double ypos Sicwime TLLLCOLOTE get the values from the module parameters xpos ypos fillcolor display p S xpos Sypos b 60 10 rect fillColor black 2 10 3 Colors 10 3 1 Color names Any valid Tk color specification is accepted English color names blue lightgrey wheat or rgb rrggbb format where r g b are hex digits It is also possible to specify colors in HSB hue saturation brightness as hhssbb with h s b being hex digits HSB makes it easier to scale colors e g from white to bright red You can produce a transparent background by specifying a hyphen as background color In message display strings kind can also be used as a special color name It will map to a color depending on the message kind See the getKind method of cMessage 10 3 2 Icon colorization The i display string tag allows for colorization of icons It accepts a target color and a percentage as the degree of colorization Percentage has no effect if
202. e schedule it at current sim time wait interval transferTo main retrieve current event if current event is not e error delete e note actual impl reuses events return Thus the receive and wait calls are special points in the activity function because they are where e simulation time elapses in the module and e other modules get a chance to execute Starter messages Modules written with activity need starter messages to boot These starter messages are inserted into the FES automatically by OMNeT at the beginning of the simulation even before the initialize functions are called Coroutine stack size The simulation programmer needs to define the processor stack size for coroutines This cannot be automated 16 or 32 kbytes is usually a good choice but you may need more if the module uses recursive functions or has local variables which occupy a lot of stack space OMNeT has a built in mechanism that will usually detect if the module stack is too small and overflows OMNeT can also tell you how much stack space a module actually uses so you can find out if you overestimated the stack needs initialize and finish with activity http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Because local variables of activity are preserved across events you can store everything state information packet buffers etc in them Local variables can be init
203. e code you d write is the following class FooPacket public FooPacket_Base here come the mandatory methods constructor copy constructor operator dup virtual void setPayloadLength int newlength void FooPacket setPayloadLength int newlength adjust message length setBitLength length getPayloadLength newlength http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual set the new length FooPacket_Base setPayloadLength newlength Abstract fields The purpose of abstract fields is to let you to override the way the value is stored inside the class and still benefit from inspectability in Tkenv For example this is the situation when you want to store a bitfield in a single int or short and still you want to present bits as individual packet fields It is also useful for implementing computed fields You can declare any field to be abstract with the following syntax message FooPacket customize true abstract bool urgentBit For an abstract field the message compiler generates no data member and generated getter setter methods will be pure virtual virtual bool getUrgentBit const 0 virtual void setUrgentBit bool urgentBit 0 Usually you ll want to use abstract fields together with the Generation Gap pattern so that you can immediately redefine the abstract pure virtual methods and supply you
204. e exponential 0 01 param gen msgLength 10 param fifo bitsPerSec 1000 24 5 Scalar Data Contains an output scalar value Syntax scalar moduleName scalarName value Examples scalar net switchA relay processed frames 100 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Scalar lines may be immediately followed by attribute lines OMNeT uses the following vector attributes e unit measurement unit e g s for seconds 24 6 Vector Declaration Defines an output vector Syntax vector vectorld moduleName vectorName vector vectorid moduleName vectorName columnSpec Where columnSpec is a string encoding the meaning and ordering the columns of data lines Characters of the string mean e E event number e T simulation time e V vector value Common values are TV and ETV The default value is Tv Vector lines may be immediately followed by attribute lines OMNeT uses the following vector attributes unit measurement unit e g s for seconds e enum symbolic names for values of the vector syntax is IDLE 0 BUSY 1 OFF 2 e type data type one of int double and enum interpolationmode hint for interpolation mode on the chart none do not connect the dots sample hold backward sample hold linear e min minimum value e max maximum value 24 7 Vector Data Adds a value to an output vector This is the same as in older
205. e is still useful because by far the most common way of leaking memory in a simulation is by not deleting messages 9 3 Tkenv the graphical user interface Tkenv is a portable graphical windowing user interface Tkenv supports interactive execution of the simulation tracing and debugging Tkenv is recommended in the development stage of a simulation or for presentation and educational purposes since it allows one to get a detailed picture of the state of simulation at any point of execution and to follow what happens inside the network 9 3 1 Command line switches A simulation program built with Tkenv accepts all the general command line switches In addition the r runnumber option allows only specifying a single run Multiple runs are not supported Tkenv configuration options http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual e tkenv default config Specifies which config Tkenv should set up automatically on startup The default is to ask the user e tkenv default run Specifies which run of the default config see tkenv default config Tkenv should set up automatically on startup The default is to ask the user e tkenv extra stack Specifies the extra amount of stack that is reserved for each activity simple module when the simulation is run under Tkenv e tkenv image path Specifies the path for loading module icons e tkenv plugin path Specifies the search path for Tkenv plug
206. e is under transmission other messages have to wait until the transmission is completed The module sends another message while the gate is busy a runtime error will be thrown The OMNeT class library provides functions to check whether a certain output gate is transmitting and find out when when it finishes transmission If the connection with a data rate is not directly connected to the simple module s output gate but is the second one in the path you have to check the second gate s busy condition NOTE In OMNeT versions prior to 4 0 sending on a busy gate was permitted and messages got implicitly queued up The behaviour of the simulation kernel was changed because in practice sending on a busy gate was more often result of a programming error than calculated behaviour Implementation of message sending Message sending is implemented like this the arrival time and the bit error flag of a message are calculated right inside the send call then the message gets inserted into the FES with the calculated arrival time The message does not get scheduled individually for each link This implementation was chosen because of its run time efficiency NOTE The consequence of this implementation is that any change in the channel s parameters delay bit rate bit error rate will only affect messages sent after the change Messages already under way will not be influenced by the change This is not a huge problem in practice but if it
207. e name as the NED type so here Queue One can explicitly specify the C class with the class property Classes with namespace qualifiers are also accepted as shown in the following example that uses the mylib Queue class simple Queue Wekeomewicra ss IMc CaASaesey sp class mylib Queue display i block queue gatesi aoue LMe CUTpPUEROUE If you have several modules that are all in a common namespace then a better alternative to class is the namespace property The C namespace given with namespace will be prepended to the normal class name In the following example the C classes will be mylib App mylib Router and mylib Queue namespace mylib simple App ee Simple Router aa simple Queue l E As you ve seen namespace can be specified on file level Moreover when placed in a file called package ned the namespace will apply to all files in the same directory and all directories below The implementation C classes need to be subclassed from the cSimpleModule library class chapter 4 of this http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual manual describes in detail how to write them Simple modules can be extended or specialized via subclassing The motivation for subclassing can be to set some open parameters or gate sizes to a fixed value see 3 6 and 3 7 or to replace the C class with a different one Now by default the der
208. e one can create connections with the gate operator that automatically expands the gate vector The gate size can be queried from various NED expressions with the sizeof operator NED normally requires that all gates be connected To relax this requirement you can annotate selected gates with the loose property which turns off connectivity check for that gate Also input gates that solely exist so that the module can receive messages via sendDirect see 4 6 6 should be annotated with directIn It is also possible to turn off connectivity check for all gates within a compound module by specifying the allowunconnected keyword in the module s connections section Let us see some examples In the following example the Classifier module has one input for receiving jobs which it will send to one of the outputs The number of outputs is determined by a module parameter simple Classifier parameters int numCategories garei Lte Ly output out numCategories The following Sink module also has its in gate defined as vector so that it can be connected to several modules simple Sink gates aLiajowre alsa p A node for building a square grid Gates around the edges of the grid are expected to remain unconnected hence the loose annotation Simple GridNode gates inout neighbour 4 loose WirelessNode below is expected to receive messages radio transmissions via direct sending so its
209. e second argument is omitted or it is NULL simtimeToStr will place the result into a static buffer which is overwritten with each call An example Char lowe 32 ev printi cl s8 t2 35 n simtimeToStr tl simTimeToStr t2 buf The simtimeToStrShort is similar to simt imeToStr but its output is more concise The strToSimtime function parses a time specification passed in a string and returns a simtime_t If the string cannot be entirely interpreted 1 is returned Simtime_t t strToSimtime 30s 152ms Another variant st rToSimtime0 can be used if the time string is a substring in a larger string Instead of taking a char it takes a reference to char char s as the first argument The function sets the pointer to the first character that could not be interpreted as part of the time string and returns the value It never returns 1 if nothing at the beginning of the string looked like simulation time it returns 0 const char s 30s 152ms and something extra simtime_t t strToSimtime0 s now s points to and something extra 6 4 Generating random numbers Random numbers in simulation are never random Rather they are produced using deterministic algorithms Algorithms take a seed value and perform some deterministic calculations on them to produce a random number and the next seed Such algorithms and their implementations are called random number generators or RNGs or sometimes pseudo r
210. e this method to let the module react to runtime parameter changes A typical use is to re read the changed parameter and update the module state if needed For example if a timeout value changes one can restart or modify running timers The primary motivation for this functionality was to facilitate the implementation of scenario manager modules which can be programmed to change parameters at certain simulation times Such modules can be very convenient in studies involving transient behaviour The following example shows a queue module which supports runtime change of its serviceTime parameter void Queue handleParameterChange const char parname if strcmp parname serviceTime 0 queue service time parameter changed re read it serviceTime par serviceTime if there any job being serviced modify its service tim if endServiceMsg gt isScheduled cancelEvent endServiceMsg scheduleAt SimTime serviceTime ndServiceMsg 4 3 5 Reusing module code via subclassing It is often needed to have several variants of a simple module A good design strategy is to create a simple module class with the common functionality then subclass from it to create the specific simple module types An example Class MoChliriScllicainsooircPicOcOCOl s jotlolie WeaimsjoomcPicocrcocol protected vireca en OneCluntase aulee elects Sulina iUiten O Define_
211. eT tries it as old icon as well 10 4 3 Icon size Icons come in various sizes normal large small very small Sizes are encoded into the icon name s suffix _v1 _1 _s _vs In display strings one can either use the suffix i device router_1 or the is icon size display string tag i device router is 1 but not both at the same time we recommend using the is tag whenever possible 10 5 Layouting OMNeT implements an automatic layouting feature using a variation of the SpringEmbedder algorithm Modules which have not been assigned explicit positions via the p tag will be automatically placed by the algorithm SpringEmbedder is a graph layouting algorithm based on a physical model Graph nodes modules repent each other like electric charges of the same sign and connections are sort of springs which try to contract and pull the nodes they re attached to There is also friction built in in order to prevent oscillation of the nodes The layouting algorithm simulates this physical system until it reaches equilibrium or times out The physical rules above have been slightly tweaked to get better results The algorithm doesn t move any module which has fixed coordinates Predefined row matrix ring or other arrangements defined via the 3rd and further args of the p tag will be preserved you can think about them as if those modules were attached to a wooden framework so that they can only move as one unit
212. earance of messages in the graphical runtime environment override the getDisplayString method of cMessage or cPacket to return a display string b wiath height oval Ellipse with the given height and width Defaults width 10 height 10 b wiath height rect Rectangle with the given height and width Defaults width 10 height 10 o fillcolor outlinecolor borderwidth Specifies options for the rectangle or oval For color notation see section 10 3 Defaults fillcolor red outlinecolor black borderwidth 1 i iconname color percentage Use the named icon It can be colorized and percentage specifies the amount of colorization If color name is kind a message kind dependent colors is used like default behaviour Defaults iconname no default if no icon name is present a small red solid circle will be used color no coloring percentage 30 tt tooltip text Displays the given text in a tooltip when the user moves the mouse over the message icon http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 23 Appendix Configuration Options 23 1 Configuration Options This section lists all configuration options that are available in ini files A similar list can be obtained from any simulation executable by running it with the h configdetails option cmdenv autoflush lt bool gt default false per run setting Call fflush stdout after each event banner or status update affec
213. ect than for those which are not If there is no extends the generated class will not be derived from cOwnedOb ject thus it will not have getName getClassName etc methods To create a class with those methods you have to explicitly write extends cOwnedObject class MyClass extends cOwnedObject Defining plain C structs You can define C style structs to be used as fields in message classes C style meaning containing only data and no methods Actually in the C a struct can have methods and in general it can do anything a class can The syntax is similar to that of defining messages SE BUCe My se Buc char array 10 short version However the generated code is different The generated struct has no getter or setter methods instead the fields are represented by public data members For the definition above the following code is generated generated C SELLE My Sieicweic t Char array lio short version A struct can have primitive types or other structs as fields It cannot have string or class as field http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Inheritance is supported for structs struct Base struct MyStruct extends Base But because a struct has no member functions there are limitations e dynamic arrays are not supported no place for the array allocation code e generation gap or abst
214. ected configuration The r command line option http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual overrides this setting cmdenv status frequency lt int gt default 100000 per run setting When cmdenv express mode true print status update every n events Typical values are 100 000 170007000 configuration class lt string gt global setting Part of the Envir plugin mechanism selects the class from which all configuration information will be obtained This option lets you replace omnetpp ini with some other implementation e g database input The simulation program still has to bootstrap from an omnetpp ini which contains the configuration class setting The class should implement the cConfiguration interface constraint lt string gt per run setting For scenarios Contains an expression that iteration variables S syntax must satisfy for that simulation to run Example i lt S jtl cpu time limit lt double gt unit s per run setting Stops the simulation when CPU usage has reached the given limit The default is no limit debug on errors lt bool gt default false global setting When set to true runtime errors will cause the simulation program to break into the C debugger if the simulation is running under one or just in time debugging is activated Once in the debugger you can view the
215. eets such as OpenOffice Calc Microsoft Excel Gnumeric or KSpread Data can be imported from csv or other formats exported with scavetool see 11 3 Spreadsheets have good charting and statistical features A useful functionality spreadsheets offer for analysing scalar files is PivotTable Excel or DataPilot OpenOffice The drawback of using spreadsheets is limited automation leading to tedious and repetitive tasks also the number of rows is usually limited to about 32 000 64 000 that can be painful when working with large vector files 11 4 2 GNU R R is a free software environment for statistical computing and graphics R has an excellent programming language and powerful plotting capabilities and it is supported on all major operating systems and platforms R is widely used for statistical software development and data analysis The program uses a command line interface though several graphical user interfaces are available Several OMNeT related packages such as SimProcTC and Syntony already use R for data analysis and plotting In the future OMNeT is going to be extended with features that further facilitate using it with R 11 4 3 MATLAB or Octave MATLAB is a commercial numerical computing environment and programming language MATLAB allows easy matrix manipulation plotting of functions and data implementation of algorithms creation of user interfaces and interfacing with programs in other languages Octave is an o
216. efine FSM_Print fsm exiting ev lt lt FSM lt lt fsm getName lt lt exiting leaving state entering state lt lt fsm getStateName lt lt endl Implementation The FSM_Switch is a macro It expands to a switch statement embedded in a for loop which repeats until the FSM reaches a steady state The actual code is rather scary but if you re dying to see it it is in cfsm h Infinite loops are avoided by counting state transitions if an FSM goes through 64 transitions without reaching a steady state the simulation will terminate with an error message An example Let us write another bursty generator It will have two states SLEEP and ACTIVE In the SLEEP state the module does nothing In the ACTIVE state it sends messages with a given inter arrival time The code was taken from the Fifo2 sample simulation define FSM DEBUG include lt omnetpp h gt class BurstyGenerator public cSimpleModule t protected parameters double sleepTimeMean double burstTimeMean double sendIATime CPE MSC llSinec las FSM and its states CHOME Sm enum NIT 0 LEEP FSM _ Steady 1 CTIVE FSM Steady 2 END FSM_Transient CP PEOP z dy 1 variables used alimic Le cMessage startStopBurst cMessage sendMessage ff che wWiiecual tuiMaccions http omnetpp org doc omnetpp4
217. eflection code that allows you to inspect these data structures in the Tkenv GUI The mypacket_m cc file should be compiled and linked into your simulation If you use the opp_makemake tool to generate your makefiles the latter will be automatically taken care of What is message subclassing not There might be some confusion around the purpose and concept of message definitions so it seems to be a good idea to deal with them right here It is not e an attempt to reproduce the functionality of C with another syntax Do not look for complex C types templates conditional compilation etc Also it defines data only or rather an interface to access data not any kind of active behaviour e a generic class generator This is meant for defining message contents and data structure you put in messages Defining methods is not supported on purpose Also while you can probably ab use the syntax to generate classes and structs used internally in simple modules this is probably not a good idea The goal is to define the interface getter setter methods of messages rather than their implementations in C A simple and straightforward implementation of fields is provided if you d like a different internal representation for some field you can have it by customizing the class There are questions you might ask e Why doesn t it support std vector and other STL classes Well it does Message definitions focus on the
218. eld wanne 5 4 6 2 Packet transmissions When a message is sent out on a gate it usually travels through a series of connections until it arrives at the destination module We call this series of connections a connection path or simply path Several connections in the path may have an associated channel but there can be only one channel per path that models nonzero transmission duration This channel is called the transmission channel Transmitting a packet The first packet can be simply send out on the output gate However subsequent packets may only be sent when the transmission channel is free that is it has finished transmitting earlier packets You can get a pointer to the transmission channel by calling the getDatarateChannel method on the output gate The channel s isBusy and getTransmissionFinishTime methods can tell you whether a channel is currently transmitting and when the transmission is going to finish When the latter is less or equal the current simulation time the channel is free If the channel is currently busy a timer self message needs to be scheduled and the packet should be stored until then for example in a queue The output gate also has isBusy and getTransmissionFinishTime methods which are basically shortcuts to getDatarateChannel gt isBusy and getDatarateChannel gt getTransmissionFinishTime When performance is important it is recommended to obtain
219. eld values are initialized to zero Initial values You Can initialize field values with the following syntax message FooPacket A int sourceAddress int destAddress 0 0 bool hasPayload false Initialization code will be placed in the constructor of the generated class Enum declarations You can declare that an int or other integral type field takes values from an enum The message compiler can than generate code that allows Tkenv display the symbolic value of the field Example message FooPacket int payloadType enum PayloadTypes The enum has to be declared separately in the message file Fixed size arrays You can specify fixed size arrays message FooPacket long route 4 The generated getter and setter methods will have an extra k argument the array index virtual long getRoute unsigned k const virtual void setRoute unsigned k long route If you call the methods with an index that is out of bounds an exception will be thrown Dynamic arrays If the array size is not known in advance you can declare the field to be a dynamic array message FooPacket long route In this case the generated class will have two extra methods in addition to the getter and setter methods one for setting the array size and another one for returning the current array size http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual
220. ells bits or signals travelling in a network entities travelling in a system and so on Attributes A cMessage object has number of attributes Some are used by the simulation kernel others are provided just for the convenience of the simulation programmer A more or less complete list The name attribute is a string const char which can be freely used by the simulation programmer The message name appears in many places in Tkenv for example in animations and it is generally very useful to choose a descriptive name This attribute is inherited from cOwnedOb ject see section 6 1 1 The message kind attribute is supposed to carry some message type information Zero and positive values can be freely used for any purpose Negative values are reserved for use by the OMNeT simulation library The length attribute understood in bits is used to compute transmission delay when the message travels through a connection that has an assigned data rate The bit error flag attribute is set to true by the simulation kernel with a probability of 1 1 ber 9 when the message is sent through a connection that has an assigned bit error rate ber e The priority attribute is used by the simulation kernel to order messages in the message queue FES that have the same arrival time values The time stamp attribute is not used by the simulation kernel you can use it for purposes such as noting the time when the message was enqueued
221. emory debugging tool like the ones described below Memory debugging tools If you suspect that you may have memory allocation problems crashes associated with double deletion or accessing already deleted block or memory leaks you can use specialized tools to track them down By far the most efficient most robust and most versatile tool is Valgrind originally developed for debugging KDE Other memory debuggers are NJAMD MemProf MPatrol dmalloc and ElectricFence Most of the above tools support tracking down memory leaks as well as detecting double deletion writing past the end of an allocated block etc A proven commercial tool Rational Purify It has a good reputation and proved its usefulness many times 9 6 4 Simulation executes slowly Check the following if you think your simulation is running too slow e Turn on express mode with the cmdenv express mode true configuration option e Be sure that event logging is turned off record event 1log false configuration option e Turn of vector file recording if you do not absolutely need it vector recording false e If you are running under Tkenv disable animation features close inspectors hide the timeline hide object tree turn off log filtering e Compile your code as release instead of debug in some cases this can give you 5x speedup What can you do if the simulation executes much slower than you expect The best advice that can be given here is that you sho
222. en the message will arrive to its destination module SD SendDirectEntry sending a message directly to a destination gate sm int senderModuleld id of the source module from which the message is being sent dm int destModulelId id of the destination module to which the message is being sent http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual dg int destGatelId id of the gate at the destination module to which the message is being sent pd simtime_t propagationDelay 0 propagation delay that is while the message is propagated through the connection td simtime_t transmissionDelay 0 transmission delay that is while the whole message is sent from the source gate SH SendHopEntry sending a message through a connection identified by its source module and gate id sm int senderModuleld id of the source module from which the message is being sent sg int senderGateld id of the gate at the source module from which the message is being sent pd simtime_t propagationDelay 0 propagation delay that is while the message is propagated through the connection td simtime_t transmissionDelay 0 transmission delay that is while the whole message is sent from the source gate DM DeleteMessageEntry deleting a message id int messagelId id of the message being deleted pe long prev
223. ents on field level The WATCH macros to be used for this purpose are WATCH_OBJ and WATCH_PTR Both expect the object to be subclassed from cObject WATCH_OBJ expects a reference to such class and WATCH_PTR expects a pointer variable ExtensionHeader hdr ExtensionHeader hdrPtr WATCH _OBd hdr WACH IP IIR lacliel2 EAI CAUTION With WATCH_PTR the pointer variable must point to a valid object or be NULL at all times otherwise the GUI may crash while trying to display the object This practically means that the pointer should be initialized to NULL even if not used and should be set to NULL when the object to which it points gets deleted delete watchedPtr watchedPtr NULL set to NULL when object gets deleted 6 9 4 STL watches The standard C container classes vector map set etc also have structured watches available via the following macros WATCH_VECTOR WATCH_PTRVECTOR WATCH_LIST WATCH_PTRLIST WATCH_SET WATCH_PTRSET WATCH_MAP WATCH_PTRMAP The PTR less versions expect the data items T to have stream output operators operator lt lt because that s how they will display them The PTR versions assume that data items are pointers to some type which has operator lt lt WATCH_PTRMAP assumes that only the value type second is a pointer the key type first is not If you happen to use pointers as key then define
224. er ev lt lt Owner of lt lt msg gt getName lt lt is lt lt lt lt Wil lt lt o se eirClassNemea lt lt YY VY lt lt o seqerrulilPaicia lt lt Encil The other direction enumerating the objects owned can be implemented with the forEachChild method by it looping through all contained objects and checking the owner of each object Why do we need this The traditional concept of object ownership is associated with the right to delete objects In addition to that keeping track of the owner and the list of objects owned also serves other purposes in OMNeT e enables methods like getFullPath to be implemented e prevents certain types of programming errors namely those associated with wrong ownership handling e enables Tkenv to display the list of simulation objects present within a simple module This is extremely useful for finding memory leaks caused by forgetting to delete messages that are no longer needed Some examples of programming errors that can be caught by the ownership facility e attempts to send a message while it is still in a queue encapsulated in another message etc e attempts to send schedule a message while it is still owned by the simulation kernel i e scheduled as a http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual future event attempts to send the very same message object to multiple destinations at the same time
225. er by explaining how one can customize the network graphics and how to write NED source code comments from which documentation can be generated The following chapters 7 8 9 and 11 deal with practical issues like building and running simulations and analyzing results and present the tools OMNeT provides to support these tasks e Chapter 14 is devoted to the support of distributed execution e The chapters 15 and 16 explain the architecture and internals of OMNeT as well as ways to extend it and embed it into larger applications e The appendices provide a reference of the NED language configuration options file formats and other details http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 1 3 Credits OMNeT has been developed by Andras Varga andras omnetpp org andras varga omnest com In the early stage of the project several people have contributed to OMNeT Although most contributed code is no longer part of the OMNeT nevertheless I d like to acknowledge the work of the following people First of all I d like thank Dr Gy rgy Pongor pongor hit bme hu my advisor at the Technical University of Budapest who initiated the OMNeT as a student project My fellow student akos Kun started to program the first NED parser in 1992 93 but it was abandoned after a few months The first version of nedc was finally developed in summer 1995 by three exchange students from TU Del
226. er str while tokenizer hasMoreTokens const chau token t Okeni zerr next OkeniOr if stremp token X 0 result push_back DEFAULT_VALUE fi elise result push_back atof token 4 5 Accessing gates and connections 4 5 1 Gate objects http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Module gates are represented by cGate objects Gate objects know to which other gates they are connected and what are the channel objects associated with the links Accessing gates by name The cModule class has a number of member functions that deal with gates You can look up a gate by name using the gate method cGate outGate gate out This works for input and output gates However when a gate was declared inout in NED it is actually represented by the simulation kernel with two gates so the above call would result in a gate not found error The gate method needs to be told whether the input or the output half of the gate you need This can be done by appending the Si or So to the gate name The following example retrieves the two gates for the inout gate Gi cGate gIn gate g i cGate gOut gate gSo Another way is to use the gateHalf function which takes the inout gate s name plus either cGate INPUT or cGate OUTPUT cGate gIin gateHalf g cGate INPUT cGate gOut gateHalf g cGate OUTPUT Th
227. er functions in the coroutine library nor does he need to care about the coroutine library implementation It is important to understand however how the event loop found in discrete event simulators works with coroutines When using coroutines the event loop looks like this simplified while FES not empty and simulation not yet complete retrieve first event from FES t timestamp of this event http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual transferTo module containing the event That is when the module has an event the simulation kernel transfers the control to the module s coroutine It is expected that when the module decides it has finished the processing of the event it will transfer the control back to the simulation kernel by atransferTo main Call Initially simple modules using activity are booted by events starter messages inserted into the FES by the simulation kernel before the start of the simulation How does the coroutine know it has finished processing the event The answer when it requests another event The functions which request events from the simulation kernel are the receive and wait so their implementations contain a transferTo main Call somewhere Their pseudocode as implemented in OMNeT receive transferTo main retrieve current event return the event remember events messages wait create event
228. er it it can send it on destroy it immediately or store it for further handling The same applies to messages that have been scheduled they belong to the simulation kernel until they are delivered back to the module To enforce the rules above all message sending functions check that you actually own the message you are about to send If the message is with another module it is currently scheduled or in a queue etc you ll get a runtime error not owner of message The feature does not increase runtime overhead significantly because it uses the object ownership management described in Section 6 11 it merely checks that the owner of the message is the module that wants to send it 4 6 5 Delayed sending It is often needed to model a delay processing time etc immediately followed by message sending In OMNeT it is possible to implement it like this wait someDelay send msg outgate If the module needs to react to messages that arrive during the delay wait cannot be used and the timer mechanism described in Section 4 6 9 Self messages would need to be employed There is also a more straightforward method than those mentioned above delayed sending Delayed sending can http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual be achieved by using one of these functions sendDelayed cMessage msg double delay const char gateName int index sendDelayed c
229. er would test and debug the simulation with a powerful graphical user interface and finally run it with a simple and fast user interface that supports batch execution http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Component libraries Module types can be stored in files se existing module types and create com parate from the place of their actual use This enables the user to group ponent libraries Universal standalone simulation programs A simulation executable can store several independent models that use the same set of simple modules The user can specify in the configuration file which model is to be run This allows one to build one large executable that contains several simulation models and distribute it as a standalone simulation tool The flexibility of the topology description language also supports thi s approach 2 3 2 What is in the distribution If you installed the source distribution the omnetpp directory on your system should contain the following subdirectories If you installed a precompiled distribution some of the directories may be missing or there might be additional directories e g containing software bundled with OMNeT The simulation system itself omnetpp OMNeT root directory bin OMNeT xecutables include header files for simulation models lib library files images icons and backgrounds f
230. ervals are separated by comma Example 100 200 400 900 warnings lt bool gt default true per run setting Enables warnings 23 2 Predefined Configuration Variables Predefined variables that can be used in config values S runid A reasonably globally unique identifier for the run produced by concatenating the configuration name run number date time etc S inifile Name of the primary inifile S configname Name of the active configuration S runnumber Sequence number of the current run within all runs in the active configuration S network Value of the network configuration option S experiment Value of the experiment label configuration option S measurement Value of the measurement label configuration option S replication Value of the replication label configuration option S processid PID of the simulation process S datetime Date and time the simulation run was started S resultdir Value of the result dir configuration option S repetition The iteration number in 0 N 1 where N is the value of the repeat http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual configuration option S seedset Value of the seed set configuration option S iterationvars Concatenation of all user defined iteration variables in name value form S iter
231. es 3 once for each host Third recording a random valued volatile parameter will just save a random number from that distribution This is rarely what you need and the simulation kernel will also issue a warning if this happens xx interarrivalTime exponential 1s xx interarrivalTime save as scalar true wrong saves random values These pitfalls are not rare in practice so it is usually more convenient to rely on the iteration variables in the result analysis That is one can rewrite the above example as xx interarrivalTime exponential mean 1 s and refer to the mean iteration variable instead of the interarrivalTime module parameter s during result analysis save as scalar true is not needed because iteration variables are automatically saved into the result files http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 8 6 4 Experiment Measurement Replication We have introduced three concepts that are useful for organizing simulation results generated by batch executions or several batches of executions During a simulation study a person prepares several experiments The purpose of an experiment is to find out the answer to questions like how does the number of nodes affect response times in the network For an experiment several measurements are performed on the simulation model and each measurement runs the simulation model with a different parameter settings To
232. es are described in section 17 4 17 17 4 7 Resolving the implementation C class The procedure for determining the C implementation class for simple modules and for channels are identical It goes as follows we are going to say component instead of simple module or channel If the component extends another component and has no class property the C implementation class is inherited from the base type If the component contains a class property the C class name will be composed of the current namespace see 17 4 7 and the value of the class property The class property should contain a single value NOTE The class property may itself contain a namespace declaration ie may contain If the component contains no class property and has no base class the C class name will be composed of the current namespace and the unqualified name of the component IMPORTANT NED subclassing does not imply subclassing the C implementation If you want to subclass a simple module or channel in NED as well as in C you explicitly need to specify the class property otherwise the derived simple module or channel will continue to use the C class from its super type Current namespace The current namespace is the value of the first namespace property found while searching the following order ODOC the current NED file http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual the
233. es like skiplist may perform better than heap in some cases In case you re interested the FES implementation is in the cMessageHeap Class but as a simulation programmer you won t ever need to care about that 4 2 Defining simple module types 4 2 1 Overview As mentioned before 4 1 3 a simple module is nothing more than a C class which has to be subclassed from cSimpleModule with one or more virtual member functions redefined to define its behavior The class has to be registered with OMNeT via the Define_Module macro The Define_Module line http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual should always be put into cc or cpp files and not header file h because the compiler generates code from it For completeness there is also a Define_Module_Like macro but its use is discouraged and might even be removed in future OMNeT releases The following HelloModule is about the simplest simple module one could write We could have left out the initialize method as well to make it even smaller but how would it say Hello then Note cSimpleModule as base class and the Define_Module line file HelloModule ce include lt omnetpp h gt class HelloModule public cSimpleModule protected yilccual yoro tmicializel virtual void handleMessage cMessage msg DP register module class with opp Define Module HelloModule
