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1. 367 CHAPTER 17 The Open Communications Interface How Does it Work 368 The Bi directional plug in uses a layered design that theoretically enables any connection oriented OCI plug in to support bi directional functionality Initially however only bi directional IIOP is supported In Figure 16 a server is shown that is capable of receiving both bi directional IIOP connections and regular IIOP connections Server OCI OCI Bi dir IOP OCI IOP A Requests amp Requests Callbacks Callbacks OCI ocl IOP IOP OCI Bi dir Client B Client A Figure 16 Connection Requirements Any callback requests from the Server to Client A will travel down the existing connection already established by the client On the other hand any callback requests from the Server to Client B require a new IIOP connection to be established from the server to the client Peers The Bi directional OCI Plug in The Bi directional plug in requires each peer in a bi directional connection to have a unique identifier called the peer ID Currently this identifier is just a simple ISO LATIN1 string In IIOP terms a unique endpoint is derived from the hostname port combination However since the Bi directional OCI plug in has no knowledge of the underlying protocol a separate identification scheme is currently required and must be provided by the application It is therefore the applicat
2. stop server Server name Stop a server reset server server name Reset a server Note that the imradmin utility also needs to be configured with the IMR initial reference see Connecting to the Service on page 163 The host argument is optional If host is not specified the local host name is used The server name argument refers to the name of the server The format of the poa name argument is poal poa2 poa3 where poai is a child of the Root POA poaz is a child of poa1 and poa3 is a child of poa2 Refer to Information Managed by the IMR on page 154 for further details In very rare circumstances it s possible for the IMR and OAD to become confused as to the state of a server In this case it might be necessary to manually reset the state of the server using the reset server command It is also necessary to use this command if the server continually crashes on startup and has reached the maximum number of retries specified by its max_spawns attribute This prevents the OAD from continually starting the same broken server The mkref utility creates IMR based object references for use by clients Since the Object ID is required to create a reference this utility can only be used to create references for objects created by POAs using the usER_ID object identification policy Its usage is shown below mkref H host P port server name object id poal poa2 poan host The ho
3. MinorAllocationFailure Memory allocation failure 385 CHAPTER 18 Exceptions and Error Messages IMP_LIMIT Minor Exception Code MinorNoUsableProfile No usable profile in IOR MinorMessageSizeLimit Maximum message size exceeded MinorThreadLimit Can t create new thread 386 CORBA System Exceptions COMM _FAILURE Minor Exception Code MinorRecv recv failed MinorSend send failed MinorRecvZero recv returned zero MinorSendZero send returned zero MinorSocket socket failed MinorSetsockopt setsockopt failed MinorGetsockopt getsockopt failed MinorBind bind failed 7 MinorListen listen failed MinorConnect connect failed MinorAccept accept failed MinorSelect select failed MinorGethostname gethostname failed MinorGethostbyname gethostbyname failed r MinorWSAStartup WSAStartup failed MinorWSACleanup WSACleanup failed MinorNoGIOP Not a GIOP message MinorUnknownMessage Unknown GIOP message MinorWrongMessage Wrong GIOP message MinorMessageError Got a message error message MinorFragment Invalid fragment message MinorUnknownReqid Unknown request ID MinorVersion Incompatible GIOP version MinorPipe Creation of pipe failed i MinorSetSoTimeout setSoTimeout fail
4. Java package hello public class Hello impl extends HelloPOA public void say hello System out println Hello World Fo wWON HUH BPWN HE 0 4 The implementation class Hello impl must inherit from the generated class HelloPOA 6 8 As with the C implementation the say_he11o method simply prints Hello World on standard output 16 Implementing the Example in Java Server class main method Create a file Server java in the directory hello and enter the following Server Class code which holds the server s main and run methods aI HU PWN PH Java package hello public class Server public static void main String args java util Properties props System getProperties props put org omg CORBA ORBClass com ooc OBServer ORB props put org omg CORBA ORBSingletonClass com ooc CORBA ORBSingleton int status 0 org omg CORBA ORB orb null CEY orb org omg CORBA ORB init args props status run orb catch Exception ex ex printStackTrace status 1 ae Koay Ke LIL CEY catch Exception ex orb destroy ex printStackTrace status 1 System exit status 17 CHAPTER 1 Getting Started 18 20 22 26 28 39 41 These properties are necessary to use the Orbacus ORB instead of the JDK s ORB The ORB must be initialized using orB init The ORB class resides
5. ReadULongLongArrayOverf low Overflow while reading ulonglong array Minor ReadFloatArrayOverflow Overflow while reading float array Minor ReadDoubleArrayOverflow Overflow while reading double array Minor ReadLongDoubleArrayOverflow Overflow while reading longdouble array Minor ReadInvTypeCodeIndirection Invalid type code indirection MinorWriteObjectLocal Attempt to marshal a locality constrained object MinorLongDoubleNot Supported Long double is not supported 389 CHAPTER 18 Exceptions and Error Messages NO_IMPLEMENT Minor Exception Code 390 MinorMissingLocalValueImplementat ion Missing local value implementation MinorIncompat ibleValueImplementationVersion Incompatible value implementation version MinorNotSupportedByLocalObject Operation not supported by local object MinorDIINotSupportedByLocalObject DII operation not supported by local object CORBA System Exceptions NO RESOURCES Minor Exception Code MinorInvalidBinding Portable Interceptor operation not supported in binding 391 CHAPTER 18 Exceptions and Error Messages BAD_INV_ORDER Minor Exception Code 392 MinorDependencyPreventsDestruction Dependency exists in Interface Repository prevents destruction of object MinorIndestructibleObject Attempt to destroy indestructible object in Interf
6. Run the service in debug mode In order to use the Naming Service as a native Windows NT service it is first necessary to add the ooc naming endpoint configuration property to the HKEY LOCAL MACHINE NT registry key see Using the Windows NT Registry on page 65 for more details If the service is to be persistent the path to the database file must be stored in the following property 1 HKEY LOCAL MACHINE Software 00C Properties ooc naming database Next the service should be installed with ntnameservice i This adds the Orbacus Naming Service entry to the services dialog in the Control Panel To start the naming service select the Orbacus Naming Service entry and press start If the service is to be started automatically when the machine is booted select the orbacus Naming Service entry 1 Please note that services do not have access to network drives so the path to the database must be on a local hard drive 185 CHAPTER 8 Orbacus Names 186 then click Startup Next select Startup Type Automatic and press OK Alternatively the service could have been installed using the s option which configures the service for automatic start up ntnameservice s If you want to remove the service run ntnameservice u Note If the executable for the Naming Service is moved it must be uninstalled and re installed Any trace information provided by the service will be placed in the Windows NT Event Vi
7. 40 Hello var hello helloImpl gt _this 41 290 42 53 25 33 55 58 62 63 65 Programming Example 42 CORBA Object_var obj 43 orb gt resolve_initial_ references Balancer 44 LoadBalancing GroupFactory var factory 45 LoadBalancing GroupFactory _ narrow obj 46 47 obj orb gt resolve_initial_ references LoadUpdater 48 LoadBalancing Util LoadUpdater_var updater 49 LoadBalancing Util LoadUpdater _narrow obj 50 51 obj orb gt resolve _ initial references LoadAlert 52 LoadBalancing Util LoadAlert_var alert 53 LoadBalancing Util LoadAlert narrow obj 54 55 LoadAlert_impl loadAlertImpl new LoadAlert_impl alert 56 PortableServer ServantBase_var alertServant loadAlertImpl 57 LoadBalancing LoadAlert_var loadAlert 58 loadAlertImpl gt _this 59 60 manager gt activate 61 62 LoadBalancing Group_var group factory gt get Hello 63 group gt set_load_ alert memberId loadAlert 64 65 updater gt register_member memberId Hello 66 67 Gio s cn 68 69 return EXIT SUCCESS 70 Get the GroupFactory and the LoadUpdater and LoadaAlert utility objects Create the member POA Create the LoadAlert servant and activate it on the root POA Set the member s LoadAlert object Note that this should be done after activating the POA manager since it may result in a request to this server Re
8. Parameters buf The buffer to fill block If set to TRUE the operation blocks until the buffer is full If set to FALSE the operation fills as much of the buffer as possible without blocking Returns FALSE if a connection loss is detected TRUE otherwise Module OCI Raises COMM FAILURE In case of an error receive_timeout void receive timeout in Buffer buf in unsigned long timeout Similar to receive but it is possible to specify a timeout On return the caller can test whether there was a timeout by checking if the buffer has been filled completely Parameters buf The buffer to fill timeout The timeout value in milliseconds A zero timeout is equivalent to calling receive buf FALSE Raises COMM FAILURE In case of an error receive_timeout_detect boolean receive timeout detect in Buffer buf in unsigned long timeout Similar to receive timeout but it signals a connection loss by returning FALSE instead of raising COMM_FATLURE Parameters buf The buffer to fill timeout The timeout value in milliseconds A zero timeout is equivalent to calling receive buf FALSE Returns FALSE if a connection loss is detected TRUE otherwise GW Raises COMM FAILURE In case of an error send void send in Buffer buf in boolean block Sends a buffer s contents Parameters buf The buffer to send 439 CHAPTER E Open Communic
9. Similar to data this operation returns a C pointer but to the n th element of the array of octets with n being the value of the position counter length readonly attribute unsigned long length The buffer length pos attribute unsigned long pos The position counter Note that the buffer s length and the position counter don t depend on each other There are no restrictions on the values permitted for the counter This implies that it s even legal to set the counter to values beyond the buffer s length advance void advance in unsigned long delta Increment the position counter Parameters delta The value to add to the position counter rest_length unsigned long rest_length Returns the rest length of the buffer The rest length is the length minus the position counter s value If the value of the position counter exceeds the buffer s length the return value is undefined Module OCI Returns The rest length is full boolean is full Checks if the buffer is full The buffer is considered full if its length is equal to the position counter s value Returns TRUE if the buffer is full FALSE otherwise 435 CHAPTER E Open Communications Interface Reference Interface OCI Plugin Attributes Operations 436 local interface Plugin The interface for a Plugin object which is used to initialize an OCI plug in id readonly attribute PluginId id The plugin id tag
10. windows motif mac h help look CLASS Use the specified Look amp Feel class windows Use the Windows Look amp Feel if available motif Use the Motif Look amp Feel if available mac Use the Macintosh Look amp Feel if available h Display the command line options supported by the help program CLASSPATH Requirements The Orbacus IMR Console requires the classes in 0B jar OBIMR jar and OBUtil jar Implementation Repository In order to locate an IMR Service the application uses the initial IMR Service Lookup Service as provided to the ORB with options such as oRBservice or ORBconfig If the service is not found an error is displayed and the IMR Console exits 176 The Menus The Menus The File Menu The Edit Menu The menus provide access to all of the features of the application In addition the most common actions are also available in the toolbar as well as in a popup menu that is displayed when pressing the right mouse button over an item in the binding table or context tree The File menu contains the Exit menu item which is used to exit the Orbacus IMR Console The operations in the Edit menu provide the means for manipulating OADs servers and POAs Create Create a new OAD server or POA Modify Modify the selected object Delete Delete the selected object Cut Move the selected server to the clipboard Paste Insert the server contained in the cli
11. 24 We need to retrieve the Orbacus specific Delegate object so that we can get the connector info Get the OCI connector info and narrow to an IIOP connector info The if block is only entered if this really was an IIOP connector info The address and port are obtained and displayed on standard output The IIOP OCI Plug in The IIOP OCI Plug in Client Installation Server Installation In this section The IIOP plug in implements the Internet Inter ORB Protocol as described in 4 By default the ORB automatically installs the client and server i e Connector Factory and Acceptor Factory components of the IIOP plug in and IIOP is the default protocol used by the ORB For configuration purposes the identifier of the IIOP plug in is iiop The client side IIOP plug in is installed as shown below ooc oci client iiop no keepalive The following options are supported no keepalive Disable the use of TCP keepalives The server side IIOP plug in is installed as shown below ooc oci server iiop This sections covers the following topics Endpoint Configuration page 354 Command line Options page 356 Static Linking page 357 353 CHAPTER 17 The Open Communications Interface Endpoint Configuration 354 The configuration options for an IIOP endpoint are shown below iiop bac klog N bind ADDR host ADDR ADDR multi profile no keepaliv
12. 48 Initializing the Java ORB Initializing the Java ORB The ORB implementation included in JDK 1 3 and newer can be considered a minimal ORB suitable primarily for use in basic client oriented tasks In order to use the Orbacus ORB instead of the JDK s default ORB you must start your application with the following properties java Dorg omg CORBA ORBClass com ooc CORBA ORB Dorg omg CORBA ORBSingletonClass com ooc CORBA ORBSingleton MyApp An alternative is to set these properties in your program before initializing the ORB For example Java import org omg CORBA public static void main String args java util Properties props System getProperties props put org omg CORBA ORBClass com ooc CORBA ORB props put org omg CORBA ORBSingletonClass com ooc CORBA ORBSingleton ORB orb ORB init args props Wis Sree The orB init call interprets arguments starting with orB and oa Unlike the C version these arguments are not removed see Advanced Property Usage on page 69 for more information 49 CHAPTER 3 ORB and Object Adapter Initialization Object Adapter Initialization In Orbacus the object adapter is not initialized until the Root POA is first resolved For example C CORBA Object_var poaObj orb gt resolve_initial_ references RootPOA Java org omg CORBA Object poaObj orb resolve_initial_ references Root POA
13. CHAPTER 12 The Interface Repository Connecting to the Interface Repository The object key of the IFR is DefaultRepository which identifies an object of type CORBA Repository The object key can be used when composing URL style object references For example the following URL identifies the IFR running on host ifrhost at port 10000 corbaloc ifrhost 10000 DefaultRepository Refer to Chapter 5 for more information on URLs and configuring initial services 256 Configuration Issues Configuration Issues Although applications can interact with the IFR as with any other CORBA server it does have special status within the ORB Specifically use of the standard operation object get_interface requires the presence of an IFR PIDL interface Object InterfaceDef get _interface He The exact semantics of get_interface can be a source of confusion In Orbacus as with most other ORBs the get_interface operation is a remote operation That is when a client invokes get_interface on an object reference the request is sent to the server The server knows the interface type of the object reference and interacts with the IFR to locate the appropriate CORBA InterfaceDef object to return to the client Therefore the server must be configured for the IFR It is not necessary to configure the client for the IFR if the client s only interaction with the IFR is via get_interface 257 CHAPTER 12 The Interface
14. IMR Security IMR Security It is very important that only the IMR s public endpoint also referred to as its forward endpoint be accessible outside of the network firewall Otherwise anyone can mimic the IMR and cause an OAD to run any command they decide For additional security the information managed by the IMR may only be modified when the IMR is running in administrative mode That is e OAD registration and removal e server registration and removal e modification of server attributes and e POA registration and removal are only possible when the IMR is running in administrative mode An attempt to modify the information managed by the IMR when it is not running in administration mode will result in a CORBA NO_PERMISSION exception 157 CHAPTER 6 The Implementation Repository Usage The IMR and OAD are currently implemented using Orbacus for C but Orbacus for Java servers can also be launched by the IMR Both the IMR and OAD are contained in the IMR server which may be started in one of three modes master Start only the IMR slave Start only the OAD dual Start both the IMR and OAD Command line usage is as follows imr h help v version m master s slave a administrative d database A admin endpoint F forward endpoint S slave endpoint L locator endpoint h Display the command line options supported by the
15. Module OB page 406 Module OBPortableServer page 417 BiDirPolicy page 419 405 CHAPTER B Orbacus Policy Reference Module OB Constants 406 CONNECTION_REUSE_POLICY_ID const CORBA PolicyType CONNECTION REUSE POLICY ID 1330577411 This policy type identifies the connection reuse policy CONNECT_TIMEOUT_POLICY_ID const CORBA PolicyType CONNECT TIMEOUT POLICY ID 1330577416 This policy type identifies the connect timeout policy INTERCEPTOR_POLICY_ID const CORBA PolicyType INTERCEPTOR POLICY ID 1330577415 This policy type identifies the interceptor policy LOCATE_REQUEST_POLICY_ID const CORBA PolicyType LOCATE REQUEST POLICY ID 1330577418 This policy type identifies the locate request policy LOCATION_TRANSPARENCY_POLICY_ID const CORBA PolicyType LOCATION TRANSPARENCY POLICY ID 1330577414 This policy type identifies the location transparency policy LOCATION_TRANSPARENCY_RELAXED const short LOCATION TRANSPARENCY RELAXED 1 The LOCATION TRANSPARENCY RELAXED LocationTransparencyPolicy value LOCATION_TRANSPARENCY_STRICT const short LOCATION TRANSPARENCY STRICT 0 The LOCATION TRANSPARENCY STRICT LocationTransparencyPolicy value PROTOCOL POLICY_ID const CORBA PolicyType PROTOCOL POLICY ID 1330577410 This policy type identifies the protocol policy REQUEST_TIMEOUT_POLICY_ID const CORBA PolicyType REQUEST TIMEOUT POLICY ID 1330577417 This policy type identifies the req
16. Parameters buf The buffer to fill timeout The timeout value in milliseconds A zero timeout is equivalent to calling send buf FALSE Returns FALSE if a connection loss is detected TRUE otherwise Raises COMM FAILURE In case of an error get_info TransportInfo get_info Returns the information object associated with the Transport Returns The Transport information object 441 CHAPTER E Open Communications Interface Reference Interface OCI TransportInfo Attributes Operations 442 local interface TransportInfo Information on an OCI Transport object Objects of this type must be narrowed to a Transport information object for a concrete protocol implementation for example to OCI IIOP Transport Info in case the plug in implements IIOP See Also Interface OCI Transport id readonly attribute PluginId id The plugin id tag readonly attribute ProfilelId tag The profile id tag connector_info readonly attribute ConnectorInfo connector _info The ConnectorInfo object for the Connector that created the Transport object that this TransportInfo object belongs to If the Transport for this Transportinfo was not created by a Connector this attribute is set to the nil object reference acceptor_info readonly attribute AcceptorInfo acceptor_info The AcceptorInfo object for the Acceptor that created the Transport object that this TransportInfo object belongs
17. This policy is used to specify retry behavior after communication failures Namely e the types of failures for which retries are allowed e the time between successive retries and e the maximum number of retries OB TimeoutPolicy If an object has this policy and a connection cannot be established or no response is available for a request after value milliseconds a CORBA NO_RESPONSE exception is raised If an object has OB ConnectTimeout Policy Or OB RequestTimeout Policy set those policies have precedence OBPortableServer InterceptorCall Policy This policy determines whether server side interceptors will be called for requests on a POA Server side interceptors are enabled by default To disable server side interceptors for a POA create the POA using this policy with a value of false OBPortableServer Communication sConcurrencyPolicy See ooc orb oa conc_model on page 59 and ooc orb poamanager manager conc_model on page 61 OBPortableServer EndpointConfig urationPolicy See ooc orb poamanager manager endpoint on page 61 OBPortableServer GlOPVersionPol icy See ooc orb poamanager manager version on page 61 305 CHAPTER 15 Using Policies Programming Examples This section provides several examples of setting policies programmatically Please note however that policies used to configure the ORB can easily be set at the ORB level without
18. random Non adaptive strategy where members are selected at random There are no configuration properties for this strategy round robin Non adaptive strategy where members are selected in round robin order There are no configuration properties for this strategy least load Adaptive strategy where the least loaded members are chosen in round robin order The configuration properties for this strategy are as follows tolerance Type CORBA ULong Members with a load difference that is less than tolerance are considered to have the same load The default value for this property is O This alleviates the member selection problem 1 on page 263 load per client Type CORBA ULong The load per client property is an estimate of the load for a given client connection It is used so that a member s load can be adjusted without having to wait for the next load update It is also used to estimate the effect of load re balancing The default value for this property is O This alleviates the member selection problem 1 on page 263 critical load Type CORBA ULong A member with a load greater than critical load is re balanced if there exists a member with a load that is less than critical load minus load per client This property has a default value of O which disables load re balancing This alleviates the member selection problem 3 on page 264 272 reject load dampening multiplier min dispersion tolerance
19. There are two basic types of policies those used to configure the ORB and those used to create a new POA Furthermore the configuration of ORB policy objects is accomplished at two levels ORB Level These policies override the system defaults The ORB has an initial reference ORBPolicyManager A PolicyManager has a set of operations through which the current set of overriding policies can be obtained and new policies can be applied e Object Level The object interface contains operations to retrieve and set policies for itself Policies applied at the object level override those applied at the thread level or the ORB level For more information on Policies the PolicyManager interface and the CORBA Object policy operations see 8 and 4 Supported Policies Supported Policies The following is a brief description of the Orbacus specific policies that are currently supported For a detailed description please refer to Appendix B For standard policies please refer to 4 Table 4 Orbacus policies Policy Description BiDirPolicy BidirectionalPolicy This policy is used to enable CORBA 3 compliant BiDir GIOP functionality on both the Object and POA levels Enabling this policy with a value of BiDirPolicy BOTH on both levels will result in connection reuse when the server is required to make requests to the client The default value is BiDirPolicy NORMAL disabled BiDir functionality Both the client
20. e A special Reactor for use with the X11 Window System This Reactor handles X11 events which for example can trigger X11 callbacks and CORBA network events simultaneously See The X11 Reactor on page 339 e A special Reactor for use with Microsoft Windows 95 98 NT 2000 This Reactor handles Windows messages and CORBA network events simultaneously See The Windows Reactor on page 340 The default Reactor is the select Reactor If one of the other Reactors is to be used it must be initialized explicitly The X11 Reactor 1 7 11 13 15 17 22 The Reactor An application that wants to use the X11 Reactor can obtain a special X11 Reactor using OB GetX11Reactor which it must pass to OBCORBA ORB_ init wo aN aunFWNH 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25m C include lt X11 Intrinsic h gt include lt OB CORBA h gt include lt OB Logger h gt include lt OB Properties h gt include lt OB X11 h gt int main int argc char argv XtAppContext appContext Widget topLevel XtAppInitialize amp appContext MyApplication 0 0 amp argc argv 0 0 0 OB Reactor_var reactor OB GetX11Reactor appContext CORBA ORB var OBCORBA ORB init argc argv OB Properties nil OB Logger nil reactor POA initialization not shown orb gt run Cleanup not shown Include header files Initialize the X11 applic
21. help server v Display the version of the server version m Run the server in master mode master s Run the server in slave mode slave a Run the IMR in administrative mode The IMR will administrative run in non administrative mode by default d DIRECTORY Specifies the directory in which the IMR maintains database DIRECTORY its database files If not specified the current working directory is used 158 Usage A INFO admin endpoint INFO Specifies the IMR s administrative endpoint settings This is the endpoint that the OADs and IMR enabled servers use to communicate with the IMR For security reasons access to this endpoint can be restricted If not specified iiop port 9999 is used F INFO forward endpoint INFO Specifies the IMR s public endpoint which is used by clients for server requests If not specified iiop port 9998 is used S INFO slave endpoint INFO Specifies the endpoint used by the OAD Note that all of the OADs in a domain must use the same endpoint If not specified iiop port 9997 is used L INFO locator endpoint INFO Specifies the endpoint used by the Initial Service Locator see The Initial Service Locator on page 147 If not specified iiop port 2809 is used a Note that only one of the mor s options may be specified Also if neither the mor s option is specified then the server is started in dua
22. or unauthorized modifications 169 CHAPTER 6 The Implementation Repository Programming Example 170 12 16 In this section we will show how to modify the C version of the Hello World server see Chapter 1 to use a persistent object reference This will allow the server to use the IMR for indirect binding Modifications to the Java version of the server are similar The code for both the C and Java persistent Hello World servers may be found in the demo hello imr directories of the Orbacus for C and Java distributions The Hello World server presented in Chapter uses the Root POA to activate its Hello servant Since the Root POA uses the TRANSIENT life span policy the object reference it creates will not be persistent Hence the Hello World server must be modified so that the Hello servant is activated using a child POA with the Persistent life span policy The new child POA will also use the UsSER_ID object identification policy so that the mkre utility may be used Further the Hello servant is no longer activated under the Root POA so it becomes necessary for it to override the default_POA method The modified servant s class declaration is shown below 1 C 2 3 include lt Hello skel h gt 4 5 class Hello impl public POA Hello 6 public PortableServer RefCountServantBase 7 q 8 PortableServer POA var poa_ 3 10 public alae 12 Hello _impl PortableServer POA p
23. 215 CHAPTER 9 Orbacus Names Console The Toolbar 216 In addition to the operations offered by the menu bar some frequently needed functions are available by icons located in the toolbar as shown in Figure 7 cee aee x Figure 7 A closer look at the toolbar The icon on the toolbar s left is the Upwards icon which changes the naming context to the parent of the context currently being displayed The next five icons correspond to the New Context New Binding Cut Copy Paste and Delete items as described in The Edit Menu on page 210 The Simple List and Details items from the View menu are the next two icons in the toolbar They determine whether the binding table displays only the ID and Kind fields or if Orbacus Names is available also the date and time the binding was last modified The last item in the menubar corresponds to the Refresh operation from the View menu The Popup Menu The Popup Menu When selecting an item in the binding table or a tree node with the right mouse button a popup menu with a choice of operations is displayed as shown in Figure 8 Open Context Cut Copy Paste Change ID Change Kind Change IOR Delete Unlink Save IOR to File Figure 8 A popup menu offers important operations This is another convenient alternative for executing frequently used operations 217 CHAPTER 9 Orbacus Names Console 218 In this chapter CHAPTER 10 Orbacu
24. 356 357 358 359 360 361 364 365 366 367 368 369 370 371 372 373 374 375 376 377 CONTENTS CORBA System Exceptions 378 INITIALIZE Minor Exception Code 381 UNKNOWN Minor Exception Code 382 BAD_PARAM Minor Exception Code 383 NO MEMORY Minor Exception Code 385 IMP_LIMIT Minor Exception Code 386 COMM_FAILURE Minor Exception Code 387 MARSHAL Minor Exception Code 388 NO_IMPLEMENT Minor Exception Code 390 NO_RESOURCES Minor Exception Code 391 BAD_INV_ORDER Minor Exception Code 392 TRANSIENT Minor Exception Code 393 INTF_REPOS Minor Exception Code 394 OBJECT_NOT_EXIST Minor Exception Code 395 INV_POLICY Minor Exception Code 396 Non Compliant Application Asserts 397 Appendix A Boot Manager Reference 401 Interface OB BootManager 402 Interface OB BootLocator 404 Appendix B Orbacus Policy Reference 405 Module OB 406 Interface OB ConnectTimeoutPolicy 408 Interface OB ConnectionReusePolicy 409 Interface OB InterceptorPolicy 410 Interface OB LocateRequestPolicy 411 Interface OB LocationTransparencyPolicy 412 Interface OB ProtocolPolicy 413 Interface OB RequestTimeoutPolicy 414 Interface OB RetryPolicy 415 Interface OB TimeoutPolicy 416 Module OBPortableServer 417 Interface OBPortableServer InterceptorCallPolicy 418 BiDirPolicy 419 Appendix C Reactor Reference 421 Module OB 422 Interface OB Reactor Appendix D Logger Reference Interface OB Logger Interface OB WLogger Appendix E Open Communications
25. CONTENTS Chapter 3 ORB and Object Adapter Initialization Initializing the C ORB Initializing the Java ORB Object Adapter Initialization Configuring the ORB and Object Adapter ORB Properties OA Properties Command line Options Using a Configuration File Using the Windows NT Registry Defining Properties Precedence of Properties Advanced Property Usage Using POA Managers The Root POA Manager Anonymous POA Managers The POA Manager Factory Creating a POA Manager POA Manager Policies Endpoints Command line Options and Endpoints Dispatching Requests Callbacks ORB Destruction Server Event Loop Chapter 4 CORBA Objects Overview Implementing Servants Implementing Servants using Inheritance Implementing Servants using Delegation Creating Servants Creating Servants using C Creating Servants using Java Activating Servants Implicit Activation of Servants using C Implicit Activation of Servants using Java Explicit Activation of Servants using C Explicit Activation of Servants using Java Deactivating Servants Factory Objects Factory Objects using C Factory Objects using Java Caveats Obtaining the POA for a Servant Getting the POA for a Currently Executing Request Chapter 5 Locating Objects Obtaining Object References Lifetime of Object References Hostname Port Number Object Key Stringified Object References Using a File Using a URL Object Reference URLs corbaloc URLs corbaname URLs file URLs re
26. Closes the Transport After calling close no operations on this Transport object and its associated TransportInfo object may be called To ensure that no messages get lost when close is called shutdown should be called first Then dummy data should be read from the Transport using one of the 437 CHAPTER E Open Communications Interface Reference 438 receive operations until either an exception is raised or until connection closure is detected After that its save to call close i e no Messages can get lost Raises COMM_FAILURE In case of an error shutdown void shutdown Shutdown the Transport Upon a successful shutdown threads blocking in the receive operations will return or throw an exception After calling shutdown no operations on associated TransportInfo object may be called To fully close the Transport close must be called Raises COMM_FAILURE In case of an error receive void receive in Buffer buf in boolean block Receives a buffer s contents Parameters buf The buffer to fill block If set to TRUE the operation blocks until the buffer is full If set to FALSE the operation fills as much of the buffer as possible without blocking Raises COMM_ FAILURE In case of an error receive_detect boolean receive detect in Buffer buf in boolean block Similar to receive but it signals a connection loss by returning FALSE instead of raising COMM FAILURE
27. E in this case These are the contents of Ipackage E java Java package M IPackage IDL M I E 1 0 This comment describes exception E x final public class E extends org omg CORBA UserException public E 45 CHAPTER 2 Generating Code with Orbacus Now you can use javadoc to extract the comments from the generated Java files and produce nicely formatted HTML documentation For additional information please refer to the javadoc documentation 46 In this chapter CHAPTER 3 ORB and Object Adapter Initialization This chapter describes the initialization of client and server ORBs in various languages This chapter contains the following sections Initializing the C ORB page 48 Initializing the Java ORB page 49 Object Adapter Initialization page 50 Configuring the ORB and Object Adapter page 51 Using POA Managers page 71 ORB Destruction page 82 Server Event Loop page 83 47 CHAPTER 3 ORB and Object Adapter Initialization Initializing the C ORB In C the ORB is initialized with CORBA ORB_init For example C int main int argc char argv CORBA ORB_ var orb CORBA ORB init argc argv PT scat The CORBA ORB_ init Call interprets arguments starting with orB and oa All of these arguments passed through the argc and argv parameters are automatically removed from the argument list
28. EndpointConfigurationPolicy This example shows how to create a new POA Manager with a list of endpoints for the Root POA Manager The C version is presented first followed by the Java version Au FWY PH a 8 9 10 TI 12 13 14 15 16 E7 18 ie 20 21 22 Vi Cee CORBA Object_var poaObj orb gt resolve_initial_ references RootPOA OBPortableServer POA_var rootPOA OBPortableServer POA narrow poaObj POAManagerFactory var factory rootPOA gt the POAManagerFactory OBPortableServer POAManagerFactory var pmFactory OBPortableServer POAManagerFactory _ narrow factory POAManager var myPOAManager PolicyList pl String_var config CORBA string dup iiop host localhost port 5555 bind localhost pl length 1 pl 0 pmFactory gt create_endpoint_configuration_policy config in try catch const POAManagerFactory ManagerAlreadyExists amp ex myPOAManager create POAManager MyPOAManager pl do something And now the same example in Java 317 CHAPTER 15 Using Policies 318 woomaIdIianaunFrWNPH 10 17 i ils 14 15 16 L7 18 T9 20 21 22 23 24 25 Java org omg CORBA Object obj orb resolve initial references Root POA org omg PortableServer POA rootPOA org omg PortableServer POAHelper narrow obj org omg PortableServer POAManagerFactory factory rootPOA the the POAManagerFactory com