234. es make to recursively descend into all subdirectories subdirectories are expected to contain makefiles themselves e X directory Xdirectory except directory With r and deep option ignore the given directory e dsubdir d subdir subdir subdir Causes make to recursively descend into the given directory e n nolink Produce object files but do not create executable or library e make so Build shared library so dll or dylib a make 1ib Create static library a or lib e Idir Additional NED and C include directory e Ldir Add a directory to the library path e llibrary Additional library to link against 7 2 2 Basic use Once you have the source files ned msg cc h ina directory change there and type opp_makemake This will create a file named Makefile If you type make your simulation program should build If you already had a Makefile in that directory opp_makemake will refuse to overwrite it You can force overwriting the old Makefile with the f option ce opp_makemake f The name of the output file will be derived from the name of the project directory see later You can override it with the o option opp_makemake f o aloha In addition to the default target that builds the simulation executable the Makefile also contains the following targets mae o fall The default target is to build the simulation executable Adds or
235. escribe the most frequently used command line options To get a complete list of supported command line options run a simulation executable or opp_run with the hn option fifo h Specifying ini files The default ini file iS omnetpp ini and is loaded if no other ini file is given on the command line Ini files can be specified both as plain arguments and with the option so the following two commands are equivalent fifo experiment ini common ini fifo f experiment ini f common ini Multiple ini files can be given and their contents will get merged This allows for partitioning the configuration into separate files for example to simulation options module parameters and result recording options Specifying the NED path NED files are loaded from directories listed on the NED path More precisely they are loaded from the listed directories and their whole subdirectory trees Directories are separated with a semicolon http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual NOTE Semicolon is used as separator on both Unix and Windows The NED path can be specified in several ways e using the NEDPATH environment variable e using the n command line option e inini files with the ned path configuration option NED path resolution rules are as follows e OMNeT checks for NED path specified on the command line with the n option e if not found on t
236. ese methods throw an error if the gate does not exist so they cannot be used to determine whether the module has a particular gate The hasGate method can be used then An example if hasGate optOut send new cMessage optOut A gate can also be identified and looked up by a numeric gate ID You can get the ID from the gate itself get Id method or from the module by gate name findGate method The gate method also has an overloaded variant which returns the gate from the gate ID int gateld int gateld gate in gt getld or PAGATS alin As gate IDs are more useful with gate vectors we ll cover them in detail in a later section Gate vectors Gate vectors possess one cGate object per element To access individual gates in the vector you need to call the gate function with an additional index parameter The index should be between zero and size 1 The size of the gate vector can be read with the gateSize method The following example iterates through all elements in the gate vector for int 1 0 i lt gatesize out cGate gate gate out 1 eee i A gate vector cannot have holes in it that is gate never returns NULL or throws an error if the gate vector exists and the index is within bounds http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual For inout gates gateSize may be called with or without the i
237. espec leftgatespec lt gt channelspec lt gt rightgatespec leftgatespec leftmod leftgate parentleftgate 3 leftmod NAME vector NAME 3 leftgate NAME opt_subgate NAME opt_subgate vector NAME opt_subgate 3 parentleftgate NAME opt_subgate NAME opt_subgate vector NAME opt_subgate 3 rightgatespec rightmod rightgate parentrightgate 3 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual rightmod NAME NAME vector J rightgate NAME opt_subgate NAME opt_subgate vector NAME opt_subgate J parentrightgate NAME opt_subgate NAME opt_subgate vector NAME opt_subgate 3 opt_subgate NAME 3 channelspec channelspec_header channelspec_header opt_paramblock 3 channelspec_header dottedname likeparam LIKE dottedname J condition IF expression vector T expression J 3 expression http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual expr xmldocvalue J xmldocvalue XMLDOC stringliteral stringliteral XMLDOC stringliteral 3 expr simple_expr expr CONST expr expr expr expr expr expr expr expr expr expr expr expr expr expr expr expr expr expr expr gt expr expr
238. et Supported frame types F IEEE 202 3 Ethernet SS SS SS SS SS SSS SS SS SS SS SESS SS SS SSS SS SS SS SS AS SSS http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual I 13 3 2 Special tags The documentation tool understands the following tags and will render them accordingly author date todo bug see since warning version Example usage author Jack Foo date 2005 02 11 SS Ss SSS SSS SS Ss 13 3 3 Text formatting using HTML Common HTML tags are understood as formatting commands The most useful tags are lt i gt lt i gt italic lt b gt lt b gt bold lt tt gt lt tt gt typewriter font lt sub gt lt sub gt subscript lt sup gt lt sup gt Superscript lt br gt line break lt h3 gt heading lt pre gt lt pre gt preformatted text and lt a href gt lt a gt link as well as a few other tags used for table creation see below For example lt i gt Hello lt i gt will be rendered as Hello using an italic font The complete list of HTML tags interpreted by the documentation tool are lt a gt lt b gt lt body gt lt br gt lt center gt lt caption gt lt code gt lt dd gt lt dfn gt lt dl gt lt dt gt lt em gt lt form gt lt font gt lt hr gt lt h1 gt lt h2 gt lt h3 gt lt i gt lt input gt lt img gt lt li gt lt meta gt
239. eter may have value or default value and may also have properties see 17 4 8 Accepted parameter data types are double int string bool and xml Any of the above types can be declared volatile as well volatile int volatile string etc The presence of a data type keyword decides whether the given line defines a new parameter or refers to an existing parameter One can assign value or default value to an existing parameter and or modify its properties or add new properties Examples int a defines new parameter aioe 16 COOR new parameter with property int c default 5 new parameter with default value aime Cl SF new parameter with value assigned int e foo 5 new parameter with property and value i Op assignment to existing e g inherited parameter g default 10 overrides default value of existing parameter h legal but does nothing i foo 1 adds a property to existing parameter j foo 1 10 adds a property and value to existing parameter Parameter values are NED expressions Expressions are described in section 17 5 For volatile parameters the value expression is evaluated every time the parameter value is accessed Non volatile parameters are evaluated only once NOTE The const keyword is reserved for use within expressions to define constant subexpressions i e to denote a part within an expression the should only be evaluated once Constant
240. eter values will be passed to the C code aS const char without any conversion it is up to the simulation model to interpret them using the desired encoding Line ending may be either CR or CRLF regardless of the platform 17 1 3 Reserved words Authors have to take care that no reserved words are used as identifiers The reserved words of the NED language are allowunconnected bool channel channelinterface connections const default double extends false for gates if import index inout input int like module moduleinterface network output package parameters property simple sizeof string submodules this true types volatile xml xmldoc 17 1 4 Identifiers Identifiers must be composed of letters of the English alphabet a z A Z numbers 0 9 and underscore _ Identifiers may only begin with a letter or underscore The recommended way to compose identifiers from multiple words is to capitalize the beginning of each word camel case 17 1 5 Case sensitivity Keywords and identifiers in the NED language are case sensitive For example TCP and Tcp are two different names 17 1 6 Literals String literals String literals use double quotes The following C style backslash escapes are recognized b f n r t and xhh where h is a hexadecimal digit Numeric constants http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Numeric constants are accepted in their usua
241. etool filter p module sink AND queueing time OR transmission time O OUE CSVI E CSV IN VSC Writes the queing and transmission times of sink modules into CSV files It generates a separate files for each vector named out 1 csv out 2 csv The generated file contains a header and two columns time Queue sink queueing time 2 2318075763951 0 7 8943002235029 0 E a e a 3 59449 T OT o T 7 Go a Peel 11 3 2 Index command If the index file was deleted or the vector file was modified you need to rebuild the index file before running the filter command http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Normally the vector data is written in blocks into the vector file However if the vector file was generated by an older version of the cOutputVectorManager it might not be so In this case you have to specify the r option to rearrange the records of the vector file otherwise the index file would be too big and the indexing inefficient 11 3 3 Summary command The summary command reports the list of statistics names module names run ids configuration names in the given files to the standard output 11 4 Alternative statistical analysis and plotting tools There are several programs and packages that can also be used to analyse result files and create various plots and charts from them 11 4 1 Spreadsheet programs One straightforward solution is to use spreadsh
242. eudocode while FES not empty and simulation not yet complete retrieve first event from FES E timestamp of this event m module containing this event if m works with handleMessage m gt handleMessage event else m works with activity transferTo m Modules with handleMessage are NOT started automatically the simulation kernel creates starter messages only for modules with activity This means that you have to schedule self messages from the initialize function if you want a handleMessage simple module to start working by itself without first receiving a message from other modules Programming with handleMessage To use the handleMessage mechanism in a simple module you must specify zero stack size for the module This is important because this tells OMNeT that you want to use handleMessage and not activity Message event related functions you can use in handleMessage e send family of functions to send messages to other modules e scheduleAt to schedule an event the module sends a message to itself e cancelEvent to delete an event scheduled with scheduleAt You cannot use the receive family and wait functions in handleMessage because they are coroutine based by nature as explained in the section about activity You have to add data members to the module class for every piece of information you want to preserve This informatio
243. experimental implementation of the k split algorithm the cKSp1it class Research on k split is still under way The cKSplit class The cKSplit class is an implementation of the k sp it method Member functions WOU SSCCwINEDUMG KSjOlICCeILcs UMS _CGiciciuMe CoOuwlole _Giciiccaica s void setDivFunc KSplitDivFune _divfunc double _divdata void rangeExtension bool enabled int getTreeDepth int getTreeDepth cKSplit Grid amp grid double getRealCellValue cKSplit Grid amp grid int cell VOLC oesLimeEGieLEls p EKSplit Grid amp getGrid int k cKSplit Grid amp getRootGrid struct CKSOliic g3 Grel index of parent grid depth reldepth rootgrid s reldepth sum of cells amp all subgrids includes mother observations inherited from mother cell cell values int parent int reldepth long cortal LNE MOTNE A toe Eells Kx SS 5535 SS SSS SS SS Ss 6 7 4 Transient detection and result accuracy In many simulations only the steady state performance i e the performance after the system has reached a stable state is of interest The initial part of the simulation is called the transient period After the model has entered steady state simulation must proceed until enough statistical data has been collected to compute result with the required accuracy Detection of the end of the transient period and a certain result accuracy is s
244. f setting environment variables is system specific in Unix if you re using the bash shell adding a line export OMNETPP_IMAGE_PATH home you images images to bashrc or bash_profile will do on Windows environment variables can be set via the My Computer gt Properties dialog You can extend the image path from omnetpp ini with the tkenv image path option which gets prepended to the environment variable s value General tkenv image path home you model framework images home you extra images 10 4 2 Categorized icons Since OMNeT 3 0 icons are organized into several categories represented by folders These categories include e block icons for subcomponents queues protocols etc e device network devices servers hosts routers etc e abstract symbolic icons for various devices e misc node subnet cloud building town city etc e msg icons that can be used for messages Old pre 3 0 icons are in the o1d folder Tkenv and the IDE now load icons from subdirectories of all directories of the image path and these icons can be referenced from display strings by naming the subdirectory subdirectories as well Ssubdir icon http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual subdir subdir2 icon etc For compatibility if the display string contains a icon without a category i e subdirectory name OMN
245. f msg sendMessage FSM _ Goto fsm SEND else if msg startStopBurst cancelEvent sendMessage FSM_Goto fsm SLEEP else error invalid event in state ACTIVE break case ESM Exit SEND generate and send out job char msgname 32 sprinti mecmame VYijolo sel FFL 5 ev lt lt Generating lt lt msgname lt lt endl cMessage job new cMessage msgname job gt setBitLength long msgLength job gt setTimestamp send job out fj seexcibiicin to ACTIV r ry http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual FSM_Goto fsm ACTIVE break 4 9 Walking the module hierarchy Module vectors If a module is part of a module vector the get Index and size member functions can be used to query its index and the vector size ev lt lt This is module lt lt module gt getIndex lt lt in a vector of size lt lt module gt size lt lt n Module IDs Each module in the network has a unique ID that is returned by the get Id member function The module ID is used internally by the simulation kernel to identify modules int myModuleId getId If you Know the module ID you can ask the
246. f the parallel simulation subsystem the OMNeT framework has the potential to become a preferred platform for PDES research 15 Plug in Extensions 15 1 Overview OMNeT is an open system and several details of its operation can be customized via plug ins To create a plug in you generally need to write a C class that implements a certain interface i e subclasses from a C abstract class and register it in OMNeT The plug in class can be activated for a particular simulation with a corresponding configuration option The following plug in interfaces are supported e cRNG Interface for random number generators e cScheduler The scheduler class This plug in interface allows for implementing real time hardware in the loop distributed and distributed parallel simulation e cConfigurationEx Configuration provider plug in This plug in interface lets you replace omnetpp ini with some other implementation for example a database e cOutputScalarManager It handles recording the scalar output data The default output scalar manager is cFileOutputScalarManager defined in the Envir library e cOutputVectorManager It handles recording the output from cOut Vector objects The default output vector manager is cIndexedFileOutputVectorManager defined in the Envir library e cSnapshotManager It provides an output stream to which snapshots are written see section 6 9 5 The default snapshot manager is cFileSnapshotManager defined
247. f the simulation respectively The object name is the string passed to cOut Vector in its constructor or with the setName member function cOutVector eed End to End Delay Start and stop values can be any time specification accepted in NED and config files e g 10h 30m 45 2s As with parameter names wildcards are allowed in the object names and module path names An example General Wt WEICIE Ole recording mecry ile 60s End to End Delay vector recording true Router2 vector recording true xx vector recording false http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The above configuration limits collection of all output vectors to the 1s 60s interval and disables collection of output vectors except all end to end delays and the ones in any module called Router2 8 6 3 Saving parameters as scalars When you are running several simulations with different parameter settings you ll usually want to refer to selected input parameters in the result analysis as well for example when drawing a throughput or response time versus load or network background traffic plot Average throughput or response time numbers are saved into the output scalar files and it is useful for the input parameters to get saved into the same file as well For convenience OMNeT automatically saves the iteration variables into the output scalar file if they have numeric value
248. facilitate debugging demonstration or batch execution of simulations They are written in C compiled into libraries Simulation programs are built from the above components First msg files are translated into C code using the opp_msgc program Then all C sources are compiled and linked with the simulation kernel and a user interface library to form a simulation executable or shared library NED files are loaded dynamically in their original text forms when the simulation program starts Running the simulation and analyzing the results The simulation may be compiled as a standalone program executable thus it can be run on other machines without OMNeT being present or it can be created as a shared library In this case the OMNeT shared libraries must be present on that system When the program is started first it reads all NED files containing your model topology then it reads a configuration file usually called omnetpp ini This file contains settings that control how the simulation is executed values for model parameters etc The configuration file can also prescribe several simulation runs in the simplest case they will be executed by the simulation program one after another The output of the simulation is written into data files output vector files output scalar files and possibly the user s own output files OMNeT contains an Integrated Development Environment that provides rich environment for analyzing these file
249. ferent directories The lt tt gt examples lt tt gt directory page examples html Examples SS SS SS SS SS SS SS SSS SS SSS SS SSS STS e You can create links to the generated pages using standard HTML using the lt a href gt lt a gt tag All HTML files are placed in a single directory so you don t have to worry about specifying directories http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Example titlepage The structure of the model is described lt a hret structune html gt nere lt a gt SSS SSS SS SSS SS SS SS 13 4 3 Incorporating externally created pages You may want to create pages outside the documentation tool e g using a HTML editor and include them in the documentation This is possible all you have to do is declare such pages with the externalpage directive in any of the NED files and they will be added to the page index The pages can then be linked to from other pages using the HTML lt a href gt lt a gt tag The externalpage directive is similar in syntax to page externalpage filename html Title of the Page The documentation tool does not check if the page exists or not It is your responsibility to copy it manually into the directory of the generated documentation and to make sure the hyperlink works 14 Parallel Distributed Simulation 14 1 Introduction to Parallel Discrete Event Simulation OMNeT
250. file 7 2 12 Projects with multiple source trees 7 2 13 A multi directory example 8 Configuring Simulations 8 1 Configuring simulations 8 2 The configuration file omnetpp ini 8 2 1 An example 8 2 2 File syntax 8 2 3 File inclusion 8 3 Sections 8 3 1 The General section 8 3 2 Named configurations 8 3 3 Section inheritance 8 4 Setting module parameters 8 4 1 Using wildcard patterns 8 4 2 Using the default values 8 5 Parameter studies 8 5 1 Basic use 8 5 2 Named iteration variables 8 5 3 Repeating runs with different seeds 8 6 1 Output vectors and scalars 8 6 2 Configuring output vectors 8 6 3 Saving parameters as scalars 8 6 4 Experiment Measurement Replication 8 7 Configuring the random number generators 8 7 1 Number of RNGs 8 7 2 RNG choice 8 7 3 RNG mapping 8 7 4 Automatic seed selection 8 7 5 Manual seed configuration 9 Running Simulations 9 1 Introduction 9 1 1 Running a simulation executable 9 1 2 Running a shared library 9 1 3 Controlling the run 9 2 Cmdenv the command line interface 9 2 1 Example run 9 2 2 Command line switches 9 2 3 Cmdenv ini file options 9 2 4 Interpreting Cmdenv output 9 3 Tkenv the graphical user interface 9 3 1 Command line switches 9 4 Batch execution http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 9 4 1 Using Cmdenv 9 4 2 Using shell scripts 9 4 3 Using opp_runall 9 5 Akaroa support Multiple Replications in Parallel 9 5 1 Introduction
251. files This section describes the rules display properties are merged to create the module or channel s display string Derived NED types inherit their display string from their base NED type Submodules inherit their display string from their type Connections inherit their display string from their channel type The base NED type s display string is merged into the current display string using the following rules If a tag is present in the base display string but not in the current one the whole tag with all arguments is added to the current display string e g base i icon red current p 2 4 result p 2 4 i icon red If a tag is present both in the base and in the current display string only tag arguments present in the base but not in the current display string will be copied e g base b 40 20 current b oval result b 40 20 oval If the current display string contains a tag argument with value hyphen that argument is treated as empty and will not be inherited from other display strings Requesting the value of this argument will return its the default value If neither the base display string nor the current one has value for a tag a suitable default value will be returned and used Example of display string inheritance simple Base display i block queue use a queue icon in all instances Simple Derived extends Base display i red 60 gt
252. fo When a commana is associated with the message sending such as TCP OPEN SEND CLOSE etc the message kind field getKind setKind methods of cMessage should carry the command code When the command doesn t involve a data packet e g TCP CLOSE command a dummy packet empty cMessage can be sent Identifying the protocol In OMNeT protocol models the protocol type is usually represented in the message subclass For example instances of class IPv6Datagram represent IPv6 datagrams and EthernetFrame represents Ethernet frames and or in the message kind value The PDU type is usually represented as a field inside the message class The C dynamic_cast operator can be used to determine if a message object is of a specific protocol cMessage msg receive if dynamic_cast lt IPv 6 Datagram gt msg NULL IPv6Datagram datagram IPv6Datagram msg 5 1 4 Encapsulation Encapsulating packets It is often necessary to encapsulate a message into another when you re modeling layered protocols of computer networks Although you can encapsulate messages by adding them to the parameter list there s a better way The encapsulate function encapsulates a message into another one The length of the message will grow by the length of the encapsulated message An exception when the encapsulating outer message has zero length OMNeT assumes it is not a real packet but some
253. from cRNG and they can be accessed via cModule s get RNG method The argument to get RNG is a local RNG number which will undergo RNG mapping http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual CRNG rngl getRNG 1 cRNG contains the methods implementing the above intrand and dblrand functions The cRNG interface also allows you to access the raw 32 bit random numbers generated by the RNG and to learn their ranges intRand intRandMax as well as to query the number of random numbers generated getNumbersDrawn 6 4 4 Random variates The following functions are based on dblrand and return random variables of different distributions Random variate functions use one of the random number generators RNGs provided by OMNeT By default this is generator 0 but you can specify which one to be used OMNeT has the following predefined distributions truncnormal mean stddev normal distribution truncated to nonnegative values rng 0 a b c rng 0 triangular distribution with parameters a lt b lt s c a c pareto_shifted a b c generalized Pareto distribution with parameters a b and shift c rng 0 Discrete distributions intuniform a b rng 0 uniform integer from a b bernoulli p rng 0 result of a Bernoulli trial with probability O0 lt p lt 1 1 with probability p and O with E 5 E O 5 3 oO K H w m k ct K w Q
254. ft Jan Heijmans Alex Paalvast and Robert van der Leij nedc was first called JAR after their initials until it got renamed to nedc nedc was further developed and refactored several times until it finally retired and got replaced by nedtool in OMNeT 3 0 The second group of Delft exchange students Maurits Andr George van Montfort Gerard van de Weerd arrived in fall 1995 They performed some testing of the simulation library and wrote some example simulations for example the original version of Token Ring and simulation of the NIM game which survived until OMNeT 3 0 These student exchanges were organized by Dr Leon Rothkranz at TU Delft and Gy rgy Pongor at TU Budapest The diploma thesis of Zoltan Vass spring 1996 was to prepare OMNeT for parallel execution over PVM to OMNeT This code has been replaced with the new Parallel Simulation Architecture in OMNeT 3 0 Gabor Lencse lencse hit ome hu was also interested in parallel simulation namely a method called Statistical Synchronization SSM He implemented the FDDI model practically unchanged until now and added some extensions into NED for SSM These extensions have been removed since then OMNeT 3 0 does parallel execution on different principles The P algorithm and the original implementation of the k split algorithm was programmed in fall 1996 by Babak Fakhamzadeh from TU Delft k split was later reimplemented by Andras Several bugfixes and valuable suggestions
255. g Unit handling Operations involving numbers with units work in the following way Addition substraction and numeric comparisons require their arguments to have the same unit or compatible units in the latter case a unit conversion is performed before the operation Incompatible units cause an error Power of and bitwise operations require their arguments to be dimensionless Multiplying two numbers with units is not supported For division dividing two numbers with units is only supported if the two units are convertible i e the result will be dimensionless Dividing a dimensionless number with a number with unit is not supported 17 5 2 Referencing parameters and loop variables Identifiers in expressions occurring anywhere in component definitions are interpreted as referring to parameters of the given component Exception if an identifier occurs in a connection for loop and names a previously defined loop variable then it is understood as referring to the loop variable In submodule bodies parameters of the same submodule can be referred to with the this qualifier this destAddress Expressions may also refer to parameters of submodules defined earlier in NED file using the submoduleName paramName or the submoduleName index paramName syntax 17 5 3 The index operator The index operator is only allowed in a vector submodule s body and yields the index of the submodule instance 17 5 4 The sizeof operator The size
256. g constructor definitions are all OK and select handleMessage to be used with the module elloModule HelloModule elloModule HelloModule cSimpleModule It is also OK to omit the constructor altogether because the compiler generated one is suitable too The following constructor definition selects activity to be used with the module with 16K of coroutine stack HelloModule HelloModule cSimpleModule 16384 NOTE The Module_Class_Members macro already deprecated in OMNeT 3 2 has been removed in the 4 0 version When porting older simulation models occurrences of this macro can simply be removed from the source code 4 2 3 Constructor and destructor vs initialize and finish The initialize and finish methods will be discussed in a later section in detail but because their apparent similarity to the constructor and the destructor is prone to cause some confusion we ll briefly cover them here The constructor gets called when the module is created as part of the model setup process At that time everything is just being built so there isn t a lot things one can do from the constructor In contrast initialize gets called just before the simulation starts executing when everything else has been set up already finish is for recording statistics and it only gets called when the simulation has terminated normally It does not get c
257. g order is the reverse of the order of initialize first submodules then the encompassing compound module The bottom line is that at the moment there is no official possibility to redefine initialize and finish for compound modules the unofficial way is to write into the nedtool generated C code Future versions of OMNeT will support adding these functions to compound modules This is summarized in the following pseudocode perform simulation run build network i e the system module and its submodules recursively insert starter messages for all submodules using activity do callInitialize on system module enter event loop described earlier event loop terminated normally i e no errors do callFinish on system module clean up vo if calllnitialize call to user defined initialize function if module is compound for each submodule do calllnitialize on submodule callFinish if module is compound http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual for each submodule do callFinish on submodule call to user defined finish function initialize vs constructor Usually you should not put simulation related code into the simple module constructor This is because modules often need to investigate their surroundings maybe the whole network at the beginning of the simulation and save the collected info into in
258. ge n send endTx pe 14 E 4 840247053655 id 8 d t TRANSMIT 808000 i device pc_s id 8 d t 808000 i device pc_s mi w S S S S za i 15 1025727827674 m 2 ee 13 msg 25 another frame arrived while receiving collision EF id 0 pe 12 S id 0 tid 0 c cMessage n end reception pe 15 S t 1 12489449434 U acl 2 cxe YCollisiom 3 tremes iel 25 pe 15 Uwmwa A correct eventlog also fulfills the following requirements e simulation events are in increasing event number and simulation time order The various entry types and their supported attributes are as follows SB SimulationBeginEntry recorded at the first event v int version simulator version e g 0x401 1025 is release 4 1 rid string rund identifies the simulation run SE SimulationEndEntry optional last line of an event log file http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Bubblel Entry display a bubble message id Int txt string text displayed messag a sm int tm int m string met ModuleMethod moduleId id of the module which printed the bubble message text BeginEntry ta 7 as id of the caller module id of the module being called C method name fromModu l toModulel hod e d
259. ges which in addition to usual attributes such as timestamp may contain arbitrary data Simple modules typically send messages via gates but it is also possible to send them directly to their destination modules Gates are the input and output interfaces of modules messages are sent out through output gates and arrive through input gates An input and an output gate can be linked with a connection Connections are created within a single level of module hierarchy within a compound module corresponding gates of two submodules or a gate of one submodule and a gate of the compound module can be connected Connections spanning across hierarchy levels are not permitted as it would hinder model reuse Due to the hierarchical structure of the model messages typically travel through a chain of connections to start and arrive in simple modules Compound modules act as cardboard boxes in the model transparently relaying messages between their inside and the outside world Parameters such as propagation delay data rate and bit error rate can be assigned to connections One can also define connection types with specific properties termed channels and reuse them in several places Modules can have parameters Parameters are mainly used to pass configuration data to simple modules and to help define model topology Parameters may take string numeric or boolean values Because parameters are represented as objects in the program parameters in additi
260. given position and draw a circle with a 90 unit radius around it as a range indicator submodules ap AccessPoint display p 50 79 r 90 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Figure Range indicator using the r tag Additional decorations Sometimes you want to annotate your modules with additional information to make your model more transparent One special case is when you want to show the length of a queue cQueue embedded somewhere in a module In the following example the Server simple module contains a cQueue object which was named by the queue setName procqueue method If we specify q procqueue in the display string Tkenv will descend into the module several levels deep if needed and look for a queue object named procqueue It will display the length of the queue object along the module display q procqueue at queue You can add a text description to any module using the t displayed along the module or tt tag displayed as a tooltip The following example displays a short text along with the module and adds a tooltip text too that can be seen by hovering over them module with the mouse display t Packets sent 18 tt Additional tooltip information Packets sent 18 sour SE i Source source2 id 6 Additional tooltip information queue NOTE Generally it makes no sense to assign static texts in the NED file Usu
261. gorithms in the model The user implements the simple modules in C using the OMNeT simulation class library 2 1 2 Module types Both simple and compound modules are instances of module types While describing the model the user defines module types instances of these module types serve as components for more complex module types Finally the user creates the system module as an instance of a previously defined module type all modules of the network are instantiated as submodules and sub submodules of the system module When a module type is used as a building block there is no distinction whether it is a simple or a compound module This allows the user to split a simple module into several simple modules embedded into a compound module or vica versa aggregate the functionality of a compound module into a single simple module without affecting existing users of the module type Module types can be stored in files separately from the place of their actual usage This means that the user can group existing module types and create component libraries This feature will be discussed later in Chapter 9 2 1 3 Messages gates links Modules communicate by exchanging messages In an actual simulation messages can represent frames or packets in a computer network jobs or customers in a queuing network or other types of mobile entities Messages can contain arbitrarily complex data structures Simple modules can send messages either direct
262. gs random seed and determine the dependence of some measures on the parameter settings For example multiple runs and output scalars are the way to produce Throughput vs Offered Load plots Output scalars are recorded with the record method of cSimpleModule and you ll usually want to insert this code into the finish function An example void Transmitter finish double avgThroughput totalBits simTime recordScalar Average throughput avgThroughput You can record whole statistics objects by calling their record methods declared as part of cStatistic In the following example we create a Sink module which calculates the mean standard deviation minimum and maximum values of a variable and records them at the end of the simulation class Sink public cSimpleModule protected cStdDev eedStats WiLecuUel yole sinwiewa lize s virtual void handleMessage cMessage msg Walieewal Wesel ieslins Sin h g http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Define Module Sink volel Saks samc lali ze void Sink handleMessage cMessage msg eedStats setName End to End Delay simtime_t eed simTime msg gt getCreationTime eedStats collect eed delete msg yore Slak iealimal Sia neCcorcS ca llaie USimwleicsoin aurae ionu Sama eedStats record
263. gt expr expr lt expr expr lt expr expr amp amp expr expr expr expr expr T expr expr amp expr expr expr expr expr expr expr lt lt expr expr gt gt expr expr expr expr INT expr DOUBLE expr STRING expr NAME NAME expr NAME expr expr NAME expr expr expr NAME expr expr expr expr NAME expr expr expr expr expr NAME expr expr expr expr expr expr NAME expr expr expr expr expr expr expr NAME expr expr expr expr expr expr expr expr http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual NAME expr expr expr expr expr expr expr expr expr NAME expr expr expr expr expr expr expr expr expr expr J simple _expr identifier special_ expr literal J identifier NAME THIS NAME NAME NAME NAME expr T NAME b special_ expr INDEX INDEX SIZEOF identifier J literal stringliteral boolliteral numliteral b stringliteral STRINGCONSTANT 3 boolliteral TRUE FALSE J numliteral INTCONSTANT REALCONSTANT quantity
264. gt where lt configname gt is by convention a camel case string that starts with a capital letter Config1 WirelessPing OverloadedFifo etc For example omnetpp ini for an Aloha simulation might have the following skeleton http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual General Config PureAloha Config SlottedAlohal Config SlottedAloha2 Some configuration keys such as user interface selection are only accepted in the General section but most of them can go into Config sections as well When you run a simulation you need to select one of the configurations to be activated In Cmdenv this is done with the c command line option aloha c PureAloha The simulation will then use the contents of the Config PureAloha section to set up the simulation Tkenv of course lets you select the configuration from a dialog 8 3 3 Section inheritance Actually when you activate the PureAloha configuration the contents of the General section will also be taken into account if some configuration key or parameter value is not found in Config PureAloha then the search will continue in the General section In other words lookups in Config PureAloha will fall back to General The General section itself is optional when it is absent it is treated like an empty General section All named configurations fall back to General by default H
265. h so that the statistics we are collecting can stabilize can reach the required sample size to be statistically trustable Neither questions are trivial to answer One might just suggest to wait very long or long enough However this is neither simple how do you know what is long enough nor practical even with today s high speed processors simulations of modest complexity can take hours and one may not afford multiplying runtimes by say 10 just to be safe If you need further convincing please read Pawlikowsky02 and be horrified A possible solution is to look at the statistics while the simulation is running and decide at runtime when enough data have been collected for the results to have reached the required accuracy One possible criterion is given by the confidence level more precisely by its width relative to the mean But ex ante it is unknown how many observations have to be collected to achieve this level it must be determined runtime 9 5 2 What is Akaroa Akaroa Akaroa99 addresses the above problem According to its authors Akaroa Akaroa2 is a fully automated simulation tool designed for running distributed stochastic simulations in MRIP scenario in a cluster computing environment MRIP stands for Multiple Replications in Parallel ln MRIP the computers of the cluster run independent replications of the whole simulation process i e with the same parameters but different seed for the RNGs rand
266. han one executable file i e several shared libraries examples etc Once you have created your makefiles with opp_makemake in every source directory tree you will need a toplevel makefile The toplevel makefile usually calls only the makefiles recursively in the source directory trees 7 2 13 A multi directory example For a complex example of using opp_makemake we will check how to create the makefiles for the mobility framework First take a look at the project s directory structure and find the directories that should be used as source trees mobility framework bitmaps contrib lt source tree build libmfcontrib so from this dir core lt source tree build libmfcore so from this dir docs network template testSuite lt source tree build testSuite executable from this dir Additionally there are dependencies between these output files mfcontrib requires mfcore and testSuite requires mfcontrib and indirectly mfcore of course First create the makefile for the core directory build a shared lib from all cc files found in the core subtree and name it mfcore S cd core amp amp opp_makemak f deep make so o mfcore 0O out The contrib directory is depending on mfcore so we use the L and I options to specify the library we should link with Note that we must also add the include directories manually from the core source tree because autodiscovery works only in the same source tree cd con
267. he command line it checks for the NEDPATH environment variable e the ned path entry from the ini file gets appended to the result of the above steps e if the result is still empty it falls back to the current directory Selecting a user interface OMNeT simulations can be run under different user interfaces Currently the following user interfaces are supported e Tkenv Tcl Tk based graphical windowing user interface e Cmdenv command line user interface for batch execution You would typically test and debug your simulation under Tkenv then run actual simulation experiments from the command line or shell script using Cmdenv Tkenv is also better suited for educational or demonstration purposes Both Tkenv and Cmdenv are provided in the form of a library and you may choose between them by linking one or both into your simulation executable Creating the executable was described in chapter 7 Both user interfaces are supported on Unix and Windows platforms You can choose which runtime environment is included in your simulation executable when you generate your makefile By default both Tkenv and Cmdenv is linked in so you can choose between them during runtime but it is possible to specify only a single user interface with the u Cmdenv or u Tkenv option on the opp_makemake command line This can be useful if you intend to run your simulations on a machine where Tcl Tk is not installed By default Tkenv will be used if both
268. here an appropriate condition i can be formulated For example when generating a tree structure the condition would return whether node jis a child of node or vica versa Though this pattern is very general its usage can be prohibitive if the N number of nodes is high and the graph is sparse it has much fewer connections that N The following two patterns do not suffer from this drawback Connections of Each Node The pattern loops through all nodes and creates the necessary connections for each one It can be generalized like this for i 0 Nnodes j 0 Nconns i 1 node i out j gt node rightNodeIndex i j in j The Hypercube compound module to be presented later is a clear example of this approach BinaryTree can also be regarded as an example of this pattern where the inner j loop is unrolled The applicability of this pattern depends on how easily the rightNodelndex i j function can be formulated Enumerate All Connections A third pattern is to list all connections within a loop for i 0 Nconnections 1 node leftNodeIndex i out gt node rightNodeIndex i in The pattern can be used if eftNode ndex i and rightNodelndex i mapping functions can be sufficiently formulated The Chain module is an example of this approach where the mapping functions are extremely simple leftNodeIndex i i and rightNode ndex i i 1 The pattern can also be used to create a random subse
269. i acet iceratilonyarcs WW attr iterationvars2 Srepetition 0 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual attr measurement attr network TokenRing attr processid 3248 attr repetition 0 attr replication 0 acci resultert results attr runnumber 0 attr seedset 0 24 3 Attributes Contains an attribute for the preceding run vector scalar or statistics object Attributes can be used for saving arbitrary extra information for objects processors should ignore unrecognized attributes Syntax attr name value Example attr network largeNet 24 4 Module Parameters Contains a module parameter value for the given run This is needed so that module parameters may be included in the analysis e g to identify the load for a throughput vs load plot It may not be practical to simply store all parameters of all modules in the result file because there may be too many We assume that NED files are invariant and don t store parameters defined in them However we store parameter assignments that come from omnetpp ini in their original wildcard form i e not expanded to conserve space Parameter values entered interactively by the user are also stored When the original NED files are present it should thus be possible to reconstruct all parameters for the given simulation Syntax param parameterNamePattern value Example param gen sendIlaTim
270. ialized at the top of the activity function so there isn t much need to use initialize You do need finish however if you want to write statistics at the end of the simulation Because finish cannot access the local variables of activity you have to put the variables and objects containing the statistics into the module class You still don t need initialize because class members can also be initialized at the top of activity Thus a typical setup looks like this in pseudocode class MySimpleModule variables for statistics collection activity Racmars Ai MySimpleModule activity declare local vars and initialize them initialize statistics collection variables while true MySimpleModule finish record statistics into file Pros and Cons of using activity Pros e initialize not needed state can be stored in local variables of activity e process style description is a natural programming model in some cases Cons e limited scalability coroutine stacks can unacceptably increase the memory requirements of the simulation program if you have several thousands or ten thousands of simple modules e run time overhead switching between coroutines is somewhat slower than a simple function call e does not enforce a good programming style using activity tends to lead to unreliable spaghetti code In most cases cons outweigh pros and it is a better idea
271. ice because you can specify simulation time and CPU time limits in the ini file see later 4 7 2 Raising errors If your simulation encounters an error condition you can throw a cRuntimeError exception to terminate the simulation with an error message and in case of Cmdenv a nonzero exit code The cRuntimeError Class has a constructor whose argument list is similar to printf if windowSize lt 1 throw cRuntimeError Invalid window size d must be gt 1 windowSize Do not include a newline n or punctuation period or exclamation mark in the error text it will be added by OMNeT You can achieve the same effect by calling the error method of cModule if windowSize lt 1 error Invalid window size d must be gt 1 windowSize Of course the error method can only be used when a module pointer is available 4 8 Finite State Machines in OMNeT Overview Finite State Machines FSMs can make life with handleMessage easier OMNeT provides a class and a set of macros to build FSMs OMNeT s FSMs work very much like OPNET s or SDL s The key points are e There are two kinds of states transient and steady At each event that is at each call to handleMessage the FSM transitions out of the current steady state undergoes a series of state changes runs through a number of transient states and finally arrives at another steady state Thus http omnetpp org doc omnetpp40 ma
272. ick that you might not expect your message class has to take ownership of the inserted messages and release them when they are removed from the message These are done via the take and drop methods Let us see an example which assumes you have added to the class an std list member called messages that stores message pointers void MessageBundleMessage insertMessage cMessage msg take msg take ownership messages push_back msg ff store pointer void MessageBundleMessage removeMessage cMessage msg messages remove msg remove pointer drop msg release ownership You will also have to provide an operator method to make sure your message objects can be copied and http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual duplicated properly this is something often needed in simulations think of broadcasts and retransmissions Section 6 10 contains more info about the things you need to take care of when deriving new classes 5 1 5 Attaching parameters and objects If you want to add parameters or objects to a message the preferred way to do that is via message definitions described in chapter 5 2 Attaching objects The cMessage Class has an internal cArray object which can carry objects Only objects that are derived from cOwnedOb ject most OMNeT classes are so can be attached The addObject getObject hasOb ject
273. imulation Kernel 16 1 Architecture 16 2 Embedding the OMNeT simulation kernel 16 2 1 The main function 16 2 2 The simulate function 16 2 3 Providing an environment object 16 2 4 Providing a configuration object 16 2 5 Loading NED files 16 2 6 How to eliminate NED files 16 2 7 Assigning module parameters 16 2 8 Extracting statistics from the model 16 2 9 The simulation loop 16 2 10 Multiple coexisting simulations 16 2 11 Installing a custom scheduler 16 2 12 Multi threaded programs 17 Appendix NED Reference 17 1 Syntax 17 1 1 NED file extension 17 1 2 NED file encoding 17 1 3 Reserved words 17 1 4 Identifiers 17 1 5 Case sensitivity 17 1 6 Literals 17 1 7 Comments 17 1 8 Grammar 17 2 Built in definitions 17 3 Packages 17 3 1 Package declaration 17 3 2 Directory structure package ned 17 4 Components 17 4 1 Simple modules 17 4 2 Compound modules 17 4 3 Networks 17 4 4 Channels 17 4 5 Module interfaces 17 4 6 Channel interfaces 17 4 7 Resolving the implementation C class 17 4 8 Properties 17 4 9 Parameters 17 4 10 Gates 17 4 11 Submodules 17 4 12 Connections 17 4 13 Inner types 17 4 14 Name uniqueness 17 4 15 Type name resolution 17 4 16 Implementing an interface 17 4 17 Inheritance 17 4 18 Network build order 17 5 Expressions 17 5 1 Operators 17 5 2 Referencing parameters and loop variables 17 5 3 The index operator http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual
274. in the Envir library The classes cRNG cScheduler etc are documented in the API Reference To actually implement and select a plug in for use Subclass the given interface class e g for a custom RNG cRNG to create your own version Register the class by putting the Register_Class MyRNGClass line into the C source Compile and link your interface class into the OMNeT simulation executable IMPORTANT make sure the executable actually contains the code of your class Over optimizing linkers esp on Unix tend to leave out code to which there seem to be no external reference 000 Add an entry to omnetpp ini to tell Envir use your class instead of the default one For RNGs this setting is rng class inthe General section http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 15 2 Plug in descriptions 15 2 1 Defining a new random number generator The new RNG C class must implement the cRNG interface and can be activated with the rng class configuration option 15 2 2 Defining a new scheduler The scheduler plug in interface allows for implementing real time hardware in the loop distributed and distributed parallel simulation The scheduler C class must implement the cScheduler interface and can be activated with the scheduler class configuration option To see examples of scheduler classes check the cRealTimeScheduler class in the simulation kernel an
275. ined types are ned IdealChannel ned DelayChannel and ned DatarateChannel ned is the package name you can get rid of it if you import the types with the import ned or similar directive Packages and imports are described in section 3 14 IdealChannel has no parameters and lets through all messages without delay or any side effect A connection without a channel object and a connection with an TdealChannel behave in the same way Still TdealChannel has its uses for example when a channel object is required so that it can carry a new property or parameter that is going to be read by other parts of the simulation model DelayChannel has two parameters e delay is a double parameter which represents the propagation delay of the message Values need to be specified together with a time unit s ms us etc e disabled is a boolean parameter that defaults to false when set to true the channel object will drop all messages DatarateChannel has a few additional parameters compared to DelayChanne1 e datarate is a double parameter that represents the bandwidth of the channel and it is used for calculating the transmission duration of packets Values need to be specified with bits per second or its multiples as unit bps Kbps Mbps Gbps etc Zero is treated specially and results in zero transmission duration i e it stands for infinite bandwidth Zero is also the default e ber and per stand for Bit Error Rate
276. information about the distribution including the sample size The k split algorithm can be extended to multi dimensional distributions but here we deal with the one dimensional version only The algorithm The k split algorithm is an adaptive histogram type estimate which maintains a good partitioning by doing cell splits We start out with a histogram range x Xhi with k equal sized histogram cells with observation counts 17 15 Ng Each collected observation increments the corresponding observation count When an observation count n reaches a split threshold the cell is split into k smaller equal sized cells with observation counts n 7 Nj 2 Nj initialized to zero The n observation count is remembered and is called the mother observation count to the newly created http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual i cells Further observations may cause cells to be split further e g N 7 1 0 7 etc thus creating a k order tree of observation counts where leaves contain live counters that are actually incremented by new observations and intermediate nodes contain mother observation counts for their children If an observation falls outside the histogram range the range is extended in a natural manner by inserting new level s at the top of the tree The fundamental parameter to the algorithm is the split factor k Experience shows that k 2 worked best 1 Gs 8 4 4 4 4 0 Figur
277. ing gt default comm global setting When cFileCommunications is selected as parsim communications class specifies the prefix directory potential filename prefix for creating the files for cross partition messages parsim filecommunications preserve read lt bool gt default false global setting When cFileCommunications is selected as parsim communications class specifies that consumed files should be moved into another directory instead of being deleted parsim filecommunications read prefix lt string gt default comm read global setting When cFileCommunications is selected as parsim communications class specifies the prefix directory where files will be moved after having been consumed parsim idealsimulationprotocol tablesize lt int gt default 100000 global setting When cIdealSimulationProtocol is selected as parsim synchronization class specifies the memory buffer size for reading the ISP event trace file parsim mpicommunications mpibuffer lt int gt global setting When cMPICommunications is selected as parsim communications class specifies the size of the MPI communications buffer The default is to calculate a buffer size based on the number of partitions http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual parsim namedpipecommunications prefix lt string gt default
278. ing has adding new tags adding arguments to existing tags removing tags or replacing arguments The internal storage method allows very fast operation it will generally be faster than direct string manipulation The class doesn t try to interpret the display string in any way nor does it know the meaning of the different tags it merely parses the string as data elements separated by semicolons equal signs and commas An example dispStr gt parse a 1 GES Site tas gt insertTag 0 OF SOS a H Slaten O OSEE g result x joe jim a 1 2 p beta 3 dispStr gt setTagArg dispStr gt setTagArg dispStr gt setTagArg ev lt lt cilspSicic Ssicxe ee alpnap 3 5 d d a 2 X X X P 10 6 2 Bubbles Modules can let the user know about important events such as a node going down or coming up by displaying a bubble with a short message Going down Coming up etc This is done by the bubble method of cComponent The method takes the string to be displayed as a const char pointer An example loulololle Yecollisionl 2 ramas 4 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Collision 2 frames Q 9 server If the module contains a lot of code that modifies the display string or displays bubbles it is recommended to make these calls conditional on ev isGUI The ev isGUI call returns false when the si
279. ing in the background on some host e On each host where you want to run a simulation engine start akslave in the background Each akslave establishes a connection with the akmaster Then you use akrun to start a simulation akrun waits for the simulation to complete and writes a report of the results to the standard output The basic usage of the akrun command is akrun n num_hosts command argument where command is the name of the simulation you want to start Parameters for Akaroa are read from the file named Akaroa in the working directory Collected data from the processes are sent to the akmaster process and when the required precision has been reached akmaster tells the simulation processes to terminate The results are written to the standard output The above description is not detailed enough help you set up and successfully use Akaroa for that you need to read the Akaroa manual Configuring OMNeT for Akaroa First of all you have to compile OMNeT with Akaroa support enabled The OMNeT simulation must be configured in omnetpp ini so that it passes the observations to Akaroa The simulation model itself does not need to be changed it continues to write the observations into output vectors cOutVector objects see chapter 6 You can place some of the output vectors under Akaroa control You need to add the following to omnetpp ini General rng class cAkaroaRNG outputvectormanager class cAkOutputVe
280. ins Tkenv plugins are tcl files that get evaluated on startup Tkenv specific configuration options can be specified also on command line by prefixing them with double dash e g tkenv option value See Appendix 23 for the list of possible configuration options NOTE The usage of the Tkenv user interface is detailed in the OMNeT User Guide s Tkenv chapter 9 4 Batch execution Once your model works reliably you ll usually want to run several simulations You may want to run the model with various parameter settings or you may want should want to run the same model with the same parameter settings but with different random number generator seeds to achieve statistically more reliable results Running a simulation several times by hand can easily become tedious and then a good solution is to write a control script that takes care of the task automatically Unix shell is a natural language choice to write the control script in but other languages like Perl Matlab Octave Tcl Ruby might also have justification for this purpose Of course before running simulation batches you must set a condition to stop your simulation This is usually a time limit set by the sim time limit configuration option but you can limit your simulation by using wall clock time cpu time limit or by directly ending a simulation with an API call if some condition is true 9 4 1 Using Cmdenv To execute more than one run using the Cmdenv use the r optio
281. intensiveness of processing an event P is independent of the size of the model Depending on the nature of the simulation model and the performance of the computer P is usually in the range of 20 000 500 000 ev sec E event density is the number of events that occur per simulated second ev simsec E depends on the model only and not where the model is executed E is determined by the size the detail level and also the nature of the simulated system e g cell level ATM models produce higher E values than call center simulations R relative speed measures the simulation time advancement per second simsec sec R strongly depends on both the model and on the software hardware environment where the model executes Note that R P E e L lookahead is measured in simulated seconds simsec When simulating telecommunication networks and using link delays as lookahead L is typically in the msimsec usimsec range e T latency sec characterizes the parallel simulation hardware r is the latency of sending a message from one LP to another r can be determined using simple benchmark programs The authors measurements on a Linux cluster interconnected via a 100Mb Ethernet switch using MPI yielded r 22us which is consistent with measurements reported in ongfarrell2000 Specialized hardware such as Quadrics Interconnect quadrics can provide 7 5ys or better In large simulation models P E and R usually stay relatively constant that is display
282. interface getter setter methods of the classes optionally leaving the implementation to you so you can implement fields dynamic array fields using std vector This aligns with the idea behind STL it was designed to be nuts and bolts for C programs e Why does it support C data types and not octets bytes bits etc That would restrict the scope of message definitions to networking and OMNeT wants to support other application areas as well Furthermore the set of necessary concepts to be supported is probably not bounded there would always be new data types to be adopted e Why no embedded classes Good question As it does not conflict with the above principles it might be added someday The following sections describe the message syntax and features in detail 5 2 2 Declaring enums http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual An enum declared with the enum keyword generates a normal C enum plus creates an object which stores text representations of the constants The latter makes it possible to display symbolic names in Tkenv An example enum ProtocolTypes me is Wee 2 Enum values need to be unique 5 2 3 Message declarations Basic use You can describe messages with the following syntax message FooPacket int sourceAddress int destAddress bool hasPayload Processing this description with the message compiler will produce
283. ion The queues and switches are connected with links that have nonzero propagation delays Our OMNeT model for CQN wraps tandems into compound modules iiiii AITTI itititit Figure The Closed Queueing Network CQN model To run the model in parallel we assign tandems to different LPs Figure below Lookahead is provided by delays on the marked links CPUO Figure Partitioning the CQN model To run the CQN model in parallel we have to configure it for parallel execution In OMNeT the configuration is in a text file called omnetpp ini For configuration first we have to specify partitioning that is assign modules to processors This is done by the following lines General tandemQueue 0 partition id 0 tandemQueue 1 partition id 1 tandemQueue 2 partition id 2 The numbers after the equal sign identify the LP Then we have to select the communication library and the parallel simulation algorithm and enable parallel simulation General parallel simulation true parsim communications class cMPICommunications parsim synchronization class cNullMessageProtocol When the parallel simulation is run LPs are represented by multiple running instances of the same program When using LAM MPI lammpi the mpirun program part of LAM MPI is used to launch the program on the desired processors When named pipes or file communications is selected the op
284. ion on startup in order to be able to report invalid or mistyped option names and other errors 15 3 2 Reading values from the configuration http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The configuration is accessible via the getConfig method of cEnvir It returns a pointer to the configuration object cConfiguration ECOMELCUICEELOM COmrileG Sw GisicCoimicag 5 cConfiguration provides several methods for querying the configuration no sections flattened view etc const char getAsCustom cConfigOption entry const char fallbackValue NULL bool getAsBool cConfigOption entry bool fallbackValue false long getAsInt cConfigOption entry long fallbackValue 0 double getAsDouble cConfigOption entry double fallbackValue 0 Suds cia gnu eoeNs semaine ec Commlc Op euonms Cminiayy Const Char rel lboac velltie tuh s std string getAsFilename cConfigOption entry std vector lt std string gt getAsFilenames cConfigOption entry stel GSicicilimG CjScASPeicla CCOMEICGOScaom vemti y fallbackValue is returned if the value is not specified in the configuration and there is no default value bool debug ev getConfig gt getAsBool CFGID_PARSIM_ DEBUG 15 4 Implementing a new user interface It is possible to extend OMNeT with a new user interface The new user interface will ha
285. ions The random member function generates random numbers from the distribution stored by the object double rnd histogram random cStdDev assumes normal distribution You can also wrap the distribution object ina cPar CMs Paie rneer rnar rndPar setDoubleValue amp histogram The cPar object stores the pointer to the histogram or p object and whenever it is asked for the value calls the histogram object s random function double rnd double rndPar random number from the cPSquare Storing loading distributions The statistic classes have loadFromFile member functions that read the histogram data from a text file If you need a custom distribution that cannot be written or it is inefficient as a C function you can describe it in histogram form stored in a text file and use a histogram object with loadFromFile http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual You can also use saveToF ile that writes out the distribution collected by the histogram object FILE f f fopen histogram dat w histogram saveToFile f save the distribution fclose f cDoubleHistogram hist2 Hist from file Iii t2 irejoein UMs togra cere Vie hist2 loadFromFile f2 load stored distribution LGILOSS EZ Histogram with custom cells The cVarHistogram Class can be used to create histograms with
286. iousEventNumber 1 event number from which the message being deleted was sent or 1 if the message was sent from initialize Document converted from LaTeX by Itoh from Russell W Quong quong best com http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29
287. is important to model channels with changing parameters the solution is to insert simple modules into the path to ensure strict scheduling The approach of some other simulators Note that some simulators e g OPNET assign packet queues to input gates ports and messages sent are buffered at the destination module or the remote end of the link until they are received by the destination module With that approach events and messages are separate entities that is a send operation includes placing the message in the packet queue and scheduling an event which signals the arrival of the packet In some implementations output gates also have packet queues where packets will be buffered until the channel is ready available for transmission OMNeT gates don t have associated queues The place where sent but not yet received messages are buffered in the FES OMNeT s approach is potentially faster than the solution mentioned above because it doesn t have the enqueue dequeue overhead and also spares an event creation The drawback is that changes to channel parameters do not take effect immediately In OMNeT one can implement point to point transmitter modules with packet queues if needed For example the INET Framework follows this approach Connection attributes propagation delay transmission data rate bit error rate are represented by the channel object which is available via the source gate of the connection cChannel chan ou
288. ity queue that is it can keep the inserted objects ordered If you want to use this feature you have to provide a function that takes two cOwnedOb ject pointers compares the two objects and returns 1 0 or 1 as the result see the reference for details An example of setting up an ordered cQueue cQueue sortedqueue sortedqueue cOwnedObject cmpbyname true sorted by object name ascending If the queue object is set up as an ordered queue the insert function uses the ordering function it searches the queue contents from the head until it reaches the position where the new item needs to be inserted and inserts it there Iterators Normally you can only access the objects at the head or tail of the queue However if you use an iterator class cQueue Iterator you can examine each object in the queue The cQueue Iterator constructor takes two arguments the first is the queue object and the second one specifies the initial position of the iterator O tail 1 head Otherwise it acts as any other OMNeT iterator class you can use the and operators to advance it the operator to get a pointer to the current item and the end member function to examine if you re at the end or the beginning of the queue An example for cQueue Iterator iter queue 1 iter end iter cMessage msg cMessage iter ae 6 5 2 Expandable array cArray Basic usage cArray is a container class
289. ivated and a description string for help and other purposes http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The C class should implement all methods left pure virtual in EnvirBase and possibly others if you want to customize their behaviour One method that you ll surely want to reimplement is run this is where your user interface runs When this method exits the simulation program exits NOTE A good starting point for implementing your own user interface is Cmdenv just copy and modify its source code to quickly get going 16 Embedding the Simulation Kernel 16 1 Architecture OMNeT has a modular architecture The following diagram shows the high level architecture of OMNeT simulations Executing SIM Model i Model Component Library Figure Architecture of OMNeT simulation programs The rectangles in the picture represent components e Sim is the simulation kernel and class library Sim exists as a library you link your simulation program with Envir is another library which contains all code that is common to all user interfaces main is also in Envir Envir provides services like ini file handling for specific user interface implementations Envir presents itself towards Sim and the executing model via the ev facade object hiding all other user interface internals Some aspects of Envir can be customized via plugin interfaces Embedding
290. ived NED module type will inherit the C class from its base so it is important to remember that you need to write out class if you want it to use the new class The following example shows how to specialize a module by setting a parameter to a fixed value and leaving the C class unchanged simple Queue ime eapacitty simple BoundedQueu xtends Queue capacity 10 In the next example the author wrote a PriorityQueue C class and wants to have a corresponding NED type derived from Queue However it does not work as expected simple PriorityQueue extends Queue wrong still uses the Queue C class The correct solution is to add a class property to override the inherited C class simple PriorityQueue extends Queue i class PriorityQueue Inheritance in general will be discussed in section 3 13 3 4 Compound modules A compound module groups other modules into a larger unit A compound module may have gates and parameters like a simple module but no active behavior no C code is associated with it NOTE When there is a temptation to add code to a compound module then encapsulate the code into a simple module and add it as a submodule A compound module declaration may contain several sections all of them optional module Host IEWOSS parameters Gawes submodules http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29
291. l decimal or scientific notations Quantity constants A quantity constant has the form lt numeric constant gt lt unit gt for example 12 5mW or 3h 15min 37 2s When multiple measurement units are present they have to be convertible into each other i e refer to the same physical quantity Section 17 5 7 lists the units recognized by OMNeT Other units can be used as well the only downside being that OMNeT will not be able to perform conversions on them 17 1 7 Comments Comments can be placed anywhere in the NED file with the usual C syntax comments begin with a double slash and last until the end of the line 17 1 8 Grammar The grammar of the NED language can be found in Appendix 18 17 2 Built in definitions The NED language has the following built in definitions all in the ned package channels IdealChannel DelayChannel and DatarateChannel module interfaces IBidirectionalChannel and IUnidirectionalChannel The latter two are reserved for future use package ned namespace channel IdealChannel class cIdealChannel j channel DelayChannel class cDelayChannel bool disabled false double delay Os unit s channel DatarateChannel class cDatarateChannel bool disabled false double delay Os unit s double datarate Obps unit bps double ber 0 double per OF moduleinterface
292. last bit Fig below http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual A gt B ta ts message sending transmission delay propagation delay gt message arrival Figure Message transmission The above model may not be suitable to model all protocols In Token Ring and FDDI stations start to repeat bits before the whole frame arrives in other words frames flow through the stations being delayed only a few bits In such cases the data rate modeling feature of OMNeT cannot be used If a message travels along a path passing through successive links and compound modules the model behaves as if each module waited until the last bit of the message arrives and only started its transmission afterwards Fig below gt ariva Figure Message sending over multiple channels Since the above effect is usually not the desired one typically you will want to assign data rate to only one connection in the path Multiple transmissions on links If a data rate is specified for a connection a message will have a certain nonzero transmission time depending on the length of the connection This implies that a message that is passsing through an output gate reserves the gate for a given period it is being transmitted TxGate 100 Mbps e RxGate Figure Connection with a data rate http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual While a messag
293. lay is merged with special although similar rules see Chapter 10 Indices Properties are identified by names so if the same name occurs in the same context then it names the exact same property object If you want to have multiple properties with the same name then you need to distinguish them with an index An index is a name or number written in square brackets after the property name The index may be chosen to carry a meaning or it may be a dummy whose only purpose is to tell multiple properties with the same name apart The code that interprets properties may be written to observe or to ignore indices as needed The following example the simple module declares in properties the statistics it collects These declarations might be used by model editing tools by simulation code or by analysis tools Note that this is a completely hypothetical example OMNeT does not presently support declaring statistics using properties The statistic names are used as indices simple App declare two statistics collected by the C code statistic packetsReceived type integer label Number of packets received statistic responseTime type double unit s label Application response eimen simple HttpApp extends App tailor the label of the packetsReceived statistic statistic packetsReceived label Number of HTTP requests received 3 13 Inheritance Inheritance support in the NED language is only
294. le but this is not mandatory In cases when there are more than one runs ina file and it is not feasible to keep the entire file in memory during analysis the offsets of the run lines may be indexed for more efficient random access The run line may be immediately followed by attribute lines Attributes may store generic data like the network name date time of running the simulation configuration options that took effect for the simulation etc Run attribute names used by OMNeT include the following Generic attribute names e network name of the network simulated datetime date time associated with the run e processid the PID of the simulation process e inifile the main configuration file configname name of the inifile configuration e seedset index of the seed set use for the simulation Attributes associated with parameter studies iterated runs e runnumber the run number within the parameter study experiment experiment label measurement measurement label replication replication label repetition the loop counter for repetitions with different seeds e iterationvars string containing the values of the iteration variables e iterationvars2 string containing the values of the iteration variables An example run header Ulin WOKSiMRaL ing L O ZOOSO S14 iissg L193 aa syn alg attr configname TokenRingl attr datetime 20080514 18 19 44 attr experiment TokenRingl attr inifile omnetpp in
295. le node topo getTargetNode ev lt lt We are in lt lt node gt getModule gt getFullPath lt lt endl ev lt lt node gt getDistanceToTarget lt lt hops to go n ev lt lt There are lt lt node gt getNumPaths lt lt egually good directions taking the first onein cTopology LinkOut path node gt getPath 0 ev lt lt Taking gate lt lt path gt getLocalGate gt getFullName lt lt we arrive in lt lt path gt getRemoteNode gt getModule gt getFullPath lt lt on its gate lt lt path gt getRemoteGate gt getFullName lt lt endl node path gt getRemoteNode The purpose of the getDistanceToTarget member function of a node is self explanatory In the unweighted case it returns the number of hops The get NumPaths member function returns the number of edges which are part of a shortest path and path i returns the ith edge of them as cTopology LinkOut If the shortest paths were created by the SingleShortestPaths function getNumPaths will always return 1 or 0 if the target is not reachable that is only one of the several possible shortest paths are found The MultiShortestPathsTo functions find all paths at increased run time cost The cTopology s get TargetNode function returns the target node of the last shortest path search You can enable disable nodes or edges in the graph This is done
296. le delay truncnormal 0 005 0 0001 sendDirect new cMessage packet delay destinationModule inputGate At the destination module there is no difference between messages received directly and those received over connections 4 6 7 Receiving messages With activity only The message receiving functions can only be used in the activity function handleMessage gets received messages in its argument list Messages are received using the receive function receive isa member of cSimpleModule cMessage msg receive The receive function accepts an optional timeout parameter This is a delta not an absolute simulation time If an appropriate message doesn t arrive within the timeout period the function returns a NULL pointer Putaside queue and the functions receiveon receiveNew ANd receiveNewon were deprecated in OMNeT 2 3 and removed in OMNeT 3 0 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual SimicwiimMie ic cameos 3 05 cMessage msg receive timeout if msg NULL handle timeout else process messag 4 6 8 The wait function With activity only The wait function s implementation contains a receive call which cannot be used in handleMessage The wait function suspends the execution of the module for a given amount of simulation time a delta wait delay In other simulation software wait
297. le without the need to explicitly link against that library This approach has several advantages e It is possible to distribute the model as a shared library Others may be able to use it without recompiling it e You can split a large model into smaller reusable components e You can mix several models even from different projects without the need of linking or compiling Use the 1 libraryname command line option to load a library dynamically at run time OMNeT will attempt to load it using the dlopen Of LoadLibrary functions and automatically registers all simple modules in the library The prefix and suffix from the library name can be omitted the extension dl1 so dylib and also the common lib prefix on unix systems This means that you can specify the library name in a platform independent way name dll libname dll libname so and libname dylib can be loaded with 1 name It is also possible to specify the libraries to be loaded in the ini file with the 1oad 1ibs config option The values from the command line and the config file will be merged NOTE Runtime loading is not needed if your executable or shared lib was already linked against the library in question In that case the platform s dynamic loader will automatically load the library NOTE You must ensure that the library can be accessed by OMNeT You have to specify the path with your library name pre and postfixes of the library filename still can be
298. les 3 4 channels 3 5 parameters 3 6 gates 8 7 submodules 3 8 connections 3 9 module interfaces and channel interfaces 3 11 3 14 Packages Small simulation projects are fine to have all NED files in a single directory When a project grows however it sooner or later becomes inevitable to introduce a directory structure and sort the NED files into them NED natively supports directory trees with NED files and calls directories packages Packages are also useful for reducing name clashes because names can be qualified with the package name NOTE NED packages are based on the Java package concept with minor enhancements If you are familiar with Java you ll find little surprise in this section Overview When a simulation is run you must tell the simulation kernel the directory which is the root of your package tree let s call it NED source folder The simulation kernel will traverse the whole directory tree and load all NED files from every directory You can have several NED directory trees and their roots the NED source folders should be given to the simulation kernel in the NEDPATH variable NEDPATH can be specified in several ways as an environment variable NEDPATH as a configuration option ned path or as a command line option to the simulation runtime NEDPATH is described in details in chapter 9 Directories in a NED source tree correspond to packages If you have NED files in a lt root gt a b c
299. lobicSabwae Js eo aueue k buro LAS SG this will Only arrect qucuiics 0 l2 ancl Gao LI 8 4 2 Using the default values It is also possible to utilize the default values specified in the NED files The lt parameter fullpath gt default setting assigns the default value to the parameter if it has one The lt parameter fullpath gt ask setting will try to get the parameter value interactively from the user If a parameter was not set but has a default value that value will be assigned This is like having a default line at the bottom of the General section If a parameter was not set and has no default value that will either cause an error or will be interactively prompted for depending on the particular user interface NOTE In Cmdenv you must explicitly enable the interactive mode with the cmdenv interactive true option otherwise you will get an error when running the simulation More precisely parameter resolution takes place as follows If the parameter is assigned in NED it cannot be overridden in the configuration The value is applied and the process finishes If the first match is a value line matches lt parameter fullpath gt somevalue the value is applied and the process finishes If the first match is a lt parameter fullpath gt default line the default value is applied and the process http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT
300. low for an illustration The isConnected method is a bit different it returns true if the gate is fully connected that is for a compound module gate both inside and outside and for a simple module gate outside The following code prints the name of the gate a simple module gate is connected to cGate gate gate somegate CGate otherGate gate getIType CGaces OUTPUT gate getNextGate gate gt getPreviousGate if otherGate ev lt lt gate is connected to lt lt otherGate gt getFullPath lt lt endl else ev lt lt gate not connected lt lt endl 4 5 3 The connection s channel TODO 4 6 Sending and receiving messages On an abstract level an OMNeT simulation model is a set of simple modules that communicate with each other via message passing The essence of simple modules is that they create send receive store modify schedule and destroy messages everything else is supposed to facilitate this task and collect statistics about what was going on Messages in OMNeT are instances of the cMessage class or one of its subclasses Message objects are created using the C new operator and destroyed using the delete operator when they are no longer needed During their lifetimes messages travel between modules via gates and connections or are sent directly bypassing the connections or they are scheduled by and delivered to modules representing internal events of that module