29. InterceptorPolicy at the ORB level See Appendix B for more information on this policy The default value is true Value true false Sets the oB LocateRequestPolicy at the ORB level See Appendix B for more information on this policy The default value is false Value strict relaxed Sets the oB LocationTransparencyPolicy at the ORB level See Appendix B for more information on this policy The default value is relaxed Value string Sets the oB ProtocolPolicy at the ORB level See Appendix B for more information on this policy Value transparent no rebind no reconnect Sets the Messaging RebindPolicy at the ORB level The default value is transparent Value timeout gt 1 Sets the oB RequestTimeoutPolicy at the ORB level See Appendix B for more information on this policy The default value is 1 55 CHAPTER 3 ORB and Object Adapter Initialization ooc orb policy retry ooc orb policy retry interval ooc orb policy retry max ooc orb policy retry remote ooc orb policy sync_scope ooc orb policy timeout ooc orb raise_dii_exceptions ooc orb server_name 56 Value never strict always Sets the mode attribute of the oB RetryPolicy at the ORB level See Appendix B for more information on this policy The default value is strict Value timeout gt 0 Sets the interval attribute of the op RetryPolicy at the ORB level See Appendix B for more informatio
30. Module LoadBalancing Util Interface LoadBalancing Util LoadCalculator Operations local interface LoadCalculator Interface for the calculation of the server load The LoadCalculator is used by the LoadUpdater to calculate the current load of the server which will be used as the load of each member registered with the LoadUpdater The implementation provided by the Balancer calculates the load based on the number of active requests since the last invocation of calculate_load See Also Interface LoadBalancing Util LoadUpdater calculate_load unsigned long calculate_load Calculate the load 485 CHAPTER F Orbacus Balancer Reference Interface LoadBalancing Util _LoadUpdater Operations 486 local interface LoadUpdater Interface to manage load updates sent to the Balancer At regular intervals set by the update frequency the LoadUpdater gets the load from the LoadCalculator and pushes it to the load balanced group of each registered member See Also Interface LoadBalancing Util LoadCalculator get_update_frequency unsigned long get_update_ frequency Retrieve the load push frequency set_update_frequency void set_update_frequency in unsigned long millis Set the load push frequency set_load_calculator void set_load_calculator in LoadCalculator calc Set the load calculator register_ member void register_member in MemberId member _ id in GroupId grou
31. case sensitive These options are the same as for the idl command no sort Don t sort symbols alphabetically ignore case Sort case insensitive use tables Use tables for indices alt indent Use alternative indentation for argument lists The alternative format requires less horizontal space which is in particular useful if the names of the operation or arguments are long output dir DIR Write HTML files to the directory DIR 35 CHAPTER 2 Generating Code with Orbacus Translating IDL to RTF Description Options for ridl 36 ridl creates Rich Text Format RTF files from IDL files An RTF file is generated for each module and interface defined in an IDL file Comments in the IDL file are preserved and javadoc style keywords are supported The section Documenting IDL Files on page 41 provides more information h help v version d debug DNAME DNAME DEF UNAME IDIR all case sensitive These options are the same as for the idl command no sort ignore case use tables alt indent These options are the same as for the hidl command output dir DIR Write RTF files to the directory DIR single file FILE Create a single file called FILE rtf with index Create index entries font PARA NAME font size PARA SIZE Specify the font name or size for a particular paragraph type The paragraph types and their default values are shown below Type Font S
32. ior output Configuration Properties In addition to the standard configuration properties described in Chapter 3 Orbacus Properties also supports the following properties ooc property endpoint ENDPOINT Specifies the endpoint configuration for the service Note that this property is only used if the ooc orb oa endpoint property is not set CLASSPATH Requirements Orbacus Properties for Java requires the classes in oB jar and OBProperty jar 220 Connecting to the Service Connecting to the Service The object key of the Property Service is PropertyService which identifies an object of type CosPropertyService PropertySetDefFactory The object key can be used when composing URL style object references For example the following URL identifies the Property Service running on host prophost at port 10000 corbaloc prophost 10000 PropertyService Refer to Chapter 5 for more information on URLs and configuring initial services 221 CHAPTER 10 Orbacus Properties Using the Property Service with the IMR The Property Service may be used with the Implementation Repository IMR However if used with the IMR it is important to note that the corbaloc URL style object reference described in the previous section cannot be used If the IMR is used then the object reference for the Property Service must be created using one of the following methods where PropertyServer refers to the server name configured wit
33. it also provides a number of features that are essential for building high performance and scalable servers 87 CHAPTER 4 CORBA Objects Implementing Servants In this section we will implement servant classes or implementation classes for the IDL interfaces defined below wf Tio 2 interface A 3 4 void op a 5 6 7 interface B a 9 void op b 10 i ala 12 interface I A B 13 14 void op i T5 F 2 5 An interface a is defined with the operation op_a 7 10 An interface B is defined with the operation op_b 12 15 Interface 1 is defined which is derived from a and B It also defines a new operation op i 88 Implementing Servants Implementing Servants using Inheritance Overview Inheritance using C Orbacus for C and Orbacus for Java both support the use of inheritance for interface implementation To implement an interface using inheritance you write a servant class that inherits from a skeleton class generated by the IDL translator By convention the name of the servant class should be the name of the interface with the suffix imp1 e g for an interface 1 the implementation class is named I impl In C I_imp1 must inherit from the skeleton class poa _x that was generated by the IDL to C translator If x1 inherits from other interfaces for example from the interfaces a and B then 1_imp1 must also inherit from the corresponding implementation classes A imp1
34. new Named_impl 4 Named_impl implA2 new Named_impl 5 Named_impl implA3 new Named_impl 6 Named_impl imp1R new Named_impl i Named_impl imp1C new Named_impl 8 Named a implA this orb 9 Named al implAl this orb 10 Named a2 implA2 this orb ial Named a3 imp1lA3 this orb 12 Named b imp1B this orb 13 Named c implC _this orb 14 15 try 16 iy NameComponent nclName new NameComponent 1 18 nclName 0 new NameComponent 19 nclName 0 id nc 20 nclName 0 kind 21 NamingContext ncl nc bind new context nc1Name 22 2e NameComponent nc2Name new NameComponent 2 24 nc2Name 0 new NameComponent 25 nc2Name 0 id nc 26 nc2Name 0 kind 27 nc2Name 1 new NameComponent 28 nc2Name 1 id nc2 29 nc2Name 1 kind 30 NamingContext nc2 nc bind new context nc2Name Sal 32 NameComponent aName new NameComponent 1 33 aName 0 new NameComponent 34 aName 0 id a 35 aName 0 kind 36 nc bind aName a 197 CHAPTER 8 Orbacus Names 198 Sy 38 NameComponent alName new NameComponent 1 39 alName 0 new NameComponent 40 alName 0 id al Al alName 0 kind 42 nc bind alName al 43 44 NameComponent a2Name new NameComponent 1 45 a2Name 0 new NameComponent 46 a2Name 0 id a2 47 a2Name 0 kin
35. new Policy 0 12 ty ig 4 14 myPOAManager 15 pmFactory create POAManager MyPOAManager pl 16 17 catch org omg PortableServer POAManagerFactoryPackage Man agerAlreadyExists ex T8 19 do something 20 21 catch org omg CORBA PolicyError ex 22 23 do something 24 Resolve the POA Manager Factory Create a new POA Manager with the name MyPOAManager The ORB processes any configuration properties that were defined for the POA Manager and may raise the OCI InvalidParam exception if an error was found in the POA Manager s endpoint configuration Using POA Managers POA Manager Policies The POA Manager Factory interface allows a set of vendor specific policies to be used to configure the new POA Manager For Orbacus the proprietary policies are IDL module OBPortableServer local interface POAManagerFactory PortableServer PPAManagerFactory EndpointConfigurationPolicy create_endpoint_configuration_policy in string value raises CORBA PolicyError CommunicationsConcurrencyPolicy create _communications_ concurrency policy in short value raises CORBA PolicyError GlIOPVersionPolicy create_giop version policy in short value raises CORBA PolicyError J JE These policies map to the POA Manager specific configuration properties coc orb poamanager manager endpoint conc model and version see OA Properties on page 59 For exa
36. that the service waits between successive retries The default value is 1000 A double that defines the factor by which the retry_timeout property should be multiplied for each successive retry The amount of time permitted for a blocking request on a client to return before a timeout The default value is 5 seconds 235 CHAPTER 11 Orbacus Events ooc event trace events LEVEL ooc event trace lifecycle LEVEL ooc event typed_service true false Defines the output level for event diagnostic messages printed by Orbacus Events The default level is O which produces no output A level of 1 or higher produces event processing information and a level of 2 or higher produces event creation and destruction information Defines the output level for lifecycle diagnostic messages printed by Orbacus Events The default level is O which produces no output A level of 1 or higher produces lifecycle information e g creation and destruction of Suppliers and Consumers Equivalent to the t command line option CLASSPATH Requirements 236 Orbacus Events for Java requires the classes in oB jar and oBEvent jar Connecting to the Service Connecting to the Service The object key of the Event Service depends on whether it is running as a typed or untyped service The object keys and corresponding interface types are shown in Table 2 Table 2 Object Keys and Interface Types Object Key Interface
37. 21 System out printlin id desc id 22 System out println defined_in desc defined_in 23 System out println version desc version 24 System out println operations 25 for i 0 i lt desc operations length i 2B i 2h System out println i desc operations i name 2 29 System out println attributes 30 for i 0 i lt desc attributes length i Bit i 32 System out println i desc attributes i name 33 34 System out println base_interfaces 35 for i 0 i lt desc base_interfaces length i 36 37 System out printin i desc base_ interfaces i 38 259 CHAPTER 12 The Interface Repository 5 8 9 13 15 16 17 19 39 260 After initializing the ORB and obtaining an object reference we invoke _get_interface def on the object If no interface definition could be found get interface def returns nil Narrow the object reference to InterfaceDef We now have a reference to an object in the IFR that describes the most derived type of our object reference Request a complete description of the interface Print information about the interface including the names of its operations and attributes A complete example of how to use the IFR can be found in the ob demo repository subdirectory 1 Recent versions of the IDL to Java mapping introduced the _get_interface_def operation which returns org omg CORBA Object inste
38. Application Overview 14 Our Hello World application consists of two parts e The client program e The server program Start the server first since it must create the file Hello ref that the client needs in order to connect to the server As soon as the server is running you can start the client If all goes well the Hello World message will appear on the screen Implementing the Example in Java Implementing the Example in Java Generating Java from IDL In this section In order to implement this application in Java the interface specified in IDL is translated to Java classes similar to the way the C code was created Translate the code in Hello id1 to Java using the following command jidl package hello Hello idl This command generates several Java source files on which the actual implementation will be based Hello java HelloHelper java HelloHolder java HelloOperations java HelloPOA java _HelloStub java All these files are generated into a directory with the name hello This section discusses the following topics Implementing the Server page 16 Implementing the Client page 20 Compiling page 22 Running the Application page 23 15 CHAPTER 1 Getting Started Implementing the Server Implementation class Create a file Hello _imp1 java in the directory hello and enter the following code for the server s Hello implementation class
39. CHAPTER 13 Orbacus Balancer The remainder of the main function is similar to that of Chapter Now we write the run function 1 C 2 int run CORBA ORB ptr orb int argc char argv 3 4 iflearge mai gt 5 return EXIT_FAILURE 6 const char memberId argv 1 7 8 CORBA Object_var poaObj 9 orb gt resolve initial references RootPOA 10 PortableServer POA_var rootPoa ital PortableServer POA _ narrow poaObj 12 13 PortableServer POAManager var manager 14 rootPoa gt the POAManager 15 16 LoadBalancing MemberPolicyValue_var value 17 new LoadBalancing MemberPolicyValue 18 value gt group id CORBA string_dup Hello 19 value gt member_id CORBA string_dup memberId 20 CORBA Any any 21 any lt lt value retn j 22 CORBA Policy var memberPolicy 23 orb gt create_policy LoadBalancing MEMBER_ POLICY ID any 24 286 4 6 16 23 25 33 35 40 25 26 27 28 29 30 Sil 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 Programming Example CORBA PolicyList p1l 3 pl length 3 pl 0 rootPOA gt create lifespan policy PortableServer PERSISTENT pl 1 rootPOA gt create_id_ assignment policy PortableServer USER_ID pl 3 memberPolicy PortableServer POA_var helloPOA rootPOA gt create POA hello manager pl Hello impl helloImpl new Hello impl helloPOA PortableS
40. Description was deallocated again Memory that was already deallocated This message indicates multiple memory deallocations For example if CORBA string_free is called twice on the same string this message will be displayed reference count of zero Object was deleted without an object This message appears if an object was deleted by calling delete on its object reference Never use the delete operator for that use CORBA release instead 397 CHAPTER 18 Exceptions and Error Messages Message Description Object was already deleted object reference count was already zero This message appears if the number of release operations on an object reference is greater than the number of _ duplicate operations Sequence length was greater than maximum sequence length This message indicates that the application tried to set the length of a bounded sequence to a value greater than its maximum length Index for sequence operator or remove function was out of range This message appears if the argument to the sequence member functions operator Or remove exceeds the sequence length Buffer size not equal to sequence bound This message indicates that the application attempted to call allocbuf on a bounded sequence with an argument not equal to the sequence bound Null pointer was used to initialize T_var type This message indicates an attempt to initialize a var type
41. Files Overview Example Syntax With the Orbacus IDL to HTML and IDL to RTF translators hial and rial you can easily generate HTML and RTF files containing IDL interface descriptions The translators generate a nicely formatted file for each IDL module and interface Figure 1 shows an HTML example IDL Documentation for OCI Netscape File Edit View Go Communicator Help i oe Poe ee ps LAE Books e a CvmerorbaOOR Module OCI The Open Communications Interface OCI The definitions in this module provide a uniform interface to network protocols This allows for easy plug in of new protocols or other communication mechanisms into ORBs that implement the OCI Furthermore protocol implementations need only to be written once and can then be reused with all OCI compliant ORBs For more information please see the OCI documentation Module Index IIOP This module contains interfaces to gather information on the IIOP OCI plug in Interface Index AccRegistry A registry for Acceptors AcceptCB An interface for an accept callback object Acceptor An interface for an Acceptor object which is used by CORBA servers to accept chent connection requests Figure 1 Documentation generated with the IDL to HTML translator The formatting syntax supported by hial and rial is similar to that used by javadoc The following keywords are recognized 41 CHAPTER 2 Generating Code with Orbacus 42
42. ID peer The peer ID options Options specific to the underlying plug in object key A stringified object key For example corbaloc bidir iiop Client Foo corbaloc bidir_iiop Server thehost 9999 Foo The first example is a URL for a bi directional IIOP callback endpoint The second example is a URL for a bi directional IIOP endpoint on host thehost and port 9999 CHAPTER 18 Exceptions and Error Messages CHAPTER 18 Exceptions and Error Messages CORBA System Exceptions The CORBA specification defines the standard system exceptions shown in 378 the following table UNKNOWN Unknown exception type BAD PARAM An invalid parameter was passed NO_MEMORY Failure to allocate dynamic memory IMP LIMIT Implementation limit was violated COMM _FATLURE Communication failure INV_OBJREF Invalid object reference NO_PERMISSION The attempted operation was not permitted INTERNAL Internal error in ORB MARSHAL Error marshalling a parameter or result INITIALIZE Failure when initializing ORB NO_IMPLEMENT Operation implementation unavailable BAD TYPECODE Bad typecode BAD OPERATION Invalid operation NO_RESOURCES Insufficient resources for a request NO_RESPONSE Response to a request is not yet available PERSIST STORE Persistent storage failure BAD INV ORDER Routine invocation out of order TRANSIENT Transi
43. Object Adapter Initialization Command line Options There are equivalent command line options for many of the Orbacus properties The options and their equivalent property settings are shown in the following table Refer to ORB Properties on page 52 for a description of the properties Option Property OAreactive ooc orb oa conc_model reactive OAthreaded ooc orb oa conc_model threaded OAthread_per client ooc orb oa conc_model thread_per client OAthread_ per request ooc orb oa conc_model thread_per request OAthread_pool N ooc orb oa conc_model thread_pool ooc orb oa thread_pool N OAleader_follower N ooc orb oa conc_model leader_follower ooc orb oa leader follower _pool n OAversion version ooc orb oa version version ORBDefaultInitRef URL ooc orb default_init ref URL ORBid d ooc orb id d ORBInitRef name or ooc orb service name ior ORBnative_cs name ooc orb native_cs name ORBnative_wcs name ooc orb native_wces name ORBnaming or ooc orb service NameService or ORBproperty name value name value ORBreactive ooc orb conc_model reactive ORBrepository or ooc orb service InterfaceRepository or ORBServertd string ooc orb server_name string 62 Configuring the ORB and Object Adapter Option Property ORBservice name ior ooc orb service name ior ORBthreaded ooc orb conc_model threaded ORBtrace_connections level ooc orb tra
44. POA with the BidirectionalPolicy Implementation enabled to allow negotiation of Bidirectional connection reuse The C example is presented first followed by the Java version 1 C CORBA Object_var obj orb gt resolve initial references RootPOA PortableServer POA_var rootPOA PortableServer POA _narrow obj PortableServer POAManager_var manager rootPOA gt the _POAManager owCoN Aone WD CORBA Any any 10 CORBA PolicyList policies 1 11 policies length 1 12 any lt lt BiDirPolicy BOTH 13 policeiesi0l sorb gt create policy 14 BiDirPolicy BIDIRECTIONAL POLICY TYPE any 15 16 PortableServer POA var myPOA 17 rootPOA gt create POA MyPOA manager policies 2 7 Obtain the reference to the RootPOA and RootPOAManager 9 14 Create a new BidirectionalPolicy containing the value of BiDirPolicy BOTH to enable Bidirectional connection reuse negotiation 16 17 Create the new POA with this policy to enable BiDir negotiation on requests destined for this POA 321 CHAPTER 15 Using Policies And now the same example in Java 1 Java 2 org omg CORBA Object obj 3 orb resolve initial references Root POA 4 org omg PortableServer POA rootPOA 5 org omg PortableServer POAHelper narrow obj 6 org omg PortableServer POAManager manager T rootPOA the_POAManager 8 9 org omg CORBA Any any orb create_any 10 org omg CORBA Policy
45. Querying for Properties Deleting Properties Programming Example Chapter 11 Orbacus Events Usage Windows NT Native Service Configuration Properties Connecting to the Service Using the Event Service with the IMR Event Service Concepts The Event Channel Event Suppliers and Consumers Event Channel Policies Event Channel Factories Programming Example Chapter 12 The Interface Repository Usage Windows NT Native Service Configuration Properties Connecting to the Interface Repository Configuration Issues Interface Repository Utilities Programming Example Chapter 13 Orbacus Balancer Basic Concepts Load Balancing Strategies Service Security Usage Windows NT Native Service Configuration Properties Built in Load Balancing Strategies CONTENTS 220 221 222 223 224 226 227 231 232 233 235 237 238 239 240 241 243 244 247 251 252 253 255 256 257 258 259 261 262 263 266 267 268 270 272 vii CONTENTS Connecting to the Service Load Balanced IMR enabled Servers Utilities Service Administration Making References Utility Objects Utility Object Configuration Properties Programming Example Non adaptive Load Balancing Adaptive Load Balancing Running the Load Balanced Servers Chapter 14 Orbacus Watson Tracing Levels Installing Watson in C Installing Watson in Java Configuration Properties Sample Configuration File Chapter 15 Using Policies Overview Supported Policies Progra
46. Structs 474 The load per client load balancing strategy property name The load per client property is an estimate of the load produced by a client RejectLoadPropertyName const string RejectLoadPropertyName reject load The reject load load balancing strategy property name Only members with loads less than reject load are selected DampeningMultiplierPropertyName const string DampeningMultiplierPropertyName dampening multiplier The dampening multiplier load balancing strategy property name A dampening technique is used to smooth out spikes that may occur in the reported loads of members The load of a member is calculated using the dampening multiplier property as follows load mult old_load 1 mult new_load where mult is the dampening multiplier property value The dampening multiplier property must be greater than or equal to O and less than 1 CriticalLoadPropertyName const string CriticalLoadPropertyName critical load The critical load load balancing strategy property name Members with loads greater than or equal to the critical load are re balanced PropertyErrorCode enum PropertyErrorCode BAD PROPERTY BAD VALUE i This enumeration contains the various load balancing strategy configuration property error codes Property struct Property PropertyName name PropertyValue value Ji Exceptions A load balancing strategy configuration property PropertyErro
47. SystemException 41 2 41 Catch exceptions Don t ever forget to do this It can be useful to call printStackTrace on the exception object in order to get detailed information about the program flow causing the exception 201 CHAPTER 8 Orbacus Names The Event Loop 202 Next we start listening for requests 1 Java 2 try 3 4 manager activate 5 6 catch org omg PortableServer POAManagerPackage AdapterInactive ex 7 8 throw new RuntimeException 9 10 orb run Everything is ready now so we can listen for requests by calling actiavate on the POA Manager and run on the ORB Releasing Resources 2 9 16 26 Programming Example Some cleanup work should be done before exiting the program Every binding must be properly unbound and the ORB must be destroyed 1 Java 2 nc unbind cName 3 nc unbind bName 4 ne unbind aName 5 nc unbind alName 6 nc unbind a2Name 7 ne unbind a3Name 8 ne unbind nc2Name 9 nc unbind nc1Name i 11 catch RuntimeException ex iD T3 status 1 WA TS 16 af foro Ernu iy 18 try 19 20 orb destroy 2a 22 catch const RuntimeException ex 23 24 status 1 25 26 2T 28 System exit status All bindings are unbound destroy is called on the ORB This releases the resources used by the ORB The complete example can be found in the folder naming demo included with the Or
48. The default value is 15 seconds multicast Specifies that multicast should be used If this option is set the host and port options must also be specified and the host must be an IP address in the multicast range 224 0 0 0 through 239 255 255 255 By default multicast is not used 361 CHAPTER 17 The Open Communications Interface Command line Options 362 no loopback Specifies that loopback mode of the socket shall be disabled in multicast mode This prevents sending multicast packets back to the local socket For Java this functionality is only available from JDK 1 4 0 on ttl N Specifies the time to live value 0 255 of multicast packets sent System defaults apply if not specified numeric If set and if host is not specified then the canonical dotted decimal address is advertised in IORs The default behavior is to use the canonical hostname if possible port N Specifies the port number on which to bind the socket If no port is specified an unused one will be selected automatically by the operating system Use this option if you plan to publish an IOR e g in a file a naming service etc and you want that IOR to remain valid across executions of your server Without this option your server is likely to use a different port number each time the server is executed This option must be specified if multicast is used transport timeout N Specifies the
49. Two servants impl and anotherImp1 are created with new In case the servant class was written using the delegation approach an object implementing the toperations interface must be passed to the tie s constructor 1 Java 2 I _impl tie impl new I_impl tie 3 IPOATie tie new IPOATie impl A new I_imp1 tie is created An instance of rpoaTie is created taking imp1 as a parameter All operation calls to tie will then be delegated to impl 99 CHAPTER 4 CORBA Objects The tie class also provides methods for accessing and changing the implementation object 1 Java 2 public class IPOATie extends IPOA 3 4 eee 5 public IOperations delegate 6 public void _delegate IOperations delegate 7 5 This method returns the current delegate i e implementation object 6 This method changes the delegate object 100 Activating Servants Activating Servants Servants must be activated in order to receive requests from clients Servant activation informs the ORB run time which particular servant represents or incarnates a particular CORBA object Activation of a servant assigns an object identifier to the servant That object identifier is also embedded in every object reference that is created for an object and serves to link the object reference with its servant The POA s IdAssignmentPolicy value controls whether object IDs are assigned by the POA or the server application code The
50. a location forward reply redirecting the client to the object reference supplied by the BootManager The BootManager Using the BootManager 3 6 3 6 The BootManager add_binding operation binds an object id to an object reference The BootManager remove_binding operation removes an existing binding The following example illustrates how a server can add a binding for the object id myobjectId II C CORBA Object_var obj Get a reference CORBA Object_var bmgrObj orb gt resolve_initial_ references BootManager OB BootManager_var bootManager OB BootManager _narrow bmgrObj PortableServer ObjectId_var objId PortableServer string to ObjectId MyObjectId bootManager gt add_binding objId obj von Aon AeA WNP Get a reference to the BootManager object by invoking resolve _initial_references on the ORB Create the object id Create the new binding And in Java 1 Java 2 org omg CORBA Object obj Get a reference 3 org omg CORBA Object bmgrObj 4 orb resolve_initial_ references BootManager 5 com ooc OB BootManager_var bootManager 6 com ooc OB BootManagerHelper narrow bmgrObj 7 bytel objId MyObjectId getBytes 8 bootManager add_binding objId obj Get a reference to the BootManager object by invoking resolve_initial_references on the ORB Create the object id Create the new binding 141 CHAPTER 5 Locating Objects Ini
51. a higher average throughput due to a more balanced system 265 CHAPTER 13 Orbacus Balancer Service Security 266 It is very important that only Orbacus Balancer s public port also referred to as its forward port be accessible outside of the network firewall Otherwise anyone can mimic the members of a load balanced group causing a denial of service For additional security many of the operations on the service are only allowed when the service is running in administrative mode That is e creating and destroying load balanced groups e setting the load balancing strategy and e adding or removing members are only possible when the service is running in administrative mode An attempt to perform these operations when it is not running in administration mode will result in a CORBA NO_PERMISSION exception Usage Usage Orbacus Balancer is currently only implemented using Orbacus for C but Orbacus for Java servers can also be load balanced Orbacus Balancer command line usage is as follows balancer h help v version a administrative d database A admin endpoint F forward endpoint h help Display the command line options supported by the server v version Display the version of the server a administrative Run the service in administrative mode The service will run in non administrative mode by default d DIRECTORY database DIRECTORY Specifie
52. author author Denotes the author of the interface exception exception name description Adds an exception description to the exception list of an operation member member name description Adds a member description to the member list of a struct union enum or exception type param parameter name description Adds a parameter description to the parameter list of an operation return description Adds descriptive text for the return value of an operation see reference Adds a See also note since since text Comment related to the availability of new features version version The interface s version number Like javadoc hidl and ridi use the first sentence in the documentation comment as the summary sentence This sentence ends at the first period that is followed by a blank tab or line terminator or at the first ridl understands most basic HTML tags and produces an equivalent format in the generated RTF files The following HTML tags are supported lt B gt lt BR gt lt CODE gt lt DD gt lt DL gt lt DT gt lt EM gt lt HR gt lt I gt lt LI gt lt OL gt lt P gt lt TABLE gt lt TD gt lt TR gt lt U gt lt UL gt Using javadoc Adding IDL Comments Example Using javadoc If not explicitly suppressed with the no comments option the Orbacus IDL to Java translator jia1 adds IDL comments starting with to the generated Java files so that javadoc can be used to generate documentation as
53. created by the server will be saved to the specified file If you are starting the server for the first time using this database you must also use the s command line option 183 CHAPTER 8 Orbacus Names 1 COUNT limit COUNT Limits the number of bindings returned in the binding list by a call to list to COUNT bindings Using this option can reduce the memory requirements of the server t MINS timeout MINS Specifies the timeout in minutes after which a persistent server automatically compacts its database The default timeout is five minutes c SECS callback timeout SECS Specifies the timeout in seconds to be used for the Orbacus timeout policy oB TimeoutPolicy The default timeout is five seconds See Chapter 15 for more information CLASSPATH Requirements 184 Orbacus Names for Java requires the classes in OB jar and oBNaming jar Windows NT Native Service Windows NT Native Service The C version of Orbacus Names is also available as a native Windows NT service ntnameservice h help i install s start install u uninstall d debug Display the command line options supported by the server install Install the service The service must be started manually s start install Install the service The service will be started automatically uU uninstall Uninstall the service d debug
54. default Poa in the implementation class to return the POA you want to use 102 Activating Servants Implicit Activation of Servants using Java This is how Java servants are implicitly activated 1 Java 2 org omg CORBA ORB orb Get a reference to the ORB somehow 3 I impl impl new I_impl Aire resample this Orb sy To activate a servant we need the ORB A new servant imp is created The new servant is activated using the POA returned by the servant s _default_Poa operation As shown above a servant in Java must be associated with an ORB and cannot be associated with multiple ORBs The first call to _this must supply the ORB reference subsequent calls to _this for the same servant can omit the ORB reference An alternative way to associate a servant with an ORB is to call the set_delegate method defined in org omg CORBA_2_3 ORB Java org omg CORBA ORB orb Get a reference to the ORB somehow org omg CORBA 2 3 ORB orb set_delegate impl 103 CHAPTER 4 CORBA Objects Explicit Activation of Servants using C If NO_IMPLICIT ACTIVATION and SYSTEM _ID are in effect for a servant s POA you activate the servant by calling activate object 1 I impl impl 2 PortableServer POA_var poa impl default_POA 3 poa gt activate object amp imp1 1 The code instantiates a servant 2 To activate a servant we need the servant s POA 3 activate_object creates a unique I
55. enum BindingType nobject ncontext HE struct Binding Name binding_name BindingType binding_type HE As you can see each name consists of one or more components like a file is fully specified by its path in a filesystem Each name component consists of two strings id and kind which could be likened to a file s name and its extension Generally the filesystem analogy works very well when describing the Naming Service structures 191 CHAPTER 8 Orbacus Names 192 A new Naming Service entry i e a binding is created with the following operations ee void bind in Name n in Object obj raises NotFound CannotProceed InvalidName AlreadyBound void bind context in Name n in NamingContext nc raises NotFound CannotProceed InvalidName AlreadyBound NamingContext new context NamingContext bind new_context in Name n raises NotFound CannotProceed InvalidName AlreadyBound bind registers a new object with the Naming Service whereas a new context is registered with bind_context For each operation an object reference and a Name are expected as parameters New naming context objects are created with new context Or bind new context bind context and bind new context throw an AlreadyBound exception if the name is already in use in the target context To create a new binding without being concerned if the specified binding already exists use the following operations Hf Di void rebind in Na
56. h provides the standard CORBA definitions and Hello _imp1 h contains the definition of the Hello imp1 class A forward declaration for the run function The first thing a CORBA program must do is initialize the ORB This operation expects the parameters with which the program was started These parameters may or may not be used by the ORB depending on the CORBA implementation Orbacus recognizes certain options that will be explained later The run helper function is called This code catches and prints all CORBA exceptions raised by ORB init or run If the ORB was successfully created it is destroyed This releases the resources used by the ORB If destroy raises a CORBA exception this exception is caught and printed The exit status is returned If there was no error EXIT_succEss is returned Or EXIT_FAILURE otherwise run function 4 7 9 10 12 14 16 20 Implementing the Example in C Add the code for the run function to Server cpp 1 C 2 int run CORBA ORB ptr orb 3 4 CORBA Object_var poaObj 5 orb gt resolve initial references RootPOA 6 PortableServer POA_var rootPoa 7 PortableServer POA _narrow poa0bj 8 9 PortableServer POAManager_var manager 10 rootPoa gt the_POAManager LE 12 Hello _impl helloImpl new Hello _impl T PortableServer ServantBase var servant helloImpl 14 Hello var hello helloImpl gt _this 15 16 CORB
57. hostname and port number are printed on standard output 348 OCI Reference Determining a Client s IP Address 2 4 6 8 10 12 18 To determine the IP address of a client within a server method the following code can be used in a servant class method implementation C CORBA Object_var baseCurrent orb gt resolve_initial references OCICurrent OCI Current_var current OCI Current narrow baseCurrent 5 6 OCI TransportInfo_ var info current gt get_oci_transport_info 7 OCI IIOP TransportInfo var iiopInfo 1 2 3 4 8 OCI IIOP TransportInfo narrow info 9 10 if CORBA is nil iiopInfo iil 12 OCI IIOP InetAddr remoteAddr iiopInfo gt remote_addr 13 CORBA UShort remotePort iiopInfo remote port 14 I5 Courm lt m Gallia ironman 16 lt lt remoteAddr 0 lt lt lt lt remoteAddr 1 lt lt iL7 lt lt remoteAddr 2 lt lt lt lt remoteAddr 3 18 lt lt lt lt remotePort lt lt endl 19 The OCI current object is requested and narrow d to the correct OCI Current type The info object for the transport is requested and narrow d to an IIOP transport info object The remainder of the example code is only executed if this was really an IIOP transport info object The address and the port of the client calling this operation are obtained and printed on standard output 349 CHAPTER 17 The
58. in new BufferedReader lal new InputStreamReader conn getInputStream 12 String ref in readLine 13 in close 14 15 org omg CORBA Object object orb string to object ref 16 B b BHelper narrow object location is the URL of the file containing the stringified object reference Read the string from the URL connection Convert the string to an object reference Narrow the reference to a B object 131 CHAPTER 5 Locating Objects Object Reference URLs 132 Prior to the adoption of the Interoperable Naming Service INS 10 the only standard format for stringified object references was the cumbersome ror format The INS introduced two new more readable formats for object references that use a URL like syntax Object reference URLs can be passed to string_to_object just like Ior references The two new URL formats are described in detail in the specification but will be briefly discussed here The optional file URL format is also discussed as well as the proprietary relfile URL format corbaloc URLs Object Reference URLs The corbaloc URL supports any number of protocols the format of the URL depends on the protocol in use The general format of a corbaloc URL is shown below corbaloc protocol lt protocol specific gt Orbacus supports two standard protocols iiop and rir but additional protocols may be supported via transport plug ins The corbaloc URL for the iiop protoc
59. in format and syntax descriptions A vertical bar separates items in a list of choices enclosed in braces in format and syntax descriptions xix PREFACE XX In this chapter CHAPTER 1 Getting Started This chapter introduces you to Orbacus using a well known application the Hello World application is presented here in a special client server version This chapter contains the following sections The Hello World Example Application page 2 Defining the Example in IDL page 3 Implementing the Example in C page 4 Implementing the Example in Java page 15 Summary page 24 Where To Go From Here page 25 CHAPTER 1 Getting Started The Hello World Example Application C and Java applications Many books on programming start with this tiny demo program In introductory C books you ll probably find the following piece of code in the very first chapter C include lt iostream h gt int main int char cout lt lt Hello World lt lt endl return 0 Or in introductory Java books Java public class Greeter public static void main String args System out println Hello World These applications simply print Hello World to standard output and that is exactly what this chapter is about Printing Hello World with a CORBA based client server application In other words we will develop a client program t
60. in the package org omg CoRBA You must either import this package or as shown in this example you must use org omg CORBA explicitly The run helper function is called This code catches and prints all CORBA exceptions raised by orB init or run If the ORB was successfully created it is destroyed This releases the resources used by the ORB If destroy raises a CORBA exception this exception is caught and printed The exit status is returned If there was no error o is returned or 1 otherwise Server class run method 15 28 30 31 Implementing the Example in Java Add the run method to Server java 1 2 3 4 5 6 7 8 9 10 ii 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 DY 28 29 30 Bil 32 33 av ft Java static int run org omg CORBA ORB orb throws org omg CORBA UserException org omg PortableServer POA rootPOA org omg PortableServer POAHelper narrow orb resolve_ initial references RootPOA org omg PortableServer POAManager manager rootPOA the_ POAManager Hello _impl helloImpl new Hello _impl Hello hello helloImpl this orb try String ref orb object_to_ string hello String refFile Hello ref java io PrintWriter out new java io PrintWriter new java io FileOutputStream refFile out printin ref out close catch java io IOException ex ex printStackTrace return 1 manager activate
61. interface In addition Product_imp1 inherits from RefCountServantBase which makes the servant reference counted 8 13 The destroy operation deactivates the servant with the POA As a result the POA will release all references it maintains to the servant Since there are no other references to the servant left the servant s reference count will drop to zero and thus the servant is destroyed 110 11 14 Factory Objects Next we ll implement the factory 1 C 2 class Factory _impl public virtual POA Factory 3 4 4 public 5 6 virtual Product_ptr 7 createProduct throw CORBA SystemException 8 9 Product _impl impl new Product_impl orb 10 PortableServer ServantBase_var servant impl LIL PortableServer POA var poa Get servant s POA T2 PortableServer ObjectId_var id Assign an ID 13 poa gt activate_object_with_id id impl 14 return impl gt this 15 We The servant class Factory imp1 is defined as an implementation of the Factory interface A new reference counted Product servant is instantiated The servant is assigned to a ServantBase_var which decrements the servant s reference count when it goes out of scope Activates the servant and returns an object reference to the client It is important to understand how the servant is eventually destroyed The RefCountServantBase Class from which the servant inherits implements a reference count When the serva
62. is available That is the IDL defining the exception was compiled with the no typecodes option An operation on an unembedded recursive TypeCode was invoked If this message appears an operation was invoked on a recursive TypeCode that has not yet been embedded An already embedded TypeCode was reused This message indicates that an application attempted to embed a recursive TypeCode that was already embedded LongDouble type is not supported on this platform This message appears when an application uses the CORBA LongDouble type on a platform which does not support this type APPENDIX A Boot Manager Reference This appendix describes the interfaces for the Orbacus Boot Manager In this appendix This appendix contains the following sections page 402 page 404 Interface OB BootManager Interface OB BootLocator 401 CHAPTER A Boot Manager Reference Interface OB BootManager local interface BootManager Interface to manage bootstrapping of objects Exceptions NotFound exception NotFound i This exception indicates that a binding has not been found AlreadyExists exception AlreadyExists i This exception indicates that a binding already exists Operations add_binding void add_binding in PortableServer ObjectId oid in Object obj raises AlreadyExists Add a new binding to the internal table Parameters oid The obj
63. load per client reject load Usage Type CORBA ULong A connection request will be rejected if all members have a load greater than the reject load property This property has a default value of O which means that connections will never be rejected Type CORBA Float A dampening technique is used to smooth out spikes that may occur in the reported loads of members The load of a member is calculated using the dampening multiplier property as follows load mult old_load 1 mult new_load where mult is the value of the dampening multiplier property This property must be greater than or equal to O and less than 1 The default value of O which disables dampening This alleviates member selection problems 1 on page 263 and 2 on page 264 Adaptive strategy which attempts to keep the member loads within a given tolerance This strategy takes an aggressive approach to load re balancing The configuration properties for this strategy are as follows Type CORBA ULong Members with loads less than the average minus the tolerance are selected in round robin order Members with loads greater than the average plus the tolerance are re balanced If there are no members with loads less than the average minus the tolerance then members with loads within tolerance of the average are selected in round robin order The default value for this property is O This alleviates the member selection problem 1 on page 263 a
64. local interface AccFactoryInfo Information on an OCI AccFactory object See Also Interface OCI AccFactory Attributes id readonly attribute PluginId id The plugin id tag readonly attribute ProfilelId tag The profile id tag Operations describe string describe Returns a human readable description of the transport Returns The description 462 Module OCI Interface OCI AccFactoryRegistry Operations local interface AccFactoryRegistry A registry for Acceptor factories See Also Interface OCI Acceptor Interface OCI AccFactory add_factory void add_factory in AccFactory factory raises FactoryAlreadyExists Adds an Acceptor factory to the registry Parameters factory The Acceptor factory to add Raises FactoryAlreadyExists If a factory already exists with the same plugin id as the given factory get_factory AccFactory get_factory in PluginId id raises NoSuchFactory Returns the factory with the given plugin id Parameters id The plugin id Returns The Acceptor factory Raises NoSuchFactory If no factory was found with a matching plugin id get_factories AccFactorySeq get_factories Returns all registered factories Returns The Acceptor factories 463 CHAPTER E Open Communications Interface Reference Interface OCI Current Operations 464 local interface Current inherits from CORBA Current Inte
65. long as the comments are in a format compatible with javadoc Here is an example that shows how to include documentation in an IDL interface description file Let s assume we have an interface 1 in a module m IDL module M This is a comment related to interface I author Uwe Seimet version 1 0 e Sb E x interface I This comment describes exception E exception E 43 CHAPTER 2 Generating Code with Orbacus The description for operation S param arg A dummy argument return A dummy string E An a o ee H exception E Raised under certain circumstances ax string S in long arg raises E he he When running jid1 on this file the comments are automatically added to the generated Java files M I java and M IPackage E java For I java the generated code looks as follows Java package M IDL M I 1 0 This is a comment related to interface I author Uwe Seimet version 1 0 44 Using javadoc public interface I extends org omg CORBA Object Ud TDL M 1I S 1 0 The description for operation S param arg A dummy argument return A dummy string exception M IPackage E Raised under certain circumstances public String S int arg throws M IPackage E Note that jial automatically inserts the fully qualified Java name for the exception E M IPackage
66. manually install s Install and start the service start install u Uninstall the service uninstall d Run the service in debug mode debug In order to use the Event Service as a native Windows NT service it is first necessary to add the ooc event endpoint property to the HKEY LOCAL MACHINE NT registry key see Using the Windows NT Registry on page 65 for more details Next the service should be installed with nteventservice i This adds the orbacus Event Service entry to the Services dialog in the Control Panel To start the event service select the orbacus Event Service entry and press start If the service is to be started automatically when the machine is booted select the orbacus Event Service entry then click Startup Next select Startup Type Automatic and press ox Alternatively the service could have been installed using the s option which configures the service for automatic start up nteventservice s If you want to remove the service run 233 CHAPTER 11 Orbacus Events nteventservice u Note If the executable for the Event Service is moved it must be uninstalled and re installed Any trace information provided by the service is be placed in the Windows NT Event Viewer with the title EventService To enable tracing information add the desired trace configuration property i e one of the ooc event trace properties or one of the ooc orb trace properties to the HKEY L
67. manually the option must be present For further information on configuring a service with the IMR refer to Getting Started with the Implementation Repository on page 167 238 Event Service Concepts Event Service Concepts In this section This section contains the following topics The Event Channel page 240 Event Suppliers and Consumers page 241 Event Channel Policies page 243 Event Channel Factories page 244 239 CHAPTER 11 Orbacus Events The Event Channel 240 The Event Service distributes data in the form of events The term event in this context refers to a piece of information that is contributed by an event source An event channel instance accepts this information and distributes it to a list of objects that previously have connected to the channel and are listening for events The Event Service specification defines two distinct kinds of event channels untyped and typed Whereas an untyped event channel forwards every event to each of the registered clients in the form of a CORBA Any a typed event channel works more selectively by supporting strongly typed events which allow for data filtering We will only discuss the untyped event channel here For information on typed event channels and more details on the Event Service in general please refer to the official Event Service specification 9 Event Service Concepts Event Suppliers and Consumers Applications participating in
68. may still be executing requests possibly in a number of different threads Deactivation of a servant in Java is analogous to C Java org omg PortableServer POA poa impl default _POA byte id poa servant_to_id impl1 poa deactivate_object id BwWNY Pe A POA has either the TRANSIENT or the PERSISTENT policy value A transient POA generates transient object references A transient object reference remains functional only for as long as its POA remains in existence Once the POA for a transient reference is destroyed the reference becomes Deactivating Servants permanently non functional and client requests on such a reference raise either OBJECT_NOT_ EXIST Of TRANSIENT depending on whether or not the server is running at the time the request is sent Transient references remain non functional even if you restart the server and re create a transient POA with the same name as was used previously Transient POAs almost always use the sySTEM_ID policy as a matter of convenience although the combination of TRANSIENT and USER_ID is legal Object references created on a persistent POA continue to be valid beyond the POA s life time That is if you create a persistent reference on a POA destroy the POA and then recreate that POA again with the same POA name the original reference continues to denote the same CORBA object even if the server was shut down and restarted Persistent references require the same P
69. more information on the behavior of command line options Static Linking URL Support The IIOP OCI Plug in There are no special requirements for linking the IIOP plug in statically in C since the plug in is part of the Orbacus core library The IIOP plug in supports the standard iiop format for corbaloc URLs as described in corbaloc URLs on page 133 357 CHAPTER 17 The Open Communications Interface The UDP OCI Plug in The UDP plug in provides unreliable unicast and multicast functionality suitable for applications which can tolerate the potential for lost messages Only oneway operations are supported For configuration purposes the identifier of the UDP plug in is udp In this section This sections covers the following topics Client Installation page 359 Server Installation page 360 Static Linking page 364 URL Support page 365 Narrowing UDP Object References page 366 358 The UDP OCI Plug in Client Installation The client side UDP plug in is installed as shown below ooc oci client udp buffer size N packet delay MSEC packet size N no loopback ttl N trace N The following options are supported buffer size N Sets the size of the socket s send buffer Note that this is only a hint to the operating system To determine the actual size use the trace option The default value is operating system dependent packet delay MSEC S
70. name 57 ooc orb trace connections 58 ooc orb trace retry 58 ooc orb use_type_code_ cache 57 ooc property port 220 Property Service 219 R Reactor 338 Recursion 209 RTF 41 S Servants 88 Activation 101 C 98 Deactivation 106 Delegation 92 Inheritance 89 Java 99 T Toolbar 178 216 U URL 131 132 corbaloc 133 corbaname 135 file 136 relfile 137 W Windows NT Registry 65 Windows Reactor 340 X X11 Reactor 339 INDEX 491 INDEX 492
71. ooc OBPortableServer POAManagerFactory pmFactory com ooc OBPortableServer POAManagerFactoryHelper narrow facto ry org omg PortableServer POAManager myPOAManager null org omg CORBA Policy pl new Policy 1 String config iiop host localhost port 10999 bind localhost pl o pmFactory create endpoint configuration policy config try myPOAManager pmFactory create POAManager MyPOAManager POF catch org omg PortableServer POAManagerFactoryPackage Manager AlreadyExists ex catch org omg CORBA PolicyError ex do something do something GlOPVersionPolicy Programming Examples This example shows how to create a new POA Manager with a specific GIOP vesion to be used in object references generated by that POA Manager This option is useful for backward compatibility with older ORBs that reject object references using a newer version of the protocol In the example below the GIOP version is set to 1 2 The C version is presented first followed by the Java version f f C CORBA Object_var poaObj orb gt resolve_initial_ references RootPOA OBPortableServer POA_var rootPOA OBPortableServer POA narrow poaObj POAManagerFactory var factory rootPOA gt the POAManagerFactory 7 OBPortableServer POAManagerFactory var pmFactory 8 OBPortableServer POAManagerFactory _narrow factory 9 POAManager_ var myPOAManager 10 Policy
72. orb Get a reference to the ORB somehow 3 java io BufferedReader in new java io BufferedReader new java io FileReader object ref String ref in readLine org omg CORBA Object obj orb string to object ref B b BHelper narrow obj YHOO e 3 5 The stringified object reference is read 6 string_to object creates an object reference from the string 7 Use BHelper narrow to narrow the return value of string to object to B 130 Using a URL 8 13 15 16 Stringified Object References It is sometimes inconvenient or impossible for clients to have access to the same filesystem as the server in order to read a stringified object reference from a file A more flexible method is to publish the reference in a file that is accessible by clients as a URL Your clients can then use HTTP or FTP to obtain the contents of the file freeing them from any local filesystem requirements This strategy only requires that your clients know the appropriate URL and is especially suited for use in applets Note This example is shown only in Java because of Java s built in support for URLs but the strategy can also be used in C 1 Java 2 import java io 3 import java net 4 5 String location http www mywebserver object ref 6 org omg CORBA ORB orb Get a reference to the ORB somehow 7 8 URL url new URL location 9 URLConnection conn url openConnection 10 BufferedReader
73. orb conc_model ooc orb default_init_ref ooc orb default_wcs ooc orb extended_wchar ooc orb giop max_message_size Configuring the ORB and Object Adapter Value timeout gt 0 The client actively closes a connection that has been idle for timeout seconds once that connection has no more outstanding replies Note that the application must use the threaded client side concurrency model if connection timeouts are desired If this property is set to zero or not set at all then the client does not close idle connections Note that a policy can also be set on the ORB or on individual object references See OB ACMTimeoutPolicy on page 303 for more information Value reactive threaded Selects the client side concurrency model The reactive concurrency model is not currently available in Orbacus for Java The default value is threaded for both C and Java applications See Chapter 16 for more information on concurrency models Value URL Specifies a partial URL If an application calls the ORB operation resolve initial references and no match is found the ORB appends a slash character and the service identifier to the specified URL and invokes string to object to obtain the initial reference Value string Specifies the default wide character code set for the ORB Note that the CORBA specification states that a default wide character code set does not exist Therefore this option should only be us
74. other hand are polled by the event channel and supply an event in response if a new event is available Polling is done by the try_pull1 operation if it is to be non blocking or by the blocking pull call 241 CHAPTER 11 Orbacus Events 242 Ai TDi interface PullSupplier any pull raises Disconnected any try pull out boolean has event raises Disconnected void disconnect_pull_ supplier ba Event Service Concepts Event Channel Policies The untyped event channel implementation included in the Orbacus distribution features a simple event queue policy Events are buffered in the form of a queue i e a certain number of events are stored and in case of a buffer overflow the oldest events are discarded 243 CHAPTER 11 Orbacus Events Event Channel Factories 244 The standard CORBA Event Service provides no support for managing the lifecycle of event channels as a result applications requiring multiple channels are often forced to run a separate instance of the Event Service for each channel To remedy this situation Orbacus Events provides optional proprietary interfaces for event channel administration The oBEvent Channel Factory EventChannel Factory interface describes the factory for untyped event channels IDL module OBEventChannelFactory typedef string ChannelId typedef sequence lt ChannelId gt ChannelIdSeq exception ChannelAlreadyExists exception C
75. readonly attribute ProfileId tag The profile id tag init_client void init client in ParamSeq params Initialize the client side of the plug in Parameters params Plug in specific parameters init_server void init _server in ParamSeq params Initialize the server side of the plug in Parameters params Plug in specific parameters Module OCI Interface OCI Transport Attributes Operations local interface Transport The interface for a Transport object which provides operations for sending and receiving octet streams In addition it is possible to register callbacks with the Transport object which are invoked whenever data can be sent or received without blocking See Also Interface OCI Connector Interface OCI Acceptor id readonly attribute PluginId id The plugin id tag readonly attribute ProfilelId tag The profile id tag mode readonly attribute SendReceiveMode mode The send receive capabilities of this Transport handle readonly attribute Handle handle The handle for this Transport The handle may only be used to determine whether the Transport object is ready to send or to receive data e g with select on Unix based operating systems All other uses e g calls to read write close are strictly non compliant A handle value of 1 indicates that the protocol plug in does not support selectable Transports close void close
76. requiring changes to the application through the use of configuration properties See ORB Properties on page 52 for more information For the sake of clarity the psuedo code examples in this section lack exception handling In this section This section contains the following examples Connection Reuse Policy page 307 Retry Policy page 310 Timeout Policy page 312 Interceptor Call Policy page 313 CommunicationsConcurrencyPolicy page 315 EndpointConfigurationPolicy page 317 GlOPVersionPolicy page 319 Bidirectional Policby page 321 306 Programming Examples Connection Reuse Policy Connection Reuse Policy at ORB Level 2 3 4 5 The following examples demonstrate how to set OB ConnectionReusePolicy at both the ORB level and the object level in C and Java Setting a policy at the ORB level means that the ORB will honor this policy for all newly created objects Existing objects maintain their current set of policies Setting a policy at the object level overrides any ORB level policies applied to that object Setting the connection reuse policy to false at the ORB level means that the ORB will create a new connection from the client to the server for each new proxy object instead of reusing existing ones Setting the connection reuse policy to false at the object level means that the client does not reuse connections to the server only for a particular proxy object If the connection r
77. see Chapter 4 An ORB is needed to call shutdown The constructor initializes the ORB member deactivate calls shutdown on the ORB Note that shutdown is called with the argument false to avoid a deadlock A false argument instructs shutdown to terminate request processing without waiting for executing operations to complete A true argument instructs shutdown to return only once all operations have completed If shutdown were called with a true argument in this example it would deadlock That is because shutdown true would be invoked from within an operation and therefore could not ever return The client can use the deactivate call as shown below ii Cee ShutdownObject_var shutdownObj Get a reference somehow shutdownObj gt deactivate In this chapter CHAPTER 4 CORBA Objects This chapter describes how to create and use CORBA servant objects This chapter contains the following sections Overview page 86 Implementing Servants page 88 Creating Servants page 97 Activating Servants page 101 Deactivating Servants page 106 Factory Objects page 108 85 CHAPTER 4 CORBA Objects Overview 86 A CORBA object is an object with an interface defined in CORBA IDL CORBA objects have different representations in clients and servers e A server implements a CORBA object in a concrete programming language for example in C or Java This is done by writing an implementation c
78. the client and server activities of an application The client side concurrency models are Reactive and Threaded The server side concurrency models are Reactive Threaded Thread per Client Thread per Request and Thread Pool Selecting Concurrency Models Concurrency Models Concurrency models can be selected either by properties or command line parameters see Chapter 3 The default concurrency models are shown in Table 5 Table 5 Default Concurrency Models Client Server Java Threaded Threaded C Threaded Reactive 327 CHAPTER 16 Concurrency Models Single Threaded Concurrency Model Orbacus supports one single threaded concurrency model reactive Reactive servers use calls to operations like select in order to simultaneously accept incoming connection requests to receive requests from multiple clients and to send back replies This is shown in Figure 9 connect eS C l accept f0 Pm gt Tg dispatch g g connect accept Ca fO dispatch 1 att disconnect a gt eae ae Ta close lag disconnect close fy A gt Client A Server Client B Figure 9 Reactive Server Reactive clients also use operations like select to avoid blocking This means that while a request to a server is sent or a reply from that server is received the client can simultaneously send buffered
79. time in seconds after which inactive connections are reaped The default value is 60 seconds Note When using multicast all servers which belong to the same multicast group must specify the same host address and port The no loopback option for multicast communication is to be specified on the client side for Unix systems and on the server side for Windows systems The UDP plug in supports the following command line options UDPbind ADDR Equivalent to the bind endpoint option UDPhost ADDR ADDR Equivalent to the host endpoint option The UDP OCI Plug in UDPmulticast Equivalent to the multicast endpoint option UDPnumeric Equivalent to the numeric endpoint option UDPport N Equivalent to the port endpoint option See Command line Options and Endpoints on page 79 for more information on the behavior of command line options 363 CHAPTER 17 The Open Communications Interface Static Linking 364 When statically a C application an explicit reference must be made to the UDP plug in in order to include the plug in s modules Shown below is the technique used by the sample programs in the udp demo subdirectory Note that the code below is enclosed in guard macros that are only activated when statically linking These macros are appropriate for both Unix and Windows First extra include files are necessary if defined HAVE S
80. to If the Transport for this Transportinfo was not created by an Acceptor this attribute is set to the nil object reference describe string describe Returns a human readable description of the transport Returns The description Module OCI add_close_cb void add_close_cb in CloseCB cb Add a callback that is called before a connection is closed If the callback has already been registered this method has no effect Parameters cb The callback to add remove_close_cb void remove_close_cb in CloseCB cb Remove a close callback If the callback was not registered this method has no effect Parameters cb The callback to remove 443 CHAPTER E Open Communications Interface Reference Interface OCI CloseCB Operations 44A local interface CloseCB An interface for a close callback object See Also Interface OCI TransportInfo close_cb void close_cb in TransportInfo transport_info Called before a connection is closed Parameters transport_info The TransportInfo for the new closeion Module OCI Interface OCI Connector Attributes Operations local interface Connector An interface for Connector objects A Connector is used by CORBA clients to initiate a connection to a server It also provides operations for the management of IOR profiles See Also Interface OCI ConFactory Interface OCI Transport id readonly attribute Plug
81. to appreciate having a high level abstraction of your applications key interfaces captured in CORBA IDL 1 Note that after the startup of the server program you have to copy the stringified object reference i e the file Hello ref to the machine where the client program is to be run Where To Go From Here Where To Go From Here Further Reading To understand the remaining chapters of this manual you must have read the CORBA specifications in 4 5 and 6 You will not be able to understand the chapters that follow without a good understanding of CORBA in general CORBA IDL and the IDL to C or IDL to Java mappings 25 CHAPTER 1 Getting Started 26 In this chapter CHAPTER 2 Generating Code with Orbacus This chapter describes the Orbacus translators This chapter contains the following sections Orbacus Translators page 28 Translating IDL to C page 29 Translating IDL to Java page 33 Translating IDL to HTML page 35 Translating IDL to RTF page 36 The IDL to C Translator and the Interface Repository page 39 Include Statements page 40 Documenting IDL Files page 41 Using javadoc page 43 27 CHAPTER 2 Generating Code with Orbacus Orbacus Translators Overview Orbacus includes the following code generators or translators idl Translates IDL to C jidl Translates IDL to Java hidl Translates IDL to HTML ridl Translates IDL to RTF i
82. true then the LoadAlert object will be created and will be available as an initial service The default value is true Value true false If set to true then the LoadCalculator object will be created and will be available as an initial service The default value is true Value true false If set to true then the LoadUpdater object will be created and will be available as an initial service The default value is true If the LoadCalculator object is also created then this object does not have to be set in the LoadUpdater object Value timeout gt 0 Specifies the expiry time for a load alert in milliseconds The default is 1000 1 second A value of O means that load alerts never expire Value frequency gt 0 Specifies the load update frequency for the LoadUpdater object in milliseconds The default is 1000 1 second A value of O means that no load updates will be sent to the service 281 CHAPTER 13 Orbacus Balancer Programming Example Implementing a Load Balanced Server In this section 282 In this section we will show how to modify the C version of the Hello World server see Chapter 1 for load balancing First we will present the modifications necessary for non adaptive load balancing then the necessary modifications for adaptive load balancing will be presented This is followed by a description of the steps necessary to configure the service for the load balanced Hello W
83. used 59 CHAPTER 3 ORB and Object Adapter Initialization ooc orb oa endpoint ooc orb oa leader_follower_pool ooc orb oa thread_pool 00c orb oa version 60 This property is also used to determine the default value of the communications concurrency model for POA Managers see ooc orb poamanager Manager conc_model1 below The following table summarises how the setting of this property determines the POA Manager defaults Table 1 POA Managers Communications Concurrency Model Value of ooc orb oa conc_model ooc orb poamanager lt manager gt conc_model default reactive reactive leader_follower leader_follower threaded threaded thread_per_client threaded thread_per_request threaded thread_pool threaded Value string Specifies a comma separated list of endpoints for the Root POA Manager The default value is iiop See Endpoints on page 78 for more information Value n gt O Determines the number of threads in the pool used by the leader_follower concurrency model The default value is 10 This property is only effective when the coc orb oa conc_model property has the value leader follower Value n gt O Determines the number of threads to reserve for servicing incoming requests The default value is 10 This property is only effective when the o0c orb oa conc_model property has the value thread pool Value 1 0 1 1 or 1 2 ooc o