301. lso be used to implement a conditional submodule like in the example below module Host parametensk bool withTCP default true submodules ceplwicnrct 7 1 s Ql TCP conditional submodule connections ECO O ajsOue gt lo toim Lr waiclMCes ECO O djslm lt To TELO LE waliclMiCls ere As already seen in previous code examples a submodule may also have a curly brace block as body where one can assign parameters set the size of gate vectors and add modify properties like the display string display http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual It is not possible to add new parameters and gates Display strings specified here will be merged with the display string from the type to get the effective display string This is described in chapter 10 module Node gates MOE jexoserc 2 submodules TOUNO IEE sling parameters this keyword is optional routingTable routingtable txt assign parameter gatesi in sizeof port set gate vector size out sizeof port queue sizeof port Queue display t queue id id modify display string id 1000 index different id parameter for each element connections An empty body may be omitted that is queue Queue is the same as queue Queue It is possible to add new submodules to an existing compound module via subclassing this has been descri
302. lt endl There are several statistic and result collection classes cSt dDev cWeightedStdDev LongHistogram class cStatistic cDoubleHistogram cVarHistogram cPSquare and cKSp1lit They are all derived from the abstract base e cStdDev keeps the count mean standard deviation minimum and maximum value etc of the observations e cWeightedStdDev is similar to cStdDev but accepts weighted observations cWeightedStdDev can be used for example to calculate time average It is the only weighted statistics class e cLongHistogram and cDoubleHistogram are descendants of cStdl Dev and also keep an approximation of the distribution of the observations using equidistant equal sized cell histograms e cVarHistogram implements a histogram where cells do not need to be the same size You can manually add the cell bin boundaries or alternatively automatically have a partitioning created where each bin has the same number of observations or as close to that as possible e cPSquare is a class that uses the P algorithm described in JCh85 The algorithm calculates quantiles without storing the observations one can also think of it as a histogram with equiprobable cells e cKSplit uses a novel experimental method based on an adaptive histogram like algorithm Basic usage One can insert an observation into a statistic object with the collect function or the operator they are equivalent cSt dDev has
303. lt i gt will be rendered as Use the lt i gt tag like lt i gt this lt i gt to write in italic lt nohtml1 gt lt nohtm1 gt will also prevent opp_neddoc from hyperlinking words that are accidentally the same as an existing module or message name Prefixing the word with a backslash will achieve the same That is either of the following will do In lt nohtml gt IP lt nohtml gt networks routing is ff Win MIP networks routing IS Both will prevent hyperlinking the word P if you happen to have an IP module in the NED files http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 13 4 Customizing and adding pages 13 4 1 Adding a custom title page The title page is the one that appears in the main frame after opening the documentation in the browser By default it contains a boilerplate text with the generic title OMNeT Model Documentation You probably want to customize that and at least change the title to the name of the documented simulation model You can supply your own version of the title page adding a t it lepage directive to a file level comment a comment that appears at the top of a NED file but is separated from the first import channel module etc definition by at least one blank line In theory you can place your title page definition into any NED or MSG file but it is probably a good idea to create a separate index ned file f
304. ly to their destination or along a predefined path through gates and connections The local simulation time of a module advances when the module receives a message The message can arrive from another module or from the same module se f messages are used to implement timers Gates are the input and output interfaces of modules messages are sent out through output gates and arrive through input gates Each connection also called link is created within a single level of the module hierarchy within a compound module one can connect the corresponding gates of two submodules or a gate of one submodule and a gate of the compound module Fig below Due to the hierarchical structure of the model messages typically travel through a series of connections to start and arrive in simple modules Such series of connections that go from simple module to simple module are called routes Compound modules act as cardboard boxes in the model transparently relaying messages between their inside and the outside world 2 1 4 Modeling of packet transmissions Connections can be assigned three parameters which facilitate the modeling of communication networks but can be useful in other models too propagation delay bit error rate and data rate all three being optional One can specify link parameters individually for each connection or define link types and use them throughout the whole model Propagation delay is the amount of time the arriv
305. mFirstvals rangeExtFactor setRangeAutoUpper lower numFirstvals rangeExtFactor setNumFirstVals numFirstvals The following example creates a histogram with 20 cells and automatic range estimation cDoubleHistogram histogram histogram 20 histogram setRangeAuto 100 1 5 Here 20 is the number of cells not including the underflow overflow cells see later and 100 is the number of observations to be collected before setting up the cells 1 5 is the range extension factor It means that the actual range of the initial observations will be expanded 1 5 times and this expanded range will be used to lay out the cells This method increases the chance that further observations fall in one of the cells and not outside the histogram range e o eeemese oo range of initial observations histogram range Figure Setting up a histogram s range After the cells have been set up collection can go on The isTransformed function returns true when the cells have already been set up You can force range estimation and setting up the cells by calling the transform function The observations that fall outside the histogram range will be counted as underflows and overflows The number of underflows and overflows are returned by the getUnderflowCell and getOverflowCell member functions underflows calls OWS Figure Histogram structure after setting up the cells You create a P object by specif
306. mQuevej T gate op 8 tan 23 tandemQuevelz ch fb Mi scheduled events civ Figure Screenshot of CQN running in three LPs cre starting Null Mess 14 3 3 Placeholder modules proxy gates When setting up a model partitioned to several LPs OMNeT uses placeholder modules and proxy gates In the local LP placeholders represent sibling submodules that are instantiated on other LPs With placeholder modules every module has all of its siblings present in the local LP either as placeholder or as the real thing Proxy gates take care of forwarding messages to the LP where the module is instantiated see Figure below The main advantage of using placeholders is that algorithms such as topology discovery embedded in the model can be used with PDES unmodified Also modules can use direct message sending to any sibling module including placeholders This is so because the destination of direct message sending is an input gate of the destination module if the destination module is a placeholder the input gate will be a proxy gate which transparently forwards the messages to the LP where the real module was instantiated A limitation is that the destination of direct message sending cannot be a submodule of a sibling which is probably a bad practice anyway as it violates encapsulation simply because placeholders are empty and so its submodules are not present in the local LP Instantiation of compound modules is slightly
307. man html 2009 4 20 20 32 29 OMNeT Manual others open to be assigned in derived configurations If you are experimenting a lot with different parameter settings of a simulation model these techniques will make it a lot easier to manage ini files 8 4 Setting module parameters Simulations get input via module parameters which can be assigned a value in NED files or in omnetpp ini in this order Since parameters assigned in NED files cannot be overridden in omnetpp ini one can think about them as being hardcoded In contrast it is easier and more flexible to maintain module parameter settings in omnetpp ini In omnetpp ini module parameters are referred to by their full paths or hierarchical names This name consists of the dot separated list of the module names from the top level module down to the module containing the parameter plus the parameter name see section 6 1 5 An example omnetpp ini which sets the numHosts parameter of the toplevel module and the transactionsPerSecond parameter of the server module General net numHosts 15 net server transactionsPerSecond 100 8 4 1 Using wildcard patterns Models can have a large number of parameters to be configured and it would be tedious to set them one by one in omnetpp ini OMNeT supports wildcards patterns which allow for setting several model parameters at once The notation is a variation on the usual glob style patterns The most apparent differe
308. manual usman html 2009 4 20 20 32 29 OMNeT Manual property_values property_values property_value property_value J property_value property_value_tokens STRINGCONSTANT J property_value_tokens property_value_tokens property_value_token property_value_token J property_value_token NAME INTCONSTANT REALCONSTANT TRUE FALSE Sree hy Es oe a es ese ou J PHE TT 88 HE T J opt_gateblock gateblock J gateblock GATES opt_gates 3 opt_gates gates 3 gates gates gate gate J http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual gate gate_typenamesize opt_inline_properties J gate_typenamesize gatetype NAME gatetype NAME T T gatetype NAME vector NAME NAME T T NAME vector J gatetype INPUT OUTPUT INOUT J opt_typeblock typeblock J typeblock TYPES opt_localtypes opt_localtypes localtypes 3 localtypes localtypes localtype localtype J localtype propertydecl channeldefinition channelinterfacedefinition simplemoduledefinition compoundmoduledefinition http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual networkdefinition moduleinterfacedefinition al J 3 opt_submodblock submodblock J submodblock SUBMODULES opt_submodules J opt_submodules submodules 3
309. me for the output scalar file ault resultdir configname ut scalar file append lt bool gt default false per run setting What to do when the output scalar file already exists append to it opp 3 x behavior or delete it and begin a new file default ut scalar precision lt int gt default 14 per run setting The number of significant digits for recording data into the output scalar file The maximum value is 15 IEEE double precision T OMNeT Manual output vector file lt filename gt default S resultdir configname S runnumber vec per run setting Name for the output vector file output vector precision lt int gt default 14 per run setting The number of significant digits for recording data into the output vector file The maximum value is 15 IEEE double precision This setting has no effect on the time column of output vectors which are represented as fixed point numbers and always get recorded precisely output vectors memory limit lt double gt unit B default 16MB per run setting Total memory that can be used for buffering output vectors Larger values produce less fragmented vector files i e cause vector data to be grouped into larger chunks and therefore allow more efficient processing later outputscalarmanager class lt string gt def
310. ment and replication labels can be customized in a similar way making use of named iteration variables repetition runnumber and other predefined variables One possible benefit is to customize the generated measurement and replication labels For example Config PureAloha_Partl measurement S N hosts exponential mean packet generation interval One should be careful with the above technique though because if some iteration variables are left out of the measurement labels runs with all values of those variables will be grouped together to the same replications 8 7 Configuring the random number generators The random number architecture of OMNeT was already outlined in section 6 4 Here we ll cover the configuration of RNGs in omnetpp ini 8 7 1 Number of RNGs The num rngs configuration option sets the number of random number generator instances i e random number streams available for the simulation model see 6 4 Referencing an RNG number greater or equal to this number from a simple module or NED file will cause a runtime error 8 7 2 RNG choice The rng class configuration option sets the random number generator class to be used It defaults to cMersenneTwister the Mersenne Twister RNG Other available classes are cLCG32 the legacy RNG of OMNeT 2 3 and earlier versions with a cycle length of 231 2 and cAkaroaRNG Akaroa s random number generator see section 9 5 8 7 3 RNG map
311. message is currently in the FES by calling its isScheduled member if msg gt isScheduled currently scheduled else not scheduled Re scheduling an event If you want to reschedule an event which is currently scheduled to a different simulation time first you have to cancel it using cancelEvent Cancelling an event Scheduled self messages can be cancelled removed from the FES This is particularly useful because self messages are often used to model timers cancelEvent msg The cancelEvent function takes a pointer to the message to be cancelled and also returns the same pointer After having it cancelled you may delete the message or reuse it in the next scheduleAt calls cancelEvent gives an error if the message is not in the FES Implementing timers The following example shows how to implement timers cMessage timeoutEvent new cMessage timeout Ssemeqduilke Ate sammie ORO as eine OE EVE oes http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual cMessage msg receive if msg timeoutEvent timeout expired else other message has arrived timer can be cancelled now delete cancelEvent timeoutEvent 4 7 Stopping the simulation 4 7 1 Normal termination You can finish the simulation with the endSimulation function endSimulation endSimulation is rarely needed in pract
312. meter name in the path name while can be used to match several components in the path For example queue bufSize matches the bufSize parameter of any module whose name begins with queue in the model while queue bufSize or net queue bufSize selects only queues immediately on network level Also note that queue bufSize would match net queuel foo bar bufSize as well Sets negated sets Sets and negated sets can contain several character ranges and also enumeration of characters For example _a zA ZO 9 matches any letter or digit plus the underscore xyzc f matches any of the characters x y Z c d e f To include in the set put it at a position where it cannot be interpreted as character range for example a z or a z If you want to include in the set it must be the first character a z or as a negated set a z A backslash is always taken as literal backslash and NOT as escape character within set definitions Numeric ranges and index ranges Only nonnegative integers can be matched The start or the end of the range or both can be omitted 10 99 or are valid numeric ranges the last one matches any number The specification must use exactly two dots Caveat 17 19 will match a17 117 and 963217 as well because the can also match digits An example for numeric ranges General sof SCAUISUIS S46 45 slobhcSawZe IC 5 ot SCAUISOIS ILA 5 6 s
313. ml 2009 4 20 20 32 29 OMNeT Manual module by adding a WebClientApp submodule and connecting it to the inherited TCP submodule e Packages The NED language features a Java like package structure to reduce the risk of name clashes between different models NEDPATH similar to Java s CLASSPATH was also introduced to make it easier to specify dependencies among simulation models e Inner types Channel types and module types used locally by a compound module can be defined within the compound module in order to reduce namespace pollution e Metadata annotations It is possible to annotate module or channel types parameters gates and submodules by adding properties Metadata are not used by the simulation kernel directly but they can carry extra information for various tools the runtime environment or even for other modules in the model For example a module s graphical representation icon etc or the prompt string and measurement unit milliwatt etc of a parameter are already specified as metadata annotations NOTE The NED language has changed significantly in the 4 0 version Inheritance interfaces packages inner types metadata annotations inout gates were all added in the 4 0 release together with many other features Since the basic syntax has changed as well old NED files need to be converted to the new syntax There are automated tools for this purpose so manual editing is only needed to take advantage of new NE
314. mod gt getSubmodule child 5 gt getSubmodule grandchild Provided that child 5 does exist because otherwise the second version would crash with an access violation because of the NULL pointer dereference The cSimulation t igetModuleByPath function is similar to cModule s moduleByRelativePath function and it starts the search at the top level module Iterating over submodules To access all modules within a compound module use cSubModIterator For example for cSubModIterator iter getParentModule iter end iter ev lt lt iter gt getFullName iter is pointer to the current module the iterator is at The above method can also be used to iterate along a module vector since the getName function returns the same for all modules for cSubModIterator iter getParentModule iter end iter if iter gt isName getName if iter is in the same vector as this module int itsIndex iter gt getIndex do something to at Walking along links To determine the module at the other end of a connection use cGate s getPreviousGate getNextGate and getOwnerModule functions For example cModule neighbour gate out gt getNextGate gt getOwnerModule For input gates you would use get PreviousGate instead of getNextGate 4 10 Direct method calls between modules In s
315. moduledefinition networkdefinition moduleinterfacedefinition l J J packagedeclaration PACKAGE dottedname J dottedname dottedname NAME NAME 3 import IMPORT importspec http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual importspec importspec importname importname J importname importname NAME importname importname NAME xt IkkI IkkI J propertydecl propertydecl_header opt_inline_properties propertydecl_ header opt_propertydecl_keys opt_inline_properties 3 propertydecl_header PROPERTY NAME PROPERTY NAME T T J opt_propertydecl_keys propertydecl_keys 3 propertydecl_keys propertydecl_keys propertydecl_ key propertydecl_ key H propertydecl_key NAME 3 fileproperty property_namevalue 3 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual channeldefinition channelheader opt_paramblock y 3 channelheader CHANNEL NAME opt_inheritance opt_inheritance EXTENDS extendsname LIKE likenames EXTENDS extendsname LIKE likenames 3 extendsname dottedname J likenames likenames likename likename 3 likename dottedname 3 channelinterfacedefinition channelinterfaceheader opt_paramblock ca 3 channelinterfaceheader CHANNELINTERFA
316. modules like simple modules may have parameters and gates Our Node module contains an address parameter plus a gate vector of unspecified size named port The actual gate vector size will be determined implicitly by the number of neighbours when we create a network from nodes of this type The type of port is inout which allows bidirectional connections The modules that make up the compound module are listed under submodules Our Node compound module type has an app and a routing submodule plus a queue submodule vector that contains one Queue module for each port as specified by sizeof port It is legal to refer to sizeof port because the network is built in top down order and the node is already created and connected at network level when its submodule structure is built out In the connections section the submodules are connected to each other and to the parent module Single arrows are used to connect input and output gates and double arrows connect inout gates and a for loop is utilized to connect the rout ing module to each queue module and to connect the outgoing incoming link line gate of each queue to the corresponding port of the enclosing module 3 2 5 Putting it together We have seen all NED definitions but how does it get used by OMNeT When the simulation program is started it loads the NED files The program should already contain the C classes that implement the needed simple modules App Routing a
317. more complicated Since submodules can be on different LPs the compound module may not be fully present on any given LP and it may have to be present on several LPs wherever it has submodules instantiated Thus compound modules are instantiated wherever they have at least one submodule instantiated and are represented by placeholders everywhere else Figure below CPUO tander 1 placeholder CPU1 comm MPI pipe etc tandem 0 placehol lt Figure Placeholder modules and proxy gates http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Figure Instantiating compound modules 14 3 4 Configuration Parallel simulation configuration is the General section of omnetpp ini The parallel distributed simulation feature can be turned on with the parallel simulation boolean option The parsim communications class selects the class that implements communication between partitions The class must implement the cParsimCommunications interface The parsim synchronization class selects the parallel simulation algorithm The class must implement the cParsimSynchronizer interface The following two options configure the Null Message Algorithm so they are only effective if cNullMessageProtocol has been selected as synchronization class e parsim nullmessageprotocol lookahead class selects the lookahead class for the NMA the class must be subclassed from cNMPLookahead The default cla
318. most functions are not absolutely necessary to implement For example you do not need to redefine forEachChild unless your class is a container class The following methods must be implemented e Constructor At least two constructors should be provided one that takes the object name string as const char recommended by convention and another one with no arguments must be present The two are usually implemented as a single method with NULL as default name string e Copy constructor which must have the following signature for a class X X const X amp The copy constructor is used whenever an object is duplicated The usual implementation of the copy constructor is to initialize the base class with the name getName of the other object it receives then call the assignment operator see below e Destructor e Duplication function X dup const It should create and return an exact duplicate of the object It is usually a one line function implemented with the help of the new operator and the copy constructor e Assignment operator that is X amp operator const X amp for a class x It should copy the contents of the other object into this one except the name string See later what to do if the object contains pointers to other objects If your class contains other objects subclassed from cOwnedOb ject either via pointers or as data member the following function should be implemented e Iteration function
319. mulation is run under Cmdenv so one can make the code skip potentially expensive display string manipulation Better if ev isGUI bubble Going down 11 Analyzing Simulation Results 11 1 Result files 11 1 1 Results vector results scalar results unique run id attributes e g experiment measurement replication The format of result files is documented in detail in 24 11 1 2 Output vectors Output vectors are time series data values with timestamps You can use output vectors to record end to end delays or round trip times of packets queue lengths queueing times link utilization the number of dropped packets etc anything that is useful to get a full picture of what happened in the model during the simulation run Output vectors are recorded from simple modules by cOut Vector objects see section 6 8 1 Since output vectors usually record a large amount of data in omnetpp ini you can disable vectors or specify a simulation time interval for recording see section 8 6 2 All cout Vector objects write to the same common file The following sections describe the format of the file and how to process it 11 1 3 Format of output vector files An output vector file contains several series of data produced during simulation The file is textual and it looks like this net l vec http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual vector 1 subnet 4 te
320. multiply divide modulus add subtract string concatenation bitwise shift equal not equal greater greater or equal less less or equal amp amp logical operators and or xor the C C inline if Conversions bitwise and or xor Values are of type boolean long double string or xml element A long or double may have an associated measurement unit s mW etc Long and double values are implicitly converted to one another where needed Conversion is performed with the C language s built in typecast operator There is no implicit conversion between bool and numeric types so 0 is not a synonym for false and nonzero http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual numbers are not a synonym for true There is also no conversion between string and numeric types so e g foo 5 is illegal There are functions for converting a number to string and vica versa NOTE Implementation note Currently the stack based evaluation engine represents all numbers in double i e it does not use long on the stack This may change in future releases Details o Integers integer constants long parameters etc are converted to double o For bitwise operators doubles are converted to unsigned long using the C C built in conversion type cast the operation is performed then the result is converted back to double o For modulus the operands are converted to lon
321. n e gamma_d quantity gamma_d double alpha quantity theta long rng Returns a random number from the Gamma distribution lognormal double lognormal double m double w long rng Returns a random number from the Lognormal distribution e normal quantity normal quantity mean quantity stddev long rng Returns a random number from the Normal distribution pareto_shifted quantity pareto_shifted double a quantity b quantity c long rng Returns a random number from the Pareto shifted distribution e student t double student_t long i long rng Returns a random number from the Student t distribution e triang quantity triang quantity a quantity b quantity c long rng Returns a random number from the Triangular distribution e truncnormal quantity truncnormal quantity mean quantity stddev long rng Returns a random number from the Truncated Normal distribution e uniform quantity uniform quantity a quantity b long rng Returns a random number from the Uniform distribution e weibull quantity weibull quantity a quantity b long rng Returns a random number from the Weibull distribution Category random discrete e bernoulli long bernoulli double p long rng Returns a random number from the Bernoulli distribution e binomial long binomial long n double p long rng Returns a random number from the Binomial distribution e geometric long geometric double p long rng
322. n 22 S0 50 1 Run 23 S0 50 1 Srepetition 0 Srepetition 0 Srepetition 0 oi ll Siers OWN ae oe Any of these runs can be executed by passing the r lt runnumber gt option to Cmdenv So the task is now to run the simulation program 24 times with r running from 0 through 23 lohastudy r Lohastudy r lohastudy aloha u Cmdenv c loha Cmdenv cC aloha u Cmdenv c rs WH w D PPP NFO aloha u Cmdenv c AlohaStudy r 23 This batch can be executed either from the OMNeT IDE where you are prompted to pick an executable and an ini file choose the configuration from a list and just click Run or using a little command line batch execution tool opp_runal1 supplied with OMNeT Actually it is also possible to get Cmdenv execute all runs in one go by simply omitting the r option aloha u Cmdenv c AlohaStudy opp Discrete Event Simulation Preparing for running configuration AlohaStudy run 0 Preparing for running configuration AlohaStudy run 1 Preparing for running configuration AlohaStudy run 23 However this approach is not recommended because it is more susceptible to C programming errors in the model For example if any of the runs crashes the whole batch is terminated which may not be what the user wants Let us get back to the ini file We had Config AlohaStudy x numHosts Sfl 2 5 10 50 step 10
323. n and specify the runs in a comma separated format 1 2 4 9 11 or you may leave out the r option to execute all runs in the experiment WARNING Although it is very convenient we do not recommended to use this method for running simulation batches Specifying more than one runnumber would run these simulations in the same process This method is more prone to C programming errors A failure in a single run may stop and kill all the runs following it If you want to execute more than one run we recommend to run each of them in a separate process Use the opp_runall for this purpose 9 4 2 Using shell scripts The following script executes a simulation named wireless several times with parameters for the different runs given in the runs ini file Before you are executing your simulation batch you may check how many runs are available in the configuration you are using Use the x config command line option to print the number of runs or add the g to get more details http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual bin sh wireless f runs ini r 1 Waeselless fruns ima r 2 wireless f runs ini r 3 wireless f runs ini r 4 wireless f runs ini r 10 To run the above script type it in a text file called e g run give it x executable permission using chmod then you can execute it by typing run S chmod x run SA cun You can simplify the above script by u
324. n be viewed as Discrete Event Systems can be modeled using Discrete Event Simulation Other systems can be modelled e g with continuous simulation models For example computer networks are usually viewed as discrete event systems Some of the events are e start of a packet transmission e end of a packet transmission e expiry of a retransmission timeout This implies that between two events such as start of a packet transmission and end of a packet transmission nothing interesting happens That is the packet s state remains being transmitted Note that the definition of interesting events and states always depends on the intent and purposes of the person doing the modeling If we were interested in the transmission of individual bits we would have included something like start of bit transmission and end of bit transmission among our events The time when events occur is often called event timestamp with OMNeT we ll say arrival time because in the class library the word timestamp is reserved for a user settable attribute in the event class Time within the model is often called simulation time model time or virtual time as opposed to real time or CPU time which refer to how long the simulation program has been running and how much CPU time it has consumed 4 1 2 The event loop Discrete event simulation maintains the set of future events in a data structure often called FES Future Event Set or FEL Future Event List S
325. n cannot be stored in local variables of handleMessage because they are destroyed when the function returns Also they cannot be stored in static variables in the function or the class because they would be shared between all instances of the class Data members to be added to the module class will typically include things like state e g IDLE BUSY CONN_DOWN CONN_ALIVE e other variables which belong to the state of the module retry counts packet queues etc e values retrieved computed once and then stored values of module parameters gate indices routing information etc e pointers of message objects created once and then reused for timers timeouts etc e variables objects for statistics collection You can initialize these variables from the initialize function The constructor is not a very good place for this purpose because it is called in the network setup phase when the model is still under construction so a lot of information you may want to use is not yet available Another task you have to do in initialize is to schedule initial event s which trigger the first call s to http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual handleMessage After the first call handleMessage must take care to schedule further events for itself so that the chain is not broken Scheduling events is not necessary if your module only has to react to messages coming from other mod
326. n comment placement Comments should be written where nedtool will find them This is a immediately above the documented item or b after the documented item on the same line In the former case make sure there s no blank line left between the comment and the documented item Blank lines detach the comment from the documented item Example This is wrong Because of the blank line this comment is not associated with the following simple module simple Gen Do not try to comment groups of parameters together The result will be awkward 13 3 Text layout and formatting 13 3 1 Paragraphs and lists If you write longer descriptions you ll need text formatting capabilities Text formatting works like in Javadoc or Doxygen you can break up the text into paragraphs and create bulleted numbered lists without special commands and use HTML for more fancy formatting Paragraphs are separated by empty lines like in LaTeX or Doxygen Lines beginning with will be turned into bulleted lists and lines beginning with into numbered lists Example Ethernet MAC layer MAC performs transmission and reception of frames Processing of frames received from higher layers Scnds oul rane EO Ene necework no encapsulation of frames this is done by higher layers can send PAUSE message if requested by higher layers PAUSE protocol used in switches PAUSE is not implemented y
327. n discussed yet but the code is probably understandable nevertheless class Generator public cSimpleModule puo Generator cSimpleModule protected vireca IL WOsuel simalie sala we F virtual void handleMessage cMessage msg Define_Module Generator void Generator initialize i schedule first sending scheduleAt SimTime new cMessage void Generator handleMessage cMessage msg generate amp send packet cMessage pkt new cMessage sendi Oke LOUT u Il Bechecule next call scheduleAt simTime exponential 1 0 msg Example 3 Bursty traffic generator A bit more realistic example is to rewrite our Generator to create packet bursts each consisting of burstLength packets We add some data members to the class e burstLength will store the parameter that specifies how many packets a burst must contain e burstCounter will count in how many packets are left to be sent in the current burst The code class BurstyGenerator public cSimpleModule protected int burstLength iime louie ste Couimieeics WALecUe IL yore sLinaieaa lla Ze f http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual virtual void handleMessage cMessage msg Define Module BurstyGenerator void BurstyGenerator initialize init parameters and state variables
328. n element tag name or e means child element just as in usr bin gcc means an element any levels under the current element e and mean the current element the parent element and an element with any tag name respectively Element tag names and can have an optional predicate in the form position or attribute value Positions start from zero e Predicates of the form attribute Sparam are also accepted where Sparam can be one of SMODULE_FULLPATH SMODULE_FULLNAME SMODULE_NAME SMODULE_INDEX SMODULE_ID SPARENTMODULE_FULLPATH PARENTMODULE_FULLNAME SPARENTMODULE_NAME SPARENTMODULE_INDEX PARENTMODULE_ID SGRANDPARENTMODULE_FULLPATH SGRANDPARENTMODULE_FULLNAME SGRANDPARENTMODULE_NAME SGRANDPARENTMODULE_INDEX SGRANDPARENTMODULE_ID 17 5 6 Functions The functions available in NED are listed in Appendix 20 17 5 7 Units of measurement The following measurements units are recognized in constants Other units can be used as well but there are no conversions available for them i e parsec and kiloparsec will be treated as two completely unrelated units nit ame vais o pe C esis o h 3600s min 60s http omnetpp org
329. n ipin Ho MLC Liars lt wlan 90u wlan radioIn lt radiolIn module WirelessUser extends WirelessHostBase submodules webAgent WebAgent connections webAgent tcpOut gt tcp appiInt webAgent tcpIn lt tcp appOut The WirelessUser compound module can further be extended for example with an Ethernet port module DesktopUser extends WirelessUser gates inout ethg submodules Stel s ihe laSieineveINsLie s connections WO MaLeOucssr gt etn ae ling LOM lt eth 1joOwie eth phy lt gt ethg http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 3 5 Channels Channels encapsulate parameters and behaviour associated with connections Channels are like simple modules in the sense that there are C classes behind them The rules for finding the C class for a NED channel type is the same as with simple modules the default class name is the NED type name unless there is a class property namespace is also observed and the C class is inherited when the channel is subclassed Thus the following channel type would expect a CustomChannel C class to be present channel CustomChannel needs a CustomChannel C class The practical difference to modules is that you rarely need to write you own channel C class because there are predefined channel types that you can subclass from inheriting their C code The predef
330. n record their results into a single file this facilitates comparing them creating x y plots offered load vs throughput type diagrams etc 11 2 The Analysis Tool in the Simulation IDE The Simulation IDE provides an Analysis Tool for analysis and visualization of simulation results The Analysis Tool lets you load several result files at once and presents their contents somewhat like a database You can browse the results select the particular data you are interested in scalars vectors histograms apply processing steps and create various charts or plots from them Data selection processing and charting steps can be freely combined resulting in a high degree of freedom These steps are grouped into and stored as recipes which get automatically re applied when new result files are added or existing files are replaced This automation spares the user lots of repetitive manual work without resorting to scripting The Analysis Tool is covered in detail in the User Guide 11 3 Scave Tool Much of the IDE Analysis Tool s functionality is available on the command line as well via the scavetool program scavetool is suitable for filtering and basic processing of result files and exporting the result in various formats digestible for other tools scavetool has no graphics capabilities but it can be used to produce files that http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual can be directly plotte
331. n run may use one set of seeds seed set 0 the second run may use a second set seed set 1 and so on Each set contains as many seeds as there are RNGs configured All automatic seeds generate random number sequences that are far apart in the RNG s cycle so they will never overlap during simulations NOTE http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Mersenne Twister the default RNG of OMNeT has a cycle length of 219997 which is more than enough for any conceivable purpose The seed set key tells the simulation kernel which seed set to use It can be set to a concrete number such as seed set 0 but it usually does not make sense as it would cause every simulation to run with exactly the same seeds It is more practical to set it to either runnumber or to repetition The default setting is runnumber seed set S runnumber this is the default This makes every simulation run to execute with a unique seed set The second option is seed set S repetition where all repetition 0 runs will use the same seeds seed set 0 all repetition 1 runs use another seed set repetition 2 a third seed set etc To perform runs with manually selected seed sets you can just define an iteration for the seed set key seed set 5 6 8 11 In this case the repeat key should be left out as seed set already defines an iteration and there s no need for an extra loop It is
332. nager class lt string gt default cFileSnapshotManager global setting Part of the Envir plugin mechanism selects the class to handle streams to which snapshot writes its output The class has to implement the cSnapshotManager interface tkenv default config lt string gt global setting Specifies which config Tkenv should set up automatically on startup The default is to ask the user tkenv default run lt int gt default 0 global setting Specifies which run of the default config s tkenv default config Tkenv should set up automatically on startup The default is to ask the user tkenv extra stack lt double gt unit B default 48KB global setting Specifies th xtra amount of stack that is reserved for each activity simple module when the simulation is run under Tkenv tkenv image path lt path gt global setting Specifies the path for loading module icons tkenv plugin path lt path gt global setting Specifies the search path for Tkenv plugins Tkenv plugins are tcl files that get evaluated on startup http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual total stack lt double gt unit B global setting Specifies the maximum memory for activity simple module stacks You need to increase this value if you get a Cannot allocate coroutine stack error lt object full path gt type name
333. napshot from the menu An example of a snapshot file eal cSimulation simulation begin Modules in the network token 1 TokenRing comp 0 2 Computer mac 3 TokenRingMAC gen 4 Generator Usaliale po Cink comp 1 6 Computer mac 7 TokenRingMAC gen 8 Generator Faaali 28 Sink Goma 2 lO Comprrer mac TokenRingMAC gen 12 Generator sink 13 Sink end TokenRing token begin 1 params cArray n 6 1 gates cArray empty comp 0 cCompoundModule 2 comp 1 cCompoundModule 6 comp 2 cCompoundModule 10 end cArray token parameters begin num_stations cModulePar 3 L num_messages cModulePar 10000 L ia_time eMoculeRar cimunenommal O 005 0 003 is ane cModulePar 0 01 D data_rate cModulePar 4000000 L cable_delay cModulePar le O6 D end bere pal cQueue token comp 0 mac local objects send queue begin 0 gt 1 cMessage Tarr 0 0158105774 15ms Src 4 Dest 3 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 0 gt 2 cMessage Tarr 0 0163553310 16ms Src 4 Dest 3 O gt 1 cMessage Tarr 0 0205628236 20ms Src 4 Dest 3 0 gt 2 cMessage Tarr 0 024220359 24ms Src 4 Dest 3 QO gt 2 cMessage Tarr 0 0300994268 30ms Src 4 Dest 3 O gt 1 cMessage Tarr 0 0364005251