84. visibility Error Window Toggles the error message window visibility Simple List Displays minimum object information Details Displays additional object information Sort Sets sorting mode for object list Refresh Updates the complete window contents A toolbar that gives access to frequently needed operations is normally present below the menu If you don t have a need for this toolbar or if you just want to save space on the screen you can switch it off with the Toolbar toggle button The same applies to the status bar where information about the currently selected item is displayed The status bar displays an object s repository ID the host where this object is located and the port it is bound to If an item with a nil object reference is selected or if multiple items are selected the status bar is empty If an error occurs while editing bindings the console automatically displays a new window with information about what went wrong Usually this information consists of exception data The visibility of this window can be explicitly controlled with the Error Window toggle button If the console is connected to Orbacus Names as described in Chapter 8 the console can display timestamp information for each binding by making use of proprietary features of Orbacus Names This information is shown in the binding table if the Details display mode instead of the Simple List mode is active Usually the console sorts the items in the bindi
85. which ParseArgs will use to display any warning or error messages In this example a custom Logger object is not used so the code passes a nil value 69 CHAPTER 3 ORB and Object Adapter Initialization 70 8 12 13 4 8 9 Retrieve the ooc orb conc_model property and set it to threaded if its value is not valid Initialize the ORB wont nu BWDP Java java util Properties props System getProperties args com ooc CORBA ORB ParseArgs args props null String orbModel props get ooc orb conc_model if orbModel equals threaded props put ooc orb conc_model threaded org omg CORBA ORB orb org omg CORBA ORB init arg props Create a java util Properties object Initialize the properties for the ORB After invoking com ooc CORBA ORB ParseArgs props contains the ORB properties The return value of ParseArgs is a string array with all oRB and oa arguments removed As in the C example a Logger object is not used Retrieve the coc orb conc_model property and set it to threaded if its value is not valid Initialize the ORB Using POA Managers Using POA Managers In this section The CORBA specification states that a POA Manager is used to control the flow of requests to one or more POAs In Orbacus each POA Manager also encapsulates a set of network endpoints on which a server listens for new connections This design provides applications wit
86. with a null pointer operator gt was used on null pointer or nil object reference This message indicates an attempt to use operator gt on an uninitialized var type Application tried to dereference a null pointer Some CORBA _var types have built in conversion operators to a C reference type i e some var types for type T have a conversion operator to Ts This message appears if an application uses this conversion operator on an uninitialized var type Null pointer was passed as string parameter or return value According to the IDL to C mapping specification no null pointers may be passed as string parameters or return values This message appears if an application tries to do So Null value passed as parameter This message indicates that an application attempted to pass a null value across an IDL interface Non Compliant Application Asserts Message Description Self assignment caused a dangling pointer This message appears if the content of a _var type is assigned to itself For example the following code will lead to this error message Somehow get a pointer to a variable struct AVariableStruct_var var AVariableStruct ptr var var ptr BwWNY PH This will result in a dangling pointer because var will free its own content on assignment Replacement of Any content by its own value caused a dangling pointer This message appears if there is an at
87. with delete_property IDL void delete property in PropertyName property name raises PropertyNotFound InvalidProperty FixedProperty As you might have guessed by this operation s signature there are properties that cannot be deleted at all This kind of property is called a FixedProperty The Property Service defines several other special property types such as read only properties Please refer to the OMG Property Service 9 specification for details 226 Programming Example Programming Example The Property Service test suite which is part of the Orbacus distribution provides a good example of how to create properties and query for their values The code below is based on excerpts of this test suite which is located in the directory property test We will concentrate on an example in Java here As with the previous examples the Java code is very similar to what is necessary in C The example demonstrates how to create properties and how to get a list of all the properties defined within a PropertySet 1 Java 2 3 org omg CORBA Object obj null 4 5 try 6 7 obj orb resolve initial references PropertyService S 9 catch org omg CORBA ORBPackage InvalidName ex 10 ak Bn error occurred Property Service is not available 1 T3 T4 if obj null ig 16 The object reference is invalid iy 18 19 PropertySetDefFactory factory null 20 try Zl 22 factory Pro
88. 12 CORBA StringSeq_var hosts iiopInfo gt hosts als CORBA UShort port iiopInfo gt port 14 15 cout lt lt host lt lt host 0 lt lt endl 16 Olt lt lt i DO hey mas OO tee ICI 17 18 The list of registered acceptors is requested from the POA Manager The for loop iterates over all acceptors The info object for the acceptor is requested and narrowed to an IIOP acceptor info object The if block is only entered in case the info object really belongs to an IIOP plug in The hostname and port number are requested from the IIOP acceptor info object and printed on standard output 347 CHAPTER 17 The Open Communications Interface The Java version is basically equivalent to the C code and looks as follows 1 Java 2 com ococ OCI Acceptor acceptors poaManager get_acceptors 3 4 for int i 0 i lt acceptors length i 5 6 com ooc OCI AcceptorInfo info acceptors i get_info 7 com ooc OCI IIOP AcceptorInfo iiopInfo 8 com ooc OCI IIOP AcceptorInfoHelper narrow info 5 10 if iiopInfo null iil 12 String hosts iiopInfo hosts 13 short port Converter port iiopInfo port 14 i5 System out print1n host host 0 16 System out print1n port port 7 18 2 12 This is equivalent to the C version 13 The converter class is used to get a port number in int format 15 16 Like in the C version the
89. 20 virtual void alert 23 throw CORBA SystemExcept ion 22 23 alert ME alere 24 25 26 27 int run CORBA ORB ptr int char 28 29 int main int argc char argv 30 31 int status EXIT SUCCESS 32 CORBA ORB var orb 33 4 8 25 37 Programming Example 34 try 35 36 LoadBalancing LB init 37 LoadBalancing Util LBUtil init 38 orb CORBA ORB init argc argv 39 status run orb argc argv 40 41 catch const CORBA Exception amp 42 43 status EXIT FAILURE 44 45 46 if CORBA is_ nil orb 47 48 try 49 50 orb gt destroy 51 52 catch const CORBA Exception amp 53 54 status EXIT_FAILURE 55 56 57 58 return status 59 Include the header file that declares the Orbacus Balancer utility initialization function This header file also includes the header file OB BalancerUtil h which contain the definitions of the utility objects The header file oB Balancer_skel h must be included for the implementation of the LoadBalancing LoadAlert interface An implementation of the LoadBalancing LoadAlert interface that delegates to the LoadAlert utility object Invoke LoadBalancing Util LBUtil_init This function initializes the utility objects and must be called before initializing the ORB 289 CHAPTER 13 Orbacus Balancer The remainder of the main function is the same as in section Non adaptive
90. 9 10 11 12 public void op i 13 14 ig 2 15 The servant class I_imp1 is defined which implements op_i as well as the inherited operations op a and op b 91 CHAPTER 4 CORBA Objects Implementing Servants using Delegation Delegation using C 92 Sometimes it is not desirable to use an inheritance based approach for implementing an interface This is especially true if the use of inheritance would result in overly complex inheritance hierarchies for example because of use of an existing class library that requires extensive use of inheritance Therefore another alternative is available for implementing servants which does not use inheritance A special class known as a tie class can be used to delegate the implementation of an interface to another class The Orbacus IDL to C translator can automatically generate a tie class for an interface in the form of a template class A tie template class is derived from the corresponding skeleton class and has the same name as the skeleton with the suffix tie appended For the interface x from the C example above the template poa_I tie is generated and must be instantiated with a class that implements all operations of 1 By convention the name of this class should be the name of the interface with impl tie appended 1 Note that tie classes are rarely necessary Not only is the inheritance implementation less complex but it also avoids a number of probl
91. A Stringivaris orb gt object_to_string hello 17 const char refFile Hello ref 18 ofstream out refFile 19 out lt lt s lt lt endl 20 out close 21 2D Manager gt activate 23 orb gt run 24 25 return EXIT_SUCCESS 26 Using the ORB reference resolve_initial_references is invoked to obtain a reference to the Root POA The Root POA is used to obtain a reference to its POA Manager A servant of type Hello_imp1 is created and assigned to a ServantBase_var variable The servant is then used to incarnate a CORBA object using the _this operation ServantBase_var and Hello var like all var types are smart pointer i e servant and hello will release their assigned object automatically when they go out of scope The client must be able to access the implementation object This can be done by saving a stringified object reference to a file which can then be read by the client and converted back to the actual object reference The operation object_to_string converts a CORBA object reference into its string representation CHAPTER 1 Getting Started 22 23 The server must activate the POA Manager to allow the Root POA to start processing requests and then inform the ORB that it is ready to accept requests 1 If your application contains more than one object you do not need to save object references for all objects Usually you save the reference of one object which provides
92. A Object obj Get a name service reference somehow 3 orb register_initial_ reference NameService obj This is the same as the C version above Initial Services The Initial Service Locator In addition to providing the Orbacus Implementation Repository the IMR server see Chapter 6 acts as an initial service locator That is assuming that the IMR server is properly configured the name of the host running the IMR server is the only information needed to find a particular initial service To locate an initial service with name foo the IMR server must first be configured with the initial reference of this service This may be done with the ORBInitRef command line option or the ooc orb service configuration property see Chapter 3 for details Next the client that wishes to connect to foo must be configured with the default initial reference specifying the host running the IMR server The ORBDefaultInitRef command line option or the ooc orb default_init_ref configuration property may be used to configure the default initial reference For example given that the IMR server is running on imr host then the client can be started with the option ORBDefault InitRef corbaloc imr host When the client is configured with this default initial reference it may invoke resolve_initial references foo on the ORB to obtain a reference to foo 147 CHAPTER 5 Locating Objects The IORDump utility Overview Orbac
93. AME DEF passed directly to the preprocessor UNAME Removes any definition for name This option is passed directly to the preprocessor IDIR Adds DIR to the include file search path This option is passed directly to the preprocessor case sensitive The semantics of OMG IDL forbid identifiers in the same scope to differ only in case This option relaxes these semantics but is only provided for backward compatibility with non compliant IDL FILE IDL files to be loaded into the repository 252 Usage Windows NT Native Service ntirservice h help i install s start install u uninstall d debug Display the command line options supported by the server install Install the service The service must be started manually s start install Install the service and start it u uninstall Uninstall the service d debug Run the service in debug mode In order to use the IFR as a native Windows NT service it is first necessary to add the ooc ifr endpoint configuration property to the HKEY LOCAL MACHINE NT registry key see Using the Windows NT Registry on page 65 for more details Next the service should be installed with ntirservice i This adds the orbacus Interface Repository Service entry to the Services dialog in the Control Panel To start the naming service select the Orbacus Interface Repository Service entry and press s
94. And here is the same example in Java wont nun fF WN PB Java org omg CORBA Any boolAny orb create_any boolAny insert_boolean false org omg CORBA Policy policies new org omg CORBA Policy 1 policies 0 orb create policy com ooc OB CONNECTION REUSE POLICY _ID value boolAny org omg CORBA PolicyManager pm org omg CORBA PolicyManagerHelper narrow orb resolve_initial_ references ORBPolicyManager 10 pm set_policy overrides policies SetOverrideType ADD_ OVERRIDE 1 10 This is equivalent to the C version wooadtIaunF WDNR And now the same example but at the object level C first f f C CORBA Any boolAny boolAny lt lt CORBA Any from_boolean 0 CORBA PolicyList policies 1 policies length 1 policies 0 orb gt create policy OB CONNECTION REUSE POLICY ID boolAny CORBA Object_var newObj obj gt _set_policy overrides policies CORBA ADD_OVERRIDE 2 7 This is the same as in the example for the ORB level Set the policy on the object by using the set_policy overrides method This method returns a new object that has the set of policies applied Programming Examples And here is the same example in Java 1 Java 2 org omg CORBA Any boolAny orb create_any 3 boolAny insert_boolean false 4 org omg CORBA Policy policies new org omg CORBA Policy 1 5 policies 0 6 orb create_policy com ooc OB CONNECTION REU
95. B init C or org omg CORBA ORB init Java Hence the set of properties that will be used by the ORB is not available until after the ORB is initialized This poses a problem if the properties need to be validated prior to ORB initialization If you need access to an ORB s property set before it is initialized then you may elect to use the Orbacus specific operations oB ParseArgs C or com ooc CORBA ORB ParseArgs Java The following examples check the value of the ooc orb conc_model property to ensure that it is set to threaded If not the code chooses the threaded concurrency model 1 C 2 include lt OB Logger h gt 3 include lt OB Properties h gt 4 5 OB Properties var dflt OB Properties getDefaultProperties 6 OB Properties var props new OB Properties dflt 7 OB ParseArgs argc argv props OB Logger nil 8 const char orbModel props gt getProperty ooc orb conc_model 9 if strcmp orbModel threaded 0 10 Lal props gt setProperty ooc orb conc_model threaded iQ 13 CORBA ORB var orb OBCORBA ORB init argc argv props Create an op Properties object that is based on the default properties Initialize the properties for the ORB After invoking OB ParseArgs props contains the ORB properties and argv no longer contains any ORB or 0A command line arguments The oB ParseArgs operation takes an optional Logger object
96. B interface for converting object references to and from strings IDL module CORBA interface ORB string object_to string in Object obj Object string to object in string ref We ha Using stringified object references is the simplest way of bootstrapping your first object reference In short the server must create a stringified object reference for an object and make the string available to clients A client obtains the string and converts it back into an object reference and can then invoke on the object The examples discussed in the sections below are based on the IDL definitions presented at the beginning of this chapter 128 Using a File 3 5 Stringified Object References One way to publish a stringified object reference is for the server to create the string using object_to_string and then write it to a well known file Subsequently the client can read the string from the file and use it as the argument to string to object This method is shown in the following C and Java examples First we ll look at the relevant server code C CORBA ORB var orb Get a reference to the ORB somehow B_ impl bImlp new B impl PortableServer ServantBase var servant bImpl B var b bimpl gt _this CORBA String var s orb gt object to string b ofstream out object ref out lt lt s lt lt endl out close ond An fF WN HP A servant for the interface B is cr
97. BA Policy The request timeout policy This policy can be used to specify a maximum time limit for requests See Also Interface OB TimeoutPolicy Attributes value readonly attribute unsigned long value If an object has a Request TimeoutPolicy set and no response to a request is available after value milliseconds a CORBA NO_RESPONSE exception is raised The default value is 1 which means no timeout 414 Module OB Interface OB RetryPolicy Attributes local interface RetryPolicy inherits from CORBA Policy The retry policy This policy is used to specify retry behavior after communication failures i CORBA TRANSIENT and CORBA COMM FAILURE exceptions retry_interval readonly attribute unsigned long retry interval retry_max readonly attribute unsigned long retry max retry_mode readonly attribute short retry mode For retry_mode RETRY NEVER indicates that requests should never be retried and the exception is re thrown to the application RETRY STRICT will retry once if the exception completion status is COMPLETED_No in order to guarantee at most once semantics RETRY ALWAYS will retry once regardless of the exception completion status The default value is RETRY_STRICT retry_interval is the time in milliseconds between retries The default is O retry_max is the maximum number of retries The default is 1 retry _remote determines whether or not to retry on exceptions received ove
98. D for the servant Once a servant is activated calls to this on the servant return an object reference that contains the ORB assigned ID for the object If NO_IMPLICIT ACTIVATION and USER_ID are in effect for servant s POA you activate the servant by supplying the ID value as an octet sequence to activate object _with_id I_impl impl PortableServer POA_var poa impl default _POA PortableServer ObjectId_var oid PortableServer string_ to ObjectId MyObjectName poa gt activate_object_with_id oid amp impl OF WNP 3 4 The string to _Objectid helper function converts a string into an octet sequence 5 activate_object_with_id uses the octet sequence as the object ID for the servant You can use any suitable key value as an object ID Typically the key will be part of the object s state such as a social security number However you can also use keys that are not directly related to object state such as database record identifiers Once the servant is activated calls to_this on the servant return an object reference that contains the ID you assigned to the object 104 Activating Servants Explicit Activation of Servants using Java Servant activation in Java also uses activate object for SYSTEM ID and activate_object_with_id for USER_ID With system 1p the code looks as follows 1 I_impl impl new I _impl 2 orb omg PortableServer POA poa impl default POA 3 poa activate object im
99. DEF UNAME IDIR E no skeletons locality constrained all tie file list FILE no local copy case sensitive These options are the same as for the idl command no comments The default behavior of jid1 is to add any comments from the IDL file starting with to the generated Java files Specify this option if you don t want these comments added to your Java files package PKG Specifies a package name for the generated Java classes Each class will be generated relative to this package prefix package PRE PKG 33 CHAPTER 2 Generating Code with Orbacus Specifies a package name for a particular prefix Each class with this prefix will be generated relative to the specified package auto package Derives the package names for generated Java classes from the IDL prefixes The prefix ooc com for example results in the package com OOc output dir DIR Specifies a directory where jid1 will place the generated Java files Without this option the current directory is used clone Generates a clone method for struct union enum exception valuetype and abstract interface types For valuetypes only an abstract method is generated The valuetype implementer must supply an implementation for clone impl Generates example servant implementation classes For IDL interface types a class is generated in the same package as the interface classes having the same name as the interface with the suffix _imp1 Th
100. Exception Code page 381 UNKNOWN Minor Exception Code page 382 379 CHAPTER 18 Exceptions and Error Messages BAD_PARAM Minor Exception Code page 383 NO_MEMORY Minor Exception Code page 385 IMP_LIMIT Minor Exception Code page 386 COMM_FAILURE Minor Exception Code page 387 MARSHAL Minor Exception Code page 388 NO_IMPLEMENT Minor Exception Code page 390 NO_RESOURCES Minor Exception Code page 391 BAD_INV_ORDER Minor Exception Code page 392 TRANSIENT Minor Exception Code page 393 INTF_REPOS Minor Exception Code page 394 OBJECT_NOT_EXIST Minor Exception Code page 395 INV_POLICY Minor Exception Code page 396 380 INITIALIZE Minor Exception Code CORBA System Exceptions MinorORBDestroyed ORB already destroyed 381 CHAPTER 18 Exceptions and Error Messages UNKNOWN Minor Exception Code MinorUnknownUserException Unknown user exception BAD_PARAM Minor Exception Code CORBA System Exceptions MinorValueFactoryError Failure to register unregister or lookup value factory MinorRepositoryIdExists Repository ID already exists in Interface Repository MinorNameExists Name already used in Interface Repository MinorInvalidContainer Target is not a valid container MinorNameClashInInheritedContext Name clash in inherited context MinorBadAbstract InterfaceType Incorrect type for abstract interface Min
101. HARED amp amp defined OB DLL include lt OB OCI_init h gt include lt OB OCI_UDP_init h gt endif Next the plug in must be registered prior to calling oRB_ init if defined HAVE SHARED amp amp defined OB DLL When linking statically we need to explicitly register the plug in prior to ORB initialization OCI register_plugin udp OCI_init_udp endif URL Support The UDP OCI Plug in The UDP plug in supports corbaloc URLs with the following protocol syntax corbaloc udp host port object key The components of the URL are as follows e udp This selects the UDP plug in host The hostname or IP address of the server port The port on which the server is listening object key A stringified object key 365 CHAPTER 17 The Open Communications Interface Narrowing UDP Object References 366 When an application calls narrow it may result in the ORB making a twoway call to the is _a operation to determine whether narrow should succeed However twoway operations cannot be invoked on UDP object references therefore the application must take extra precautions It is only safe to use narrow when 8 the object reference has a non empty repository ID and 9 the repository ID matches the type being narrowed In all other cases the ORB will attempt to invoke is a Therefore if an application cannot be sure that narrow will succeed without invoking is a it sho
102. Interface Reference Module OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Module OCI IIOP Interface OCI Interface OCI Interface OCI Interface OCI Interface OCI Buffer Plugin Transport Transportlnfo CloseCB Connector ConnectorInfo ConnectCB ConFactory ConFactorylnfo ConFactoryRegistry Acceptor AcceptorInfo AcceptCB AccFactory AccFactorylnfo AccFactoryRegistry Current IIOP TransportInfo IOP ConnectorInfo IIOP ConFactory nfo IIOP Acceptorlnfo IIOP AccFactorylnfo Appendix F Orbacus Balancer Reference Module LoadBalancing Interface LoadBalancing LoadAlert Interface LoadBalancing Strategy Interface LoadBalancing StrategyProxy CONTENTS 423 425 426 427 429 430 434 436 437 442 444 445 447 449 450 452 453 454 457 459 460 462 463 464 465 466 467 468 469 470 471 472 477 478 479 xi CONTENTS Interface LoadBalancing Group 480 Interface LoadBalancing GroupFactory 482 Module LoadBalancing Util 483 Interface LoadBalancing Util LoadAlert 484 Interface LoadBalancing Util LoadCalculator 485 Interface LoadBalancing Util LoadUpdater 486 References 487 Index 489 xii List of Figures Fig
103. List pl 11 pl length 1 12 pl 0 pmFactory gt create_giop version policy 13 OBPortableServer GIOP_VERSION_POLICY 1 2 14 try i5 4 16 myPOAManager create POAManager MyPOAManager pl ay h 18 catch const POAManagerFactory ManagerAlreadyExists amp ex 19 20 do something Dil Au PF WNP And now the same example in Java 319 CHAPTER 15 Using Policies 320 woomaIdIianaunFrWNPH 10 13 i 13 14 I5 16 17 18 19 20 21 22 23 24 25 Java org omg CORBA Object obj orb resolve initial references Root POA org omg PortableServer POA rootPOA org omg PortableServer POAHelper narrow obj org omg PortableServer POAManagerFactory factory rootPOA the the POAManagerFactory com ooc OBPortableServer POAManagerFactory pmFactory com ooc OBPortableServer POAManagerFactoryHelper narrow facto ry org omg PortableServer POAManager myPOAManager null org omg CORBA Policy pl new Policy 1 pl 0 pmFactory create_giop version policy com ooc OBPortableServer GIOP VERSION POLICY 1 2 value try myPOAManager pmFactory create POAManager MyPOAManager pl catch org omg PortableServer POAManagerFactoryPackage Manager AlreadyExists ex catch org omg CORBA PolicyError ex do something do something Programming Examples Bidirectional Policy BidirectionalPolicy Server This example shows how to create a new
104. Load Balancing on page 283 Now we write the run function 1 C 2 int run CORBA ORB ptr orb int argc char argv 3 f 4 if arge 2 5 return EXIT_FAILURE 6 const char memberId argv 1 yi 8 CORBA Object_var poaObj 9 orb gt resolve_initial references RootPOA 10 PortableServer POA_var rootPoa 1 PortableServer POA _narrow poa0bj 12 13 PortableServer POAManager var manager 14 rootPoa gt the _POAManager r5 16 LoadBalancing MemberPolicyValue_var value Ly new LoadBalancing MemberPolicyValue 18 value gt group_id CORBA string_dup Hello i value gt member_id CORBA string dup memberId 20 CORBA Any any 21 any lt lt value retn 22 CORBA Policy_ var memberPolicy 23 orb gt create policy LoadBalancing MEMBER_ POLICY ID any 24 25 CORBA PolicyList pl 3 26 pl length 3 2 pl 0 rootPOA gt create lifespan policy 28 PortableServer PERSISTENT 29 pl 1 rootPOA gt create_id_ assignment policy 30 PortableServer USER_ID 31 pl 3 memberPolicy 32 PortableServer POA var helloPOA 33 rootPOA gt create POA hello manager pl 34 35 Hello _impl helloImpl new Hello imp helloPOA 36 PortableServer ServantBase var servant helloImpl 7 PortableServer ObjectId_var oid 38 PortableServer string_to_ObjectId hello 39 helloPOA gt activate_object_with_id oid servant
105. OA Manager Factory For this example an empty policy list is used Here is an example in C ONY HU PWN HP PRPRPPRPHE PH wo uk wWNHO 16 T7 18 i 20 C CORBA Object_var poaObj orb gt resolve_initial_ references RootPOA OBPortableServer POA var rootPOA OBPortableServer POA _ narrow poaObj POAManagerFactory var factory rootPOA gt the _POAManagerFactory OBPortableServer POAManagerFactory var pmFactory OBPortableServer POAManagerFactory narrow factory POAManager_ var myPOAManager PolicyList pl try myPOAManager pmFactory gt create POAManager MyPOAManager pl catch const POAManagerFactory ManagerAlreadyExists amp ex do something 2 6 Resolve the POA Manager Factory 7 16 Create a new POA Manager with the name MyPOAManager 75 CHAPTER 3 ORB and Object Adapter Initialization 76 2 9 10 17 And in Java Java org omg org wonadoauF WN PH com ooc CORBA Object obj orb org omg omg PortableServer POAHelper narrow obj org omg rootPOA the the POAManagerFactory resolve initial references RootPOA PortableServer POA rootPOA PortableServer POAManagerFactory factory OBPortableServer POAManagerFactory pmFactory com ooc OBPortableServer POAManagerFactoryHelper narrow fac tory 10 org omg 11 org omg PortableServer POAManager myPOAManager null CORBA Policy pl
106. OA name and object ID to be used to denote the same object This means that persistent references rely on the combination of PERSISTENT and USER_ID USER_ID must be used in conjunction with NO_IMPLICIT ACTIVATION SO servants for persistent references are always activated explicitly 107 CHAPTER 4 CORBA Objects Factory Objects 108 It is quite common to use the Factory 2 design pattern in CORBA applications In short a factory object provides access to one or more additional objects In CORBA applications a factory object can represent a focal point for clients In other words the object reference of the factory object can be published in a well known location and clients know that they only need to obtain this object reference in order to gain access to other objects in the system thereby minimizing the number of object references that need to be published The Factory pattern can be applied in a wide variety of situations including the following Security A client is required to provide security information before the factory object will allow the client to have access to another object Load balancing The factory object manages a pool of objects often representing some limited resource and assigns them to clients based on some utilization algorithm e Polymorphism A factory object enables the use of polymorphism by returning object references to different implementations depending on the criteria spec
107. OAD If the OAD is running and in a ready state it will have a status of up otherwise its status will be down Servers are registered with a name that is unique within the domain and the host corresponding to the OAD that is responsible for the server Since the name is unique within the domain it is not currently possible to register the same server with multiple OADs The server name that is registered in the IMR can be any string but it must be the same as the name used by the server i e the name specified by the orBServerid option or equivalent property The attributes of a server that are stored by the IMR are summarized below host The host corresponding to the OAD that is responsible for the server exec The path of server executable the exe extension must be included on Windows platforms If this attribute is not set then the IMR will not activate the server args The arguments to be supplied when starting the server executable Note that orpserverId server id is automatically appended to the arguments before the server process is started rundir The directory that the server process will be started from If this attribute is not set then the server process will be started from the root directory For Windows platforms the full path must be specified in the exec attribute even if this attribute is set Information Managed by the IMR mode The activation mode The possible value
108. OB jar OBNaming jar and OBUtil jar Naming Service Lookup Naming Service Lookup In order to locate a Naming Service the application takes the following steps on start up e First it checks whether a Naming Service reference was given with the f option e If this is not the case then the initial Naming Service is used as provided to the ORB with options like ORBservice or ORBconfig If both of the above steps fail an error window is displayed and the Names console exits 207 CHAPTER 9 Orbacus Names Console The Menus The File Menu 208 The menus provide access to all of the features of the application In addition the most common actions are also available in the toolbar as well as in a popup menu that is displayed when pressing the right mouse button over an item in the binding table or context tree This menu contains operations that create bindings and define the current root context New Window Opens an additional control window Switch Root Context Selects a new root naming context Load Context Recursively loads a naming context from a file Save Context As Recursively saves the selected naming context to a file Save IOR to File Saves the stringified IOR of the currently selected item to a file Close Window Closes the current window Exit Quits the Orbacus Names Console After starting the application the current root context is the naming context cor
109. OCAL MACHINE NT registry key with a REG_sz value of at least 1 234 Configuration Properties ooc ooc OOC ooc ooc ooc OOC OOC event event event event event event event event Usage In addition to the standard configuration properties described in Chapter 3 Orbacus Events also supports the following properties inactivity timeout SEC Max_events N max_retries N endpoint ENDPOINT pull_interval MSEC reap _frequency SEC retry_timeout MSEC retry_multiplier N ooc event request_timeout MSEC Proxies that are inactive for the specified number of seconds will be reaped The default value is four hours The maximum number of events in each event queue If this limit is reached and another event is received the oldest event is discarded The default value is 10 The maximum number of times to retry before giving up and disconnecting the proxy The default value is 10 Specifies the endpoint configuration for the service Note that this property is only used if the ooc orb oa endpoint property is not set This specifies the number of milliseconds between successive calls to pull on PullSupplier Default value is 0 This specifies the frequency in seconds in which inactive proxies will be reaped The default value is thirty minutes Setting this property to O disables the reaping of proxies Specifies the initial amount of time in milliseconds
110. Open Communications Interface The Java version looks as follows Java org omg CORBA Object baseCurrent orb resolve_initial references OCICurrent com ooc OCI Current current com ooc OCI CurrentHelper narrow baseCurrent YN UU BP WN PH com ooc OCI TransportInfo info current get_oci_transport_info 8 com ooc OCI IIOP TransportInfo iiopInfo 9 com ooc OCI IIOP Transport InfoHelper narrow baseInfo 10 11 if iiopInfo null IQ 4 alg int remoteAddr Converter addr iiopInfo remote_addr 14 int remotePort Converter port iiopInfo remote_port 15 16 System out println Call from T remoteAddr 0 18 remoteAddr 1 aus remoteAddr 2 20 remoteAddr 3 remotePort Bil P 2 11 This code is equivalent to the C version 13 14 Again the port number must be converted from short to int 16 20 This is also equivalent to the C version 350 OCI Reference Determining a Server s IP Address To determine the server s IP address and port that an object will attempt to connect to the following code can be used ae ees 2 CORBA Object_var obj Get an object reference somehow 3 4 OCI ConnectorInfo var info obj gt get_oci_connector_info 5 OCI IIOP ConnectorInfo var iiopInfo 6 OCI IIOP ConnectorInfo _narrow info 7 8 if CORBA is_ nil iiopInfo 9 i 10 OCI IIOP InetAddr var remoteAddr iiopInfo g
111. Orbacus User Guide Version 4 2 1 IONA Technologies PLC Orbix IONA Enterprise Integrator Enterprise Integrator Orbix E2A Application Server Orbix E2A XMLBus XMLBus are trademarks or registered trademarks of IONA Technol ogies PLC and or its subsidiaries Orbacus and JThreads C are trademarks or registered trademarks of IONA Tech nologies Inc IONA IONA Technologies the IONA logo Making Software Work Together IONA e Busi ness Platform and Total Business Integration are trademarks or registered trademarks of IONA Technologies PLC and or its subsidiaries Java and J2EE are trademarks or registered trademarks of Sun Microsystems Inc in the United States and other countries CORBA is a trademark or registered trademark of the Object Management Group Inc in the United States and other countries All other trademarks that appear herein are the property of their respective owners While the information in this publication is believed to be accurate IONA Technologies PLC makes no warranty of any kind to this material including but not limited to the implied warranties of merchantability and fitness for a particular purpose IONA Technologies PLC shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material COPYRIGHT NOTICE No part of this publication may be reproduced stored in a retrieval system or tran