334. nces to the usual rules are the distinction between and and that character ranges should be written with curly braces instead of square brackets that is any etteris a zA Z not a zA Z because square brackets are already reserved for the notation of module vector indices Pattern syntax e matches any character except dot e x matches zero or more characters except dot e matches zero or more character any character e a f set matches a character in the range a f e a f negated set matches a character NOT in the range a f e 38 150 numeric range any number i e sequence of digits in the range 38 150 e g 99 e 38 150 index range any number in square brackets in the range 38 150 e g 99 e backslash takes away the special meaning of the subsequent character Precedence If you use wildcards the order of entries is important if a parameter name matches several wildcards patterns the first matching occurrence is used This means that you need to list specific settings first and more general ones later Catch all settings should come last An example ini file General host 0 waitTime 5ms specifics come first http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual host 3 waitTime host waitTime 6ms 10ms catch all comes last Asterisk vs double asterisk The wildcard is for matching a single module or para
335. nd Queue their C code is either part if the executable or gets loaded from shared library The simulation program also loads the configuration omnetpp ini and determines from it that the simulation model to be run is the Network network Then the network gets instantiated for simulation The simulation model is built in a top down preorder fashion This means that starting from an empty system module all submodules are created their parameters and vector sizes get assigned and they get fully connected before proceeding to go into the submodules to build their internals In the following sections we ll go through the elements of the NED language and look at them in more details http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 3 3 Simple modules Simple modules are the active components in the model Simple modules are defined with the simple keyword An example simple module simple Queue parameters ine Capacityg display i block queue gatesi Lote Le CUE OUiE me Lier Both the parameters and gates sections are optional that is they can be left out if there s no parameter or gate In addition the parameters keyword itself is optional too it can be left out even if there are parameters or properties Note that the NED definition doesn t contain any code to define the operation of the module that part is expressed in C By default OMNeT looks for C classes of the sam
336. nd linked list to store the objects which are inserted into them However they do not necessarily own all of these objects Whether they own an object or not can be determined from that object s getOwner pointer The default behaviour of cQueue and cArray is to take ownership of the objects inserted This behavior can be changed via the takeOwnership flag Here s what the insert operation of cQueue or cArray does e insert the object into the internal array list data structure if the takeOwnership flag is true take ownership of the object otherwise just leave it with its original owner The corresponding source code void cQueue insert cOwnedObject obj insert into queue data structure take ownership if needed if getTakeOwnership take obj Removal Here s what the remove family of operations in cQueue or cArray does e remove the object from the internal array list data structure http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual if the object is actually owned by this cQueue cArray release ownership of the object otherwise just leave it with its current owner After the object was removed from a cQueue cArray you may further use it or if it is not needed any more you can delete it The release ownership phrase requires further explanation When you remove an object from a queue or array the ownership is expected to be transferred to the simple mod
337. nds to the start or end of the reception process it should be the same as the getDeliverOnReceptionStart flag of the input gate and getDuration returns the transmission duration 4 6 3 Delay data rate bit error rate packet error rate Connections can be assigned three parameters which facilitate the modeling of communication networks but can be useful for other models too e propagation delay sec e bit error rate errors bit e data rate bits sec Each of these parameters is optional One can specify link parameters individually for each connection or define link types also called channel types once and use them throughout the whole model The propagation delay is the amount of time the arrival of the message is delayed by when it travels through the channel Propagation delay is specified in seconds The bit error rate has influence on the transmission of messages through the channel The bit error rate ber is the probability that a bit is incorrectly transmitted Thus the probability that a message of n bits length is transferred without bit errors is Pro bit error 1 berlenatn The message has an error flag which is set in case of transmission errors The data rate is specified in bits second and it is used for transmission delay calculation The sending time of the message normally corresponds to the transmission of the first bit and the arrival time of the message corresponds to the reception of the
338. ng the gate via inheritance in a derived type and also in the gates block of a submodule body A submodule body does not allow defining new gates A gate is identified by a name and is characterized by a type input output inout and optionally a vector size Gates may also have properties see 17 4 8 Gates may be scalar or vector The vector size is specified with a numeric expression inside the square brackets The vector size may also be left open by specifying an empty pair of square brackets A gate vector size may not be overridden in subclasses or in a submodule The presence of a gate type keyword decides whether the given line defines a new gate or refers to an existing gate One can specify the gate vector size for an existing gate vector and or modify its properties or add new properties Examples gates inputa defines new gate aigqoulic ley Ciro F new gate with property imome Cll s new gate vector with unspecified size input dici new gate vector with size 8 e 10 set gate size for existing e g inherited gate vector f foo bar add property to existing gate g 10 foo bar set gate size and add property to existing gate http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Gate vector sizes are NED expressions Expressions are described in section 17 5 See the Connections section 17 4 12 for more information on gates Recognized g
339. nother channel type and may implement one or more channel interfaces 17 4 6 Inheritance rules are described in section 17 4 17 and interface implementation rules in section 17 4 16 Every channel type has an associated C class which must be subclassed from cChannel The way of associating the NED type with the C class is described in section 17 4 7 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 17 4 5 Module interfaces Module interface types are declared with the moduleinterface keyword see the NED Grammar Appendix 18 for the syntax Module interfaces may have properties 17 4 8 parameters 17 4 9 and gates 17 4 10 However parameters are not allowed to have a value assigned not even a default value A module interface type may not have inner types 17 4 13 A module interface type may extend one or more other module interface types Inheritance rules are described in section 17 4 17 17 4 6 Channel interfaces Channel interface types are declared with the channelinterface keyword see the NED Grammar Appendix 18 for the syntax Channel interfaces may have properties 17 4 8 and parameters 17 4 9 However parameters are not allowed to have a value assigned not even a default value A channel interface type may not have inner types 17 4 13 A channel interface type may extend one or more other channel interface types Inheritance rul
340. nt undisposed lt bool gt default true global setting Whether to report objects left that is not deallocated by simple module destructors after network cleanup realtimescheduler scaling lt double gt global setting When cRealTimeScheduler is selected as scheduler class ratio of simulation time to real time For example scaling 2 will cause simulation time to progress twice as fast as runtime record eventlog lt bool gt default false per run setting Enables recording an eventlog file which can be later visualized on a sequence chart See eventlog file option too repeat lt int gt default 1 per run setting For scenarios Specifies how many replications should be done with the same parameters iteration variables This is typically used to perform multiple runs with different random number seeds The loop variable is available as S repetition See also seed set key replication label lt string gt default repetition per run setting Identifies one replication of a measurement see repeat and measurement label as well This string gets recorded into result files and may be referred to during result analysis result dir lt string gt default results per run setting Value for the S resultdir variable which is used as the default directory for result files output vector file output scalar file eventlog file eve
341. nual usman html 2009 4 20 20 32 29 OMNeT Manual between two events the system is always in one of the steady states Transient states are therefore not really a must they exist only to group actions to be taken during a transition in a convenient way e You can assign program code to handle entering and leaving a state known as entry exit code Staying in the same state is handled as leaving and re entering the state e Entry code should not modify the state this is verified by OMNeT State changes transitions must be put into the exit code OMNeT s FSMs can be nested This means that any state or rather its entry or exit code may contain a further full fledged FSM_Switch see below This allows you to introduce sub states and thereby bring some structure into the state space if it would become too large The FSM API FSM state is stored in an object of type cFSM The possible states are defined by an enum the enum is also a place to define which state is transient and which is steady In the following example SLEEP and ACTIVE are steady states and SEND is transient the numbers in parentheses must be unique within the state type and they are used for constructing the numeric IDs for the states enum NIE SLEEP FSM_Steady 1 ACTIVE FSM _ Steady 2 SEND FSM Transient 1 The actual FSM is embedded in a switch like statement FSM_Switch where you have c
342. number vec roa ile S resultdir configname runnumber sca output ie Cie Ove output scalla Where resultdir isthe value of the result dir configuration option and defaults to results So the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual above defaults generate file names like results PureAloha 0 vec results PureAloha 1 vec and so on Also in OMNeT 3 x output scalar files were always appended to by the simulation program rather than being overwritten This behavior was changed in 4 0 to make it consistent with vector files that is output scalar files are also overwritten by the simulator and not appended to NOTE The old behavior can be turned back on by setting output scalar file append true Although it has nothing to do with our main topic ini files this is a good place to mention that the format of result files have been extended to include meta info such as the run ID network name all configuration settings etc These data make the files more self documenting which can be valuable during the result analysis phase and increase reproducibility of the results Another change is that vector data are now recorded into the file clustered by the output vectors which combined with index files allows much more efficient processing 8 6 2 Configuring output vectors As a simulation program is evolving it is becoming capable of collecting
343. o be able to use IPAddress in a message definition the message file Say foopacket msg should contain the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual following lines Colusoilms 1 include ipaddress h struct IPAddress The effect of the first three lines is simply that the include statement will be copied into the generated foopacket_m h file to let the C compiler know about the IPAddress class The message compiler itself will not try to make sense of the text in the body of the cplusplus directive The next line struct IPAddress tells the message compiler that IPAddress is a C struct This information will among others affect the generated code Classes can be announced using the class keyword class cSubQueue The above syntax assumes that the class is derived from cOwnedOb ject either directly or indirectly If it is not the noncobject keyword should be used class noncobject IPAddress The distinction between classes derived and not derived from cOwnedOb ject is important because the generated code differs at places The generated code is set up so that if you incidentally forget the noncobject keyword and thereby mislead the message compiler into thinking that your class is rooted in cOwnedObject when in fact it is not you ll get a C compiler error in the generated header file 5 2 6 Customizing the generated class The
344. o results in an exception if something goes wrong in an initialize The following lines actually run the simulation by calling sim gt selectNextModule and sim gt doOneEvent in an event loop until the simulation time limit is reached or some exception occurs Exceptions subclassed from cTerminationException signal the normal termination of the simulation other exceptions signal various errors If the simulation has completed successfully ok t rue the code goes on to call the finish methods of modules and channels Then regardless of whether there was an error sim gt endRun has to be called and the network is torn down with sim gt deleteNetwork Finally we deallocate the simulation manager object but the active simulation manager is not allowed to be deleted so we first deactivate it with setActiveSimulation NULL 16 2 3 Providing an environment object The environment object needs to be subclassed from the cEnvir class but since it has quite a number of pure virtual methods it is easier to start by subclassing cNullEnvir cNullEnvir defines all pure virtual methods with either an empty body or with a body that throws an unsupported method called exception You can redefine methods to be more sophisticated later on as you are progressing with the development One method that you surely want to redefine is readParameter that s how module parameters get their values For debugging p
345. ode connections nodel port lt gt datarate 100Mbps lt gt node2 port node2 port lt gt datarate 100Mbps lt gt node4 portt node4 port lt gt datarate l00Mbps lt gt nodeb Pome tay The above code defines a network type named Network Note that the NED language uses the familiar curly brace syntax and to denote comments NOTE Comments in NED not only make the source code more readable but in the OMNeT IDE they also get displayed at various places tooltips content assist etc and become part of the documentation extracted from the NED files The NED documentation system not unlike JavaDoc or Doxygen will be described in Chapter 13 The network contains several nodes named nodel node2 etc from the NED module type Node We ll define Node in the next sections The second half of the declaration defines how the nodes are to be connected The double arrow means bidirectional connection The connection points of modules are called gates and the port notation adds a new gate to the port gate vector Gates and connections will be covered in more detail in sections 3 7 and 3 9 Nodes are connected with a channel that has a data rate of 100Mbps NOTE http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual In many other systems the equivalent of OMNeT gates are called ports We have retained the term gate
346. odel contains unassigned parameters In interactive mode it asks the user In non interactive mode which is more suitable for batch execution Cmdenv stops with an error cmdenv message trace lt bool gt default false per run setting When cmdenv express mode false print a line per message sending by send scheduleAt etc and delivery on the standard output cmdenv module messages lt bool gt default true per run setting When cmdenv express mode false turns printing module ev lt lt output on off cmdenv output file lt filename gt global setting When a filename is specified Cmdenv redirects standard output into the given file This is especially useful with parallel simulation See the fname append host option as well cmdenv performance display lt bool gt default true per run setting When cmdenv express mode true print detailed performance information Turning it on results in a 3 line entry printed on each update containing ev sec simsec sec ev simsec number of messages created still present currently scheduled in FES cmdenv runs to execute lt string gt global setting Specifies which runs to execute from the selected configuration see cmdenv config name It accepts a comma separated list of run numbers or run number ranges e g 1 3 4 7 9 If the value is missing Cmdenv executes all runs in the sel
347. odule from the first line is NULL because the submodule named callee was not found or if that module is actually not of type Callee an error gets thrown from check_and_cast The second issue is how to let the simulation kernel know that a method call across modules is taking place Why is this necessary in the first place First the simulation kernel always has to know which module s code is currently executing in order to several internal mechanisms to work correctly One such mechanism is ownership handling Second the Tkenv simulation GUI can animate method calls but to be able to do that it has to know about them The solution is to add the Enter_Method or Enter_Method_Silent macro at the top of the methods that may be invoked from other modules These calls perform context switching and in case of Enter_Method notify the simulation GUI so that animation of the method call can take place Enter_Method_Silent does not animate the call Enter_Method expects a printf like argument list the resulting string will be displayed during animation void Callee doSomething Enter_Method doSomething 4 11 Dynamic module creation 4 11 1 When do you need dynamic module creation In some situations you need to dynamically create and maybe destroy modules For example when simulating a mobile network you may create a new module whenever a new user enters the simulated area and dispose of them
348. of operator expects one argument and it is only accepted in compound module definitions The sizeof identifier syntax occurring anywhere in a compound module yields the size of the named submodule or gate vector of the compound module Inside submodule bodies the size of a gate vector of the same submodule can be referred to with the this qualifier sizeof this out To refer to the size of a submodule s gate vector defined earlier in the NED file use the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual sizeof submoduleName gateVectorName Or sizeof submoduleName index gateVectorName syntax 17 5 5 The xmldoc operator The xmldoc operator can be used to assign XML type parameters that is point them to XML files or to specific elements inside XML files xmldoc has two flavours one accepts a file name the second accepts a file name plus an XPath like expression which selects an element inside the XML file xmldoc with two arguments accepts a path expression to select an element within the document The expression syntax is similar to XPath If the expression matches several elements the first element in preorder depth first traversal will be selected This is unlike XPath which selects all matching nodes The expression syntax is the following e An expression consists of path components or steps separated by or A path component can be a
349. of course also possible to manually specify individual seeds for simulations This is rarely necessary but we can use it here to demonstrate another feature parallel iterators repeat 4 seed IE mE seed 2 mt seed 3 mt 53542 45732 47853 33434 repetition 75335 35463 24674 56673 repetition 34542 67563 96433 23567 repetition toi ll The meaning of the above is this in the first repetition the first column of seeds is chosen for the second repetition the second column etc The syntax chooses the kth value from the iteration where k is the position iteration count of the iteration variable after the Thus the above example is equivalent to the following no repeat line seed l mt seedl 53542 45732 47853 33434 seed 2 mt 15335 35463 7 24674 566175 seeclil secde oc mE S4547 GV9697 VOSS 29967 1 geci NNV Il ee That is the iterators of seed 2 mt and seed 3 mt are advanced in lockstep with the seed1 iteration 8 6 Parameter Studies and Result Analysis 8 6 1 Output vectors and scalars In OMNeT 3 x the default result file names were omnetpp vec and omnetpp sca This is not very convenient for batch execution where an output vector file created in one run would be overwritten in the next run Thus we have changed the default file names to make them differ for every run The new defaults are ica S resultdir S configname S run
350. of message objects CMessage Copy lS Cie CUNO 7 dup delegates to the copy constructor which in turn relies on the assignment operator between objects operator can be used to copy contents of an object into another object of the same type This is a deep copy object contained in the object will also be duplicated if necessary operator does not copy the name string this task is done by the copy constructor NOTE Since the OMNeT 4 0 version dup returns a pointer to the same type as the object itself and nota cOb ject This is made possible by a relatively new C feature called covariant return types 6 1 7 Iterators There are several container classes in the library cOQueue cArray etc For many of them there is a corresponding iterator class that you can use to loop through the objects stored in the container For example COM We GUES ie for cQueue Iterator queueIter queue queuelIter end queueIter cOwnedObject containedObject queuelter 6 1 8 Error handling When library objects detect an error condition they throw a C exception This exception is then caught by the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual simulation environment which pops up an error dialog or displays the error message At times it can be useful to be able stop the simulation at the place of the error just before the exception is thrown
351. ograms http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Simulation kernel and user interface libraries Figure Building and running simulation This section discusses how to use the simulation system on the following platforms e Unix Linux Mac OS X with gcc e Windows with the included MinGW compiler 7 2 Using gcc The following section applies to using OMNeT on Linux Solaris Mac OS X FreeBSD and other Unix derivatives and also to MinGW on Windows NOTE The doc directory of your OMNeT installation contains Readme lt platform gt files that provide more detailed platform specific instructions 7 2 1 The opp_makemake tool The opp_makemake tool can automatically generate a Makefile for your simulation program based on the source files in the current directory or directory tree opp_makemake has several options opp_makemake h displays help The most important options are e f force Force overwriting existing Makefile e o filename Name of simulation executable or library to be built e O directory out directory Specifies the name of the output directory tree for out of directory build e deep Generates a deep Makefile A deep Makefile will cover the whole source tree under the make http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual directory not just files in that directory e r recurse Caus
352. old are present so that message files from the previous versions of OMNeT 3 x can be parsed msgfile definitions definitions definitions definition J definition namespace_decl cplusplus struct_decl class_decl message_decl packet_decl enum_decl enum message packet class struct J namespace_decl NAMESPACE namespacename namespacename namespacename NAME NAME J http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual cplusplus CPLUSPLUS opt_semicolon b struct_decl STRUCT NAME 3 class_decl CLASS NAME CLASS NONCOBJECT NAME CLASS NAME EXTENDS NAME 3 message_decl MESSAGE NAME J packet_decl PACKET NAME J enum_decl ENUM NAME J enum ENUM NAME opt_enumfields opt_semicolon ENUM NAME EXTENDS NAME opt_enumfields opt_semicolon b opt_enumfields enumfields 2 enumfields enumfields enumfield enumfield J enumfield http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual NAME NAME enumvalue J message message_header body J packet packet_header body 3 class class_header body J struct struct_header body J message_header MESSAGE NAME MESSAGE NAME EXTENDS NAME J packet_header PACKET NAME PACKE
353. om number generators generating statistically equivalent streams of simulation output data These data streams are fed to a global data analyser responsible for analysis of the final results and for stopping the simulation when the results reach a satisfactory accuracy The independent simulation processes run independently of one another and continuously send their observations to the central analyser and control process This process combines the independent data streams and calculates from these observations an overall estimate of the mean value of each parameter Akaroa2 decides by a given confidence level and precision whether it has enough observations or not When it judges that is has enough observations it halts the simulation If n processors are used the needed simulation execution time is usually n times smaller compared to a one processor simulation the required number of observations are produced sooner Thus the simulation would be sped up approximately in proportion to the number of processors used and sometimes even more Akaroa was designed at the University of Canterbury in Christchurch New Zealand and can be used free of charge for teaching and non profit research activities 9 5 3 Using Akaroa with OMNeT http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Akaroa Before the simulation can be run in parallel under Akaroa you have to start up the system e Start akmaster runn
354. ome simulation models there might be modules which are too tightly coupled for message based communication to be efficient In such cases the solution might be calling one simple module s public C methods from another module Simple modules are C classes so normal C method calls will work Two issues need to be mentioned however how to get a pointer to the object representing the module e how to let the simulation kernel know that a method call across modules is taking place http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Typically the called module is in the same compound module as the caller so the getParentModule and get Submodule methods of cModule can be used to get a cModule pointer to the called module Further ways to obtain the pointer are described in the section 4 9 The cModule pointer then has to be cast to the actual C class of the module so that its methods become visible This makes the following code cModule calleeModule getParentModule gt getSubmodule callee Callee callee check_and_cast lt Callee gt calleeModule callee gt doSomething The check_and_cast lt gt template function on the second line is part of OMNeT It does a standard C dynamic_cast and checks the result if it is NULL check_and_cast raises an OMNeT error Using check_and_cast saves you from writing error checking code if calleeM
355. on slowed down by communication between LPs if there s not enough parallelism in the model or parallelism is not exploited by sending a sufficient number of null messages O00 Optimistic synchronization allows incausalities to occur but detects and repairs them Repairing involves rollbacks to a previous state sending out anti messages to cancel messages sent out during the period that is being rolled back etc Optimistic synchronization is extremely difficult to implement because it requires periodic state saving and the ability to restore previous states In any case implementing optimistic http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual synchronization in OMNeT would require in addition to a more complicated simulation kernel writing significantly more complex simple module code from the user Optimistic synchronization may be slow in cases of excessive rollbacks 14 2 Assessing available parallelism in a simulation model OMNeT currently supports conservative synchronization via the classic Chandy Misra Bryant or null message algorithm chandymisra79 To assess how efficiently a simulation can be parallelized with this algorithm we ll need the following variables P performance represents the number of events processed per second ev sec Notations ev events sec real seconds simsec simulated seconds P depends on the performance of the hardware and the computation
356. on classes The classes are also specially instrumented allowing one to traverse objects of a running simulation and display information about them such as name class name state variables or contents This feature has made it possible to create a simulation GUI where all internals of the simulation are visible 2 3 Using OMNeT 2 3 1 Building and running simulations http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual This section provides insight into working with OMNeT in practice Issues such as model files compiling and running simulations are discussed An OMNeT model consists of the following parts NED language topology description s ned files which describe the module structure with parameters gates etc NED files can be written using any text editor but the OMNeT IDE provides excellent support for two way graphical and text editing e Message definitions msg files You can define various message types and add data fields to them OMNeT will translate message definitions into full fledged C classes e Simple modules sources They are C files with h cc suffix The simulation system provides the following components e Simulation kernel This contains the code that manages the simulation and the simulation class library It is written in C compiled into a shared or static library e User interfaces OMNeT user interfaces are used in simulation execution to
357. on of the same name e atan double atan double Trigonometric function see standard C function of the same name e atan2 double atan2 double double Trigonometric function see standard C function of the same name e ceil double ceil double Rounds down see standard C function of the same name e cos double cos double Trigonometric function see standard C function of the same name e exp double exp double Exponential see standard C function of the same name e fabs quantity fabs quantity x Returns the absolute value of the quantity e floor double floor double Rounds up see standard C function of the same name e fmod quantity fmod quantity x quantity y Returns the floating point remainder of x y unit conversion takes place if needed e hypot double hypot double double Length of the hypotenuse see standard C function of the same name log double log double Natural logarithm see standard C function of the same name e log10 double 10g10 double Base 10 logarithm see standard C function of the same name e max quantity max quantity a quantity b Returns the greater one of the two quantities unit conversion takes place if needed e min quantity min quantity a quantity b Returns the smaller one of the two quantities unit conversion takes place if needed e pow double pow double double Power see standard C function of the same name e sin double sin d
358. on to holding constants may transparently act as sources of random numbers with the actual distributions provided with the model configuration they may interactively prompt the user for the value and they might also hold expressions referencing other parameters Compound modules may pass parameters or expressions of parameters to their submodules OMNeT provides efficient tools for the user to describe the structure of the actual system Some of the main features are e hierarchically nested modules e modules are instances of module types e modules communicate with messages through channels flexible module parameters topology description language 2 1 1 Hierarchical modules An OMNeT model consists of hierarchically nested modules which communicate by passing messages to each another OMNeT models are often referred to as networks The top level module is the system module The system module contains submodules which can also contain submodules themselves Fig below The depth of module nesting is not limited this allows the user to reflect the logical structure of the actual system in the model structure Model structure is described in OMNeT s NED language http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Modules that contain submodules are termed compound modules as opposed simple modules which are at the lowest level of the module hierarchy Simple modules contain the al
359. ooted and not rooted in cOwnedOb ject declared with the message syntax or externally in C code e variable sized arrays of the above types stored as a dynamically allocated array plus an integer for the array size Further features e fields initialize to zero except struct members e fields initializers can be specified except struct members e assigning enums to variables of integral types e inheritance e customizing the generated class via subclassing Generation Gap pattern e abstract fields for nonstandard storage and calculated fields Generated code all generated methods are virtual although this is not written out in the following table Field declaration Generated code primitive types double getField void setField double d double field string type const char getField void setField const char string field fixed size arrays double getField unsigned k void setField unsigned k double d double field 4 unsigned getFieldArraySize dynamic arrays void setFieldArraySize unsigned n unsigned getFieldArraySize 3 z double getField unsigned k gonbte See a uls void setField unsigned k double d customized class See en class Foo PER Geet Ie Erie and you have to write class Foo public Poo Base abstract fields double getField 0 void setField double d abstract double field Example simulations http omnetpp org doc omnetpp40 manu
360. or it The lines you write after the t it lepage line up to the next page line see later or the end of the comment will be used as the title page You probably want to begin with a title because the documentation tool doesn t add one it lets you have full control over the page contents You can use the lt h1 gt lt h1 gt HTML tag to define a title Example Ml titlepage lt hl gt Ethernet Model Documentation lt hl1 gt Va This documents the Ethernet model created by David Wu and refined by Andras Varga at CTIE Monash University Melbourne Australia ye 13 4 2 Adding extra pages You can add new pages to the documentation in a similar way as customizing the title page The directive to be used is page and it can appear in any file level comment see above The syntax of the page directive is the following page filename html Title of the Page Please choose a file name that doesn t collide with the files generated by the documentation tool such as index html The page title you supply will appear on the top of the page as well as in the page index The lines after the page line up to the next page line or the end of the comment will be used as the page body You don t need to add a title because the documentation tool automatically adds one Example page structure html Directory Structure The model core model files and the examples have been placed into dif
361. or network graphics doc manuals readme files license APIs etc manual manual in HTML migration how to migrate your models from 3 x to 4 0 version ned2 DID definition of the XML syntax for NED files tictoc tutorial introduction into using OMNeT api API reference in HTML m nedxml api API re ference for the NEDXML library parsim api API reference for the parallel simulation library migrate tools to help model migration from 3 x to 4 0 version src OMNeT sources sim simulation kernel parsim files for distributed execution netbuilder files f or dynamically reading NED files envir common cmdenv command tkenv Tcol Tk nedxml1 NEDXML code for user interfaces line user interface P o based user interface library nedtool opp_msgc scave result analysis library eventlog eventlog processing library layout graph layouter for network graphics common common library utils opp_makemake opp_test etc test regression test suite core tests for the simulation library anim tests for graphics and animation dist tests for the built in distributions makemake tests f or opp_makemake The Eclipse based Simulation IDE is in the ide directory ide Simulation IDE features Eclipse feature definitions plugins DE plugins extensions to the IDE can be
362. ord when the type name comes from a string valued expression See section 3 11 about submodule and channel types as parameters Imports are not much use here at the time of writing the NED file it is not yet known what NED types will be suitable for being plugged in there so they cannot be imported in advance There is no problem with fully qualified names but simple names need to be resolved differently What NED does is this it determines which interface the module or channel type must implement i e like INode and then collects the types that have the given simple name AND implement the given interface There must be exactly one such type which is then used If there s none or there s more than one it will be reported as an error Let us see the following example module MobileHost parame TSnSE string mobilityType submodules mobility lt mobilityType gt like IMobility and suppose that the following modules implement the IMobility module interface inet mobility RandomWalk inet adhoc RandomWalk inet mobility MassMobility and suppose that there s also a type called inet examples adhoc MassMobility but it does not implement the interface So if mobilityType MassMobility then inet mobility MassMobility will be selected the other MassMobility doesn t interfere However if mobilityType RandomWalk then it s an error because there re two matching RandomWalk types Both RandomWalk s can still
363. orted Gnuplot has an interactive command interface For example if you have the data files foo csv and bar csv that contain two values per line x y such files can be exported with scavetool from vector files you can plot them in the same graph by typing plot foo csv with lines bar csv with lines To adjust the y range you would type set yrange 0 1 2 replot Several commands are available to adjust ranges plotting style labels scaling etc On Windows you can copy the resulting graph to the clipboard from the Gnuplot window s system menu then insert it into the application you are working with 11 4 7 Grace Grace also known as xmgrace a successor of ACE gr or Xmgr is a powerful GPL data visualization program with a menu and dialog graphical user interface for X and Motif It has also been ported to Windows Grace can export graphics in various raster and vector formats and has many useful features like built in statistics and analysis functions e g correlation histogram fitting splines etc and it also has a built in programming language 12 Eventlog 12 1 Introduction The eventlog feature and the related tools are completely new in OMNeT 4 0 They aim to help understanding complex simulation models and to help correctly implementing the desired component behaviors Using these tools you will be able to easily examine every minute detail of the simulation back and forth in terms of simulation time or step
364. ou can write delete array remove index Iteration cArray has no iterator but it is easy to loop through all the indices with an integer variable The size member function returns the largest index plus one roc smc n a lt aiecay SiweS Pp sar if array il is this position used cOwnedObject obj array i ev lt lt obj gt getName lt lt endl 6 6 Routing support cTopology 6 6 1 Overview http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The cTopology Class was designed primarily to support routing in telecommunication or multiprocessor networks A cTopology object stores an abstract representation of the network in graph form e each cTopology node corresponds to a module simple or compound and e each cTopology edge corresponds to a link or series of connecting links You can specify which modules either simple or compound you want to include in the graph The graph will include all connections among the selected modules In the graph all nodes are at the same level there s no submodule nesting Connections which span across compound module boundaries are also represented as one graph edge Graph edges are directed just as module gates are If you re writing a router or switch model the cTopology graph can help you determine what nodes are available through which gate and also to find optimal routes The cTopology object can calcul
365. ouble Trigonometric function see standard C function of the same name e sqrt double sqrt double Square root see standard C function of the same name e tan double tan double Trigonometric function see standard C function of the same name Category ned e ancestorindex Long ancestorIndex long numLevels Returns the index of the ancestor module numLevels levels above the module or channel in context fullName string fullName Returns the full name of the module or channel in context http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual e fullPath string fullPath Returns the full path of the module or channel in context e parentIndex long parent Index Returns the index of the parent module which has to be part of module vector Category random continuous e beta double beta double alphal double alpha2 long rng Returns a random number from the Beta distribution e cauchy quantity cauchy quantity a quantity b long rng Returns a random number from the Cauchy distribution e chi_square double chi_square long k long rng Returns a random number from the Chi square distribution e erlang_k quantity erlang_k long k quantity mean long rng Returns a random number from the Erlang distribution e exponential quantity exponential quantity mean long rng Returns a random number from the Exponential distributio
366. out of band signal so its length is left at zero cMessage userdata new cMessage userdata userdata gt setByteLength 2048 2K cMessage tcpseg new cMessage tcp tcpseg gt setByteLength 24 tcpseg gt encapsulate userdata ev lt lt tcpseg gt getByteLength lt lt endl gt 2048 24 2072 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual A message can only hold one encapsulated message at a time The second encapsulate Call will result in an error It is also an error if the message to be encapsulated isn t owned by the module You can get back the encapsulated message by decapsulate cMessage userdata tcpseg gt decapsulate decapsulate will decrease the length of the message accordingly except if it was zero If the length would become negative an error occurs The getEncapsulatedMsg function returns a pointer to the encapsulated message or NULL if no message was encapsulated Reference counting Since the 3 2 release OMNeT implements reference counting of encapsulated messages meaning that if you dup a message that contains an encapsulated message then the encapsulated message will not be duplicated only a reference count incremented Duplication of the encapsulated message is deferred until decapsulate actually gets called If the outer message gets deleted without its decapsulate