112. Portable Interceptors Method names parameter and return values exceptions and a call stack can be visualized The module can be loaded dynamically at application startup when shared libraries are used or linked statically to an application This chapter contains the following sections Tracing Levels page 296 Installing Watson in C page 297 Installing Watson in Java page 298 Configuration Properties page 299 295 CHAPTER 14 Orbacus Watson Tracing Levels The level of request tracing is controlled by the properties described in the next section The default value for all tracing levels is O 0 no tracing 1 displays name request id return exception status of operation 2 displays parameters and return values 3 displays the call stack 4 displays object id adapter id effective profile The tracing levels are cumulative i e the higher levels include the output generated by the lower levels In order to make request parameters results and exceptions available for tracing the option with interceptor args has to be specified to the IDL compiler 296 Installing Watson in C Installing Watson in C 10 16 If Orbacus was built with shared libraries or DLLs Orbacus Watson can be installed dynamically by defining the following configuration properties ooc orb modules watson ooc orb module watson lt library name gt Please refer to Chapter 3 for more inform
113. RB somehow CORBA Object_var obj orb gt resolve_initial references POACurrent PortableServer Current_var current PortableServer Current narrow obj if CORBA is_ nil current Got Current object OK You can keep the reference to the current object in a variable and use it from within any executing operation in a servant There is no need to refresh the current reference for the current operation not even for threaded servers The ORB takes care of ensuring that operation invocations on the current object return the correct data 116 Factory Objects In Java the code to obtain the current reference looks like this Java org omg CORBA ORB orb Get the ORB somehow org omg CORBA Object obj orb resolve_initial_references POACurrent org omg PortableServer Current current org omg PortableServer CurrentHelper narrow obj if current null Got Current object OK 117 CHAPTER 4 CORBA Objects 118 In this chapter CHAPTER 5 Locating Objects This chapter describes how to locate CORBA servant objects This chapter contains the following sections Obtaining Object References page 120 Lifetime of Object References page 124 Stringified Object References page 128 Object Reference URLs page 132 The BootManager page 138 Initial Services page 142 The IORDump utility page 148 119 CHAPTER 5 Locating Objects Obtainin
114. Reference This appendix describes the interfaces for the Open Communication Interface This appendix contains the following sections Module OCI page 430 Module OCI IIOP page 465 CHAPTER E Open Communications Interface Reference Module OCI Aliases 430 BufferSeq typedef sequence lt Buffer gt BufferSeq Alias for a sequence of buffers IOR typedef IOP IOR IOR Alias for an IOR Profileld typedef IOP ProfileId ProfileId Alias for a profile id ProfileldSeq typedef sequence lt ProfileId gt ProfileIdSeq Alias for a sequence of profile ids Pluginld typedef string PluginId Alias for a plugin id PluginldSeq typedef sequence lt PluginId gt PluginIdSeq Alias for a sequence of plugin ids ObjectKey typedef CORBA OctetSeq ObjectKey Alias for an object key which is a sequence of octets TaggedComponentSeq typedef IOP TaggedComponentSeq TaggedComponentSeq Alias for a sequence of tagged components Handle typedef long Handle Alias for a system specific handle type Constants Module OCI ProfilelnfoSeq typedef sequence lt ProfileInfo gt ProfileInfoSeq Alias for a sequence of basic information about profiles ParamSeq typedef sequence lt string gt ParamSeq Alias for a sequence of parameters CloseCBSeq typedef sequence lt CloseCB gt CloseCBSeq Alias for a sequence of close callback objects ConnectorSeq typedef sequence lt Connector gt Conne
115. Repository Interface Repository Utilities irfeed IDL files can be loaded into the IFR at runtime using irfeed See the description of the irserv command for more information on the command line options irfeed h help v version d debug DNAME DNAME DEF UNAME IDIR FILE irdel Type definitions can be removed from the IFR using irdel See the description of the irserv command for more information on the command line options irdel h help v version name The name argument represents the scoped name of the type to be removed A scoped name has the form X Y Z For example an interface 1 defined in a module m can be identified by the scoped name M 1 258 Programming Example Programming Example Below is a simple example in Java that demonstrates how to obtain an InterfaceDef object and display its contents 1 Java 2 import org omg CORBA 3 4 5 org omg CORBA ORB initialize the ORB 6 org omg CORBA Object obj get object reference somehow 7 8 org omg CORBA Object defObj obj get_interface def 9 if defObj null LO lal System err printin No Interface Repository available 12 System exit 1 13 14 15 InterfaceDef def InterfaceDefHelper narrow defObj 16 org omg CORBA InterfaceDefPackage FullInterfaceDescription dese 17 def describe interface 18 19 int a 20 System out println name desc name
116. SE POLICY ID value 7 boolAny 8 org omg CORBA Object newObj 9 obj _set_policy override policies 10 org omg CORBA SetOverrideType ADD OVERRIDE 1 10 This is equivalent to the C version 309 CHAPTER 15 Using Policies Retry Policy This example shows how to configure retries at the object level The C version is presented first followed by the Java version 1 C 2 OB RetryAttributes attrib 3 attrib mode OB RETRY STRICT 4 attrib interval 500 5 attrib max 5 6 attrib remote true F 8 CORBA Any any 9 any lt lt attrib 10 CORBA PolicyList policies 1 ial jofollalesiers Ievarejela 4l 7 12 policies 0 orb gt create_policy OB RETRY POLICY ID any 13 CORBA Object_var newObj 14 obj gt _set_policy overrides policies CORBA ADD_OVERRIDE 3 Use the RETRY STRICT mode that is retry only if the exception completion status is COMPLETED NO 4 Wait 500 milliseconds between successive retries Retry a maximum of 5 times 6 Allow retries on exceptions that are generated remotely in addition to locally generated exceptions 13 14 Set the policy on the object by using the _set_policy overrides method This method returns a new object that has the set of policies applied 310 Programming Examples And now the same example in Java ond An BAe WD HP PRRPRRPR OR WN O 16 Java com ooc OB RetryAttributes attrib new com ooc OB RetryAttribu
117. Type Event Service DefaultEventChannel CosEvent ChannelAdmin EventChannel Typed Event Default TypedEventChannel CosTypedEventChannelAdmin Service TypedEvent Channel The object key can be used when composing URL style object references For example the following URL identifies the untyped event service running on host evhost at port 10000 corbaloc evhost 10000 DefaultEventChannel Refer to Chapter 5 for more information on URLs and configuring initial services Orbacus Events also provides proprietary factory interfaces which allow construction and administration of multiple event channels in a single service The object keys and corresponding interface types of the factories are shown in Table 3 Table 3 Object Keys and Interface Types for Event Channel Factories Object Key Interface Type Event Channel DefaultEventChannelFactory OBEventChannelFactory Factory Event Channel Factory Typed Event DefaultTypedEventChannelFactory OBTypedEventChannelFactory Channel TypedEventChannelFactory Factory For a description of the factory interfaces please refer to the documented IDL files event id1 OBEventChannelFactory idl and event id1 OBTypedEvent ChannelFactory idl 237 CHAPTER 11 Orbacus Events Using the Event Service with the IMR The Event Service may be used with the Implementation Repository IMR However if used with the IMR it is important to note that the corbalo
118. Upon completion the ORB will have created the Root POA and its POA Manager and will have initialized the ORB s server side functionality 50 Configuring the ORB and Object Adapter Configuring the ORB and Object Adapter Overview In this section O rbacus applications can tailor the behavior of the ORB and object adapters using a collection of properties These properties can be defined in a number ways T U using the Windows Registry Windows NT C using a configuration file using system properties Java using command line options programmatically at run time he Orbacus configuration properties are described in the following sections nless otherwise noted every property can be used in both C and Java applications This section contains the following subsections ORB Properties page 52 OA Properties page 59 Command line Options page 62 Using a Configuration File page 64 Using the Windows NT Registry page 65 Defining Properties page 66 Precedence of Properties page 68 Advanced Property Usage page 69 1 Note that these properties have nothing to do with the Property Service as described in Appendix B 51 CHAPTER 3 ORB and Object Adapter Initialization ORB Properties ooc config ooc oci client 00c oci server 00c oci plugin name ooc orb client_shutdown_timeout 52 Value filename Selects the default configuration file This proper
119. a connection to them in a separate window ORBacus Names Ping Window olx Sophed luke software bruker Eri a Sophed demosophe esr bruker Sophed luke software bruker Sophed demosophe esr bruker Sophed luke software bruker Sophed demosophe esr bruker Sophed luke software bruker Sophed demosophe esr bruker Sophed luke software bruker Sophed demosophe esr bruker Sophed luke software bruker Sophed demosophe esr bruker Sophed luke software bruker Sophed demosophe esr bruker Sophed luke software bruker Sophed demosophe esr bruker Sophed luke software bruker Sophed demosophe esr bruker Sophed luke software bruker NSSS e e Figure 6 The Ping Window This is very similar to the Windows or Unix ping command for an IP address or a host name If there is a time out while trying to contact an object this information is displayed in the Ping Window and the console continues with the next object The Menus If you want objects that cannot be contacted for example because of a server breakdown to be unbound from the current context Clean up does the job Clean up non recursively tries to connect to the selected objects If there is a communication failure or the non existent operation returns true for a particular object the corresponding binding is automatically removed Clean up should be used with care
120. ace Repository MinorDest royWouldBlock Operation would deadlock MinorShutdownCalled ORB has shutdown MinorDuplicateSend Request has already been sent MinorServantManagerAlreadySet Servant manager already set MinorInvalidUseOfDSIArguments Invalid use of DSI arguments MinorInvalidUseOfDSIContext Invalid use of DSI context MinorRequestAlreadySent DII request has already been sent MinorRequestNotSent DII request has not been sent yet MinorResponseAlreadyReceived DII response has already been received MinorSynchronousRequest Operation not supported on synchronous DII request MinorInvalidPICall Invalid Portable Interceptor call MinorServiceContextExists A service context already exists with the given ID MinorPolicyFactoryExists A factory already exists for the given PolicyType MinorNoCreatePOA Cannot create POA while undergoing destruction MinorBadConcModel Invalid concurrency model MinorORBRunning ORB run already called TRANSIENT Minor Exception Code CORBA System Exceptions MinorRequestDiscarded Request has been discarded MinorNoUsableProfileInIOR No usable profile in IOR MinorRequest Cancelled Request has been cancelled MinorPOADest royed POA has been destroyed MinorConnectFailed Request has been cancelled MinorCloseConnection Got a close connectio
121. ad of org omg CORBA InterfaceDef Portable Java applications should use _get_ interface def In C the operation is _get_interface In this chapter CHAPTER 13 Orbacus Balancer Orbacus Balancer provides load balancing of client connections across a group of replicated objects The load balancing service provided by Orbacus Balancer is transparent and interoperable with any CORBA client However the interface between the servers and the service s strictly proprietary This chapter contains the following sections Basic Concepts on page 262 Load Balancing Strategies on page 263 Service Security on page 266 Usage on page 267 Connecting to the Service on page 275 Load Balanced IMR enabled Servers on page 276 Utilities on page 277 Programming Example on page 282 261 CHAPTER 13 Orbacus Balancer Basic Concepts 262 Let us assume that we wish to provide a library service that is made available through a set of objects These objects being a set of book objects and a library object that manages the book objects Furthermore it is desired that connections made with each of these objects be load balanced The replicated objects for each book and the replicated library objects are managed in the service by a single entity that is called a load balanced group Each member of the load balanced group must provide a replica of each obje
122. ads will be reported to the load balanced group at regular intervals by each member However this implies that 263 CHAPTER 13 Orbacus Balancer Load Re balancing 264 when making a load balancing decision loads do not necessarily represent the current loads of the members but instead past loads This is a Source of error These errors will be large when many clients connect in a short period of time This is because the actual load of members will increase dramatically before the loads can be updated Increasing the frequency of load updates will decrease the error but then the overhead of load balancing is increased due the extra network traffic Hence an optimum value must be discovered for each installation 2 Another source of error is that spikes in the load of a member may cause bad load balancing decisions 3 Yet another problem with load balancing is that in most cases it is difficult to estimate the load that a new client connection will impose on a member This becomes a bigger problem on a heavily loaded system since a load balancing decision may cause a members load to increase well past the critical level Errors of this type can be alleviated by using load re balancing However load re balancing will introduce other sources of errors as discussed in the next section Load re balancing is the transfer of a client connection from the replica of one member to the replica of another This is achieved by
123. al addresses represented as alternate addresses in tagged components If IIOP 1 0 or 1 1 is in use multiple addresses are always represented as multiple tagged profiles no keepalive Disable the use of TCP keepalives The IIOP OCI Plug in If set and if host is not specified then the canonical numeric dotted decimal address is advertised in IORs The default behavior is to use the canonical hostname if possible port N Specifies the port number on which to bind the socket If no port is specified an unused one will be selected automatically by the operating system Use this option if you plan to publish an IOR e g in a file a naming service etc and you want that IOR to remain valid across executions of your server Without this option your server is likely to use a different port number each time the server is executed See Chapter 5 for more information 355 CHAPTER 17 The Open Communications Interface Command line Options The IIOP plug in supports the following command line options IIOPbacklog N Equivalent to the backlog endpoint option IIOPbind ADDR Equivalent to the bind endpoint option IIOPhost ADDR ADDR Equivalent to the host endpoint option ITOPnumeric Equivalent to the numeric endpoint option IIOPport N Equivalent to the port endpoint option 356 See Command line Options and Endpoints on page 79 for
124. alancing MemberDataSeq typedef sequence lt MemberData gt MemberDataSeq A sequence of member data TolerancePropertyValue typedef unsigned long TolerancePropertyValue The tolerance load balancing strategy property value The default value is O LoadPerClientPropertyType typedef unsigned long LoadPerClientPropertyType The load per client load balancing strategy property value The default value is O RejectPropertyValue typedef unsigned long RejectPropertyValue The reject load load balancing strategy property value The default value is O meaning no rejections DampeningMultiplierPropertyValue typedef float DampeningMultiplierPropertyValue The dampening multiplier load balancing strategy property value The default value is 0 which disables dampening CriticalLoadPropertyValue typedef unsigned long CriticalLoadPropertyValue The critical load load balancing strategy property value The default value is O which disables re balancing MEMBER _POLICY_ID const CORBA PolicyType MEMBER POLICY ID 1000 This policy type identifies the member policy TolerancePropertyName const string TolerancePropertyName tolerance The tolerance load balancing strategy property name Members with a load difference that is less than tolerance are considered to have the same load LoadPerClientPropertyName const string LoadPerClientPropertyName load per client 473 CHAPTER F Orbacus Balancer Reference Enums
125. aming NamingContextHelper narrow obj 22 23 catch org omg CORBA BAD PARAM ex 24 25 This object does not implement a NamingContext 26 Try to resolve the name of a particular service If a service of the specified name is not known to the ORB an InvalidName exception is thrown The service type was known Now the object reference has to be narrowed to the particular service type If this fails the service is not available 143 CHAPTER 5 Locating Objects And here s the C equivalent to the Java version above 1 C 2 CORBA Object var obj 3 CosNaming NamingContext var ctx 4 5 try 6 d 7 obj orb gt resolve_initial_ references NameService a 9 catch CORBA ORB InvalidName amp 10 ital Bn error occured service is not available IQ 13 14 if CORBA is_nil obj i5 f 16 The object reference is invalid iy 18 19 ctx CosNaming NamingContext narrow obj 20 if CORBA is_ nil ctx Bil A 22 This object does not implement NamingContext 144 Initial Services Configuring the Initial Services When an application uses initial services that are not locality constrained the application must register the object references for these objects with the ORB Orbacus supports the standard orBInitRef and ORBDefault InitRef command line options for registering initial service object references ORBInitRef name URL ORBDefaultI
126. and B_impl yyy ce 2 class A impl virtual public POA A 3 i 4 public 5 virtual void op _a throw CORBA SystemException 6 7 8 class B _ impl virtual public POA B 9 10 public lal virtual void op b throw CORBA SystemException 12 13 14 class I_impl virtual public POA I 15 virtual public A impl 16 virtual public B impl iy 18 public Abo virtual void op _i throw CORBA SystemException 200 The servant class A_imp1 is defined inheriting from the skeleton class POA A If op a had any parameters these parameters would be mapped according to the standard IDL to C mapping rules 4 This is the servant class for B_imp1 1 These naming rules are not mandatory they are just a recommendation 89 CHAPTER 4 CORBA Objects Inheritance using Java 90 14 20 5 7 The servant class for I_imp1 is not only derived from roa x but also from the servant classes A impl and B_impl Note that virtual public inheritance must be used The only situation in which the keyword virtual is not necessary is for an interface 1 which does not inherit from any other interface and from which no other interface inherits This means that the implementation class I_imp1 only inherits from the skeleton class poa _x and no implementation class inherits from 1_imp1 It is not strictly necessary to have an implementation class for every interface For example it is sufficient to only have the c
127. ant because unlike org omg CORBA ORB init OBCORBA ORB_init does not read the default properties if the property parameter is not null Define Orbacus property Initialize the ORB using the Orbacus specific OBCORBA ORB_init operation 67 CHAPTER 3 ORB and Object Adapter Initialization Precedence of Properties Given that properties can be defined in several ways it s important to establish the order of precedence used by Orbacus when collecting and processing the property definitions The order of precedence is listed below from highest to lowest Properties defined at a higher precedence override the same properties defined at a lower precedence 1 Command line options 2 Configuration file specified at the command line 3 User supplied properties 4 Configuration file specified by the orBACUS_CONFIG environment variable C or the ooc config system property Java a System properties Java only 6 HKEY CURRENT USER Software 00C Properties Windows NT C only 7 HKEY LOCAL MACHINE Software 00C Properties Windows NT C only For example a property defined using a command line option overrides the same property defined in a configuration file 68 Configuring the ORB and Object Adapter Advanced Property Usage Examples With the methods for ORB initialization discussed in the previous sections the command line arguments are not processed until a call to CORBA ORB_init C OBCORBA OR
128. arate receiver thread allows messages to be received and buffered for later retrieval by the user thread with DII operations such as get_response OF poll_response Like a threaded client a threaded server uses a separate thread for receiving requests from clients but sends replies in the dispatch thread Additionally there is a separate thread dedicated to accepting incoming connection requests so that a threaded server can serve more than one client at a time Orbacus s threaded server concurrency model allows only one active thread in the user code This means that even though many requests can be received simultaneously the execution of these requests is serialized This is shown in Figure 11 For simplicity the dispatch arrows and the corresponding return arrows are omitted in this and all following diagrams fQ g0 p nail P Client A Threaded Server Client B Figure 11 Threaded Server In the example the threaded server has two clients connected to it and thus two receiver threads First A calls on the server If before returns B tries to call another operation g this request is delayed until returns The same is true for A s call to h which must wait until g returns Multi Threaded Concurrency Models Allowing only one active thread in user code has the advantage of the user code not having to take care of any kin
129. ation Use the X11 application context to obtain a X11 Reactor Initialize the ORB using the Orbacus specific oBCORBA ORB_init Enter the CORBA event loop This loop will also dispatch X11 events Alternatively the standard X11 event loop may be called which will also dispatch CORBA events 339 CHAPTER 16 Concurrency Models The Windows Reactor Using a Windows Reactor is very similar to using a X11 Reactor C include lt Windows h gt include lt OB CORBA h gt include lt OB Logger h gt include lt OB Properties h gt include lt OB OBWindows h gt wad A UN FWDNHH int main int argc char argv 1 ala HINSTANCE hInstance GetModuleHandle 0 12 ils OB Reactor_var reactor OB GetWindowsReactor hInstance 14 15 CORBA ORB var OBCORBA ORB_init argc argv 16 OB Propert iesi ini HOPTOR roggen EN Eea CEOr i Ly 18 POA initialization not shown ak 20 orb gt run 21 22 Cleanup not shown 23 2 7 Include header files 13 Use the Windows application instance to get a Windows Reactor 15 16 Initialize the ORB using the Orbacus specific oBCORBA ORB_init 20 Enter the CORBA event loop which now also dispatches Windows events The standard Windows event loop may also be called which will then also dispatch CORBA events 340 In this chapter CHAPTER 17 The Open Communications Interface The Open Communications Interface OCI defines
130. ation on these properties If Orbacus was built statically the module initialization function has to be called directly from the application code C if defined HAVE SHARED amp amp defined OB DLL include lt OB watson h gt endif int main int argc char argv CORBA ORB var orb wont anu fF WD HP 10 if defined HAVE SHARED amp amp defined OB DLL 11 12 When linking statically we need to explicitly initialize 13 Watson 14 ah 15 init_module_watson 16 endif I7 18 orb CORBA ORB_init argc argv is 20 Include oB watson h only when building statically Explicitly install the Watson module prior to initializing the ORB Specifying the configuration property ooc orb modules watson will result in an informative error message from the ORBs ModuleManager upon application startup if the module was linked statically 297 CHAPTER 14 Orbacus Watson Installing Watson in Java Since Orbacus Watson is based on Portable Interceptors it is installed using the standard mechanism for installing interceptors Specifically a property is defined which specifies the name of a class to be loaded org omg PortableInterceptor ORBInitializerClass com ooc watson RI ORBInitializer impl Note that the property has no associated value as the name of the class to be loaded is part of the property name 298 Configuration Properties Configuration Properties The beha
131. ations Interface Reference block If set to TRUE the operation blocks until the buffer has completely been sent If set to FaLsE the operation sends as much of the buffer s data as possible without blocking Raises COMM_FAILURE In case of an error send_detect boolean send_detect in Buffer buf in boolean block Similar to send but it signals a connection loss by returning FALSE instead of raising COMM_FAILURE Parameters buf The buffer to fill block If set to TRUE the operation blocks until the entire buffer has been sent If set to FALSE the operation sends as much of the buffer s data as possible without blocking Returns FALSE if a connection loss is detected TRUE otherwise Raises COMM_FAILURE In case of an error send_timeout void send_timeout in Buffer buf in unsigned long timeout Similar to send but it is possible to specify a timeout On return the caller can test whether there was a timeout by checking if the buffer has been sent completely Parameters buf The buffer to send timeout The timeout value in milliseconds A zero timeout is equivalent to calling send buf FALSE Raises COMM _FATLURE In case of an error send_timeout_detect boolean send_timeout_detect in Buffer buf in unsigned long timeout 440 Module OCI Similar to send_timeout but it signals a connection loss by returning FALSE instead of raising COMM_FAILURE
132. ava the OCI will return this as 126 127 128 127 because 128 and 129 if bit wise mapped to the Java byte type are 128 and 127 To avoid this problem we will use a helper class which converts port numbers and IP addresses to Java int types This helper class looks as follows 1 Java 2 final class Converter 3 f 4 static int port short s s 6 if s lt 0 Ff return Oxffff int s 1 8 else 9 return int s 10 IEN 12 static int addr byte bArray 13 14 int iArray new int 4 15 for int i 0 i lt 4 i 16 if bArray i lt 0 a7 iArray i Oxff int bArray i 1 18 else 19 iArray i int bArray i 20 21 return iArray 22 BS jhe 4 10 Converts short port numbers to int 12 22 Converts byte IP addresses to int The converter class is used throughout the examples in the sections below 346 OCI Reference Getting Hostnames and Port Numbers 10 12 16 The following code fragments show how it is possible to find out on what hostnames and port numbers a server is listening First the C version RCE 2 OCI AcceptorSeq var acceptors poaManager gt get_acceptors 3 4 for CORBA ULong i 0 i lt acceptors gt length i 5 6 OCI AcceptorInfo var info acceptors i gt get_info 7 OCI IIOP AcceptorInfo var iiopInfo 8 OCI IIOP AcceptorInfo _ narrow info 9 10 if CORBA is_nil iiopInfo 11
133. bacus distribution 203 CHAPTER 8 Orbacus Names 204 In this chapter CHAPTER 9 Orbacus Names Console Orbacus Names includes a graphical client for administering the service called the Orbacus Names Console The application can manage any CORBA compliant Naming Service but additional features are provided when used with Orbacus Names This chapter contains the following sections Usage page 206 Naming Service Lookup page 207 The Menus page 208 The Toolbar page 216 The Popup Menu page 217 205 CHAPTER 9 Orbacus Names Console Usage com ooc CosNamingConsole Main file FILE i ior n no updates look CLASS windows motif mac h help v version f FILE file FILE Read the Naming Service IOR from FILE i ior Print the stringified IOR of the Naming Service to standard output n no updates Disables automatic updates i e callbacks that notify interested clients of changes to the naming service look CLASS Use the specified Look amp Feel class windows Use the Windows Look amp Feel if available motif Use the Motif Look amp Feel if available mac Use the Macintosh Look amp Feel if available h help Display the command line options supported by the program CLASSPATH Requirements 206 The Orbacus Names Console requires the classes in
134. c URL style object reference described in the previous section cannot be used If the IMR is used then the object reference for the untyped Event Service must be created using one of the following methods where EventServer refers to the server name configured with the IMR e Start the Event Service with the options ORBServerlId EventServer ior causing the Event Service to print its reference to standard output e Use the mkref utility mkref EventServer DefaultEventChannel EventServicePOA For the typed Event Service the object reference must be created using one of the following methods e Start the Event Service with the options ORBServerId EventServer typed service ior causing the Event Service to print its reference to standard output e Use the mkref utility mkref EventServer DefaultTypedEventChannel EventServicePOA Object references for the Orbacus proprietary factory objects can be created using the following commands mkref EventServer DefaultEventChannelFactory EventServicePOA mkref EventServer DefaultTypedEventChannelFactory EventServicePOA When using the Event Service with the IMR the service must be started with the option orBServerId EventServer where EventServer refers to the server name configured with the IMR When the IMR is configured to start the Event Service this option is automatically added to the service s arguments However when the Event Service is started
135. ce connections evel ORBtrace_retry level ooc orb trace retry evel A few additional command line options are supported that do not have equivalent properties These options are described in the following table Option Description ORBconfig filename Causes the ORB to load the configuration file specified by filename ORBversion Causes the ORB to print its version to standard output 63 CHAPTER 3 ORB and Object Adapter Initialization Using a Configuration File 64 A convenient way to define a group of properties is to use a configuration file A sample configuration file is shown below Concurrency models ooc orb conc_model threaded ooc orb oa conc_model thread_pool ooc orb oa thread_pool 5 Initial services ooc orb service NameService corbaloc myhost 7000 NameService ooc orb service EventService corbaloc myhost 7001 DefaultEventC hannel ooc orb service TradingService corbaloc myhost 7002 TradingServ ice Note that trailing blanks are not ignored but are a part of the property You can define the name of the configuration file using a command line option an environment variable C or a system property Java Command line option ORBconfig filename Environment variable ORBACUS_CONFIG filename e Java system property ooc config filename When an ORB is initialized it first checks for the presence of the environment variable or system pr
136. common interfaces for pluggable protocols TCP IP is one possible candidate for an OCI plug in Since Orbacus uses GIOP such a plug in then implements the IIOP protocol Other candidates are SCCP Signaling Connection Control Part part of SS 7 or SAAL Signaling ATM Adaptation Layer This chapter contains the following sections Interface Summary page 342 OCI Reference page 345 The IIOP OCI Plug in page 353 The UDP OCI Plug in page 358 The Bi directional OCI Plug in page 367 341 CHAPTER 17 The Open Communications Interface Interface Summary Buffer Transport Acceptor and Connector Acceptor and Connector Factories The Registries 342 An interface for a buffer A buffer can be viewed as an object holding an array of octets and a position counter which determines how many octets have already been sent or received The Transport interface allows the sending and receiving of octet streams in the form of Buffer objects There are blocking and non blocking send receive operations available as well as operations that handle time outs and detection of connection loss Acceptors and Connectors are Factories 2 for Transport objects A Connector is used to connect clients to servers An Acceptor is used by a server to accept client connection requests Acceptors and Connectors also provide operations to manage protocol specific IOR profiles This includes operations for comparing pr
137. ct for the library service each member must provide a replica of each book object and a replica of the library object All of the replicas provided by a member must be activated on a single POA with a member policy which uniquely identifies the member within the service the uszER_1D ID assignment policy value and the PERSISTENT lifespan policy value Such a POA will be referred to as a member POA and the corresponding server will be referred to a load balanced server Object references created by a member POA will refer to the service instead of the member POA within the load balanced server When a client makes a request on an object using a reference create by a member POA the service e receives the request e determines the load balanced group e selects a member of this group and e returns a new reference to the client that refers to the replica of the object that is provided by this member The client then establishes a connection with the server using the new object reference and communicates directly with the server without the intervention of the service Load Balancing Strategies Load Balancing Strategies Member Selection Each load balanced group within the service has an associated load balancing strategy The load balancing strategy determines which member will be used to service the next client connection The strategy is also responsible for load re balancing Load re balancing is done by issuing l
138. ct is needed before operations such as send recv Or accept can be used by the ORB 1 For more information on send_deferred get_response and poll_response see the chapter The Dynamic Invocation Interface in 4 2 Instead of directly using operations like select Orbacus uses a Reactor to provide for flexible integration with existing event loops and to allow the installation of user supplied event handlers See The Reactor on page 338 for more information 329 CHAPTER 16 Concurrency Models 330 The maximum nesting level for the reactive concurrency model is usually much higher than for threaded concurrency models The reason is that the maximum nesting level for threaded models is determined by the maximum number of threads allowed per process whereas the reactive concurrency model is only limited by the maximum stack size per process Multi Threaded Concurrency Models Multi Threaded Concurrency Models In this section This section covers the following concurrency models Threaded Clients and Servers page 332 Thread per Client Server page 334 Thread per Request Server page 335 Thread Pool Server page 336 Leader_Follower page 337 331 CHAPTER 16 Concurrency Models Threaded Clients and Servers 332 For a threaded client outgoing requests are sent by the user thread but a separate receiver thread for handling replies is allocated for each connection to a server The sep
139. ctions may be reused or are private to specific objects Attributes value readonly attribute boolean value If an object has a connect ionReusePolicy set with value set to FALSE then other object references will not be permitted to use connections made on behalf of this object If set to TRUE then connections are shared The default value iS TRUE 409 CHAPTER B Orbacus Policy Reference Interface OB InterceptorPolicy Attributes 410 local interface InterceptorPolicy inherits from CORBA Policy The interceptor policy This policy can be used to control whether the client side interceptors are called value readonly attribute boolean value If an object reference has an InterceptorPolicy set and value S FALSE then any installed client side interceptors are not called Otherwise interceptors are called for each method invocation The default value is TRUE Module OB Interface OB LocateRequestPolicy Attributes local interface LocateRequestPolicy inherits from CORBA Policy The locate request policy This policy can be used to specify whether the ORB sends locate request messages value readonly attribute boolean value If an object has a LocateRequest Policy set to false then the ORB will not send locate request messages for the object 411 CHAPTER B Orbacus Policy Reference Interface OB LocationTransparencyPolicy local interface LocationTransparencyPolicy inherits from CORBA P
140. ctorSeq Alias for a sequence of Connectors ConnectCBSeq typedef sequence lt ConnectCB gt ConnectCBSeq Alias for a sequence of connect callback objects ConFactorySeq typedef sequence lt ConFactory gt ConFactorySeq Alias for a sequence of Connector factories AcceptorSeq typedef sequence lt Acceptor gt AcceptorSeq Alias for a sequence of Acceptors AcceptCBSeq typedef sequence lt AcceptCB gt AcceptCBSeq Alias for a sequence of accept callback objects AccFactorySeq typedef sequence lt AccFactory gt AccFactorySeq Alias for a sequence of AccFactory objects Version const string Version 1 0 The OCI version If an interface or implementation changes in an incompatible way this version will be changed 431 CHAPTER E Open Communications Interface Reference Enums Structs Exceptions 432 SendReceiveMode enum SendReceiveMode Sendonly ReceiveOnly SendReceive Indicates the send receive capabilities of an OCI component Profilelnfo struct ProfileInfo ObjectKey key octet major octet minor ProfileId id unsigned long index TaggedComponentSeq components i Basic information about an IOR profile Profiles for specific protocols contain additional data For example an IIOP profile also contains a hostname and a port number Members key The object key major The major version number of the ORB s protocol For example the major GIOP version if
141. ctory narrow factory POAManager var myPOAManager PolicyList pl pl length 1 pl 0 pmFactory gt create_communications_ concurrency policy OBPortableServer COMMUNICATIONS CONCURRENCY POLICY THREADED try myPOAManager create POAManager MyPOAManager pl catch const POAManagerFactory ManagerAlreadyExists amp ex do something And now the same example in Java 315 CHAPTER 15 Using Policies 316 woomaIdIianaunFrWNPH 10 17 12 13 14 15 16 aly 18 T9 20 21 22 23 24 25 Java org omg CORBA Object obj orb resolve initial references Root POA org omg PortableServer POA rootPOA org omg PortableServer POAHelper narrow obj org omg PortableServer POAManagerFactory factory rootPOA the the POAManagerFactory com ooc OBPortableServer POAManagerFactory pmFactory com ooc OBPortableServer POAManagerFactoryHelper narrow facto ry org omg PortableServer POAManager myPOAManager null org omg CORBA Policy pl new Policy 1 pl 0 pmFactory create_communications concurrency policy com ooc OBPortableServer COMMUNICATIONS CONCURRENCY POLICY TH READED value try myPOAManager pmFactory create POAManager MyPOAManager POF catch org omg PortableServer POAManagerFactoryPackage Manager AlreadyExists ex catch org omg CORBA PolicyError ex do something do something Programming Examples
142. cy models and multi threaded concurrency models Single threaded concurrency models describe how an ORB behaves while a request is sent or received in a single threaded environment For example one model is to simply let the ORB block while sending and receiving messages Another model is to let the ORB do some work while sending and receiving messages for example to receive user input through a keyboard or a GUI or to simply transfer buffered messages Multi threaded concurrency models describe how the ORB makes use of multiple threads for example to send and receive messages in the background Multi threaded concurrency models also describe how several threads can be active in the user code and the strategy the ORB employs to create these threads There is no one size fits all approach with respect to concurrency models Each concurrency model provides a unique set of properties each having advantages and disadvantages For example applications using callbacks must have a concurrency model that allows nested method invocations to avoid deadlocks Other applications must be optimized for speed in which case a concurrency model with the least overhead will be chosen Some ORBs are highly specialized providing only the most frequently used concurrency models for a specific domain Orbacus takes a different approach by supporting several concurrency models Orbacus allows different concurrency models to be established for
143. d 48 nc bind a2Name a2 49 50 NameComponent a3Name new NameComponent 1 51 a3Name 0 new NameComponent 52 a3Name 0 id a3 53 a3Name 0 kind 54 nc bind a3Name a3 55 56 NameComponent bName new NameComponent 2 57 bName 0 new NameComponent 58 bName 0 id ncl1 59 bName 0 kind 60 bName 1 new NameComponent 61 bName 1 id b 62 bName 1 kind 63 nc bind bName b 64 65 NameComponent cName new NameComponent 3 66 cName 0 new NameComponent 67 cName 0 id nci 68 cName 0 kind 69 cName 1 new NameComponent 70 cName 1 id nc2 Hal cName 1 kind 72 cName 2 new NameComponent T3 cName 2 id c 74 cName 2 kind 75 nc bind cName c 76 Several sample objects are created that will later be bound to our Naming Service These objects implement an interface called Namea In this example the details of this interface are not important Namea might even be an interface without any operations defined in it Programming Example 17 75 Create and bind some new contexts and bind the sample objects to these contexts Each binding name consists of several NameComponents that are similar to the path components of a file located somewhere in a filesystem Objects are bound with the Naming Service s bind operation for contexts the corresponding operation bind_con
144. d of thread synchronization This means that the user code can be written as if for a single threaded system but without losing the advantage of the ORB optimizing its operation by using multiple threads internally The threaded concurrency model is still fast No calls to operations like select are required Time consuming thread creation is only necessary when a new client is connecting but not for each request However thread context switching makes this approach slower than the reactive concurrency model at least on a single processor computer 333 CHAPTER 16 Concurrency Models Thread per Client Server The thread per client server concurrency model is very similar to the threaded server concurrency model except that the ORB allows one active thread per client in the user code This is shown in Figure 12 fQ p hO EX gt a Client A Thread per Client Client B Server Figure 12 Thread per Client Server A s call to and B s call to g are carried out simultaneously each in its own thread However if A tries to call another operation h for example by sending requests from different threads in a multi threaded client or by using the DII operation send_deferred in a single threaded client as long as has not finished yet the execution of h is delayed until returns The thread per client model is still efficient Like wit
145. d servers are started Note that members cannot be added automatically by the load balanced servers if the service is not running in administrative mode 5 Configure the load balancing strategy The set strategy Or set custom strategy commands of the 1badmin utility may be used to configure the group s load balancing strategy For example to use the least 1load strategy lbadmin ORBInitRef Balancer corbaloc lbhost 10000 Balancer 292 Programming Example set strategy least load tolerance 5 load per client 5 Note that the strategy may also be changed after the load balanced servers are started 6 Start the load balanced servers For example to start a server for the member with ID member1 run server ORBInitRef Balancer corbaloc lbhost 10000 Balancer member1 7 Create object references for use by the clients To create an object reference run lbmkref H lbhost 10001 Hello IDL Hello 1 0 Hello gt Hello ref Note that the object references created by the load balanced servers can also be used by the clients After all members have been registered and the load balancing strategy is configured it is recommended to restart the service in non administrative mode This will prevent any accidental or unauthorized modifications 293 CHAPTER 13 Orbacus Balancer 294 In this chapter CHAPTER 14 Orbacus Watson Orbacus Watson is a loadable module that provides request tracing capabilities based on
146. d to load alerts Orbacus Balancer provides utility objects that the developer may use to help implement this functionality The utility objects provided by Orbacus Balancer are part of the LoadBalancing Util module and are provided as initial services see The BootManager on page 138 Each utility object is described below For further detail refer to Appendix F and for an example refer to Adaptive Load Balancing on page 288 The LoadAlert object is used to manage load alerts sent by the service The name of the LoadAlert initial service is LoadAlert The LoadCalculator object is used by the LoadUpdater object see below to calculate the current load of the server which will be used as the load of each member registered with the LoadUpdater object The implementation provided by the service calculates the load based on the number of active requests The LoadUpdater object is used to manage load updates sent to the Balancer At regular intervals the LoadUpdater object gets the load from the LoadCalculator object and pushes it to the load balanced group of each registered member Utilities Utility Object Configuration Properties ooc balancer util create_alert ooc balancer util create_calculat or ooc balancer util create_updater ooc balancer trace alert_expire ooc balancer trace load_update The Orbacus Balancer utility objects support the following properties Value true false If set to
147. e numeric port N backlog N Specifies the maximum length of the listen backlog queue Note that the operating system may have a smaller limit which will override this value If not specified a default value of 50 is used in Java and 5 in C bind ADDR Specifies the hostname or dotted decimal address of the network interface on which to bind the socket If not specified the socket will be bound to all available interfaces This option is useful in situations where a host has several network interfaces but the server should only listen for connections on a particular interface host ADDR ADDR Specifies a list of one or more hostnames and or dotted decimal addresses representing the addresses that should be advertised in IORs Using IIOP 1 0 or 1 1 multiple addresses are represented as multiple tagged profiles Using IIOP 1 2 multiple addresses can be represented as either multiple tagged profiles or as a single tagged profile with a tagged component for each additional address The multi profile option determines how multiple addresses are represented in IIOP 1 2 If host is not specified the canonical hostname is used multi profile If set multiple addresses in the host option are represented as multiple tagged profiles in an IOR By default multiple addresses are represented as a single tagged profile using the first address in the host list as the primary address with all addition
148. e After starting the Event Service server you can start these clients in any order The demo applications obtain the initial Event Service reference as already demonstrated i e by calling resolve initial references When started each supplier provides information about the current date and time and each client displays the event data in its console window This is the push supplier s main loop 1 Java 2 while consumer_ null 5 4 java util Date date new java util Date 5 String s PushSupplier says date toString 6 7 Any any orb_ create_any 8 any insert_string s 9 10 try ai 12 consumer_ push any 13 i 14 catch Disconnected ex 15 16 Supplier was disconnected from event channel Ly 18 19 try 20 21 Thread sleep 1000 22 23 catch InterruptedException ex 24 25 26 4 8 The current date and time is inserted into the any 247 CHAPTER 11 Orbacus Events 248 10 17 19 25 4 8 13 19 The event data in this example date and time are pushed to the event channel From the push supplier s view the event channel is just a consumer implementing the Pushconsumer interface After sleeping for one second the steps above are repeated The example s pull supplier works similarly to the push supplier except that the event channel explicitly polls the supplier for new events This is done by either pull or try_pull The pull supplier does
149. e Naming Service in the string to object operation The corbaname URL extends the capabilities of the corbaloc URL to allow the object key to identify a binding in a Naming Service For example consider this URL corbaname ns1 5001 NameService ctx MyObject When the ORB interprets this URL it attempts to resolve a naming context object located at host ns1 on port 5001 and having the object key NameService Once the naming context has been resolved the ORB attempts to lookup the binding named Myobject in the naming context ctx If successful the result of string to object is the object reference associated with the binding 135 CHAPTER 5 Locating Objects file URLs 136 A file URL provides a convenient way to obtain object references using an IOR or URL reference that is in a file The format of a file URL is file lt absolute file name gt Using the file URL and given that the file object ref is located in the tmp directory the client side example of on page 129 may be simplified as follows C CORBA ORB var orb Get a reference to the ORB somehow CORBA Object_var obj orb gt string to object file tmp object ref B var b B _narrow obj Tava org omg CORBA ORB orb Get a reference to the ORB somehow org omg CORBA Object obj orb string_ to object file tmp object ref B b BHelper narrow obj Object Reference URLs relfile URLs Orbacus also provides th
150. e Logging facility output to multiple devices e Documentation Tools Translators see Orbacus Translators on page 28 IDL to Hypertext Markup Language HTML IDL to Rich Text Format RTF e JThreads C Java like threading for C See the Orbacus JThreads User Guide Qualities of Service e Load Balancing balance client requests across a set of replicated objects and stateless servers XV PREFACE CORBA features xvi Fault Tolerance transparent failover by implementing multiple profile Interoperable Object References Active Connection Management reclaim idle connections automatically conserving threads sockets memory and other important system resources Security FreeSSL plug in provides secure authentication and encryption facilities See the Orbacus FreeSSL User Guide Concurrency Single and Multithreaded models to exploit power of multiprocessor hardware Dynamic Loading Of Modules transparently install extensions and services such as transactions interceptors and protocol plug ins Flexibility through pluggable transport protocols See The Open Communications Interface on page 341 CORBA 2 5 support CORBA Services e Naming Events and Property services are part of the Orbacus product e Orbacus interoperates with the Orbix Notification Orbix Trader and Orbix Telecom Logging services Portable Interceptors provide a hook for adding code that is called upon fo
151. e generated class extends the POA class of the interface For IDL valuetypes a class is generated in the same package as the valuetype with the suffix valueFactory_imp1 You must not use no skeletons in combination with this option impl tie Similar to imp1 but implementation classes for interfaces implement the Operations interface to facilitate the use of TIE classes You must not use no skeletons in combination with this option with interceptor args Generate code with support for arguments result and exception list values for interceptors Note that use of this option will generate proprietary stubs and skeletons which are not compatible with ORBs from other vendors 1 Prefix refers to the value of the pragma prefix statement in an IDL file For example the statement pragma prefix ooc com defines ooc comas the prefix The prefix is included in the Interface Repository identifiers for all types defined in the IDL file 34 Translating IDL to HTML Translating IDL to HTML Synopsis Description Options for hidl hidl options idl files Creates HTML files from IDL files An HTML file is generated for each module and interface defined in an IDL file Comments in the IDL file are preserved and javadoc style keywords are supported The section Documenting IDL Files on page 41 provides more information h help v version d debug DNAME DNAME DEF UNAME IDIR all
152. e is shown below h help Display this information add oad host Register an OAD for the specified host add server server name exec host Register a server under the OAD specified by host with the given exec attribute add poa server name poa name Register a POA for the specified server remove oad host Unregister an OAD remove server Server name Unregister a server remove poa Se ver name poa name Unregister a POA get oad status host Get the status of an OAD get server info server name Get the attributes and state information for a server get poa status server name poa name Get the status of a POA list oads List all OADs list servers List all servers list poas server name List all POAs tree Display all OADs servers and POAs in a tree like format tree oad host Display an OAD and its associated servers and POAs in a tree like format tree server Server name Display a server and its associated POAs in a tree like format Making References Utilities set server Server name exec host args rundir mode activate_poas update_timeout failure timeout max_spawns value Set an attribute of a server e g set server srv max_spawns 2 sets the max_spawns attribute for the server srv to 2 start server server name Start a server
153. e proprietary relfile URL This URL is the same as the file URL except that it takes a relative file name instead of an absolute file name 137 CHAPTER 5 Locating Objects The BootManager 138 Consider the following corbaloc URL corbaloc myhost 10000 MyObjectId In this example MyObjectid is the complete object key Normally object keys require more information than a simple name to uniquely identify a POA and a servant within the POA The CORBA specification does not standardize how a server can configure these simple object keys therefore each ORB implementation must provide a proprietary solution In Orbacus the BootManager provides the mapping from a simple object key to a complete object reference The BootManager BootManager Interface Here is the IDL interface for the BootManager module OB local interface BootManager exception NotFound exception AlreadyExists void add_binding in PortableServer ObjectId oid in Object obj raises AlreadyExists void remove _binding in PortableServer ObjectId oid raises Not Found We We For the complete IDL description please see Appendix A 139 CHAPTER 5 Locating Objects How the BootManager Works 140 When an Orbacus server receives a request the ORB verifies that the key has the ORB s internal format If not the ORB will ask the BootManager if it has a mapping for the foreign key If a match is found the ORB will return
154. e reference and check for errors 29 31 36 38 63 65 73 75 Programming Example The PropertySetDefFactory object is used to create a PropertySetDef instance Note that PropertySetDef is a subclass of PropertySet Each property consists of a name and a value in the form of a CORBA any Three properties are defined The first has the name LongProperty and stores a long value The second one is called StringProperty and stores a string The remaining property represents a short value If for some reason a property cannot be created an exception is thrown Now we try to get a list of all the properties that were previously defined With get_all_ properties the PropertySetDef returns its properties As we have set the how_many parameter to O we have to use the PropertiesIterator for each item An application would normally provide a positive integer for how_ many The iterator has fulfilled its duty and can now be destroyed 229 CHAPTER 10 Orbacus Properties 230 In this chapter CHAPTER 11 Orbacus Events Some applications need to exchange information without explicitly knowing about each other Often a server isn t even aware of the nature and number of clients that are interested in the data the server has to offer A special mechanism is required that provides decoupled data transfer between servers and clients This requirement is addressed by the CORBA Event Service Orbacus Events is compliant wit
155. eated and is used to incarnate a CORBA object The object reference of the servant is stringified The stringified object reference is written to a file In Java the server code looks like this 1 Java 2 org omg CORBA ORB orb Get a reference to the ORB somehow 3 B impl biImpl new B impl 4 Bb bimpl this orb 5 String ref orb object_to_string b 6 java io PrintWriter out new java io PrintWriter 7 new java io FileOutputStream object ref 8 out printin ref 9 out close A servant for the interface B is created and is used to incarnate a CORBA object The object reference of the servant is stringified The stringified object reference is written to a file 129 CHAPTER 5 Locating Objects Now that the stringified object reference resides in a file our clients can read the file and convert the string to an object reference 1 C 2 CORBA ORB var orb Get a reference to the ORB somehow Seles Ere omn Wob yj EC ERESSE NE 4 string s 5 an ss 3 6 CORBA Object_var obj orb gt string to object s c_str 7 B var b B _narrow obj 3 5 The stringified object reference is read 6 string_to object creates an object reference from the string Since the return value of string to object is of type CORBA Object_ptr B narrow must be used to get a B ptr which is assigned to a self managed B var in this example 1 Java 2 org omg CORBA ORB
156. ecause other events aren t of interest After extracting the string it is displayed in the console window 249 CHAPTER 11 Orbacus Events 250 15 23 In contrast to the push consumer the pull consumer has to actively query the event channel for new events This is how the pull consumer loop looks 1 Java 2 while supplier_ null 3 d 4 Any any null 5 6 try zo d 8 any supplier _ pull 9 10 catch Disconnected ex 11 12 Supplier was diconnected from event channel 13 14 15 try 16 17 String s any extract_string 18 System out print1n s 19 20 catch MARSHAL ex 21 22 Ignore unknown event data 23 24 A CORBA Any is prepared for later use Using pu11 the consumer polls the event channel for new events The event channel acts as a pull supplier in this case The pull operation blocks until a new event is available The consumer expects a string wrapped in a CORBA any The string value is extracted and displayed If an exception is raised the any contained some other data type which is simply ignored In all of these examples the event channel acts either as a consumer if the clients are suppliers or a supplier if the clients are consumers of events Actually each client is not directly connected to the event channel but to a proxy that receives or sends events on behalf of the channel For more information on the Event Service and for the complete defi
157. ect id to bind obj The object reference Raises AlreadyExists Thrown if binding already exists remove_binding void remove _binding in PortableServer ObjectId oid raises NotFound Remove a binding from the internal table Parameters oid The object id to remove Raises Not Found Thrown if no binding found 402 Interface OB BootManager set_locator void set_locator in BootLocator locator Set the BootLocator The BootLocator is called when a binding for an object id does not exist in the internal table Parameters locator The BootLocator reference See Also Interface OB BootLocator 403 CHAPTER A Boot Manager Reference Interface OB BootLocator local interface BootLocator Interface used by BootManager to assist in locating objects See Also Interface OB BootManager Operations locate void locate in PortableServer ObjectId oid out Object obj out boolean add raises BootManager Not Found Locate the object corresponding to the given object id Parameters oid The object id obj The object reference to associate with the id add Whether the binding should be added to the internal table Raises Not Found Raised if no binding found 404 In this appendix APPENDIX B Orbacus Policy Reference This appendix describes the Orbacus Policy interfaces This appendix contains the following sections
158. ect_cb in ConnectCB cb Add a callback that is called whenever a new connection is established If the callback has already been registered this method has no effect Parameters cb The callback to add remove_connect_cb void remove_connect_cb in ConnectCB cb Remove a connect callback If the callback was not registered this method has no effect Parameters cb The callback to remove Module OCI Interface OCI ConFactoryRegistry Operations local interface ConFactoryRegistry A registry for Connector factories See Also Interface OCI Connector Interface OCI ConFactory add_factory void add_factory in ConFactory factory raises FactoryAlreadyExists Adds a Connector factory to the registry Parameters factory The Connector factory to add Raises FactoryAlreadyExists If a factory already exists with the same plugin id as the given factory get_factory ConFactory get_factory in PluginId id raises NoSuchFactory Returns the factory with the given plugin id Parameters id The plugin id Returns The Connector factory Raises NoSuchFactory If no factory was found with a matching plugin id get_factories ConFactorySeq get_factories Returns all registered factories Returns The Connector factories 453 CHAPTER E Open Communications Interface Reference Interface OCI Acceptor Attributes Operations 454 local inter
159. ed 387 CHAPTER 18 Exceptions and Error Messages MARSHAL Minor Exception Code 388 MinorNoValueFactory Unable to locate value factory MinorDSTResultBeforeContext DSI result cannot be set before context MinorDSTInvalidParameterList DSI argument list does not describe all parameters MinorLocalObject Attempt to marshal local object MinorWcharSentByClient wchar data sent by client on GIOP 1 0 connection MinorWcharSentByServer wchar data returned by server on GIOP 1 0 connection MinorReadOverflow Input stream buffer overflow MinorReadBooleanOverf low Overflow while reading boolean MinorReadCharOverf low Overflow while reading char MinorReadWCharOverf low Overflow while reading wchar MinorReadOctetOverflow Overflow while reading octet MinorReadShortOverf low Overflow while reading short MinorReadUShortOverflow Overflow while reading ushort MinorReadLongOverf low Overflow while reading long MinorReadULongOverf low Overflow while reading ulong MinorReadLongLongOverflow Overflow while reading longlong MinorReadULongLongOverf low Overflow while reading ulonglong MinorReadFloatOverflow Overflow while reading float MinorReadDoubleOverflow Overflow while reading double MinorReadLongDoubleOverf low Overflow while reading longdouble Mino
160. ed for sending and receiving octet streams to and from the client Parameters block If set to TRUE the operation blocks until a new connection has been accepted If set to FaLSE the operation returns a nil object reference if there is nO new connection ready to be accepted Returns The new Transport object Raises COMM FAILURE In case of an error connect_self Transport connect_self Connect to this acceptor This operation can be used to unblock threads that are blocking in accept Returns The new Transport object Raises TRANSIENT If the server cannot be contacted COMM FAILURE In case of other errors 455 CHAPTER E Open Communications Interface Reference 456 add_profiles void add profiles in ProfileInfo profile info inout IOR ref Add new profiles that match this Acceptor to an IOR Parameters profile_info The basic profile information to use for the new profiles ref The IOR get_local_profiles ProfileInfoSeq get_local_profiles in IOR ref From the given IOR get basic information about all profiles for which are local to this Acceptor Parameters ref The IOR from which the profiles are taken Returns The sequence of basic information about profiles If this sequence is empty there is no profile in the IOR that is local to the Acceptor get_info AcceptorInfo get_info Returns the information object associated with the Acceptor Ret
161. ed when communicating with a broken ORB that expects a particular wide character code set and does not correctly support the negotiation of wide character code sets Value true false Enables transfers of wide characters IDL types wchar and wstring with IIOP 1 0 using Unicode as the code set This proprietary extension is required in order to exchange wide characters with Orbix E which only supports IIOP 1 0 The default is false Value max gt 0 53 CHAPTER 3 ORB and Object Adapter Initialization ooc orb id ooc orb modules ooc orb module name ooc orb native_cs ooc orb native_wcs 54 Specifies the maximum GIOP message size in bytes If set to O no maximum message size will be used If a message is sent or received that exceeds the maximum size the ORB will raise the IMP_LIMIT system exception Value id Specifies the identifier of the ORB to be used by the application Value string Specifies a comma separated list of modules to be loaded dynamically by the ORB The ORB locates the shared library for a module using a well known name 1ibname so UNIX 1ibname s1 HP UX or name a11 Windows where name is the module name The ORB then invokes the initialization function init_module_name in that shared library The initialization function takes no arguments and returns void A module initialization function will typically register an ORBInitializer which allows interceptors and initial ref
162. een used for some length of time is automatically released and expiration in which an object reference is only valid for a certain length of time after which a client must obtain a new reference The implementation of these solutions is beyond the scope of this manual 113 CHAPTER 4 CORBA Objects Obtaining the POA for a Servant 114 As mentioned in the previous sections every servant inherits a _default_poa function from its skeleton class The default implementation of this function returns the Root POA If you instantiate servants on anything but the Root POA you must override the function in the servant otherwise calls to_this will create incorrect object references Usually this involves remembering the POA reference for a servant in a private member variable and returning that reference from a call to default_poa If all servants for objects of a particular interface type use the same POA you can use a static member variable In C you can use an approach similar to the following if C class Product_impl public virtual POA Product public virtual PortableServer RefCountServantBase PortableServer POA_var poa_ public void Product_imp1 PortableServer POA_ptr poa poa_ PortableServer POA duplicate poa wondoajuwF WD HP H H FO PRR mB wN virtual PortableServer POA ptr _default_POA LY 18 PR au return PortableServer POA _ duplicate poa_ The co
163. eferences to the servant are held in the server the object will be eligible for garbage collection Here s our implementation of the factory 1 Java 2 public class Factory impl extends FactoryPOA 3i 4 public Product createProduct s d 6 Product_impl result new Product_impl orb_ 7 org omg PortableServer POA poa Get servant s POA 8 byte id Assign an ID 9 poa activate_object_with_id id result 10 return result this orb_ ial 2 Servant class Factory_imp1 is defined as an implementation of the Factory interface 4 11 The createProduct operation instantiates a new Product servant activates it with the POA and returns an object reference to the client 112 Caveats Factory Objects In these simple examples the factory objects do not maintain any references to the Product servants they create it is the responsibility of the client to ensure that it destroys a Product object when it is no longer needed This design has a significant potential for resource leaks in the server as it is quite possible that a client will not destroy its Product objects either because the programmer who wrote the client forgot to invoke destroy or because the client program crashed before it had a chance to clean up You should keep these issues in mind when designing your own factory objects 1 1 Two possible strategies for handling this issue include time outs in which a servant that has not b
164. embers MemberIdSeq list_members Enumerate the members destroy void destroy Destroy the load balanced group 481 CHAPTER F Orbacus Balancer Reference Interface LoadBalancing GroupFactory Operations 482 interface GroupFactory Used to create destroy and retrieve load balanced groups create Group create in GroupId group_id raises GroupExists Create a new load balanced group with the given id get Group get in GroupId group_id raises GroupNotFound Get the load balanced group with the given id list GroupIdSeq list List the set of existing load balanced groups shutdown void shutdown Shutdown the Balancer Module LoadBalancing Util Module LoadBalancing Util The definitions in this module provide the interface for the Orbacus Balancer utility objects that are provided by the Balancer These utility objects can be used to implement the features required by load balanced servers that use adaptive load balancing 483 CHAPTER F Orbacus Balancer Reference Interface LoadBalancing Util LoadAlert Operations 484 local interface LoadAlert Interface to manage load alerts sent by the Balancer alert void alert Forward the next request to the Balancer get_alert_expire unsigned long get_alert_expire Retrieve the alert expire time set_alert_expire void set_alert_expire in unsigned long millis Set the alert expire time
165. ems that arise with the life cycle of objects particularly in threaded servers We suggest that you use the tie approach only if you have no other option 2 Again you are free to choose whatever name you like This is just a recommendation Implementing Servants In contrast to the inheritance based approach it is not necessary for the class implementing 1 s operations i e I_impl_tie to be derived from a skeleton class Instead an instance of poa I tie delegates all operation calls to I_impl_tie as shown in Figure 3 POALI l POA tie delegates to _impl_tie Figure 3 Class Hierarchy for Delegation Implementation in C Here is our definition of I_imp1_tie C class I_impl tie public virtual void op _a throw CORBA SystemException virtual void op b throw CORBA SystemException virtual void op _i throw CORBA SystemException OI Aon PF WNP he I_impl tie is defined and not derived from any other class I_impl_tie must implement all of 1 s operations including inherited operations A servant class for 1 can then be defined using the I_skel_tie template 1 C 2 typedef POA I tie lt I impl tie gt I impl The servant class I_imp1 is defined as a template instance of POA I tie parameterized with I _impl tie 93 CHAPTER 4 CORBA Objects The tie template generated by the IDL compiler contains functions that permit you cha
166. ent Loop A server s event loop is entered by calling PoaManager activate on each POA Manager and then calling ORB run For example in Java Java org omg CORBA ORB orb Initialize the orb org omg PortableServer POAManager manager Get Root POA manager manager activate orb run And in C C CORBA ORB_ var orb Initialize the orb PortableServer POAManager var manager Get the Root POA manager manager gt activate orb gt run You can deactivate a server by calling ORB shutdown which causes ORB run to return For example consider a server that can be shut down by a client by calling a deactivate operation on one of the server s objects First the IDL code RIDE interface ShutdownObject he void deactivate 83 CHAPTER 3 ORB and Object Adapter Initialization 84 2 3 9 12 14 17 On the server side ShutdownObject can be implemented like this C class ShutdownObject_imp1 public POA ShutdownObject public PortableServer RefCountServantBase CORBA ORB_var orb_ wont ajuwnF WN BP public 10 ShutdownObject_imp CORBA ORB ptr orb 11 orb_ CORBA ORB _ duplicate orb 12 13 14 i5 virtual void deactivate throw CORBA SystemException 16 17 orb_ gt shutdown false 18 A servant class for Shutdownobject is defined For more information on how to implement servant classes