367. output vector files Syntax itshape vectorld column1 column2 Simulation times and event numbers within an output vector are required to be in increasing order Performance note Data lines belonging to the same output vector may be written out in clusters of sizes roughly multiple of the disk s physical block size Then since an output vector file is typically not kept in memory during analysis indexing the start offsets of these clusters allows one to read the file and seek in it more efficiently This does not require any change or extension to the file format 24 8 Index Header The first line of the index file stores the size and modification date of the vector file If the attributes of vector file differs from the information stored in the index file then the IDE automatically rebuilds the index file Syntax http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual file filesize modificationDate 24 9 Index Data Stores the location and statistics of blocks in the vector file Syntax itshape vectorld offset length firstEventNo lastEventNo firstSimtime lastSimtime count min max sum sqrsum where e offset the start offset of the block e length the length of the block e firstEventNo lastEventNo the event number range of the block optional e firstSimtime lastSimtime the simtime range of the block e count min max sum sqrsum collected statistics of the values in the block
368. ovided it s in a NED directory 17 4 16 Implementing an interface A module type may implement one or more module interfaces and a channel type may implement one or more channel interfaces using the like keyword The module or channel type is required to have at least those parameters and gates that the interface has Regarding component properties parameter properties and gate properties defined in the interface the module or channel type is required to have at least those properties with at least the same values It may have additional properties and properties may add more keys and values NOTE Implementing an interface does not cause the properties parameters and gates to be interited by the module http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual or channel type they have to be added explicitly NOTE A module or channel type may have extra properties parameters and gates in addition to those in the interface 17 4 17 Inheritance e A simple module may only extend a simple module e A compound module may only extend a compound module A channel may only extend a channel e A module interface may only extend a module interface or several module interfaces A channel interface may only extend a channel interface or several channel interfaces A network is a shorthand for a compound module with the isNetwork property set so the same rules apply to it as to compound mod
369. owever for each configuration it is possible to specify a fall back section explicitly using the extends key Consider the following ini file skeleton General Config SlottedAlohaBase Config SlottedAlohal extends SlottedAlohaBase Config SlottedAloha2 extends SlottedAlohaBase Config SlottedAloha2a extends SlottedAloha2 Config SlottedAloha2b extends SlottedAloha2 If you activate the SlottedAloha2b configuration lookups will consider sections in the following order this is also called the section fallback chain SlottedAloha2b SlottedAloha2 SlottedAlohaBase General The effect is the same as if the contents of the sections SlottedAloha2b SlottedAloha2 SlottedAlohaBase and General were copied together into one section one after another Config SlottedAloha2b being at the top and General at the bottom Lookups always start at the top and stop at the first matching entry The concept is similar to inheritance in object oriented languages and benefits are similar too you can factor out the common parts of several configurations into a base configuration and the other way round you can reuse existing configurations as opposed to copying them by using them as a base In practice you will often have abstract configurations too in the C Java sense which assign only a subset of parameters and leave the http omnetpp org doc omnetpp40 manual us
370. owing fields may be recorded e weights sum of the weights e weightedSum the weighted sum of the observations e sqrSumWeights sum of the squared weights weightedSqrSum weighted sum of the squared observations 24 12 Histogram Bin Represents a bin in a histogram object Syntax bin binLowerBound value Histogram name and module is defined on the statistic line which is followed by several bin lines to contain data Any non bin line marks the end of the histogram data The binLowerBound column of bin lines represent the lower bound of the given histogram cell Bin lines are in increasing binLowerBound order The value column of bin lines represent observation count in the given cell value k is the number of observations greater or equal than binLowerBound k but smaller than binLowerBound k 1 Value is not necessarily an integer because the cKSplit and cPSquare algorithms produce non integer estimates The first bin line is the underflow cell and the last bin line is the overflow cell Example Lm LNE 0 bim 4 losin 2 6 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual bi im 4 2 bim 1 25 Appendix Eventlog File Format This appendix documents the format of the eventlog file Eventlog files are written by the simulation when enabled Everything that happens during the simulation gets recorded into the file With certain granularity of course and subject
371. ows the parallel simulation algorithm to process its own internal messages from other partitions the null message algorithm processes incoming null messages here The Null Message Protocol implementation itself is modular it employs a separate configurable lookahead discovery object Currently only link delay based lookahead discovery has been implemented but it is possible to implement more sophisticated ones The Ideal Simulation Protocol ISP see bagrodia00 implementation consists in fact of two parallel simulation http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual protocol implementations the first one is based on the null message algorithm and additionally records the external events events received from other LPs to a trace file the second one executes the simulation using the trace file to find out which events are safe and which are not Note that although we implemented a conservative protocol the provided API itself would allow implementing optimistic protocols too The parallel simulation algorithm has access to the executing simulation model so it could perform saving restoring model state if model objects support this Unfortunately support for state saving restoration needs to be individually and manually added to each class in the simulation including user programmed simple modules We also expect that because of the modularity extensibility and clean internal architecture o
372. p ini file which can be used to run the Fifo example simulation General network FifoNet sim time limit 100h cpu time limit 300s debug on errors true record eventlog true Conmigo Haste description low job arrival rate x gen sendlaTime exponential 0 2s xx gen msgLength 100b tn bi POnolesPensecs OOOPS Contig IaLiE description high job arrival rate xx gen sendlaTime exponential 0 01s x gen msgLength 10b fifo bitsPerSec 1000bps The file is grouped into sections named General Config Fifol and Config Fifo2 each one containing several entries Lines that start with are comments 8 2 2 File syntax The ini file is a text file consisting of entries grouped into different sections The order of the sections doesn t matter http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Lines that start with are comments and will be ignored during processing Long lines can be broken up using the backslash notation if the last character of a line is it will be merged with the next line There is no limit on the file size or the maximum line length Example General this is a comment ws foo this is a single value for the foo parameter 8 2 3 File inclusion OMNeT supports including an ini file in another via the include keyword This feature allows you to partition large ini files
373. p has a parameter called destAddress others have been omitted for now and two gates named out and in for sending and receiving application packets The argument of display is called a display string and it defines the rendering of the module in graphical environments i defines the default icon Generally words like display are called properties in NED and they are used to annotate various objects with metadata Properties can be attached to files modules parameters gates connections and other objects and parameter values have a very flexible syntax 3 2 4 The Node compound module Now we can assemble App Routing and Queue into the compound module Node A compound module can be thought of as a cardboard box that groups other modules into a larger unit which can further be used as a building block for other modules networks are also a kind of compound module http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Figure The Node compound module module Node Wekeeme wera se display i misc node_vs gold gatesi inout poreik submodules app App TOWNE LINC ROUTLACA queue sizeof port Queue Conmecite lems couci LOCAIOME gt egos Wins COME LING Locallin lt eis OUt Oi 1 0 S Zeo jo ice i OME LING ouri gueure a kan routing in i lt queue i owr CMeCe i lame lt gt pore lil Compound
374. p_prun OMNeT utility can be used to start the processes Alternatively one can run the processes by hand the p flag tells OMNeT the index of the given LP and the total number of LPs cgn p0 3 amp cqn p1 3 amp a Can p23 amp http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual For PDES one will usually want to select the command line user interface and redirect the output to files OMNeT provides the necessary configuration options The graphical user interface of OMNeT can also be used as evidenced by Figure below independent of the selected communication mechanism The GUI interface can be useful for educational or demonstration purposes OMNeT displays debugging output about the Null Message Algorithm ElTs and EOTs can be inspected etc ile Eat Sireufate Trace Inspect View Options Help C H OMMeT Tkemy cqnB lt 3 gt 2 2 OMNe Tes Theny can E Ele Godt Simulate Trace imspect View Qp ons CH OMIe Te Thanny Con lt 2 gt j 4 Ele Edt Simulate Trace jaspect View Opto Ru Mis Cp Ly safe d at PRP d GD As jE Run 1 cqnB Event 0 fa Msgs scheduled 3 Msgs create amp Ev sec wa Simsec sec n a gt Ba cane ClosedQueueing fomnectirg reote 1 parameters cArray pasoi Saon gates cArray gate cord tare W class members cH gate oyt tan r yo processing mo fi o tandemQueueto ct gate cand tani OE tnde
375. package ned file in the current package the package ned file of the parent package or the first ancestor package searching upwards NOTE Note that namespaces coming from multiple namespace properties in different scopes do not nest but rather the nearest one wins The namespace property should contain a single value 17 4 8 Properties Properties are a means of adding metadata annotations to NED files component types parameters gates submodules and connections Identifying a property Properties are identified by name It is possible to have several properties on the same object with the same name as long as they have unique indices An index is an identifier in square brackets after the property name The following example shows a property without index one with the index foo and a third with the index bar statistile as tariis tiie EGO f statistic bar Property value The value of the property is specified inside parentheses The value consists of key valuelist pairs separated by semicolons values are separated with commas Example prop keyl valuell valuel2 valuel3 key2 value21 value22 Keys must be unique If the key equal sign part key is missing the valuelist belongs to the default key Examples prop valuel value2 prop valuel value2 keyl valuell valuel2 valuel13 Property values have a liberal syntax see Appendix 18 V
376. par destAddr longValue Or using overloaded operators msg adakan destAddr msg gt par destAddr 168 long destAddr msg gt par destAddr 5 2 Message definitions 5 2 1 Introduction In practice you ll need to add various fields to cMessage to make it useful For example if you re modelling packets in communication networks you need to have a way to store protocol header fields in message objects Since the simulation library is written in C the natural way of extending cMessage is via subclassing it However because for each field you need to write at least three things a private data member a getter and a setter method and the resulting class has to integrate with the simulation framework writing the necessary C code can be a tedious and time consuming task OMNeT offers a more convenient way called message definitions Message definitions provide a very compact syntax to describe message contents C code is automatically generated from message definitions saving you a lot of typing A common source of complaint about code generators in general is lost flexibility if you have a different idea how the generated code should look like there s little you can do about it In OMNeT however there s nothing to worry about you can customize the generated class to any extent you like Even if you decide to heavily customize the generated class message definitions still save you a great deal of manual
377. pen source Matlab like package available on nearly all platforms Currently Octave relies on Gnuplot for plotting and has more limited graphics capabilities than GNU R or MATLAB 11 4 4 NumPy and MatPlotLib MatPlotlib is a plotting library for the Python programming language and its NumPy numerical mathematics extension It provides a pylab API designed to closely resemble that of MATLAB thereby making it easy to learn for experienced MATLAB users Matplotlib is distributed under a BSD style license 11 4 5 ROOT http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual ROOT is a powerful object oriented data analysis framework with strong support for plotting and graphics in general ROOT was developed at CERN and is distributed under a BSD like license ROOT is based on CINT a C C interpreter aimed at processing C C scripts It is probably harder to get started using ROOT than with either Gnuplot or Grace but if you are serious about analysing simulation results you will find that ROOT provides power and flexibility that would be unattainable the other two programs Curt Brune s page at Stanford http www slac stanford edu curt omnet shows examples what you can achieve using ROOT with OMNeT 11 4 6 Gnuplot Gnuplot is a very popular command line program that can generate two and three dimensional plots of functions and data The program runs on all major platforms and it is well supp
378. per is assigned ned DatarateChannel will be chosen Otherwise if delay or disabled is present it will be ned DelayChanne1 otherwise it is ned IdealChannel Naturally if other parameter names are assigned in an connection without an explicit channel type it will be an error with ned DelayChannel has no such parameter or similar message 3 10 Multiple connections Simple programming constructs loop conditional allow creating multiple connections easily This will be shown in the following examples Chain One can create a chain of modules like this module Chain parameters SLIME CONEA submodules node count Node gares s port 2 connections allowunconnected Ror 1 O covlimc 2 node i port 1 lt gt node it l port 0 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Binary Tree One can build a binary tree in the following way simple BinaryTreeNode Giaweiss imode ene LGE FLCTE inout parent module BinaryTree parameters int height submodules node 2 height 1 BinaryTreeNode connections allowunconnected for 10 2 herghe I 2 node i left lt gt node 2 i 1 parent nodelil right lt gt nodel2 i t2 parent Note that not every gate of the modules will be connected By default an unconnected gate produces a run time error message when the simulation is started but this error mess
379. ping The RNG numbers used in simple modules may be arbitrarily mapped to the actual random number streams actual RNG instances from omnetpp ini The mapping allows for great flexibility in RNG usage and random number http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual streams configuration even for simulation models which were not written with RNG awareness RNG mapping may be specified in omnetpp ini The syntax of configuration entries is the following General lt modulepath gt rng N M where N M are numeric M lt num rngs This maps module local RNG N to physical RNG M The following example maps all gen module s default N 0 RNG to physical RNG 1 and all noisychannel module s default N 0 RNG to physical RNG 2 General num rngs 3 mee Sim Ll sscmei 0 il zkr moisychanne Hak rage This mapping allows variance reduction techniques to be applied to OMNeT models without any model change or recompilation 8 7 4 Automatic seed selection Automatic seed selection gets used for an RNG if you don t explicitly specify seeds in omnetpp ini Automatic and manual seed selection can co exist for a particular simulation some RNGs can be configured manually and some automatically The automatic seed selection mechanism uses two inputs the run number and the RNG number For the same run number and RNG number OMNeT always selects the same seed value for any simulation mo
380. quantity http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual quantity INTCONSTANT NAME quantity REALCONSTANT NAME INTCONSTANT NAME REALCONSTANT NAME 3 opt_semicolon 19 Appendix NED XML Binding This appendix shows the DTD for the XML binding of the NED language and message definitions lt ELEMENT files ned file msg file gt Sa an CNED 2 gt lt ELEMENT ned file comment package import property decl property simple module compound module modul interface lt ATTLIST ned file channel channel interface gt filename CDATA REQUIRED version CDATA MN lt comments and whitespace comments include marks Note that although nearly all elements may contain comment elements there are places e g within expressions wher they are ignored by the implementation gt lt ELEMENT comment EMPTY gt lt ATTLIST comment Default value is a space or a newline depending on the context locid NMTOKEN REQUIRED content CDATA IMPLIED gt lt ELEMENT package comment gt lt ATTLIST package name CDATA REQUIRED gt lt ELEMENT import comment gt lt ATTLIST import import spec CDATA REQUIRED gt
381. r implementation 5 2 7 Using STL in message classes You may want to use STL vector or stack classes in your message classes This is possible using abstract fields After all vector and stack are representations of a sequence same abstraction as dynamic size vectors That is you can declare the field as abstract T fld and provide an underlying implementation using vector lt T gt You can also add methods to the message class that invoke push_back push pop etc on the underlying STL object See the following message declaration Se Bue ee item rme a double b message STLMessage customize true abstract item HOO abstract Item barii use vector lt Iitem gt use stack lt Item gt oo fy w so l If you compile the above in the generated code you ll only find a couple of abstract methods for foo and bar no data members or anything concrete You can implement everything as you like You can write the following C file then to implement foo and bar with std vector and std stack include lt vector gt include lt stack gt http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual include stlmessage_m h class STLMessage public STLMessage_Bas protected Siccls lt WeCrOr lt lESGmS r007 srel SStack lt licem gt oar jOWSLALE s STLMessage const char name NULL int kind 0 STLMessage_Base name kin
382. r less fit on single line the amount of information that can be conveniently displayed is limited An example stream output operator std ostream amp operator lt lt std ostream amp os const ClientInfo amp cli OS lt lt Wacker lt lt cli clienta lt lt Y jorc lt 4 Gli cliemePorts imo encli eSEUICIA OS And the WATCH line WATCH currentClientInfo 6 9 2 Read write watches Watches for primitive types and std string allow for changing the value from the GUI as well but for other types you need to explicitly add support for that What you need to do is define a stream input operator operator gt gt and use the WATCH_RW macro instead of WATCH The stream input operator std ostream amp operator gt gt std istream amp is ClientInfo cli http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual ff read a line from is and parse its contents into cli re cunni is And the WATCH_RW line WATCH_RW currentClientInfo 6 9 3 Structured watches WATCH and WATCH_RW are basic watches they allow one line of unstructured text to be displayed However if you have a data structure generated from message definitions See Chapter 5 then one can do better The message compiler automatically generates meta information describing individual fields of the class or struct which makes it possible to display the cont
383. ract fields see later cannot be used because they would build upon virtual functions Using structs and classes as fields In addition to primitive types you can also use other structs or objects as a field For example if you have a struct named IPAddress you can write the following message FooPacket IPAddress src The IPAddress structure must be known in advance to the message compiler that is it must either be a struct or class defined earlier in the message description file or it must be a C type with its header file included via cplusplus and its type announced see Announcing C types The generated class will contain an IPAddress data member that is not a pointer to an IPAddress The following getter and setter methods will be generated virtual const IPAddress amp getSrc const virtual void setSrc const IPAddress amp src Pointers Not supported yet 5 2 5 Using existing C types Announcing C types If you want to use one of your own types a class struct or typedef declared in a C header in a message definition you have to announce those types to the message compiler You also have to make sure that your header file gets included into the generated _m h file so that the C compiler can compile it Suppose you have an IPAddress structure defined in an ipaddress h file ipaddress h struct IPAddress int byte0 bytel byte2 byte3 T
384. rallel runs allowed WARNING Use the parallel execution option only if you have enough memory to run several simulations side by side If you run out of memory your operating system will start swapping and the overall performance of the system will be greatly reduced Always specify the number of processes after the j option otherwise the make program will try to start a runs at the same time As a rule of thumb if you have 4 cores and enough memory use j4 The form of the command is opp_runall j2 aloha u Cmdenv c PureAlohaExperiment r 0 23 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual You can use the x ConfigName g command line options with your simulation to check the number of available runs Using the export filename option only generates the makefile but does not start it You can run your batch later by invoking the generated makefile 9 5 Akaroa support Multiple Replications in Parallel 9 5 1 Introduction Typical simulations are Monte Carlo simulations they use pseudo random numbers to drive the simulation model For the simulation to produce statistically reliable results one has to carefully consider the following e When is the initial transient over when can we start collecting data We usually do not want to include the initial transient when the simulation is still warming up e When can we stop the simulation We want to wait long enoug
385. rameters gates connections NED files pac and virtually anything in NED display class namespace unit prompt loose direct properties that have been mentioned in previous sections but those examples only scratch the surface of be done with properties kages n are all what can Using properties one can attach extra information to NED elements Some properties are interpreted by NED by the simulation kernel other properties may be read and used from within the simulation model or provide NED editing tools hints for Properties are attached to the type so you cannot have properties per instance different properties All instances of modules connections parameters etc created from any particular location in the NED files have identical properties The following example shows the syntax for annotating various NED elements prop file property module Example parameters prop module property int a prop default 1 parameter property gatesi output out prop http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual submodules Sre Sounce parameters prop submodule property count prop adding a property to a parameter gates out prop adding a property to a gate connections Sie Ou gt Croo gt sinkl niz Sice Oure gt Clneiomeai Cloiecejag S Sali lt in Data model Properties ma
386. ration class from scratch can be a lot of work and it may be more practical to reuse SectionBasedConfiguration with a different configuration reader class This can be done with sectionbasedconfig configreader class config option interpreted by SectionBasedConfiguration Specify the following in your boot time ini file General configuration class SectionBasedConfiguration sectionbasedconfig configreader class lt my new reader class gt The configuration reader class should look like this include cconfigreader h class DatabaseConfigurationReader public cConfigurationReader Register_Class DatabaseConfigurationReader 15 2 4 Defining a new output scalar manager cOutputScalarManager handles recording the scalar output data The default output scalar manager is cFileOutputScalarManager defined in the Envir library The new class can be activated with the outputscalarmanager class configuration option 15 2 5 Defining a new output vector manager cOutputVectorManager handles recording the output from cOut Vector objects The default output vector manager is cIndexedFileOutputVectorManager defined in the Envir library The new class can be activated with the outputvectormanager class configuration option 15 2 6 Defining a new snapshot manager cSnapshotManager provides an output stream to which snapshots are written See section 6 9 5 The default http omnetpp org doc omnetpp40 m
387. rce files i e those created by the opp_msgc compiler will be generated in the source folder rather than in the output folder 7 2 9 Building shared and static libraries By default the makefile will create an executable file but it is also possible to build shared or static libraries Shared libraries are usually a better choice Use make so to create shared libraries and make 1ib to build static libraries The nolink option completely avoids the linking step which is useful for top level makefiles that only invoke other makefiles or if you want to do the linking manually 7 2 10 Recursive builds The recurse option enables recursive make when you build the simulation make will descend into the subdirectories and runs make in them too By default recurse decends into all subdirectories the X directory option can be used to make it ignore certain subdirectories This option is especially useful for top level makefiles The recurse option automatically discovers subdirectories but this is sometimes inconvenient Your source directory tree may contain parts which need their own hand written Makefile This can happen if you include source files from an other non OMNeT project With the d dir or subdir dir option you can explicitly specify which directories to recurse into and also the directories need not be direct children of the current directory The recursive make options recurse d subdir imply
388. refreshes dependencies in the Makefile Deletes all files that were produced by the make process 7 2 3 Debug and release builds opp_makemake generates a makefile that can create both release and debug builds By default it creates debug version but it is easy to override this behaviour Just define the MODE variable on the make command line S make MODE release If you want to create release builds by default you should use the mode mode option for opp_makemake when generating your makefiles opp_makemak mode releas http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 7 2 4 Using external C C libraries If you are using external libraries you should specify the include path for the header files with the I includedir option You should specify this option if you are using anything outside from the source directory tree except the system and OMNeT headers which are always included automatically To define an external library to be linked with use Ldir to specify the directory of the external library and llibrary to specify the name of the external dependency 7 2 5 Building directory trees It is possible to build a whole source directory tree with a single makefile A source tree will generate a single output file executable or library A source directory tree will always have a Makefile in its root and source files may be placed anywhere in the tree To tu
389. rely in practice or when it isn t necessary for the simulation to run further because the model time or the CPU time has reached a given limit or because the statistics have reached the desired accuracy At this time before the program exits the user will typically want to record statistics into output files 4 1 3 Simple modules in OMNeT In OMNeT events occur inside simple modules Simple modules encapsulate C code that generates events and reacts to events in other words implements the behaviour of the model The user creates simple module types by subclassing the cSimp1eModule class which is part of the OMNeT class library cSimpleModule just as cCompoundModule is derived from a common base class cModule cSimpleModule although packed with simulation related functionality doesn t do anything useful by itself you have to redefine some virtual member functions to make it do useful work These member functions are the following e void initialize e void handleMessage cMessage msg e void activity e void finish In the initialization step OMNeT builds the network it creates the necessary simple and compound modules and connects them according to the NED definitions OMNeT also calls the initialize functions of all modules The handleMessage and activity functions are called during event processing This means that the user will implement the model s behavior in these functions handleMessage
390. rent simulation time T and e the elapsed time wall clock time since the beginning of the simulation run The second line displays info about simulation performance e ev sec indicates performance how many events are processed in one real time second On one hand it depends on your hardware faster CPUs process more events per second and on the other hand it depends on the complexity amount of calculations associated with processing one event For example protocol simulations tend to require more processing per event than e g queueing networks thus the latter produce higher ev sec values In any case this value is independent of the size number of modules in your model e simsec sec shows relative speed of the simulation that is how fast the simulation is progressing compared to real time how many simulated seconds can be done in one real second This value virtually depends on everything on the hardware on the size of the simulation model on the complexity of events and the average simulation time between events as well e ev simsec Is the event density how many events are there per simulated second Event density only depends on the simulation model regardless of the hardware used to simulate it in a cell level ATM simulation you ll have very hight values 10 while in a bank teller simulation this value is probably well under 1 It also depends on the size of your model if you double the number of modules in your model yo
391. resolve to cSimulation getActiveSimulation and cSimulation getActiveSimulation gt getEnvir Every cSimulation instance should have its own associated environment object cEnvir Environment objects may not be shared among several cSimulation instances cSimulation s destructor deletes the associated cEnvir instance as well cSimulation instances may be reused from one simulation to another but it is also possible to make a new instance for each simulation run NOTE It is not possible to run different simulations concurrently from different theads due to the use of global variables which are not easy to get rid of like the active simulation manager pointer and the active environment object pointer Static buffers and objects like string pools are also used for efficiency reasons at some places inside the simulation kernel 16 2 11 Installing a custom scheduler The default event scheduler is cSequentialScheduler To replace it with a different scheduler e g cRealTimeScheduler or your own scheduler class add a setScheduler Call into main http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual cScheduler scheduler new CustomScheduler simulation setScheduler scheduler It is usually not a good idea to change schedulers in the middle of a simulation so set Scheduler may only be called when no network is set up 16 2 12 Multi threaded programs
392. rfac lt ATTLIST channel name NMTOKEN REQUIRED gt lt ELEMENT parameters comment lt ATTLIST parameters Ss mpl aeat true false falses lt ELEMENT param lt ATTLIST param comment expression property gt name parameters gt property param pattern gt IMPLIED type double int string bool xml is volatile true false false name NMTOKEN REQUIRED value CDATA IMPLIED is default true false false gt lt ELEMENT pattern lt ATTLIST pattern pattern CDATA REQUIRED value CDATA IMPLIED is default true false false gt comment expression comment lt ELEMENT property lt ATTLIST property property key gt 1s Implicit truel false false name NMTOKEN REQUIRED index NMTOKEN IMPLIED gt lt ELEMENT property key comment literal gt property gt lt ATTLIST property key name CDATA IMPLIED gt lt ELEMENT gates comment gate gt lt ELEMENT gate comment expression property gt lt ATTLIST gate name NMTOKEN REQUIRED type input output inout IMPL is vector true false false ve
393. ring Tags 22 1 Module and connection display string tags Supported module and connection display string tags are listed in the following table Tag argument index Description name p 0 x X position of the center of the icon shape defaults to automatic graph layouting pli y Y position of the center of the icon shape defaults to automatic graph layouting arrangement Arrangement of submodule vectors Values row r column c matrix m ring ri exact x p 3 arr part Depends on arrangement matrix gt ncols ring gt rx exact gt dx row gt dx column gt dy p 4 arr par2 Depends on arrangement matrix gt dx ring gt ry exact gt dy p 5 arr par3 Depends on arrangement matrix gt dy width Width of object Default 40 height Height of object Default 24 b 2 shape Shape of object Values rectangle rect oval oval Default rect fill color Fill color of the object colorname or RRGGBB or HHSSBB Default 8080ff eo overlay icon An icon added to the upper right corner of the original image i2 1 overlay icon color A color to colorize the overlay icon colorname or RRGGBB or HHSSBB i overlay icon colorization Amount of colorization in percent Default 30 o r 0 range Radius of the range indicator range fill color Fill color of the range indicator colorname or RRGGBB or HHSSBB range border color Border color of the range indicator colorname or
394. rm 12 response time TV 2 895 2355 66666666 4 126 4577 66664666 vector 2 Wisiblomeie Zi SiewaeY queue length TV 2 16 960 2 00000000000 63663666 i 23 086 2355 6066606666 2AT 00000000 0000EAN There two types of lines vector declaration lines beginning with the word vector and data lines A vector declaration line introduces a new output vector and its columns are vector Id module of creation name of cOutVector object and multiplicity usually 1 Actual data recorded in this vector are on data lines which begin with the vector Id Further columns on data lines are the simulation time and the recorded value vector data clustering for efficiency indexed access how to configure the IndexVectorFileManager 11 1 4 Scalar results Scalar results are recorded with recordScalar calls usually from the finish methods of modules Format of scalar files The corresponding output scalar file by default omnetpp sca will look like this s ales Vlan NOSTA mac Wtremes sent 99 s allaie Vlan NOSTA mac Wiremes teckel 3088 scalar lan hostA mac bytes sent 64869 scalar lan hostA mac bytes rcvd 3529448 Every record call generates one scalar line in the file If you record statistics objects cStatictic subclasses such as cSt dDev via their record methods they ll generate several lines mean standard deviation etc In addition several simulation runs ca
395. rns on this option use the opp_makemak deep option opp_makemake will collect all cc and msg files from the whole subdirectory tree and generate a makefile that covers all If you need to exclude a specific directory use the X exclude dir path option Multiple Xx options are accepted An example opp_makemak f deep X experimental X obsolete 7 2 6 Automatic include dirs If your source tree contains several subdirectories maybe several levels deep it can be annoying that you should specify relative paths for your header files in your cc files or you should specify the include path explicitly by the includepath option opp_makemake has a command line option which adds all directories in the current source tree to the compiler command line This option is turned on by default NOTE You may turn off this mechanism with the no deep includes option The only requirement is that your include statements must unambigously specify the name of the header file i e if you have two common h files one in subdir1 and the other in subdir2 specify include subdirl common h instead of include common h If you want to include a directory which is outside of your source directory tree you always must specify it with the I external include dir option 7 2 7 Dependency handling Dependency information is used by the makefile to minimize the time required to compile and link your project If your makefile contains up to d
396. rray cQueue is that only owned objects are copied and the contained but not owned ones will have their pointers taken over and their original owners left unchanged In fact the same question arises in three places the assignment operator operator the copy constructor and the dup method In OMNeT the convention is that copying is implemented in the assignment operator and the other two just rely on it The copy constructor just constructs an empty object and invokes assignment while dup is implemented as new cArray this 7 Building Simulation Programs 7 1 Overview http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual As it was already mentioned an OMNeT model physically consists of the following parts e NED language topology description s These are files with the ned extension e Message definitions in files with msg extension e Simple modules implementations and other C code in cc files or cpp on Windows To build an executable simulation program you first need to translate the MSG files into C using the message compiler opp_msgc After this step the process is the same as building any C C program from source all C sources need to be compiled into object files 0 files using gcc on Mac Linux or mingw on Windows and all object files need to be linked with the necessary libraries to get an executable or shared library NOTE Compiling NED files
397. s It is often necessary to duplicate a message for example sending one and keeping a copy This can be done in the same way as for any other OMNeT object cMessage Copy msg dupi or cMessage copy new cMessage msg The two are equivalent The resulting message is an exact copy of the original including message parameters cMsgPar or other object types and encapsulated messages 5 1 2 Self messages Using a message as self message Messages are often used to represent events internal to a module such as a periodically firing timer on expiry of a timeout A message is termed se f message when it is used in such a scenario otherwise self messages are normal messages of class cMessage or a Class derived from it When a message is delivered to a module by the simulation kernel you can call the isSelfMessage method to determine if it is a self message it other words if it was scheduled with scheduleAt or was sent with one of the send methods The isScheduled method returns true if the message is currently scheduled A scheduled message can also be cancelled cancelEvent http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual bool isSelfMessage bool isScheduled r The following methods return the time of creating and scheduling the message as well as its arrival time While the message is scheduled arrival time is the time it will be
398. s It is not expected that someone will process the result files using OMNeT alone output files are text files in a format which can be read into math packages like Matlab or Octave or imported into spreadsheets like OpenOffice Calc Gnumeric or MS Excel some preprocessing using sed awk or perl might be required this will be discussed later All these external programs provide rich functionality for statistical analysis and visualization and it is outside the scope of OMNeT to duplicate their efforts This manual briefly describes some data plotting programs and how to use them with OMNeT Output scalar files can be visualized with the OMNeT IDE too It can draw bar charts x y plots e g throughput vs offered load or export data via the clipboard for more detailed analysis into spreadsheets and other programs User interfaces The primary purpose of user interfaces is to make the internals of the model visible to the user to control simulation execution and possibly allow the user to intervene by changing variables objects inside the model This is very important in the development debugging phase of the simulation project Just as important a hands on experience allows the user to get a feel of the model s behaviour The graphical user interface can also be used to demonstrate a model s operation The same simulation model can be executed with different user interfaces without any change in the model files themselves The us
399. s exported from the graphical editor and usage diagrams as well as inheritance diagrams The documentation tool integrates with Doxygen meaning that it can hyperlink simple modules and message classes to their C implementation classes in the Doxygen documentation If you also generate the C documentation with some Doxygen features turned on such as inline sources and referenced by relation combined with extract all extract private and extract static the result is an easily browsable and very informative presentation of the source code Of course one still has to write documentation comments in the code In the 4 0 version the documentation tool is part of the Eclipse based simulation IDE 13 2 Documentation comments Documentation is embedded in normal comments All comments that are in the right place from the documentation tool s point of view will be included in the generated documentation In contrast Javadoc and Doxygen use special comments those beginning with lt or a similar marker to distinguish documentation from normal comments in the source code In OMNeT there s no need for that NED and the message syntax is so compact that practically all comments one would want to write in them can serve documentation purposes Example as An ad hoc traffic generator to test the Ethernet models simple Gen parameters string destAddress destination MAC address S