167. ent failure request can be reissued FREE MEM Cannot free memory INV_IDENT Invalid identifier syntax INV_FLAG Invalid flag was specified In this section CORBA System Exceptions INTF_REPOS Error accessing interface repository BAD CONTEXT Error processing context object OBJ_ADAPTER Failure detected by object adapter DATA CONVERSION Error in data conversion OBJECT NOT EXIST Non existent object references should be discarded TRANSACTION REQUIRED Active transaction context required TRANSACTION ROLLEDBACK Transaction has rolled back or is marked to be rolled back INVALID TRANSACTION Invalid transaction context INV_POLICY Invalid Policy CODESET INCOMPATIBLE Incompatible client and server native code sets REBIND Thrown on a OBJECT FORWARD or LOCATION FORWARD status depending on the RebindPolicy TIMEOUT Time to live period was exceeded TRANSACTION UNAVAILABLE Transaction service context could not be processed TRANSACTION _ MODE Mismatch between TransactionPolicy and current transaction mode BAD_QOS Object cannot support the required QOS In the following subsections the minor exception codes are presented Minor codes that are Orbacus specific are presented as MinorCodeName that is are tagged with the superscript This section describes the following minor exception codes INITIALIZE Minor
168. ent handler s handle unregister_handler void unregister_handler in EventHandler handler Remove an event handler from the Reactor Parameters handler The event handler to remove dispatch boolean dispatch in TypeMask type mask Dispatch events Parameters type_mask If not zero this operation will return once all registered event handlers that match the type mask have unregistered Returns TRUE if all event handlers that match the type mask have unregistered or FALSE if event dispatching has been interrupted interrupt_dispatch void interrupt _dispatch 423 CHAPTER C Reactor Reference 424 Interrupt event dispatching After calling this operation interrupt will return with FALSE dispatch_one_event boolean dispatch_one_event in long timeout Dispatch at least one event Parameters timeout The timeout in milliseconds A negative value means no timeout i e the operation will not return before at least one event has been dispatched A zero timeout means that the operation will return immediately if there is no event to dispatch Returns TRUE if at least one event has been dispatched or FALSE otherwise event_ready boolean event_ready Check whether an event is available Returns TRUE if an event is ready or FALSE otherwise In this appendix APPENDIX D Logger Reference This appendix describes the Orbacus Logger interfaces This appendix contains t
169. er the interaction between clients and the IMR is strictly specified by the GIOP specification so any client that is CORBA compliant may interact with the IMR When a server is using the IMR object references created by one of its persistent POAs refer to the IMR rather than to the server itself When the client makes a request using this reference the IMR receives the request activates the server if necessary using the OAD and returns a new object reference to the client that identifies the server at its current host and port The client then establishes a connection with the server using the new object reference and communicates directly with the server without the intervention of the IMR However should the server fail a well behaved client will contact the IMR again which may restart the server and allow the client to resume its activities 1 Binding refers to the process of opening a connection and associating an object reference with its servant 153 CHAPTER 6 The Implementation Repository Information Managed by the IMR OADs Servers 154 The IMR provides support for the indirect binding and automatic activation of servers within a given domain In order to provide this support the IMR manages three types of entities OADs servers and POAs An OAD is responsible for the activation of servers on a given host Each OAD is registered in the IMR using a host name The IMR also maintains the status of each
170. erences to be installed This property is only supported in C In Java the standard mechanism for installing an ORBInitializer should be used See 7 for more information on ORBInitializers Value string Specifies the name of a module s shared library or DLL In most cases this property is not necessary because the ORB attempts to locate the library using a well known name as described above for the coc orb modules property The value of this property can be a simple filename in which case the ORB will attempt to load the library using the search path or it can be an absolute pathname Value string Specifies the native character code set for the ORB The default is ISO 8859 1 Value string Specifies the native wide character code set for the ORB The default is UTF 16 ooc orb policy connect_timeout ooc orb policy connection_reuse ooc orb policy interceptor ooc orb policy locate_request ooc orb policy location_transpare ncy ooc orb policy protocol ooc orb policy rebind ooc orb policy request_timeout Configuring the ORB and Object Adapter Value timeout gt 1 Sets the oB ConnectTimeout Policy at the ORB level See Appendix B for more information on this policy The default value is 1 Value true false Sets the oB ConnectionReusePolicy at the ORB level See Appendix B for more information on this policy The default value is true Value true false Sets the oB
171. erver ServantBase var servant helloImpl PortableServer ObjectId_var oid PortableServer string to ObjectId hello helloPOA gt activate _object with id oid servant Hello var hello helloImpl gt tms O manager gt activate orb gt run return EXIT SUCCESS Check the arguments for the member ID Create the member policy The group ID will be Hello and the member ID is an argument of the program Create the member POA Create the Hello servant and activate it on the member POA The remainder of the run function is similar to that of Chapter 287 CHAPTER 13 Orbacus Balancer Adaptive Load Balancing 288 To use adaptive load balancing the Hello server must send load updates to the service and react to load alerts The Orbacus Balancer utility objects will be used to help implement this functionality The modified server program is shown below 1 C 2 include lt OB CORBA h gt 3 include lt OB Balancer init h gt 4 include lt OB BalancerUtil init h gt 5 include lt OB Balancer_skel h gt 6 include lt Hello_impl h gt ni 8 class LoadAlert_impl 9 virtual public POA LoadBalancing LoadAlert 10 virtual public PortableServer RefCountServantBase ii 4 12 LoadBalancing Util LoadAlert_var alert_j 13 14 public 15 LoadAlert_imp1 LoadBalancing Util LoadAlert_ptr alert 16 8 alert _ LoadBalancing Util LoadAlert duplicate alert 17 18 19
172. erver together with a Java client or vice versa This is one of the primary advantages of using CORBA if something is defined in CORBA IDL the programming language used for the implementation is irrelevant CORBA applications can talk to each other regardless of the language they are written in 23 CHAPTER 1 Getting Started Summary What have we learnt 24 At this point you might be inclined to think that this is the most complicated method of printing a string that you have ever encountered in your career as a programmer At first glance a CORBA based approach may indeed seem complicated On the other hand think of the benefits this kind of approach has to offer You can start the server and client applications on different machines with exactly the same results Regarding the communication between the client and the server you don t have to worry about platform specific methods or protocols at all provided there is a CORBA ORB available for the platform and programming language of your choice If possible get some hands on experience and start the server on one machine the client on another As you will see CORBA based applications run interchangeably in both local and network environments One last point to note you likely won t be using CORBA to develop systems as simple as our Hello World example The more complex your applications become and today s applications are complex the more you will learn
173. es 138 148 Configuring 145 Resolving 143 Interface Repository 251 IP Address 349 351 irdel 258 irfeed 258 J javadoc 43 N Names Console 205 Name Service Configuration 187 Initialization 195 Persistence 188 0 OAD 153 Object Activation Daemon 153 Object Adapter Configuration 59 Initialization 50 Object Key 127 Object References 120 Objects Locating 119 Persistent 106 Transient 106 OCI 341 Acceptor 342 Acceptor Factory 342 Bi directional Plug in 367 Connector 342 Connector Factory 342 IIOP Plug in 353 358 367 Info Objects 343 Registries 342 Transport 342 Open Communications Interface 341 Options hidl 35 irgen 38 489 INDEX jidl 33 ridl 36 ORB Configuration 52 Destruction 82 ORBacus Names 181 P POA 87 156 POA Manager 71 Root POA Manager 72 Policies 301 ACMTimeoutPolicy 303 BidirectionalPolicy 303 ConnectionReusePolicy 303 ConnectTimeoutPolicy 303 InterceptorCallPolicy 305 InterceptorPolicy 304 LocationTransparencyPolicy 304 ProtocolPolicy 304 RequestTimeoutPolicy 304 RetryPolicy 305 TimeoutPolicy 305 Popup Menu 217 Port 126 347 Portable Object Adapter 87 Programming Examples Event Service 247 Implementation Repository 170 282 Interface Repository 259 Name Service 194 OCI 345 Policies 306 Property Service 227 Properties ooc config 52 ooc event max_events 235 ooc event max_retries 235 ooc event port 235 ooc event pull_interval 235 ooc event retry_multiplier 235 ooc e
174. es of items such as classes functions variables and data structures For example text might refer to the CORBA Object class Constant width paragraphs represent code examples or information a system displays on the screen For example include lt stdio h gt Italic Italic words in normal text represent emphasis and new terms Italic words or characters in code and commands represent variable values you must supply such as arguments to commands or path names for your particular system For example cd users your_name Note Some command examples may use angle brackets to represent variable values you must supply This is an older convention that is replaced with italic words or characters xviii PREFACE Keying conventions This guide may use the following keying conventions No prompt When a command s format is the same for multiple platforms a prompt is not used A percent sign represents the UNIX command shell prompt for a command that does not require root privileges A number sign represents the UNIX command shell prompt for a command that requires root privileges The notation gt represents the DOS or Windows command prompt Horizontal or vertical ellipses in format and syntax descriptions indicate that material has been eliminated to simplify a discussion Brackets enclose optional items in format and syntax descriptions Braces enclose a list from which you must choose an item
175. essed by the IIOP plug in the endpoint configuration property will be ooc orb oa endpoint iiop port 5555 iiop port 5556 Note that there are now two endpoints the command line options resulted in an additional endpoint being appended to the existing property value 79 CHAPTER 3 ORB and Object Adapter Initialization Dispatching Requests As explained in 4 a POA Manager is initially in the holding state where incoming requests on the POA Manager s endpoints are queued To dispatch requests the POA Manager must be activated using the activate operation 80 Callbacks Using POA Managers In mixed client server applications in which callbacks occur it is important to remember that callbacks will not be dispatched until the POA Manager has been activated If the POA Manager has not been activated the application will likely hang In general applications should activate the POA Manager prior to making any request that might result in a callback 81 CHAPTER 3 ORB and Object Adapter Initialization ORB Destruction 82 Applications must destroy the ORB before returning from main so that resources used by the ORB are properly released To destroy the ORB in C invoke destroy on the ORB C CORBA ORB var orb Initialize the orb WIP oe orb gt destroy And in Java Java org omg CORBA ORB orb Initialize the orb TE ove orb destroy Server Event Loop Server Ev
176. euse policy is set to true at some later point communications channels that were previously created with a connection reuse policy set to false will not be reused That is the connection reuse policy is sticky in the sense that the reuse policy that was in effect at the time that a communications channel is created stays with it Setting the reuse policy at the object level means that for a client the ORB will not reuse the communications channel that is associated with the proxy object Our first example shows how the connection reuse policy can be set at the ORB level First in C I C CORBA Any boolAny boolAny lt lt CORBA Any from_boolean 0 CORBA PolicyList policies policies length 1 policies 0 orb gt create _ policy OB CONNECTION REUSE POLICY ID boolAny CORBA Object_var pmObj orb gt resolve_initial_ references ORBPolicyManager 10 CORBA PolicyManager_ var pm tal CORBA PolicyManager _ narrow pmObj 12 pm gt set_policy overrides policies CORBA ADD OVERRIDE wa Idan WN PH Create an any and insert the value O false Create a sequence containing one policy object 307 CHAPTER 15 Using Policies Connection Reuse Policy at Object Level 308 6 7 Ask the ORB to create a connection reuse policy Pass the any that contains the value for this policy 8 10 Obtain the ORB level policy manager object 12 Add the policies to the ORB level policy manager
177. ewer with the title NamingService To enable tracing information add the desired trace configuration property i e the ooc naming trace_level property or one of the coc orb trace properties to the HKEY LOCAL MACHINE NT registry key with a REG_sz value of at least 1 Configuration Properties In addition to the standard configuration properties described in Chapter 3 Orbacus Names also supports the following properties Configuration Properties ooc naming callback_timeout SECS Equivalent to the c command line option ooc naming database FILE Equivalent to the d command line option ooc naming no updates Equivalent to the n command line option ooc naming endpoint ENDPOINT Specifies the endpoint configuration for the service Note that this property is only used if the ooc orb oa endpoint property is not set ooc naming timeout MINS Equivalent to the t command line option ooc naming trace_level LEVEL Defines the output level for diagnostic messages printed by Orbacus Names The default level is O which produces no output A level of 1 or higher produces messages related to database operations a level of 2 or higher produces messages related to adding and removing listeners and a level of 3 or higher produces messages related to binding operations 187 CHAPTER 8 Orbacus Names Persistence 188 Orbacus Names can optionally be used in a persistent mode in which all data mana
178. face Acceptor An interface for an Acceptor object which is used by CORBA servers to accept client connection requests It also provides operations for the management of IOR profiles See Also Interface OCI AccFactoryRegistry Interface OCI AccFactory Interface OCI Transport id readonly attribute PluginId id The plugin id tag readonly attribute ProfileId tag The profile id tag handle readonly attribute Handle handle The handle for this Acceptor Like with the handle for Transports the handle may only be used with operations like select A handle value of 1 indicates that the protocol plug in does not support selectable Transports close void close Closes the Acceptor accept or listen may not be called after close has been called Raises COMM FAILURE In case of an error shutdown void shutdown Module OCI Shutdown the Acceptor After shutdown the socket will not listen to further connection requests Raises COMM FAILURE In case of an error listen void listen Sets the acceptor up to listen for incoming connections Until this method is called on the acceptor new connection requests should result in a connection request failure Raises COMM FATLURE In case of an error accept Transport accept in boolean block Used by CORBA servers to accept client connection requests It returns a Transport object which can be us
179. fect Parameters 447 CHAPTER E Open Communications Interface Reference cb The callback to remove 448 Module OCI Interface OCI ConnectCB local interface ConnectCB An interface for a connect callback object See Also Interface OCI Connector nfo Operations connect_cb void connect_cb in TransportInfo transport_info Called after a new connection has been established If the application wishes to reject the connection CORBA NO_PERMISSION may be raised Parameters transport_info The TransportInfo for the new connection 449 CHAPTER E Open Communications Interface Reference Interface OCI ConFactory Attributes Operations 450 local interface ConFactory A factory for Connector objects See Also Interface OCI Connector Interface OCI ConFactoryRegistry id readonly attribute PluginId id The plugin id tag readonly attribute ProfileId tag The profile id tag describe_profile string describe profile in IOP TaggedProfile prof Returns a description of the given tagged profile Parameters prof The tagged profile Returns The profile description create_connectors ConnectorSeq create_connectors in IOR ref in CORBA PolicyList policies Returns a sequence of Connectors for a given IOR and a list of policies The sequence includes one or more Connectors for each IOR profile that matches this Connector factory and satisfies the l
180. finition of the constructor and _default_poa method follow 1 C 2 Hello impl Hello impl PortableServer POA ptr poa 3 poa_ PortableServer POA _duplicate poa a 5 6 7 PortableServer POA ptr Hello impl _default_POA 8 9 return PortableServer POA duplicate poa_ 10 The modified server program is shown below 1 C 2 include lt OB CORBA h gt 3 include lt OB Balancer_init h gt 4 include lt Hello_impl h gt 5 6 int run CORBA ORB ptr int char Wi 8 int main int argc char argv 9 10 int status EXIT SUCCESS 11 CORBA ORB var orb 12 13 try 14 15 LoadBalancing LB_init 16 orb CORBA ORB_init argc argv 17 status run orb argc argv 18 19 catch const CORBA Exception amp 20 Dale status EXIT_FAILURE 22 23 284 15 Programming Example 24 if CORBA is_ nil orb 25 26 try 2 28 ide desero 29 30 catch const CORBA Exception amp Sil 32 status EXIT FAILURE 33 34 25 36 return status 37 Include the header file that declares the Orbacus Balancer initialization function This header file also includes the header files oB Balancer h and OB BalancerPolicyTypes h which contain the definitions necessary for non adaptive load balancing Invoke LoadBalancing LB init This function initializes the server for load balancing and must be called before initializing the ORB 285
181. for the servant A_imp1 is decremented which leads to the destruction of the servant geta returns an object reference to the a_imp1 servant implicitly creating and activating the CORBA object if necessary 121 CHAPTER 5 Locating Objects 122 2 4 6 21 11 15 17 20 In Java the interfaces can be implemented like this 1 Java 2 public class A impl extends APOA a fl a 5 6 public class B_impl extends BPOA 7l 8 org omg CORBA ORB orb _ 9 A impl a _ 10 Wa public B_imp1 org omg CORBA ORB orb 12 13 orb orb 14 a_ new A impl 15 16 17 A getA 18 U9 return a_ _this orb_ 20 The servant class A_imp1 is defined which inherits from the skeleton class APOA The servant class B_imp1 is defined which inherits from the skeleton class BPOA B_imp1 s constructor stores a reference to the orb and creates a new A impl servant geta returns an object reference to the a_imp1 servant implicitly creating and activating the CORBA object if necessary A client written in C could use code like the following to get references to A C B var b Get a B object reference somehow A var a b gt getA And in Java Java Bbe Get a B object reference somehow Aa b getA Obtaining Object References In this example once your application has a reference to a B object it can obtain a reference to an a object using geta The question that arises
182. g Object References Using CORBA an object can obtain a reference to another object in a multitude of ways One of the most common ways is by receiving an object reference as the result of an operation as demonstrated by the following example Ae TDs interface A he interface B A getA he woaIdtnajnFFWNE 2 4 An interface a is defined 6 9 An interface B is defined with an operation returning an object reference to an a 120 2 5 7 28 14 17 19 22 24 27 Obtaining Object References On the server side a and B can be implemented in C as follows DCT 2 class A impl public POA A 3 public PortableServer RefCountServantBase 4 d 5 A 6 7 class B_impl public POA B 8 public PortableServer RefCountServantBase 9 10 A impl a aal 12 public 13 14 B impl I5 16 a_ new A impl 17 18 19 B_impl1 20 21 a a Aae saz 22 23 24 virtual A ptr getA throw CORBA SystemException 25 26 recurnko mi _telaulis By 28 The servant class A_imp1 is defined which inherits from the skeleton class poA A and the class RefCountServantBase which provides a reference counting implementation The servant class B_imp1 inherits from the skeleton class poa B and the reference counting class RefCountServantBase An instance of the servant class A_imp1 is created in the constructor for B_impl In the destructor for B_imp1 the reference count
183. garding the formatting of GIOP 1 2 LocateReply messages Orbacus uses the correct formatting as of version 4 1 Unfortunately all versions of Orbacus 4 0 x use the incorrect formatting as do some other ORB implementations As a result the default value of this policy is false which means the ORB will not send LocateRequest messages and therefore will not receive improperly formatted replies OB LocationTransparencyPolicy This policy determines how strictly the ORB will enforce location transparency The default behavior is relaxed An application may wish to sacrifice performances to have strict CORBA compliance for local invocations OB ProtocolPolicy This policy allows an application to influence how the ORB orders and filters the profiles of an object reference The value of the policy is a list of transport plug in identifiers which determine the preferred order in which the ORB should attempt to establish connections Only those profiles which match an entry in the list will be used If no profile from the object reference matches a transport in the list or the ORB was unable to establish a connection then a TRANSIENT exception is raised OB RequestTimeoutPolicy If an object has this policy and no response is available for a request after value milliseconds a CORBA NO_RESPONSE exception is raised Table 4 Supported Policies Orbacus policies Policy Description OB RetryPolicy
184. ged by the service is saved in a file If you do not run the service in its persistent mode all of the data will be lost when the service terminates It is also important to note that when using the service in its persistent mode you should always start the service on the same port see Chapter 3 for more information Connecting to the Service Connecting to the Service The object key of the Naming Service is NameService which identifies an object of type CosNaming OBNamingContext The OBNamingContext interface is derived from the standard interface CosNaming NamingContextExt and provides additional Orbacus specific functionality For a description of the oBNamingContext interface please refer to the documented IDL file naming id1 oBNaming idl The object key can be used when composing URL style object references For example the following URL identifies the naming service running on host nshost at port 10000 corbaloc nshost 10000 NameService Refer to Chapter 5 for more information on URLs and configuring initial services 189 CHAPTER 8 Orbacus Names Using the Naming Service with the IMR The Naming Service may be used with the Implementation Repository IMR However if used with the IMR it is important to note that the corbaloc URL style object reference described in the previous section cannot be used If the IMR is used then the object reference for the Naming Service must be created using one of the follow
185. generating and accepting events are called suppliers and consumers respectively Suppliers and consumers each come in two different versions namely push suppliers and pull suppliers and push consumers and pull consumers What s the difference between pushing events and pulling events Let s have a look at the consumer side first Some consumers must be immediately informed when new events become available on an event channel Such consumers usually act as push consumers They implement the PushConsumer interface which ensures that the event channel actively forwards events to them using the push operation jie SEDI interface PushConsumer void push in any data raises Disconnected void disconnect_push_consumer he Push consumers are passive that is are servers Conversely pull consumers are active that is are clients Pull consumers poll an event channel for new events As events may arrive at a greater rate than they are polled for by a pull consumer or accepted and processed by a push consumer some events might get lost A buffering policy implemented by the event channel determines whether events are buffered and what happens in case of an event queue overflow Like consumers suppliers can also use push or pull behavior Push suppliers are the more common type in which the supplier directly forwards data to the event channel and thus plays the client role in the link to the channel Pull suppliers on the
186. getting a member to forward the next client request back to the service Load re balancing is useful when the loads of the members become imbalanced Through load re balancing these imbalances can be corrected resulting in a higher average throughput Several factors may contribute to a load imbalance e Clients not generating a consistent load while connected e Clients not connected for the same amount of time e Heterogeneous hosts e Non dedicated hosts e Member selection errors For effective load re balancing we must be able track client connections and the load generated by each connection However the concept of a connection is hidden from the CORBA developer so in general all that is Choosing a Load Balancing Strategy Load Balancing Strategies available is the load for each member of the load balanced group Hence we must make certain approximations when making load re balancing decisions For these approximations to hold the following assumptions must made e The average load created by a client can be reliably estimated e The load created by a client does not deviate much from the average load e Dedicated hosts e Homogeneous hosts Since load re balancing decisions are based on approximations that will only be reasonable when certain conditions are meant there is always the chance of a load re balancing error Let us say that a load re balancing error occurs when the load that is transferred from
187. gister the member with the LoadUpdater The remainder of the run function is the same as in section Non adaptive Load Balancing on page 283 291 CHAPTER 13 Orbacus Balancer Running the Load Balanced Servers In this section we present the step required to set up the Orbacus Balancer for the Hello World load balanced servers We will assume that Orbacus has been installed in the directory usr local Orbacus and the executables balancer lbadmin and lbmkref all exist in a directory that is in the search path The steps are as follows 1 Create a configuration file for Orbacus Balancer containing the following balancer conf ooc balancer admin_endpoint iiop port 10000 ooc balancer forward_endpoint iiop port 10001 ooc balancer dbdir usr local Orbacus db This file is placed in the usr local Orbacus etc directory 2 Start the service in administrative mode balancer ORBconfig usr local Orbacus etc balancer conf administrative 3 Create the load balanced group Before starting the load balanced servers the associated load balanced group must be created This can be done using the 1badmin utility as follows lbadmin ORBInitRef Balancer corbaloc lbhost 10000 Balancer create group Hello Where lbhost is the host running the service 4 Add the members The members can be added to the group explicitly using the add member command of the lbadmin utility or they can be added automatically when the load balance
188. h 9 This chapter does not provide a complete description of the service It only provides an overview suitable to get you started For more information please refer to the specification This chapter contains the following sections Usage page 232 Connecting to the Service page 237 Using the Event Service with the IMR page 238 Event Service Concepts page 239 Programming Example page 247 231 CHAPTER 11 Orbacus Events Usage Orbacus includes functionally equivalent implementations of the Event Service in C eventserv h help v version i ior t typed service u untyped service and Java com ooc CosEvent Server h help v version i ior t typed service u untyped service Options h Display the command line options supported by the help server v Display the version of the server version e Print the stringified IOR of the server to standard output SS LOK t Run a typed event service typed service u Run an untyped event service This is the default untyped service behavior 232 Usage Windows NT Native Service The C version of Orbacus Events is also available as a native Windows NT service nteventservice h help i install s start install1 u uninstall d debug h Display the command line options supported by the server help i Install the service The service must be started
189. h a great deal of flexibility e endpoints can be activated and deactivated on demand e a group of endpoints can be controlled using a single POA Manager and serviced by one or more POAs This section contains the following sections The Root POA Manager page 72 Anonymous POA Managers page 73 The POA Manager Factory page 74 Creating a POA Manager page 75 POA Manager Policies page 77 Endpoints page 78 Command line Options and Endpoints page 79 Dispatching Requests page 80 Callbacks page 81 71 CHAPTER 3 ORB and Object Adapter Initialization The Root POA Manager As its name suggests the Root POA Manager is the POA Manager of the Root POA When the Root POA is first resolved using resolve initial references the Root POA Manager is automatically created to manage the Root POA For administrative purposes the name of the Root POA Manager is RootPOAManager 72 Using POA Managers Anonymous POA Managers An application can implicitly create POA Managers by supplying a nil value for the POA Manager argument to the create _Poa operation In fact this is the only portable means of creating POA Managers In this text we ll refer to POA Managers created in this way as anonymous POA Managers One limitation of anonymous POA Managers in Orbacus is that their endpoints cannot be configured externally via properties therefore anonymous POA Managers always use the default endpoin
190. h the IMR e Start the Property Service with the options ior ORBServerId PropertyServer causing the Property Service to print its reference to standard output e Use the mkref utility mkref PropertyServer PropertyService PropertyServicePOA When using the Property Service with the IMR the service must be started with the option oRBServerId PropertyServer where PropertyServer refers to the server name configured with the IMR When the IMR is configured to start the Property Service this option is automatically added to the service s arguments However when the Property Service is started manually the option must be present For further information on configuring a service with the IMR refer to Getting Started with the Implementation Repository on page 167 222 Creating Properties Creating Properties A property handled by the CORBA Property Service consists of two components the property s name and its value The name is a CORBA string and the associated value is represented by a CORBA Any Hit Toi typedef string PropertyName struct Property PropertyName property name any property value he New properties are created using a factory object implementing the PropertySet interface A new property is created using the define property operation IDL void define property in PropertyName in any property value raises InvalidPropertyName ConflictingProperty UnsupportedTypeCode UnsupportedPro
191. h the threaded concurrency model no threads need to be created except when new connections are accepted 334 Multi Threaded Concurrency Models Thread per Request Server If the thread per request server concurrency model is chosen the ORB creates a new thread for each request This is shown in Figure 13 f gl h a lt T T T T Client A Thread per Request Client B Server Figure 13 Thread per Request Server For simplicity there are no separate arrows for dispatch and thread creation in the diagram With the thread per request model requests are never delayed When they arrive a new thread is created and the request is executed in the user code using this thread On return the thread is destroyed Besides using a reactive client together with a reactive server the thread per request server in combination with a threaded client is the only other model that allows nested method calls with an unlimited nesting level The thread pool model also allows nested method calls but the nesting level is limited by the number of threads in the pool The thread per request concurrency model is inefficient The main problem results from the overhead involved in creating new threads namely one for each request 335 CHAPTER 16 Concurrency Models Thread Pool Server 336 The thread pool model uses threads from a pool to carry out re
192. hannelNotAvailable interface EventChannelFactory CosEvent ChannelAdmin EventChannel create_channel in ChannelId id raises ChannelAlreadyExists CosEvent ChannelAdmin EventChannel get_channel by id in ChannelId id raises ChannelNotAvailable ChannelIdSeq get_channels void shutdown Event Service Concepts The oBTypedEvent Channel Factory TypedEvent ChannelFactory interface describes the factory for typed event channels J Tbe module OBTypedEventChannelFactory interface TypedEventChannelFactory CosTypedEventChannelAdmin TypedEventChannel create_channel in OBEventChannelFactory ChannelId id raises OBEventChannelFactory ChannelAlreadyExists CosTypedEventChannelAdmin TypedEvent Channel get_channel by id in OBEventChannelFactory ChannelId id raises OBEventChannelFactory ChannelNotAvailable OBEventChannelFactory ChannelIdSeq get_channels void shutdown We HR At start up the untyped Event Service creates a single channel having the identifier DefaultEventChannel and the typed Event Service creates a single channel having the identifier Default TypedEvent Channel A channel s identifier also serves as its object key therefore a channel can be located using a corbaloc URL see corbaloc URLs on page 133 For example a channel with the identifier TelemetryData can be located on the host myhost at port 2098 using the following URL c
193. hat invokes a say_hello operation on an object in a server program The server responds by printing Hello World on its standard output Defining the Example in IDL Defining the Example in IDL CORBA based program How do we write a CORBA based Hello World program The first step is to create a file containing our IDL definitions Since our example application isn t a complicated one the IDL code needed for this example is simple Save the IDL code shown below to a file called Hello idl Lo f f Tei 2 interface Hello 3 4 void say_hello 5 An interface with the name Hello is defined An IDL interface is conceptually equivalent to a pure abstract class in C or to an interface in Java The only operation defined is say_hello which neither takes any parameters nor returns any result CHAPTER 1 Getting Started Implementing the Example in C Generating C from IDL The next step is to translate the IDL code to C using the IDL to C translator Translate the code in Hello id1 to C using the following command idl Hello idl This command will create the files Hello h Hello cpp Hello _skel h e Hello _skel cpp Now we will implement the server and client In this section This section discusses the following topics Implementing the Server page 5 Writing the Server Program page 7 Implementing the Client page 11 Compiling and Linking page 13 Running the Applicatio