400. s a C identifier that will let you refer to the configuration option in cConfiguration member functions It is actually pointer to a cConfigOption object that the macro creates e NAME is the name of the option a string e TYPE is the data type of the option it must be one of CFG_BOOL CFG_INT CFG_DOUBLE CFG_STRING CFG_FILENAME CFG_FILENAMES CFG_PATH CFG_CUSTOM The most significant difference between filesystem related types filename filenames path and plain string is that relative filenames and paths get automatically converted to absolute when the configuration is read with the base directory being the location of the ini file where the configuration entry was read from e UNITis a string that names the measurement unit in which the option s value is to be interpreted it implies type CFG_DOUBLE e DEFAULTVALUE is the default value in textual form string this should be NULL if the option has no default value e DESCRIPTION is an arbitrarily long string that describes the purpose and and operation of the option It will be used in help texts etc For example the debug on errors macro is declared in the following way Register_GlobalConfigOption CFGID_DEBUG_ON_ERRORS debug on errors CFG_BOOL false When enabled runtime errors will etc etc NOTE Registration is necessary because from the 4 0 version OMNeT validates the configurat
401. s and connections A compound module type may extend another compound module type and may implement one or more module interfaces 17 4 5 Inheritance rules are described in section 17 4 17 and interface implementation rules in section 17 4 16 17 4 3 Networks The network keyword A network declared with the network keyword is equivalent to a compound module module keyword with the isNetwork true property NOTE A simple module can only be designated to be a network by spelling out the isNetwork property the network keyword cannot be used for that purpose The isNetwork property The isNetwork property is only recognized on simple modules and compound modules The value may be empty true or false isNetwork isNetwork isNetwork true isNetwork false The empty value corresponds to isNetwork true The isNetwork property does not get inherited that is a subclass of a module with isNetwork set does not automatically become a network The isNetwork property needs to be explicitly added to the subclass to make it a network Rationale Subclassing may introduce changes to a module that make it unfit to be used as a network 17 4 4 Channels Channel types are declared with the channel keyword see the NED Grammar Appendix 18 for the syntax Channel types may have properties 17 4 8 and parameters 17 4 9 A channel type may not have inner types 17 4 13 A channel type may extend a
402. s pointer it is possible to call its factory method and create an instance of the corresponding module class without having to include the C header file containing module s class declaration into your source file The cModuleType object also knows what gates and parameters the given module type has to have This info comes from compiled NED code Simple modules can be created in one step For a compound module the situation is more complicated because its internal structure submodules connections may depend on parameter values and gate vector sizes Thus for compound modules it is generally required to first create the module itself second set parameter values and gate vector sizes and then call the method that creates its submodules and internal connections As you know already simple modules with activity need a starter message For statically created modules this message is created automatically by OMNeT but for dynamically created modules you have to do this explicitly by calling the appropriate functions Calling initialize has to take place after insertion of the starter messages because the initializing code may insert new messages into the FES and these messages should be processed after the starter message 4 11 3 Creating modules The first step finding the factory object cModuleType moduleType cModuleType get WirelessNode Simplified form cModuleType has a createScheduleInit const char nam
403. s the result e trim string trim string s Discards whitespace from the start and end of s and returns the result Category units e convertUnit quantity convertUnit quantity x string unit Converts x to the given unit e dropUnit double dropUnit quantity x Removes the unit of measurement from quantity x e replaceUnit quantity replaceUnit quantity x string unit Replaces the unit of x with the given unit e unitOf string unitOf quantity x Returns the unit of the given quantity 21 Appendix Message Definitions Grammar This appendix contains the grammar for the message definitions language http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual In the language space horizontal tab and new line characters count as delimiters so one or more of them is required between two elements of the description which would otherwise be unseparable two slashes may be used to write comments that last to the end of the line The language is fully case sensitive Notation e rule syntax is that of bison yacc e uppercase words are terminals lowercase words are nonterminals e NAME CHARCONSTANT STRINGCONSTANT INTCONSTANT REALCONSTANT represent identifier names and string character integer and real number literals defined as in the C language e other terminals represent keywords in all lowercase Nonterminals ending in _
404. sage parameters might account for a large part of execution time sometimes as much as 80 Using cMsgPars is also error prone because cMsgPar objects have to be added dynamically and individually to each message object In contrast subclassing benefits from static type checking if you mistype the name of a field in the C code already the compiler can detect the mistake If you still need cMsgPars for some reason here s a short summary At the sender side you can add a new named parameter to the message with the addPar member function then set its value with one of the methods setBoolValue setLongValue setStringValue setDoubleValue setPointerValue setObjectValue and setXMLValue There are also overloaded assignment operators for the corresponding C C types At the receiver side you can look up the parameter object on the message by name and obtain a reference to it with the par member function hasPar can be used to check first whether the message object has a parameter object with the given name Then the value can be read with the methods boolValue longValue stringValue doubleValue pointerValue objectValue xmlValue or by http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual using the provided overloaded type cast operators Example usage msg gt addPar destAddr msg gt par destAddr setLongValue 168 long destAddr msg gt
405. sageEvent scheduleAt 0 0 sendMessageEvent void FFGenerator handleMessage cMessage msg ASSERT msg sendMessageEvent http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual cMessage m new cMessage packet m gt setBitLength par msgLength send m out numSent double deltaT double par sendlaTime scheduleAt SsimTime deltaT sendMessageEvent void FFGenerator finish recordScalar packets sent numSent FFGenerator FFGenerator cancelAndDelete sendMessageEvent The corresponding NED declaration file FFGenerator ned simple FFGenerator paname Tensi volatile double sendIaTime gatesi Qurcjoule GLE 4 2 5 Using global variables If possible avoid using global variables including static class members They are prone to cause several problems First they are not reset to their initial values to zero when you rebuild the simulation in Tkenv or start another run in Cmdenv This may produce surprising results Second they prevent you from running your simulation in parallel When using parallel simulation each partition of your model may run in a separate process having its own copy of the global variables This is usually not what you want The solution is to encapsulate the variables into simple modules as private or protected data
406. se CDATA PLIED ilo PLIED NMTOKEN IMPLIED CDATA PLIED NMTOKEN REQUIREI lus true false false CDATA PLIED io PLIED 12r r21 bidir REQUIRED gt comment lt ATTLIST channel spec expression parameters gt type CDATA IMPLIED like type CDATA IMPLIED like param CDATA IMPLIED gt lt ELEMENT connection group comment loop condition connection gt lt ELEMENT loop comment expression gt lt ATTLIST loop param name NMTOKEN REQUIRED from value CDATA IMPLIED to value CDATA IMPLIED gt lt ELEMENT condition comment expression gt lt ATTLIST condition condition CDATA IMPLIED gt el xx Expressions gt lt ELEMENT expression comment operator function ident literal gt lt ATTLIST expression target CDATA IMPLIED gt lt ELEMENT operator comment operator function ident literal gt lt ATTLIST operator name CDATA REQUIRED gt lt l functions index const and sazeor gt lt ELEMENT function comment operator function ident literal gt lt ATTLIST function name NMTOKEN REQUIRED gt lt
407. simulation object a global variable to get back the module pointer dime acl LOOs cModule mod simulation getModule id Module IDs are guaranteed to be unique even when modules are created and destroyed dynamically That is an ID which once belonged to a module which was deleted is never issued to another module later Walking up and down the module hierarchy The surrounding compound module can be accessed by the get ParentModule member function cModule parent getParentModule For example the parameters of the parent module are accessed like this double timeout getParentModule gt par timeout cModule s findSubmodule and getSubmodule member functions make it possible to look up the module s submodules by name or name index if the submodule is in a module vector The first one returns the numeric module ID of the submodule and the latter returns the module pointer If the submodule is not found they return 1 or NULL respectively int submodID compoundmod gt findSubmodule child 5 cModule submod compoundmod gt getSubmodule child 5 The getModuleByRelativePath member function can be used to find a submodule nested deeper than one level below For example compoundmod gt getModuleByRelativePath child 5 grandchild http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual would give the same results as compound
408. simulation time of each event If you specify the fingerprint option in the config file the simulation runtime will compare the computed checksum with the provided one If there is a difference it will generate an error This feature is very useful if you make some cosmetic changes to your source and want to be reasonable sure that your changes did not altered the behaviour f the model record eventlog You can turn on the recording of the simulator events The resulting file can be analyzed later in the IDE with the sequence chart tool NOTE It is possible to specify a configuration option also on command line in which case the command line takes precedence You should prefix the option name with a double dash and should not put any spaces around the equal sign e g debug on errors true To get the list of all possible configuration options type opp run n config 9 2 Cmdenv the command line interface The command line user interface is a small portable and fast user interface that compiles and runs on all platforms Cmdenv is designed primarily for batch execution Cmdenv simply executes some or all simulation runs that are described in the configuration file If one run stops with an error message subsequent ones will still be executed The runs to be executed can be passed via command line argument or in the ini file 9 2 1 Example run When run the Fifo example under Cmdenv you should see something like this
409. sing a for loop In the example below the variable i iterates through the values of list given after the in keyword It is very practical since you can leave out or add runs or change the order of runs by simply editing the list to demonstrate this we skip run 6 and include run 15 instead oln sm fOr t dm 3 2 11 45 7 15 9 10 cdo uLreless runs ini r i done If you have many runs you can use a C style loop bin sh cor i 1le Si lt 50p atst e clo wireless f runs ini r i done 9 4 3 Using opp_runall OMNeT has a utility program called opp_runall1 which allows you to execute a simulation batch in command line mode You must specify the whole command line you would use to run your batch in Cmdenv There are advantages running your batches this way Each simulation run executes in a separate operating system process This means that a crash because of a programming error does not affect the outcome of the other runs They are totally independent of each other e If you happen to have a multi core processor machine you can take advantage of the processing power by running sevaral runs parallel The command basically creates a makefile which contains a separate target for each run By default the makefile will be executed causing each target to run You can give additional options to the opp_runall command to activate parallel building The j option can be used to specify the maximum number of pa
410. so be overridden in subclasses Rationale The latter is needed for ease of use of channels and their delay ber per datarate parameters Gate inheritance http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Gate vector size may not be overridden in subclasses 17 4 18 Network build order When a network in instantiated for simulation the module tree is built in a top down preorder fashion This means that starting from an empty system module all submodules are created their parameters and vector sizes get assigned and they get fully connected before proceeding to go into the submodules to build their internals This implies that inside a compound module definition including in submodules and connections one can refer to the compound module s parameters and gate sizes because they are already built at the time of usage The same rules apply to compound or simple modules created dynamically during runtime 17 5 Expressions NED language expressions have a C like syntax with some variations on operator names see Expressions may refer to module parameters loop variables inside connection for loops gate vector and module vector sizes and other attributes of the model Expressions can use built in and user defined functions as well 17 5 1 Operators The following operators are supported in order of decreasing precedence unary minus negation bitwise complement power of
411. ss is cLinkDelayLookahead e parsim nullmessageprotocol laziness expects a number in the 0 7 interval the default is 0 5 and it ontrols how often NMA should send out null messages the value is understood in proportion to the lookahead e g 0 5 means every lookahead 2 simsec The parsim debug boolean option enables disables printing log messages about the parallel simulation algorithm It is turned on by default but for production runs we recommend turning it off Other configuration options configure MPI buffer sizes and other details see options that begin with parsim in Appendix 23 When you are using cross mounted home directories the simulation s directory is on a disk mounted on all nodes of the cluster a useful configuration setting is General fname append host true It will cause the host names to be appended to the names of all output vector files so that partitions do not overwrite each other s output files See section 9 5 3 14 3 5 Design of PDES Support in OMNeT Design of PDES support in OMNeT follows a layered approach with a modular and extensible architecture The overall architecture is depicted in Figure below http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Simulation Model 4 Simulation Kernel Synchronization Event scheduling sending receiving Parttching communications library MPI sockets etc Figure Architecture of O
412. stack trace or examine variables description lt string gt per run setting Descriptive name for the given simulation configuration Descriptions get displayed in the run selection dialog eventlog file lt filename gt default S resultdir configname runnumber elog per run setting Name of the event log file to generate eventlog message detail pattern lt custom gt per run setting A list of patterns separated by character which will be used to write message detail information into the event log for each message sent during the simulation The message detail will be presented in the sequence chart tool Each pattern starts with an object pattern optionally followed by character and a comma separated list of field patterns In both patterns and or not and various field match expressions can be used The object pattern matches to class name the field pattern matches to field name by default EVENTLOG MESSAGE DETAIL PATTERN DETAIL PATTERN DETAIL PATTERN DETAIL PATTERN OBJECT PATTERN FIELD PATTERNS OBJECT PATTERN MATCH EXPRESSION FIELD PATTERNS FIELD PATTERN FI
413. strate the need for synchronization or for simple testing For the communication between LPs logical processes OMNeT primarily uses MPI the Message Passing Interface standard mpiforum94 An alternative communication mechanism is based on named pipes for use on shared memory multiprocessors without the need to install MPI Additionally a file system based communication mechanism is also available It communicates via text files created in a shared directory and can be useful for educational purposes to analyse or demonstrate messaging in PDES algorithms or to debug PDES algorithms Implementation of a shared memory based communication mechanism is also planned for the future to fully exploit the power of multiprocessors without the overhead of and the need to install MPI Nearly every model can be run in parallel The constraints are the following e modules may communicate via sending messages only no direct method call or member access unless mapped to the same processor e no global variables e there are some limitations on direct sending no sending to a submodule of another module unless mapped to the same processor e lookahead must be present in the form of link delays e currently static topologies are supported we are working on a research project that aims to eliminate this limitation PDES support in OMNeT follows a modular and extensible architecture New communication mechanisms can be added by implementing a compa
414. subexpressions are not supported yet The following properties are recognized for parameters unit prompt The prompt property The prompt property defines a prompt string for the parameter The prompt string is used when if a simulation runtime user interface interactively prompts the user for the parameter s value The prompt property is expected to contain one string value for the default key http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The unit property A parameter may have a unit property to associate it with a measurement unit The unit property should contain one string value for the default key Examples Qumi US unit s unit second unit second When present values assigned to the parameter must be in the same or in a compatible that is convertible unit Examples double a unit s 5s OK double a unit s 5 Ii errors should be Sis double a unit s 5kg error incompatible unit unit behavior for non numeric parameters string XML is unspecified may be ignored or may be an error The unit property of a parameter may not be modified via inheritance Example simple A double p unit s simple B extends A p unit mW illegal cannot override unit 17 4 10 Gates Gates can be defined in the gates section of component types The size of a gate vector see below may be specified at the place of defini
415. t debug information Envir lt gt Tkenv Cmdenv Tkenv and Cmdenv are concrete user interface implementations When a simulation program is started the main function which is part of Envir determines the appropriate user interface class creates an instance and runs it by invoking its run method Sim s or the model s calls on the ev object are delegated to the user interface 16 2 Embedding the OMNeT simulation kernel This section discusses the issues of embedding the simulation kernel or a simulation model into a larger application We assume that you don t just want to change one or two aspects of the simulator like event scheduling or result recording or create a new user interface a la Cmdenv or Tkenv if so see chapter 15 For the following discussion we assume that you write the embedding program from scratch i e starting froma main function 16 2 1 The main function Here s an minimalistic program that initializes the simulation library and runs two simulations In later sections we ll go through details of the code and discuss how to elaborate it include lt omnetpp h gt imc imelalin slime aimee Claas euccpy ff the following line MUST be at the top of main cStaticFlag dummy f f tmicialilzgacions ExecuteOnStartup executeAll SimTime setScaleExp 12 oad NEDENES cSimulation loadNedSourceFolder foodir cSimulation
416. t distributions and values input interactively by the user Numeric valued parameters can be used to construct topologies in a flexible way Within a compound module parameters can define the number of submodules number of gates and the way the internal connections are made 2 1 6 Topology description method The user defines the structure of the model in NED language descriptions Network Description The NED language will be discussed in detail in Chapter 3 2 2 Programming the algorithms The simple modules of a model contain algorithms as C functions The full flexibility and power of the programming language can be used supported by the OMNeT simulation class library The simulation programmer can choose between event driven and process style description and can freely use object oriented concepts inheritance polymorphism etc and design patterns to extend the functionality of the simulator Simulation objects messages modules queues etc are represented by C classes They have been designed to work together efficiently creating a powerful simulation programming framework The following classes are part of the simulation class library e modules gates connections etc parameters e messages e container classes e g queue array e data collection classes statistic and distribution estimation classes histograms P algorithm for calculating quantiles etc e transient detection and result accuracy detecti
417. t of a full graph with a fixed number of connections In the case of irregular structures where none of the above patterns can be employed you can resort to listing all connections like you would do it in most existing simulators 3 11 Submodule type as parameter A submodule type may be specified with a module parameter of the type string or in general with any string typed expression The syntax uses the like keyword Let us begin with an example network Net6 parame tersi string nodeType submodules node 6 lt nodeType gt like INode http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual address index connections It creates a submodule vector whose module type will come from the nodeType parameter For example if nodeType SensorNode then the module vector will consist of sensor nodes provided such module type exists and it qualifies the latter will be explained right now The missing piece is the like INode bit INode must be an existing module interface which the SensorNode module type must implement more about this later The corresponding NED declarations moduleinterface INode parameters int address gatesi inout Borei 2 module SensorNode like INode paramet ensk int address garesk imour Portik 3 12 Properties metadata annotations Properties allow adding metadata annotations to modules pa
418. t scale well for large simulations 9 6 3 Memory leaks and crashes The most common problems in C are associated with memory allocation usage of new and delete memory leaks that is forgetting to delete objects or memory blocks no longer used e crashes usually due to referring to an already deleted object or memory block or trying to delete one for a second time e heap corruption eventually leading to crash due to overrunning allocated blocks i e writing past the end of an allocated array By far the most common ways leaking memory in simulation programs is by not deleting messages cMessage objects or subclasses Both Tkenv and Cmdenv are able to display the number of messages currently in the simulation see e g section 9 2 4 If you find that the number of messages is steadily increasing you need to find where the message objects are You can do so by selecting nspect From list of all objects from the Tkenv menu and reviewing the list in the dialog that pops up If the model is large it may take a while for the dialog to appear If the number of messages is stable it is still possible you re leaking other cOwnedOb ject based objects You can also find them using Tkenv s nspect From list of all objects function If you re leaking non cOwnedOb ject based objects or just memory blocks structs int double struct arrays etc allocated by new you cannot find them via Tkenv You ll probably need a specialized m
419. ta members NewClass NewClass delete array if msg gt getOwner this delete msg The destructor should delete all data structures the object allocated cOwnedOb ject based objects should only be deleted if they are owned by the object details will be covered in section 6 11 http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual NewClass NewClass dup const return new NewClass this The dup functions is usually just one line like the one above NewClass amp NewClass operator const NewClass amp other if amp other this imeewiem SENSA cOwnedObject operator other data other data for Ane Oe 0 Mic array i other array i l queue other queue queue setName other queue getName msg amp amp msg gt getOwner this delete msg if other msg amp amp other msg gt getOwner const_cast lt cMessage gt amp other take msg other msg gt dup else MSE OTMEr mE rewrturm wells A Complexity associated with copying and duplicating the object is concentrated in the assignment operator so it is usually the one that requires the most work from you of all methods required by cOwnedObject If you do not want to implement object copying and duplication you should implement the assignment operator to call copyNot Supported it ll throw an exception that stops the
420. te a model of a server which processes jobs from a queue Whenever it begins processing a job the server model will want to schedule an event to occur when the job finishes processing so that it can begin processing the next job http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual In OMNeT you solve such tasks by letting the simple module send a message to itself the message would be delivered to the simple module at a later point of time Messages used this way are called self messages Self messages are used to model events which occur within the module Scheduling an event The module can send a message to itself using the scheduleAt function scheduleAt accepts an absolute simulation time usually calculated as simTime delta scheduleAt absoluteTime msg scheduleAt Simtime delta msg Self messages are delivered to the module in the same way as other messages via the usual receive calls or handleMessage the module may call the isSelfMessage member of any received message to determine if it is a self message As an example here s how you could implement your own wait function in an activity simple module if the simulation kernel didn t provide it already cMessage msg new cMessage scheduleAt Simtime waitTime msg cMessage recvd receive if recvd msg hmm some other event occurred meanwhile error You can determine if a
421. ted by nedtool of OMNeT 3 x 16 2 7 Assigning module parameters As already mentioned modules get values for their input parameters by calling the readParameter method of the environment object cEnvir NOTE readParameter is only called for parameters that have not been set to a fixed i e non default value in the NED files The readParameter method should be written so that it can assign the parameter For doing so it can recognize the parameter from its name par gt getName from its full path par gt getFullPath from the owner module s class par gt get Owner gt getClassName or NED type name cComponent par gt getOwner gt getNedTypeName Then it can set the parameter using one of the typed setter methods setBoolValue setLongValue etc or set it to an expression provided in string form parse method It can also accept the default value if there is one acceptDefault The following code is a straightforward example that answers parameter value requests from a pre filled table elass Customs imalearciontay g jouloilae CiNuulisiayalie protected parameter fullpath value pairs needs to be pre filled std map lt std string std string gt paramValues pupbitiiek virtual void readParameter cPar par if paramValues find par gt getFullPath paramValues end par gt parse paramValues par gt getF
422. ternal tables Code like that cannot be placed into the constructor since the network is still being set up when the constructor is called finish vs destructor Keep in mind that finish is not always called so it isn t a good place for cleanup code which should run every time the module is deleted finish is only a good place for writing statistics result post processing and other operations which are supposed to run only on successful completion Cleanup code should go into the destructor Multi stage initialization In simulation models when one stage initialization provided by initialize is not sufficient one can use multi stage initialization Modules have two functions which can be redefined by the user void initialize int stage int numInitStages const At the beginning of the simulation initialize 0 is called for all modules then initialize 1 initialize 2 etc You can think of it like initialization takes place in several waves For each module numInitStages must be redefined to return the number of init stages required e g for a two stage init numInitStages should return 2 and initialize int stage must be implemented to handle the stage 0 and stage 1 cases Note const in the numtnitstages declaration If you forget it by C rules you create a different function instead of redefining the existing one in the base class thus the existing one will remain in effect and return 1
423. tgate gt getChannel cChannel is a small base class All interesting attributes are part of its subclass cDatarateChannel so you have to cast the pointer before getting to the delay error and data rate values cDatarateChannel chan check_and_cast lt cDatarateChannel gt outgate gt getChannel http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual double d chan gt getDelay double e chan gt getBitErrorRate double r chan gt getDatarate You can also change the channel attributes with the corresponding set Xxx functions Note however that as it was explained in section changes will not affect messages already sent even if they have not begun transmission yet Channel transmission state The isBusy member function returns whether the gate is currently transmitting and if so the get TransmissionFinishTime member function returns the simulation time when the gate is going to finish transmitting If the gate in not currently transmitting getTransmissionFinishTime returns the simulation time when it finished its last transmission An example cMessage packet new cMessage DATA packet gt setByteLength 1024 1K ic gate TxGate gt isBusy 1f gate is busy wait until it M becomes frr wait gate TxGate gt getTransmissionFinishTime simTime send packet TxGate
424. that holds objects derived from cOwnedOb ject cArray stores the pointers of the objects inserted instead of making copies cArray works as an array but it grows automatically when it gets full Internally cArray is implemented with an array of pointers when the array fills up it is reallocated cArray objects are used in OMNeT to store parameters attached to messages and internally for storing module parameters and gates Creating an array http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual CiMeweny aiucicesy eiereeny F Adding an object at the first free index Chae pE NC wee Mor alia uocail E int index array add p Adding an object at a given index if the index is occupied you ll get an error message cPar p new cMsgPar par int index array addAt 5 p Finding an object in the array aime singles kar ray a icaLinel F Getting a pointer to an object at a given index GPar 7p CPar array index You can also search the array or get a pointer to an object by the object s name int index array find par Relic 7o ePer array pert You can remove an object from the array by calling remove with the object name the index position or the object pointer array remove par array remove index array remove p The remove function doesn t deallocate the object but it returns the object pointer If you also want to deallocate it y
425. the same problem by interpreting the gate ID as a bitfield basically containing bits that identify the gate name and other bits that hold the index This also means that the theoretical upper limit for a gate size is now smaller albeit it is still big enough so that it can be safely ignored for practical purposes The following example iterates through a gate vector using IDs int baseId getBaselId out int size gateSize out ior slime a 0e a lt salwee iar 1 cGate gate gate baseId i ll ees Enumerating all gates If you need to go through all gates of a module there are two possibilities One is invoking the get Gat eNames method that returns the names of all gates and gate vectors the module has then you can call isGateVector name to determine whether individual names identify a scalar gate or a gate vector then gate vectors can be enumerated by index Also for inout gates get GateNames returns the base name without the Si So suffix so the two directions need to be handled separately The gateType name method can be used to test whether a gate is inout output or inout it returns cGate INOUT cGate INPUT or cGate OUTPUT Clearly the above solution can be quite hairy An alternative is to use the GateIterator class provided by cModule It goes like this for cModule GatelIterator i this i end it cGate gate i Where this
426. the elements A queue object has a head and a tail Normally new elements are inserted at its head and elements are removed at its tail FRONT BACK removal insertion pop insert Figure cQueue insertion and removal The basic cQueue member functions dealing with insertion and removal are insert and pop They are used like this cQueue queue my queue cMessage msg insert messages for ine i 0 1 lt 10 i msg new cMessage queue insert msg remove messages while queue empty msg cMessage queue pop delete msg The length member function returns the number of items in the queue and empty tells whether there s http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual anything in the queue There are other functions dealing with insertion and removal The insertBefore and insertAfter functions insert a new item exactly before and after a specified one regardless of the ordering function The front and back functions return pointers to the objects at the front and back of the queue without affecting queue contents The pop function can be used to remove items from the tail of the queue and the remove function can be used to remove any item known by its pointer from the queue queue remove msg Priority queue By default cOQueue implements a FIFO but it can also act as a prior
427. the following methods for getting statistics out of the object getCount getMin getMax getMean getStddev getVariance getSum getSqrSum with the obvious meanings An example usage for cStdDev cStdDev stat stat ve or aime a p ia lt il p ass strat collect norna lED long numSamples SCAN GSielCouline g double smallest stat getMin largest stat getMax double mean stat getMean standardDeviation stat getStddev variance stat getVariance 6 7 2 Distribution estimation Initialization and usage http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The distribution estimation classes cLongHistogram cDoubleHistogram cVarHistogram cPSquare and cKSp1lit are derived from cDensityEstBase Distribution estimation classes except for cPSquare assume that the observations are within a range You may specify the range explicitly based on some a priori info about the distribution or you may let the object collect the first few observations and determine the range from them Methods which let you specify range settings are part of cDensityEstBase The following member functions exist for setting up the range and to specify how many observations should be used for automatically determining the range setRange lower upper setRangeAuto numFirstvals rangeExtFactor setRangeAutoLower upper nu
428. ting When cLCG32 is selected as random number generator seed for the kth RNG Substitute k for S in the key seed mt lt int gt per run setting When Mersenne Twister is selected as random number generator default seed for RNG number k Substitute k for S in the key seed mt p lt int gt per run setting With parallel simulation When Mersenne Twister is selected as random number generator default seed for RNG number k in partition number p Substitute k for the first S in the key and p for the second seed set lt int gt default runnumber per run setting Selects the kth set of automatic random number seeds for the simulation Meaningful values include S repetition which is the repeat loop counter s repeat key and runnumber sim time limit lt double gt unit s per run setting Stops the simulation when simulation time reaches the given limit The default is no limit simtime scale lt int gt default 12 global setting Sets the scale exponent and thus the resolution of time for the 64 bit fixed point simulation time representation Accepted values are 18 0 for example 6 selects microsecond resolution 12 means picosecond resolution with a maximum simtime of 110 days snapshot file lt filename gt default resultdir S configname S runnumber sna per run setting Name of the snapshot file snapshotma
429. to reduce collisions with other uses of the otherwise overloaded word port router port TCP port I O port etc The above code would be placed into a file named Net 6 ned It is a convention to put every NED definition into its own file and to name the file accordingly but it is not mandatory to do so One can define any number of networks in the NED files and for every simulation the user has to specify which network he wants to set up The usual way of specifying the network is to put the network option into the configuration by default the omnetpp ini file General network Network 3 2 2 Introducing a channel It is cumbersome to have to repeat the data rate for every connection Luckily NED provides a convenient solution one can create a new channel type that encapsulates the data rate setting and this channel type can be defined inside the network so that it does not litter the global namespace The improved network will look like this bff BR Network ff network Network iEWDSS channel C extends ned DatarateChannel datarate 100Mbps submodules nodel Node node2 Node node3 Node connections nodel port gt lt gt e node2 port G C lt gt imocled4 porn node4 port gt lt gt moOcke6 porert Later sections will cover the concepts used inner types channels the DatarateChannel built in type inheritance in details
430. tra data in it i e within parens is ignored except a single word false which is reserved to remove the property Thus simulation model or tool source code that interprets properties should handle all the following forms as equivalent to Ghost host host true host anything but false host a 1 b 2 and host false should be interpreted as the lack of the Ghost tag Modifying properties When you subclass a NED type use a module type as submodule or use a channel type for a connection you may add new properties to the module or channel or to its parameters and gates and you can also modify existing properties When modifying a property the new property gets merged with the old one with a few simple rules New keys simply get added If a key already exists in the old property items in its valuelist overwrite items on the same position in the old property A single hyphen as valuelist item serves as antivalue it removes the item at the corresponding position http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Some examples prop a b c prop aprop aye prop foo a b new prop foo A c bar 1 2 prop foo A b c bar 1 2 NOTE The above merge rules are part of NED but the code that interprets properties may have special rules for certain properties For example the unit property of parameters is not allowed to be overridden and disp
431. trib amp amp opp_makemak f deep make so o mfcontrib 0 out I core basicModules I core utils L out CONFIGNAME core lmfcore The testSuite will be created as an executable file which depends on both mfcont rib and mfcore cd testSuite amp amp opp_makemak f deep 0o testSuite 0 out I GOre utils I core basic Modules I Gontrib utils I contrib applLayer L out S CONFIGNAME contrib lmfcontrib Now the last step is to create a top level makefile in the root of the project that calls the previously created http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual makefiles in the correct order We will use the nolink option exclude every subdirectory from the build X and explicitly call the above makefiles d dirname opp_makemak f nolink O out d testSuite d core d contrib X Finally we have to specify the dependencies between the above directories Add the lines below to the makefrag file in the project directory root Comirwwlo_ellies COre chlr testou erdiki C imcieillo_clilic 8 Configuring Simulations 8 1 Configuring simulations Configuration and input data for the simulation are in a configuration file usually called omnetpp ini The following sections explain omnetpp ini 8 2 The configuration file omnetpp ini 8 2 1 An example For a start let us see a simple omnetp
432. ts both express and normal mode Turning on autoflush may have a performance penalty but it can be useful with printf style debugging for tracking down program crashes cmdenv config name lt string gt global setting Specifies the name of the configuration to be run for a value Foo section Config Foo will be used from the ini file See also cmdenv runs to execute Th c command line option overrides this setting lt object full path gt cmdenv ev output lt bool gt default true per object setting When cmdenv express mode false whether Cmdenv should print debug messages ev lt lt from the selected modules cmdenv event banner details lt bool gt default false per run setting When cmdenv express mode false print extra information after event banners cmdenv event banners lt bool gt default true per run setting When cmdenv express mode false turns printing event banners on off cmdenv express mode lt bool gt default true per run setting Selects normal debug trace or express mode cemdenv extra stack lt double gt unit B default 8KB global setting Specifies th xtra amount of stack that is reserved for each activity simple module when the simulation is run under Cmdenv cmdenv interactive lt bool gt default false global setting Defines what Cmdenv should do when the m
433. u can expect the event density double too The third line displays the number of messages and it is important because it may indicate the health of your simulation e Created total number of message objects created since the beginning of the simulation run This does not mean that this many message object actually exist because some many of them may have been deleted since then It also does not mean that you created all those messages the simulation kernel also creates messages for its own use e g to implement wait in an activity simple module e Present the number of message objects currently present in the simulation model that is the number of messages created see above minus the number of messages already deleted This number includes the messages in the FES e In FES the number of messages currently scheduled in the Future Event Set The second value the number of messages present is more useful than perhaps one would initially think It can be an indicator of the health of the simulation if it is growing steadily then either you have a memory leak and losing messages which indicates a programming error or the network you simulate is overloaded and queues are steadily filling up which might indicate wrong input parameters Of course if the number of messages does not increase it does not mean that you do not have a memory leak other memory leaks are also possible Nevertheless the valu
434. uNe Olle fF module Node submodules trafGen TrafGen profile xmldoc data xml It is also possible to assign an XML element within a file to the parameter module Node submodules trafGen TrafGen prorile xmleloe Wall xml Horori le ic Geimil y trafGen2 TrafGen prorila xmicoe Yall sal WYjoroiriile ic qem2 lt xml gt XXX example 3 7 Gates Gates are the connection points of modules OMNeT has three types of gates input output and inout the latter being essentially an input and an output gate glued together A gate whether input or output cannot be connected to two or more other gates For compound module gates http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual this means one connection outside and one inside It is possible though generally not recommended to connect the input and output sides of an inout gate separately One can create single gates and gate vectors The size of a gate vector can be given inside square brackets in the declaration but it also possible to leave it open by just writing a pair of empty brackets When the gate vector size is left open one can still specify it later wnen subclassing the module or when using the module for a submodule in a compound module However it does not need to be specified becaus
435. uch simulators usually work according to the following pseudocode initialize this includes building the model and inserting initial events to FES http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual while FES not empty and simulation not yet complete retrieve first event from FES t timestamp of this event process event processing may insert new events in FES or delete existing ones j finish simulation write statistical results etc The first initialization step usually builds the data structures representing the simulation model calls any user defined initialization code and inserts initial events into the FES to ensure that the simulation can start Initialization strategy can differ considerably from one simulator to another The subsequent loop consumes events from the FES and processes them Events are processed in strict timestamp order in order to maintain causality that is to ensure that no event may have an effect on earlier events Processing an event involves calls to user supplied code For example using the computer network simulation example processing a timeout expired event may consist of re sending a copy of the network packet updating the retry count scheduling another timeout event and so on The user code may also remove events from the FES for example when canceling timeouts The simulation stops when there are no events left this happens ra
436. uld be given with the constraint configuration key An example numNodes n 10 100 step 10 A n umNeighbors m 2 10 step 2 constraint Sm lt sqrt Sn The expression syntax supports most C language operators including boolean conditional and binary shift operations and most lt math h gt functions data types are boolean double and string The expression must evaluate to a boolean NOTE It is not supported to refer to other iteration variables in the definition of an iteration variable i e you cannot write things like j i 10 although it might get implemented in future OMNeT releases 8 5 3 Repeating runs with different seeds It is directly supported to perform several runs with the same parameters but different random number seeds There are two configuration keys related to this repeat and seed set The first one simple specifies how many times a run needs to be repeated For example repeat 10 causes every combination of iteration variables to be repeated 10 times and the repetition predefined variable holds the loop counter Indeed repeat 10 is equivalent of adding repetition 0 9 to the ini file The repetition loop always becomes the innermost loop The seed set configuration key affects seed selection Every simulation uses one or more random number generators as configured by the num rngs key for which the simulation kernel can automatically generate seeds The first simulatio
437. uld use a good profiler to find out how much time is spent in each part of the program Do not make the mistake of omitting this step thinking that you know which part is slow Even for experienced programmers profiling session is all too often full of surprises It often turns out that lots of CPU time is spent in completely http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual innocent looking statements while the big and complex algorithm doesn t take nearly as much time as expected Don t assume anything profile before you optimize A great profiler on Linux is the Valgrind based callgrind and its visualizer KCachegrind Unfortunately it won t be ported to Windows anytime soon On Windows you re out of luck commercial products may help or port your simulation to Linux The latter goes usually much smoother than one would expect 10 Network Graphics And Animation 10 1 Display strings Display strings specify the arrangement and appearance of modules in graphical user interfaces currently only Tkenv they control how the objects compound modules their submodules and connections are displayed Display strings occur in NED description s display property Display strings can be used in the following contexts e submodules display string may contain position arrangement for module vectors icon icon color auxiliary icon status text communication range as circle or filled circle
438. ule You can specify the ratio between 1 pixel and 1 unit with the bgs tag The p tag allows the automatic arrangement of module vectors They can be arranged in a row a column a matrix or a ring or you may specify their positions later at runtime using the setDisplayString method The rest of the arguments in the p tag depends on the layout type row p 100 100 r deltax A row of modules with deltaX units between the modules column p 100 100 c deltaY A column of modules with deltaX units between the modules matrix p 100 100 m noOfCols deltaX deltaY A matrix with noOfCols columns deltaX and deltaY units between rows and columns ring p 100 100 ri rx ry A ring oval with rx and ry as the horizontal and vertical radius exact default p 100 100 x deltaX deltaY Place each module at 100 deltax 100 deltaY The coordinates are usually set at runtime A matrix layout for a module vector Ceci sjolany Vjo m 4 50 50 host 0 host 1 host 2 host 3 9 9 9 9 server host 4 host 5 host 6 host 7 38 8 host 8 host 9 host 10host 11 88 host 12host 13host 14host 15 3 Z Z host 16host 17host 18host 19 93388 y Figure Matrix arrangement using the p tag Wireless range In wireless simulations it is very useful to show some kind of range around your module This can be an interference range transmission range etc The following example will place the module at a
439. ule output gate or a compound module input gate to the destination http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual gate a submodule input gate or a compound module output gate Connections may be written either left to right or right to left that is a gt b is equivalent to b lt a Gates are specified as modulespec gatespec to connect a submodule or as gatespec to connect the compound module modulespec is either a submodule name for scalar submodules or a submodule name plus an index in square brackets for submodule vectors For scalar gates gatespec is the gate name for gate vectors it is either the gate name plus an index in square brackets or gatename The gatename notation causes the first unconnected gate index to be used If all gates of the given gate vector are connected the behavior is different for submodules and for the enclosing compound module For submodules the gate vector expands by one For the compound module it is an error to use on gate vector with no unconnected gates Rationale The reason it is not supported to expand the gate vector of the compound module is that the module structure is built in top down order new gates would be left unconnected on the outside as there is no way in NED to go back and connect them afterwards When the operator is used with i or o e g gSi or g o see later it will actually add a gate pair input outp
440. ule s local objects list This is accomplished by the drop function which transfers the ownership to the object s default owner getDefaultOwner is a virtual method returning cOwnedOb ject defined in cOwnedOb ject and its implementation returns the currently executing simple module s local object list As an example the remove method of cQueue is implemented like this Actual code in src sim is structured somewhat differently but the meaning is the same cOwnedObject cQueue remove cOwnedObject obj remove object from queue data structure release ownership if needed if obj gt getOwner this drop obj return obj Destructor The concept of ownership is that the owner has the exclusive right and duty to delete the objects it owns For example if you delete a cQueue containing cMessages all messages it contains and owns will also be deleted The destructor should delete all data structures the object allocated From the contained objects only the owned ones are deleted that is where obj gt getOwner this Object copying The ownership mechanism also has to be taken into consideration when a cArray or cQueue object is duplicated The duplicate is supposed to have the same content as the original however the question is whether the contained objects should also be duplicated or only their pointers taken over to the duplicate cArray or cQueue The convention followed by cA
441. ules Inheritance may e add new properties parameters gates inner types submodules connections as long as names do not conflict with inherited names e modify inherited properties and properties of inherited parameters and gates e it may not modify inherited submodules connections and inner types Other inheritance rules e for inner types new inner types can be added but inherited ones cannot be changed e for properties contents will be merged rules like for display strings values on same key and same position will overwrite old ones for parameters type cannot be redefined value may be redefined in subclasses or at place of usage for gates type cannot be redefined vector size may be redefined in subclasses or at place of usage for gate parameter properties extra properties can be added existing properties can be overridden extended like for standalone properties e for submodules new submodules may be added but inherited ones cannot be modified e for connections new connections may be added but inherited ones cannot be modified See other rules for specifics Property inheritance Generally properties may be modified via inheritance Inheritance may e add new keys e add overwrite values for existing keys e remove a value from an existing key by using the special value Parameter inheritance Default values for parameters may be overridden in subclasses Parameter non default assignments may al
442. ules finish is normally used to record statistics information accumulated in data members of the class at the end of the simulation Application area handleMessage is in most cases a better choice than activity When you expect the module to be used in large simulations involving several thousand modules In such cases the module stacks required by activity would simply consume too much memory For modules which maintain little or no state information such as packet sinks handleMessage is more convenient to program Other good candidates are modules with a large state space and many arbitrary state transition possibilities i e where there are many possible subsequent states for any state Such algorithms are difficult to program with activity or the result is code which is better suited for handleMessage see rule of thumb below Most communication protocols are like this Example 1 Protocol models Models of protocol layers in a communication network tend to have a common structure on a high level because fundamentally they all have to react to three types of events to messages arriving from higher layer protocols or apps to messages arriving from lower layer protocols from the network and to various timers and timeouts that is self messages This usually results in the following source code pattern class FooProtocol public cSimpleModule protected state variables M
443. ullPath else if par gt containsValue http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual par gt acceptDefault else Chirow T eRUNTIMEEnr ror YO walwue ior sa Paw Soeice wll azicia e_sieie 16 2 8 Extracting statistics from the model There are several ways you can extract statistics from the simulation Via C calls into the model Modules in the simulation are C objects If you add the appropriate public getter methods to the module classes you can call them from your main program to obtain statistics Modules may be looked up with the getModuleByPath method of cSimulation then cast to the specific module type via check_and_cast lt gt so that the getter methods can be invoked cModule mod simulation getModuleByPath Network client 2 app WebApp appMod check_and_cast lt WebApp gt mod int numRequestsSent appMod gt getNumRequestsSent double avgReplyTime appMod gt getAvgReplyTime The drawback of this approach is that getters need to be added manually to all affected module classes which might not be practical especially if modules come from external projects Via cEnvir callbacks A more general way is to catch recordScalar method calls in the simulation model cModule s recordScalar method delegates to the similar function in cEnvir You may define the latter function such that it stores all recor
444. um process stack size allowed by the operating system ulimit s see next section Windows You need to set a low reserved stack size in the linker options for example 64K stack 65536 linker flag will do The reserved stack size is an attribute in the Windows exe files internal header It can be set from the linker or with the editbin Microsoft utility You can use the opp_stacktool program which relies on another Microsoft utility called dumpbin to display reserved stack size for executables You need a low reserved stack size because the Win32 Fiber API which is the mechanism underlying activity uses this number as coroutine stack size and with 1MB being the default it is easy to run out of the 2GB possible address space 2GB 1MB 2048 A more detailed explanation follows Each fiber has its own stack by default 1MB this is the reserved stack http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual space i e reserved in the address space but not the full 1MB is actually committed i e has physical memory assigned to it This means that a 2GB address space will run out after 2048 fibers which is way too few In practice you won t even be able to create this many fibers because physical memory is also a limiting factor Therefore the 1MB reserved stack size RSS must be set to a smaller value the coroutine stack size requested for the module plus the ext ra
445. unld but it will be some string concatenated from the simulated network s name the time date the hostname and other pieces of data to make it unique A simulation run will typically write into two result files vec and sca However when using parallel distributed simulation the user will end up with several vec and sca files because different partitions a separate process each will write into different files However all these files will contain the same runld so it is possible to relate data that belong together Entry types are e version result file version e run simulation run identifier e attr run vector scalar or statistics object attribute param module parameter e scalar scalar data e vector vector declaration e vector id vector data e file vector file attributes e Statistic statistics object e field field of a statistics object e bin histogram bin 24 1 Version http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Specifies the format of the result file It is written at the beginning of the file Syntax version versionNumber The version described in this document is 2 Version 1 files are produced by OMNeT 3 3 or earlier 24 2 Run Declaration Marks the beginning of a new run in the file Entries after this line belong to this run Syntax run runid Example Ulin TOkenRkingl 0 20080514 1a 3 1934 SZAG Typically there will be one run per fi
446. upport is described in the next section 4 3 2 activity http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Process style description With activity you can code the simple module much like you would code an operating system process or a thread You can wait for an incoming message event at any point of the code you can suspend the execution for some time model time etc When the activity function exits the module is terminated The simulation can continue if there are other modules which can run The most important functions you can use in activity are they will be discussed in detail later e receive to receive messages events e wait to suspend execution for some time model time e send family of functions to send messages to other modules e scheduleAt to schedule an event the module sends a message to itself e cancelEvent to delete an event scheduled with scheduleAt e end to finish execution of this module same as exiting the activity function The activity function normally contains an infinite loop with at least a wait or receive call in its body Application area Generally you should prefer handleMessage to activity The main problem with activity is that it doesn t scale because every module needs a separate coroutine stack It has also been observed that activity does not encourage a good programming st
447. upported by OMNeT The user can attach transient detection and result accuracy objects to a result object cStatistic s descendants The transient detection and result accuracy objects will do the specific algorithms on the data fed into the result object and tell if the transient period is over or the result accuracy has been reached The base classes for classes implementing specific transient detection and result accuracy detection algorithms are e cTransientDetection base class for transient detection e cAccuracyDetection base class for result accuracy detection Basic usage http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual Attaching detection objects to a cStatistic and getting pointers to the attached objects addTransientDetection cTransientDetection object addAccuracyDetection cAccuracyDetection object cTransientDetection getTransientDetectionObject cAccuracyDetection getAccuracyDetectionObject Detecting the end of the period e polling the detect function of the object e installing a post detect function Transient detection Currently one transient detection algorithm is implemented i e there s one class derived from cTransientDetection The cIDExpandingWindows Class uses the sliding window approach with two windows and checks the difference of the two averages to see if the transient period is over void setParameters int reps 3
448. uration In the latter two cases the like keyword is used and a channel interface type 17 4 6 needs to be specified as http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual well which the concrete channel type needs to implement to be eligible to be chosen In the second case the string expression is specified in angle braces lt gt in the third case an empty pair of angle braces is used lt gt The syntax is similar to the submodule syntax see 17 4 11 NOTE When using the lt gt syntax the actual NED type should be provided with the type name configuration option where the object pattern should be the source gate plus channel host g o channel type name EthernetChannel NOTE As bidirectional connections those using double arrows lt gt are a shorthand for two uni directional connections bidirectional connections with channels will actually create two channel objects one for each direction Channel parameters and properties A channel definition may or may not have a body a curly brace delimited block An empty channel body is equivalent to a missing one A channel body may contain parameters 17 4 9 A channel body cannot define new parameters It is only allowed to assign existing parameters It is also allowed to add or modify properties and parameter properties Implicit channel type When a connection uses an unnamed channel typ
449. urce module identifying the connection dm int destModulelId id of the destination module dg int destGatelId id of the gate at the destination module CD ConnectionDeletedEntry deleting a connection sm int sourceModuleId id of the source module identifying the connection sg int sourceGatelId id of the gate at the source module identifying the http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual connection CS ConnectionDisplayStringChangedEntry a connection display string change sm int sourceModuleId id of the source module identifying the connection sg int sourceGatelId id of the gate at the source module identifying the connection d string displayString the new display string MS ModuleDisplayStringChangedEntry a module display string change id int moduleld id of the module d string displayString the new display string E EventEntry an event that is processing of a message long eventNumber unique event number t simtime_t simulationTime simulation time when th vent occurred m int modulelId id of the processing module ce long causeEventNumber 1 event number from which the message being processed was sent or 1 if the message was sent from initialize msg long messagelId life time unique id of the message being processed
450. urposes you may also redefine sputn where module log messages are written cNullEnvir only provides one random number generator so your simulation model uses more than one you also http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual need to redefine the getNumRNGs and getRNG k methods To print or store simulation records redefine recordScalar recordStatistic and or the output vector related methods Other cEnvir methods are invoked from the simulation kernel to inform the environment about messages being sent events scheduled and cancelled modules created and so on The following example shows a minimalistic environment class that s enough to get started m elass CusctonSimulacswoniiny 3 POLLE CiNe ll ILisimyalse pubiic constructor CUSTOMS imMULeacLOMhay sine aC ehan aw e e oa on E GEINGULILmiowaLie aie aV eE model parameters accept defaults virtual void readParameter cPar par if par gt containsValue par gt acceptDefault else throw cRuntimeError no value for s par gt getFullPath c_str send module log messages to stdout WiLrcuial woulcl sputa const Char Ss dar m 1 voleh 3 itwieLce Ss 1 im Siccloue 5 16 2 4 Providing a configuration object The configuration object needs to subclass from cConfiguration cConfiguration also has several methods b
451. ut to maintain equal gate size for the two directions The syntax to associate a channel see 17 4 4 with the connection is to use two arrows with a channel specification in between see later The same syntax is used to add properties such as display to the connection Inout gates An inout gate is represented as a gate pair an input gate and an output gate The two sub gates may also be referenced and connected individually by adding the i and o suffix to the name of the inout gate A bidirectional connection which uses a double arrow to connect two inout gates is also a shorthand for two uni directional connections that is aco lt gt lo Gf is equivalent to ago gt 10 Cals acoja lt 10 GOs In inout gate vectors gates are always in pairs that is sizeof g i sizeof g o always holds It is maintained even when g i or gSo is used the operator will add a gate pair not just an input or an output gate Specifying channels A channel specification associates a channel object with the connection A channel object is an instance of a channel type see 17 4 4 The channel type that will be instantiated as channel object may be specified in several ways e with a concrete channel type name or e may be implicitly determined from the set of parameters used see later or by astring valued expression that evaluates to the name of a channel type or e the type name may come from the config
452. ut even if you reuse the underlying C class of built in channel types they may be read and used by other parts of the model For example adding a cost parameter or cost property may be observed by the routing algorithm and used for routing decisions The following example shows a cost parameter and annotation using a property backbone channel Backbone extends ned DatarateChannel backbone double cost default 1 3 6 Parameters Parameters are variables that belong to a module Parameters can be used in building the topology number of nodes etc and to supply input to C code that implements simple modules and channels Parameters can be of type double int bool string and xml they can also be declared volatile For the numeric types a unit of measurement can also be specified unit property to increase type safety Parameters can get their value from NED files or from the configuration omnetpp ini A default value can also be given default which gets used if the parameter is not assigned otherwise Let us see an example before we go into details simple App parameternsk int address local node address string destAddresses destination addresses volatile double sendIaTime unit s default exponential ls time between generating packets volatile int packetLength unit byte length of one packet Values Parameters may get their values from several
453. ut the typed ones getAsBool getAsInt etc have default implementations that delegate to the much fewer string based methods get ConfigValue etc It is fairly straightforward to implement a configuration class that emulates an empty ini file Class MimanyComirieg s PUSLE CCoOMmiriGmicacioem protected class NullKeyValue public KeyValue jOWISILaLe 3 Wilieval GOMSic Clic Ceetiney ComSic meicmicm NUIIbe virtual const char getValue const return NULL virtual const char getBaseDirectory const return NULL NullKeyValue nullKeyValue protected virtual const char substituteVariables const char value return value jOwWoLALE 3 virtual const char getConfigValue const char key const return NULL virtual const KeyValue amp getConfigEntry const char key const return nullKeyValue virtual const char getPerObjectConfigValue const char objectFullPath GOS Ewe niche ii key o Ubi alex EC OMS eae rS Wes em NUT virtual const KeyValue amp getPerObjectConfigEntry const char objectFullPath const char keySuffix const return nullKeyValue 16 2 5 Loading NED files http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual NED files can be loaded with any of the following static methods of cSimulation loadNedSourceFolder loadNedFile and loa
454. ve fully equal rights to Cmdenv and Tkenv that is it can be activated by starting the simulation executable with the u lt name gt command line or the user interface configuration option it can be made the default user interface it can define new command line options and configuration options and so on User interfaces must implement i e subclass from cRunnableEnvir and must be registered to OMNeT with the Register_OmnetApp macro In practice you ll almost always want to subclass EnvirBase instead of cRunnableEnvir because EnvirBase already implements lots of functionality that otherwise you d have to NOTE If you want something completely different from what EnvirBase provides such as when embedding the simulation kernel into another application then you should be reading section 16 2 not this one An example user interface include envirbase h class FooEnv public EnvirBase m Register_OmnetApp FooEnv FooEnv 30 an experimental user interface The envirbase h header comes from the src envir directory so it is necessary to add it to the include path T The arguments to Register_OmnetApp include the user interface name for use with the u and user interface options the C class that implements it a weight for default user interface selection if u is missing the user interface with the largest weight will get act
455. ve that long finish is not invoked but you can still manually invoke it You can use the callFinish function to arrange finish to be called It is usually not a good idea to invoke finish directly If you re deleting a compound module callFinish will recursively invoke finish for all submodules and if you re deleting a simple module from another module callFinish will do the context switch for the duration of the call http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The finisn function is even made protected IN cSimpleModule in order to discourage its invocation from other modules Example MOC seca LLE raS A mod gt deleteModule 4 11 6 Creating connections Connections can be created using cGate s connectTo method The earlier connect global functions that accepted two gates have been deprecated and may be removed from further OMNeT releases connectTo should be invoked on the source gate of the connection and expects the destination gate pointer as an argument srcGate gt connectTo destGate The source and destination words correspond to the direction of the arrow in NED files As an example we create two modules and connect them in both directions cModuleType moduleType cModuleType get TicToc cModule a modtype gt createScheduleInit a this cModule b modtype gt createScheduletInit b this
456. virtual long getRoute unsigned k const virtual void setRoute unsigned k long route virtual unsigned getRouteArraySize const virtual void setRouteArraySize unsigned n The set ArraySize method internally allocates a new array Existing values in the array will be preserved copied over to the new array The default array size is zero This means that you need to call the set ArraySize before you can start filling array elements String members You can declare string valued fields with the following syntax message FooPacket string hostName The generated getter and setter methods will return and accept const char pointers virtual const char getHostName const virtual void setHostName const char hostName The generated object will have its own copy of the string Note that a string member is different from a character array which is treated as an array of any other type For example message FooPacket chore hara inao will generate the following methods virtual char getChars unsigned k virtual void setChars unsigned k char a 5 2 4 Inheritance composition So far we have discussed how to add fields of primitive types int double char to cMessage This might be sufficient for simple models but if you have more complex models you ll probably need to e set up a hierarchy of message packet classes that is not only subclass from cMessage
457. when they leave the area As another example when implementing a server or a transport protocol it might be convenient to dynamically create modules to serve new connections and dispose of them when the connection is closed You would write a manager module that receives connection requests and creates a module for each connection The Dyna example simulation does something like this Both simple and compound modules can be created dynamically If you create a compound module all its submodules will be created recursively It is often convenient to use direct message sending with dynamically created modules Once created and started dynamic modules aren t any different from static modules for example one could also delete static modules during simulation though it is rarely useful http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual 4 11 2 Overview To understand how dynamic module creation works you have to know a bit about how normally OMNeT instantiates modules Each module type class has a corresponding factory object of the class cModuleType This object is created under the hood by the Define_Module macro and it has a factory function which can instantiate the module class this function basically only consists of a return new module class statement The cModuletType object can be looked up by its name string which is the same as the module class name Once you have it
458. work The subclassing approach for adding message parameters was originally suggested by Nimrod Mesika The first message class Let us begin with a simple example Suppose that you need message objects to carry source and destination addresses as well as a hop count You could write a mypacket msgq file with the following contents message MyPacket int srcAddress int destAddress ine hops 32 The task of the message subclassing compiler is to generate C classes you can use from your models as well as reflection classes that allow Tkenv to inspect these data structures If you process mypacket msg with the message subclassing compiler it will create the following files for you mypacket_m h and mypacket_m cc mypacket_m h contains the declaration of the MyPacket C class and it should be included into your C sources where you need to handle MyPacket objects http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual The generated mypacket_m h will contain the following class declaration class MyPacket public cMessage virtual int getSrcAddress const virtual void setSrcAddress int srcAddress So in your C file you could use the MyPacket class like this include mypacket_m h MyPacket pkt new MyPacket pkt pkt gt setSrcAddress localAddr The mypacket_m cc file contains implementation of the generated MyPacket class as well as r
459. wunconnected syntax see 17 4 10 Connections and connection groups The connections section may contain any number of connections and connection groups A connection group is one or more connections grouped with curly braces Both connections and connection groups may be conditional i keyword or may be multiple for keyword Any number of for and if clauses may be added to a connection or connection loop they are interpreted as if they were nested in the given order Loop variables of a for may be referenced from subsequent conditions and loops as well as in module and gate index expressions in the connections See the NED Grammar 18 for the exact syntax Example connections A Oulie gt 19 LN crout gt Claim wi joSOp erouc fay S sea ror t O Siveoir Gril ai 152 05 Example connection groups iit fro acotit gt ooi aoln lt lo OUE for i 0 sizeof c 1 if i 2 0 c i out gt out i elij l im lt imi s for I 0 si zeot dh I for J 9 sizeof d FfF al Cli ou ly adaa for i 0 sizeof e 1 for j 0 sizeof e Sli owes elj ein ac al 75 Connection syntax The connection syntax uses arrows gt lt to connect input and output gates and double arrows lt gt to connect two inout gates The latter is also said to be a bidirectional connection Arrows point from the source gate a submod
460. x that is the directories recursed into will be automatically excluded from deep makefiles You can control the order of traversal by adding dependencies into the makefrag file see 7 2 11 NOTE With d it is also possible to create infinite recursions opp_makemake cannot detect them it is your responsibility that cycles do not occur Motivation for recursive builds e toplevel makefile e integrating sources that have their own makefile 7 2 11 Customizing the Makefile http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual It is possible to add rules or otherwise customize the generated makefile by providing a makefrag file When you run opp_makemake it will automatically insert makefrag into the resulting Makefile With the i option you can also name other files to be included into the Makefile makefrag will be inserted after the definitions but before the first rule so it is possible to override existing definitions and add new ones and also to override the default target makefrag can be useful if some of your source files are generated from other files for example you use generated NED files or you need additional targets in your makefile or just simply wants to override the default target in the makefile 7 2 12 Projects with multiple source trees In the case of a large project your source files may be spread across several directories and your project may generate more t
461. x as a single entity can be broken down into smaller modules and used as a compound module Component Based Simple modules and compound modules are inherently reusable which not only reduces code copying but more importantly allows component libraries like the INET Framework MiXiM Castalia etc to exist e Interfaces Module and channel interfaces can be used as a placeholder where normally a module or channel type would be used and the concrete module or channel type is determined at network setup time by a parameter Concrete module types have to implement the interface they can substitute For example given a compound module type named MobileHost contains a mobility submodule of the type IMobility where IMobility is a module interface the actual type of mobility may be chosen from the module types that implemented IMobility RandomWalkMobility TurtleMobility etc e Inheritance Modules and channels can be subclassed Derived modules and channels may add new parameters gates and in the case of compound modules new submodules and connections They may set existing parameters to a specific value and also set the gate size of a gate vector This makes it possible for example to take a GenericTCPClientApp module and derive an FTPClientApp from it by setting certain parameters to a fixed value or to derive a WebClientHost compound module from a BaseHost compound http omnetpp org doc omnetpp40 manual usman ht
462. y contain data given in parentheses the data model is quite flexible Properties may contain lists enum Sneezy Sleepy Dopey Doc Happy Bashful Grumpy They may contain key value pairs separated by semicolons coords x 10 31 y 30 2 unit km In key value pairs each value can be a comma separated list nodeinfo id 742 labels swregion routers critical The above examples are special cases of the general data model According to the data model properties contain key valuelist pairs separated by semicolons Items in valuelist are separated by commas Wherever key is missing values go on the valuelist of the default key the empty string prop is the same as prop The syntax for value items is a bit restrictive they may contain words numbers string constants and some more but not arbitrary strings Whenever the syntax does not permit some value it should be enclosed in quotes This quoting does not make any difference in the value because the parser automatically drops one layer of quotes thus class TCP and class TCP are exactly the same There are also some conventions One can use properties to tag some NED element with a label for example a host property could be used to mark all module types that represent various hosts This property could be used e g by editing tools by topology discovery code inside the simulation model etc The convention for such a label property is that any ex
463. ying the number of cells cPSquare psquare interarrival times 20 Afterwards a cPSquare can be used with the same member functions as a histogram Getting histogram data There are three member functions to explicitly return cell boundaries and the number of observations is each cell http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual getNumCells returns the number of cells getBasepoint int k returns the kth base point getCellValue int k returns the number of observations in cell k and getCellPDF int k returns the PDF value in the cell i e between getBasepoint k and getBasepoint k 1 The getCelliInfo k method returns multiple data cell bounds counter relatile frequency packed together in a struct These functions work for all histogram types plus cPSquare and cKSplit cal 0 1 lt Y gt base point 0 1 Figure base points and cells An example long n histogram getCount ve or int i 0 i lt histogram getNumCells i double cellWidth histogram getBasepoint i 1 histogram getBasepoint i int count histogram getCellValue i double pdf histogram getCellPDF i bd ee The get PDF x and getCDF x member functions return the value of the Probability Density Function and the Cumulated Density Function at a given x respectively Random number generation from distribut
464. yle There is one scenario where activity s process style description is convenient when the process has many states but transitions are very limited ie from any state the process can only go to one or two other states For example this is the case when programming a network application which uses a single network connection The pseudocode of the application which talks to a transport layer protocol might look like this activity while true open connection by sending OPEN command to transport layer receive reply from transport layer if open not successful wait some time continue loop back to while while there s more to do send data on network connection if connection broken wait some time receive data on network connection if connection broken wait some time continue outer loop loop back to outer while continue outer loop loop back to outer while http omnetpp org doc omnetpp40 manual usman html 2009 4 20 20 32 29 OMNeT Manual close connection by sending CLOSE command to transport layer if close not successful handle error wait some time If you have to handle several connections simultaneously you may dynamically create them as instances of the simple module above Dynamic module creation will be discussed later There are situations when you certainly do not want to use activity If your activity function
465. yloadLength If you process the above code with the message compiler the generated code will contain a FooPacket_Base class instead of FooPacket Then you would subclass FooPacket_Base to produce FooPacket while doing your customizations by redefining the necessary methods class FooPacket_Base public cMessage protected lae Sre make constructors protected to avoid instantiation FooPacket_Base const char name NULL FooPacket_Base const FooPacket_Base amp other jOUWIOILLE 2 virtual int getSrc const vircual yoi SeieSice inci Srey There is a minimum amount of code you have to write for FooPacket because not everything can be pre generated as part of FooPacket_Base e g constructors cannot be inherited This minimum code is the following you ll find it the generated C header too as a comment class FooPacket public FooPacket_Base jOUlOLLE 3 FooPacket const char name NULL FooPacket_Base name FooPacket const FooPacket amp other FooPacket_Base other FooPacket amp operator const FooPacket amp other FooPacket_Base operator other return this virtual FooPacket dup return new FooPacket this Register_Class FooPacket Note that it is important that you redefine dup and provide an assignment operator operator So returning to our original example about payload length affecting packet length th

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