194. he following sections Interface OB Logger page 426 Interface OB WLogger page 427 425 CHAPTER D Logger Reference Interface OB Logger local interface Logger The Orbacus message logger interface Operations info void info in string msg Log an informational message Parameters msg The message error void error in string msg Log an error message Parameters msg The error message warning void warning in string msg Log a warning message Parameters msg The warning message trace void trace in string category in string msg Log a trace message Parameters category The trace category msg The trace message 426 Interface OB WLogger Interface OB WLogger Operations local interface WLogger Logger The Orbacus message logger interface with support for wide strings winfo void winfo in wstring msg Log an informational message Parameters msg The message werror void error in wstring msg Log an error message Parameters msg The error message wwarning void warning in wstring msg Log a warning message Parameters msg The warning message wtrace void trace in wstring category in wstring msg Log a trace message Parameters category The trace category msg The trace message 427 CHAPTER D Logger Reference 428 In this appendix APPENDIX E Open Communications Interface
195. however is How do obtain a reference to a B object This chapter answers that question by describing a number of ways an application can bootstrap its first object reference 123 CHAPTER 5 Locating Objects Lifetime of Object References All of the strategies described in this chapter involve the publication of an object reference in some form A common source of problems for newcomers to CORBA is the lifetime and validity of object references Using IIOP an object reference can be thought of as encapsulating several pieces of information e hostname e port number e object key If any of these items were to change any published object references containing the old information would likely become invalid and its use might result in a TRANSIENT Of OBJECT_NOT_ExisT exception The sections that follow discuss each of these components and describe the steps you can take to ensure that a published object reference remains valid 124 Hostname Lifetime of Object References By default the hostname in an object reference is the canonical hostname of the host on which the server is running Therefore running the server on a new host invalidates any previously published object references for the old host Orbacus provides the 110Phost option to allow you to override the hostname in any object references published by the server This option can be especially helpful when used in conjunction with the Domain Name System DNS
196. ich produces no output Configuring the ORB and Object Adapter OA Properties Overview ooc orb oa conc_model Configuring an object adapter is achieved by setting properties on POA Managers These properties are grouped into two categories global properties and properties specific to a particular POA Manager Global properties have the prefix ooc orb oa while properties specific to a particular POA Manager have the prefix ooc orb poamanager name where name is the name of the POA Manager see Using POA Managers on page 71 Unless otherwise noted a POA Manager will search for configuration properties using the following algorithm e First use properties defined specifically for that POA Manager e Next use global properties e Finally use default settings See Using POA Managers on page 71 for more information on POA Managers Value reactive threaded thread_per client thread_per request thread pool leader follower Selects the server side concurrency model The default value is thread per client The reactive and leader follower concurrency models are only available in Orbacus for C See Chapter 16 for more information on concurrency models If this property is set to thread_pool then the property o0c orb oa thread_pool determines how many threads are in the pool If this property is set to leader _follower then the property o0c orb oa leader_follower_pool determines how many threads are to be
197. ies J An InvalidProperties exception indicates that specified properties were not valid and could not be used to create the strategy PropertyErrorSeq error Module LoadBalancing Interface LoadBalancing LoadAlert interface LoadAlert Implemented by a server that wishes to receive load alerts a signal to redirect requests back to the Balancer Operations alert void alert Redirect the next request back to the Balancer 477 CHAPTER F Orbacus Balancer Reference Interface LoadBalancing Strategy Operations 478 interface Strategy Used to choose the next member to service a new client connection The Balancer provides several implementations of the Strategy interface get_name string get_name Retrieve the name of the strategy get_properties PropertySeq get_properties Get the property set of the strategy adjust void adjust in MemberDataSeq members Update the members get_next MemberId get_next raises MemberNot Found Get an un loaded member push_load void push_load in MemberId member_id in unsigned long load raises MemberNotFound StrategyNotAdaptive Update the load of a member destroy void destroy Destroy the strategy Module LoadBalancing Interface LoadBalancing StrategyProxy Operations interface StrategyProxy Acts as a proxy for the load balancing strategy get_name string get_name Retrieve the name of the st
198. ified by a client These are only a few examples of the potential applications of the Factory pattern The examples listed above can also be used in any combination depending on the requirements of the system being designed Note that the factory pattern applies equally to persistent and transient objects A simple application of the Factory pattern in which a new object is created for each client is illustrated below The implementation uses the following interface definitions IDL interface Product He void destroy interface Factory Product createProduct oOwWOIt AU PF WDNDP 2 5 7 10 Factory Objects The Product interface is defined The destroy operation allows a client to destroy the object when it is no longer needed The Factory interface is defined The createProduct operation returns the object reference of a new Product 109 CHAPTER 4 CORBA Objects Factory Objects using C First we ll implement the Product interface 1 C 2 class Product_impl1 3 public virtual POA Product 4 public virtual PortableServer RefCountServantBase 5 6 public 7 8 virtual void destroy throw CORBA SystemException 9 10 PortableServer POA var poa default _POA ital PortableServer ObjectId_var id poa gt servant _to_id this 12 poa gt deactivate_object id 13 ha 2 4 The servant class Product_imp1 is defined as an implementation of the Product
199. in which the rroPhost option specifies a hostname alias that is mapped by DNS to the canonical hostname See Command line Options and Endpoints on page 79 for more information on the II0Phost option 125 CHAPTER 5 Locating Objects Port Number 126 Each time a server is executed the Root POA manager selects a new port number on which to listen for incoming requests Since the port number is included in published object references subsequent executions of the server could invalidate existing object references To overcome this problem Orbacus provides the 110Pport option that causes the Root POA manager to use the specified port number You will need to select an unused port number on your host and use that port number every time the server is started See Command line Options and Endpoints on page 79 for more information on the 110Pport option Lifetime of Object References Object Key Each object created by a server is assigned a unique key that is included in object references published for the object Furthermore the order in which your server creates its objects may affect the keys assigned to those objects To ensure that your objects always have the same keys activate your objects using POAs with the perststeEnt life span policy and the uSER_ID object identification policy 127 CHAPTER 5 Locating Objects Stringified Object References The CORBA specification defines two operations on the OR
200. inId id The plugin id tag readonly attribute ProfilelId tag The profile id tag connect Transport connect Used by CORBA clients to establish a connection to a CORBA server It returns a Transport object which can be used for sending and receiving octet streams to and from the server Returns The new Transport object Raises TRANSIENT If the server cannot be contacted COMM _FATLURE In case of other errors connect_timeout Transport connect timeout in unsigned long timeout Similar to connect but it is possible to specify a timeout On return the caller can test whether there was a timeout by checking whether a nil object reference was returned Parameters 445 CHAPTER E Open Communications Interface Reference 446 timeout The timeout value in milliseconds Returns The new Transport object Raises TRANSIENT If the server cannot be contacted COMM FAILURE In case of other errors get_usable_profiles ProfileInfoSeq get_usable profiles in IOR ref in CORBA PolicyList policies From the given IOR and list of policies get basic information about all profiles for which this Connector can be used Parameters ref The IOR from which the profiles are taken policies The policies that must be satisfied Returns The sequence of basic information about profiles If this sequence is empty there is no profile in the IOR that matches this Connector and the l
201. ing methods where NamingServer refers to the server name configured with the IMR e Start the Naming Service with the options ior ORBServerId NamingServer causing the Naming Service to print its reference to standard output e Use the mkref utility mkref NamingServer NameService RootContextPOA When using the Naming Service with the IMR the service must be started with the option orBServerId NamingServer where NamingServer refers to the server name configured with the IMR When the IMR is configured to start the Naming Service this option is automatically added to the service s arguments However when the Naming Service is started manually the option must be present For further information on configuring a service with the IMR refer to Getting Started with the Implementation Repository on page 167 190 Bindings Bindings Object references registered with the Naming Service are maintained in a hierarchical structure similar to a filesystem A file in a filesystem is analogous to an object binding in the Naming Service The equivalent for a folder in a filesystem is a naming context in Naming Service terms The pieces of information stored in a Naming Service are called bindings A binding consists of an object s name and its type as defined in the CosNaming module IDL typedef string Istring struct NameComponent Istring id Istring kind typedef sequence lt NameComponent gt Name
202. ion s responsibility to ensure that each server and client has a unique peer ID In IIOP object references can be made persistent i e valid across process restarts by ensuring that the process is restarted on the same host and port and that the object keys in the object references will continue to be valid The same is true of peer IDs If you want a bi directional IIOP object reference to remain valid across process restarts you must use the same peer ID host port and object key Conversely if an object reference is transient then the peer ID can vary along with the host port and object key 369 CHAPTER 17 The Open Communications Interface Client Installation 370 The client side bi directional plug in is installed as shown below ooc oci client ID options bidir protocol ID The following options are supported protocol ID Specifies the identifier of the underlying plug in This parameter is required Because the bi directional plug in is layered on another plug in the underlying plug in must be installed first For example to install bi directional IIOP the IIOP plug in is installed first and then the bi directional plug in is installed ooc oci client iiop bidir protocol iiop Note that a bi directional application generally needs to install both the client and server side plug ins Server Installation The Bi directional OCI Plug in The server side bi directional plug i
203. ist of policies equal boolean equal in Connector con Find out whether this Connector is equal to another Connector Two Connectors are considered equal if they are interchangeable Parameters con The connector to compare with Returns TRUE if the Connectors are equal FALSE otherwise get_info ConnectorInfo get_info Returns the information object associated with the Connector Returns The Connector information object Module OCI Interface OCI ConnectorInfo Attributes Operations local interface ConnectorInfo Information on a OCI Connector object Objects of this type must be narrowed to a Connector information object for a concrete protocol implementation for example to OCI IIOP ConnectorInfo in case the plug in implements IIOP See Also Interface OCI Connector id readonly attribute PluginId id The plugin id tag readonly attribute ProfileId tag The profile id tag describe string describe Returns a human readable description of the transport Returns The description add_connect_cb void add_connect_cb in ConnectCB cb Add a callback that is called whenever a new connection is established If the callback has already been registered this method has no effect Parameters cb The callback to add remove_connect_cb void remove_connect_cb in ConnectCB cb Remove a connect callback If the callback was not registered this method has no ef
204. ist of policies Parameters ref The IOR for which Connectors are returned policies The policies that must be satisfied Returns The sequence of Connectors Module OCI equivalent boolean equivalent in IOR iorl in IOR ior2 Checks whether two IORs are equivalent taking only profiles into account matching this Connector factory Parameters ior1 The first IOR to check for equivalence ior2 The second IOR to check for equivalence Returns TRUE if the IORs are equivalent raLsE otherwise hash unsigned long hash in IOR ref in unsigned long maximum Calculates a hash value for an IOR Parameters ref The IOR to calculate a hash value for maximum The maximum value of the hash value Returns The hash value get_info ConFactoryInfo get_info Returns the information object associated with the Connector factory Returns The Connector factory information object 451 CHAPTER E Open Communications Interface Reference Interface OCI ConFactoryInfo Attributes Operations 452 local interface ConFactoryInfo Information on an OCI ConFactory object See Also Interface OCI ConFactory id readonly attribute PluginId id The plugin id tag readonly attribute ProfilelId tag The profile id tag describe string describe Returns a human readable description of the transport Returns The description add_connect_cb void add_conn
205. ix contains the following section Module OB page 422 421 CHAPTER C Reactor Reference Module OB Aliases Constants Native Types 422 Handle typedef long Handle An event handler s handle Mask typedef long Mask An event handler s mask The mask determines which events the event handler is interested in TypeMask typedef long TypeMask An event handler s type mask The type mask determines which category the event handler belongs to A value of zero means no specific category EventRead const Mask EventRead 1 The mask for read events EventWrite const Mask EventWrite 2 The mask for write events TypeClient const TypeMask TypeClient 1 The type mask for client event handlers TypeServer const TypeMask TypeServer 2 The type mask for server event handlers EventHandler native EventHandler An event handler is a native type Module OB Interface OB Reactor Operations local interface Reactor A generic Reactor interface register_handler void register _handler in EventHandler handler in Mask handler mask in TypeMask type_mask in Handle h Register an event handler with the Reactor or change the registration of an already registered event handler Parameters handler The event handler to register mask The type of events the event handler is interested in type_mask The category the event handler belongs to h The ev
206. ize body roman Times New Roman 12pt Translating IDL to RTF Type Font Size entry swiss Tahoma 12pt extra same as body 12pt heading swiss Arial 18pt index same as heading 15pt literal roman Courier New 10pt symbol roman Symbol 12pt 37 CHAPTER 2 Generating Code with Orbacus Generating C from an Interface Repository Synopsis irgen name base Description irgen generates C code directly from the contents of an Interface Repository See The IDL to C Translator and the Interface Repository on page 39 for an example Options for irgen h help v version no skeletons no type codes locality contrained no virtual inheritance tie impl impl all c suffix SUFFIX h suffix SUFFIX skel suffix SUFFIX header dir DIR other header dir DIR output dir DIR file list FILE dll import DEF with interceptors args no Local copy These options are the same as for the idl command The argument to irgen is the pathname to use as the base name of the output filenames For example if the pathname you supply is output file then irgen will produce output file cpp output file h output file_skel cpp and output file skel h Note that irgen will generate code for a of the type definitions contained in the Interface Repository server See Chapter 12 for more information on the Interface Repository 38 The IDL to C Translat
207. l receive a TRANSIENT exception The configuration options for a bi directional endpoint are shown below Note that the plug in identifier for endpoint configuration purposes is formed by combining bidir with the identifier of the underlying plug in e g bidir iiop bidir ID callback options The only option supported by the bi directional plug in is callback which creates a callback endpoint If this option is specified it must be the only option If callback is not the first and only option all additional options are passed to the underlying plug in for processing For example a server would typically use a configuration such as ooc orb oa endpoint bidir iiop port 7000 This creates a bi directional IIOP endpoint on the static port 7000 On the other hand a bi directional client would use the following configuration ooc orb oa endpoint bidir iiop callback This creates a callback endpoint which can only receive requests when an existing outgoing bi directional IIOP connection has been established from this client to the server that wishes to make a callback The Bi directional OCI Plug in Command line Options No command line options are supported 373 CHAPTER 17 The Open Communications Interface Configuration Properties The bi directional plug in supports a single configuration property ooc bidir peer Specifies the peer ID If not specified a unique peer ID is used 374 Sta
208. l as a parameter All operation calls to tie will then be delegated to impl In this example the lifetime of imp1 is coupled to the lifetime of the servant tie That is when the tie is destroyed delete imp1 is called by the tie s destructor In case you don t want the lifetime of imp1 to be coupled to the lifetime of the tie for example because you want to create a servant on the stack and not on the heap making it illegal to call delete on the tie use the following code C I_impl tie impl POARC CSE eE new POA I tie lt I impl tie gt amp impl false eUwUNEBE A new I_impl_tie is created this time on the stack not on the heap An instance of poa I tie is created The false parameter tells tie not to Call delete On impl Creating Servants Creating Servants using Java 2 3 Every tie class generated by the IDL to Java translator has two constructors Tava public class IPOATie extends IPOA public IPOATie IOperations delegate public IPOATie IOperations delegate POA poa The second constructor allows a POA instance to be supplied which will be used as the return value for the tie s default_poa method If the POA instance is not supplied the default _poa method will return the root POA of the ORB with which the tie has been associated This example demonstrates how to create servants using Java 1 Java 2 I impl impl new I impl 3 I impl anotherImpl new I _impl
209. l bin on their respective hosts First we register the servers using the imradmin utility imradmin ORBInitRef IMR corbaloc master 10000 IMR add server Serverl usr local bin serverl slavel imradmin ORBInitRef IMR corbaloc master 10000 IMR add server Server2 usr local bin server2 slave2 Next we set the server arguments imradmin ORBInitRef IMR corbaloc master 10000 IMR set server Serverl args ORBInitRef IMR corbaloc master 10000 IMR imradmin ORBInitRef IMR corbaloc master 10000 IMR set server Server2 args _ ORBInitRef IMR corbaloc master 10000 IMR A C server can automatically register itself with the IMR using the ORBregister command line option For example to registered Server1 run the following on slave1 usr local bin serverl ORBregister Serverl ORBInitRef IMR corbaloc master 10000 IMR If the server requires command line options then these options must be added using the imradmin utility Add each POA to the IMR In this example the servers are registered without setting the activate_poas attribute so the attribute defaults to true Hence all Getting Started with the Implementation Repository persistent POAs will be registered automatically If this were not the case the POAs would have to be registered manually 7 Configure your servers to use the IMR There are three ways to configure a server to use the IMR i Use the orBregister command line
210. l mode 159 CHAPTER 6 The Implementation Repository Windows NT Native Service 160 The imr server is also available as a native Windows NT service ntimrservice h help i install s start install u uninstall d debug h Display the command line options supported by help the service i Install the service The service must be started Jsinstall manually s Install and start the service start install u Uninstall the service uninstall d Run the service in debug mode debug In order to use the IMR server as a native Windows NT service first add the desired configuration properties to the HKEY_LOCAL MACHINE NT registry key see Using the Windows NT Registry on page 65 for more details For example add the ooc imr admin endpoint ooc imr forward endpoint and ooc imr slave_endpoint properties so that the IMR and OAD will use non default endpoint settings Next the service should be installed with ntimrservice i This adds the orbacus Implementation Repository entry to the Services dialog in the Control Panel To start the service select the orbacus Implementation Repository entry and press start If the service is to be started automatically when the machine is booted select the orbacus Implementation Repository entry then click Startup Next select startup Type Automatic and press ox Alternatively the service could have been installed usi
211. lass I_imp1 as long aS I_impl implements all interface operations including the operations of the base interfaces f f C class I_impl virtual public POA I public virtual void op_a throw CORBA SystemException virtual void op b throw CORBA SystemException virtual void op _i throw CORBA SystemException o yAn PWN PHP E Now I_imp1 is only derived from Poa x but not from the other servant classes I_impl must implement all operations from the interface 1 as well as the operations of all interfaces from which 1 is derived Several files are generated by the Orbacus IDL to Java translator for an interface 1 including I 4java which defines a Java interface x containing public methods for the operations and attributes of 1 and IPOA java which is an abstract skeleton class that serves as the base class for servant classes In contrast to C Java s lack of multiple inheritance currently makes it impossible for a servant class to inherit operation implementations from other servant classes except when using delegation based implementation Implementing Servants For our interface x it is therefore necessary to implement all operations in a single servant class I_imp1 regardless of whether those operations are defined in x or in an interface from which 1 is derived 1 Java 2 public class I_impl extends IPOA 3 4 public void op a 5 6 7 8 public void op b
212. lass I_imp1 inherits the implementation of op_b from B_imp1 and provides an implementation of op_a and op _i Since a Java class can only extend one class it s not possible for I_imp1 to inherit the implementations of both op_aand op b Creating Servants Creating Servants Servants are created the same way in both C and Java once your servant class is written you simply instantiate a servant with new 1 You can also instantiate servants on the stack However this only works only for some POA policies so servants are usually instantiated on the heap 97 CHAPTER 4 CORBA Objects Creating Servants using C 98 2 3 Here is how to create servants using C 1 C 2 I_impl servant pointer new T impl 3 I_impl another servant_pointer new I impl Two servants are created with new Note that this merely instantiates the servants but does not inform the ORB that these servants exist yet The ORB server side run time only learns of the existence of the servants once you activate them In case the servant class was written using the delegation approach an object of the class implementing 1 s operations must be passed to the servant s constructor C I_impl_tie impl new I impl tie POA T tie lt I impl tie gt tie pointer new POA I tie lt I _ impl tie gt impl Ae UNBE A new I_impl tie is created with new An instance of Poa I tie parameterized with I_imp1l tie is created taking imp
213. lass for the CORBA object and by instantiating this class The resulting implementation object is called a servant e Aclient that wants to make use of an object implemented by a server creates an object that delegates all operation calls to the servant via the ORB Such an object is called a proxy When a client invokes a method on the local proxy object the ORB packs the input parameters and sends them to the server which in turn unpacks these parameters and invokes the actual method on the servant Output parameters and return values if any follow the reverse path back to the client From the client s perspective the proxy acts just like the remote object since it hides all the communication details within itself A servant must somehow be connected to the ORB so that the ORB can invoke a method on the servant when a request is received from a client This connection is handled by the Portable Object Adapter POA as shown in Figure 2 Client Server Servant Proxy POA ORB Figure 2 Servants Proxies and the Object Adapter Overview The Portable Object Adapter in Orbacus replaces the deprecated Basic Object Adapter BOA The BOA was deprecated by the OMG because it had a number of serious deficiencies and was under specified The POA is a far more flexible and powerful object adapter than the BOA The POA not only allows you to write code that is portable among ORBs from different vendors
214. lfile URLs The BootManager BootManager Interface How the BootManager Works Using the BootManager Initial Services Resolving an Initial Service Configuring the Initial Services The Initial Service Locator The IORDump utility Chapter 6 The Implementation Repository Background Information Managed by the IMR IMR Security Usage CONTENTS 105 106 108 110 112 113 114 116 119 120 124 125 126 127 128 129 131 132 133 135 136 137 138 139 140 141 142 143 145 147 148 151 153 154 157 158 CONTENTS Windows NT Native Service 160 Configuration Properties 162 Connecting to the Service 163 Utilities 164 Getting Started with the Implementation Repository 167 Programming Example 170 Chapter 7 The Implementation Repository Console 175 Usage 176 The Menus 177 Chapter 8 Orbacus Names 181 Usage 183 Windows NT Native Service 185 Configuration Properties 187 Persistence 188 Connecting to the Service 189 Using the Naming Service with the IMR 190 Bindings 191 Name Resolution 193 Programming Example 194 Initialization 195 Binding 197 Exceptions 200 The Event Loop 202 Releasing Resources 203 Chapter 9 Orbacus Names Console 205 Usage 206 Naming Service Lookup 207 The Menus 208 The Edit Menu 210 The View Menu 212 The Tools Menu 214 The Toolbar 216 The Popup Menu 217 Chapter 10 Orbacus Properties 219 vi Usage Connecting to the Service Using the Property Service with the IMR Creating Properties
215. lt lt endl 9 We must include oB corBA h which contains definitions for the standard CORBA classes as well as for other useful things We must also include the Hello_imp1 class definition contained in the header file Hello _imp1 h The say_hello function simply prints Hello World on standard output Implementing the Example in C Writing the Server Program Overview main function Now we will write the server program To simplify exception handling and ORB destruction we will split the server into two functions main and run where main only creates the ORB and calls run Create a file with the name Server cpp and enter the code for the main function shown below ond nu FF WDNY PE 10 NVMNNNPRPPP PPP Pe WNHROWAIYD UO ARWNHE C include lt OB CORBA h gt include lt Hello_impl h gt include lt fstream h gt int run CORBA ORB ptr int main int argc char argv int status EXIT SUCCESS CORBA ORB var orb try orb CORBA ORB_init argc argv status run orb catch const CORBA Exception amp status EXIT_FAILURE CHAPTER 1 Getting Started 2 5 16 17 19 22 24 34 36 24 if CORBA is_nil orb 25 26 try 27 28 orb gt destroy 29 30 catch const CORBA Exception amp 31 32 status EXIT_FAILURE 33 34 35 36 return status a7 I Several header files are included Of these oB CoRBA
216. lt ports Next the service should be installed with ntbalancerservice i This adds the orbacus Balancer entry to the Services dialog in the Control Panel To start the service select the Orbacus Balancer entry and press Start If the service is to be started automatically when the machine is booted select the orbacus Balancer entry then click Startup Next select Automatic for the Startup Type and press OK Alternatively the service could have been installed using the s option which configures the service for automatic start up ntbalancerservice s If you want to remove the service run Usage ntbalancerservice u Note If the executable for the service is moved it must be uninstalled and re installed Any trace information provided by the service is be placed in the Windows NT Event Viewer with the title Balancer To enable tracing information add the desired trace configuration property i e one of the ooc balancer trace properties or one of the coc orb trace properties to the HKEY LOCAL MACHINE NT registry key with a REG _sz value of at least 1 269 CHAPTER 13 Orbacus Balancer Configuration Properties ooc balancer administrative ooc balancer dbdir ooc balancer admin_endpoint ooc balancer forward_endpoint ooc balancer trace database ooc balancer trace lifecycle ooc balancer trace load_balance 270 In addition to the standard configuration properties described in Chapter Orbac
217. mal 98 12 09 pdf Framingham MA Object Management Group Object Management Group 1999 Naming Service Specification ftp ftp omg org pub docs ptc 99 12 03 pdf Framingham MA Object Management Group 487 CHAPTER G 488 11 12 13 14 IONA Technologies Inc 2001 JThreads C http www orbacus com jtc Waltham MA IONA Technologies Inc IONA Technologies Inc 2001 JThreads C User s Manual Waltham MA IONA Technologies Inc IONA Technologies Inc 2001 Orbacus http www orbacus com ob Waltham MA IONA Technologies Inc Schmidt D C 1995 Reactor An Object Behavioral Pattern for Concurrent Event Demultiplexing and Event Handler Dispatching In Pattern Languages of Program Design ed James O Coplien and Douglas C Schmidt Reading MA Addison Wesley Index B Basic Object Adapter 87 Bindings 191 BOA 87 Callbacks 81 Command line Options 62 Concurrency Models Threaded 332 Thread per Client 334 Thread per Request 335 Thread Pool 336 Configuration File 64 Currently Executing Request 116 D Documenting IDL Files 41 E Event Channel 240 Event Consumers 241 Event Loop 83 Event Service 231 Event Suppliers 241 Exceptions 377 H Hello World example application 2 Hostname 125 347 HTML 41 IFR 251 Implementation Repository 151 153 Implementation Repository Administration 164 IMR 151 153 IMR Console 175 included IDL files 40 Initial Servic
218. me n in Object obj raises NotFound CannotProceed InvalidName void rebind context in Name n in NamingContext nc raises NotFound CannotProceed InvalidName Use the unbind operation to delete a particular binding if wash void unbind in Name n raises NotFound CannotProceed InvalidName Name Resolution Name Resolution Besides registering objects an equally important task of the Naming Service is name resolution A name is passed to the resolve or resolve_str operation and an object reference is returned if the name exists JO TDL Object resolve in Name n raises NotFound CannotProceed InvalidName Object resolve str in StringName n raises NotFound CannotProceed InvalidName The resolve and resolve_str operations are only useful when a particular name is known in advance Sometimes it is necessary to ask for a list of all bindings registered with a particular naming context The list operation returns a list of bindings Aff TD typedef sequence lt Binding gt BindingList void list in unsigned long how many out BindingList bl out BindingIterator bi If the number of bindings is especially large the BindingIterator interface is provided so that you don t have to query for all available bindings at once Simply get a certain number of bindings specified with how many and get the rest if any using the BindingIterator Aff TD interface BindingIterator boolean next_one out Bi
219. mming Examples Connection Reuse Policy Retry Policy Timeout Policy Interceptor Call Policy CommunicationsConcurrencyPolicy EndpointConfigurationPolicy GlOPVersionPolicy Bidirectional Policby Chapter 16 Concurrency Models Concurrency Models Single Threaded Concurrency Model Multi Threaded Concurrency Models Threaded Clients and Servers Thread per Client Server viii 275 276 277 278 279 280 281 282 283 288 292 295 296 297 298 299 300 301 302 303 306 307 310 312 313 315 317 319 321 325 326 328 331 332 334 Thread per Request Server Thread Pool Server Leader_Follower The Reactor The X11 Reactor The Windows Reactor Chapter 17 The Open Communications Interface Interface Summary Class Diagram OCI Reference A Converter Class for Java Getting Hostnames and Port Numbers Determining a Client s IP Address Determining a Server s IP Address The IIOP OCI Plug in Endpoint Configuration Command line Options Static Linking The UDP OCI Plug in Client Installation Server Installation Endpoint Configuration Static Linking URL Support Narrowing UDP Object References The Bi directional OCI Plug in How Does it Work Peers Client Installation Server Installation Endpoint Configuration Command line Options Configuration Properties Static Linking URL Support Chapter 18 Exceptions and Error Messages CONTENTS 335 336 337 338 339 340 341 342 344 345 346 347 349 351 353 354
220. mpl_tie is defined to implement the toperations interface I impl tie must implement all of r s operations including inherited operations public void op a public void op b public void op i public class I_impl tie implements IOperations Figure 4 illustrates the relationship between the classes generated by the IDL to Java translator and the servant implementation classes IPOA _impl IPOATie O gt delegates to Operations _impl_tie Figure 4 Class Hierarchy for Inheritance and Delegation Implementation in Java 95 CHAPTER 4 CORBA Objects 96 2 7 9 14 16 21 As noted earlier Java s lack of multiple inheritance makes it impossible to inherit an implementation from another servant class Using tie classes however does allow implementation inheritance but only in certain situations For example let s implement each of our sample interfaces using delegation 1 Java 2 public class A_impl implements AOperations 3 4 public void op a 5 6 7 8 9 public class B impl implements BOperations 10 ital public void op b 12 13 14 15 16 public class I_impl extends B_impl implements IOperations uy 18 public void op a 19 20 21 22 public void op i 23 24 25 Class a_imp1 is defined as implementing Aoperations Class B_imp1 is defined as implementing Boperations C
221. mples of how to use these policies refer to Using Policies on page 301 77 CHAPTER 3 ORB and Object Adapter Initialization Endpoints 78 Orbacus supports a flexible mechanism for configuring a POA Manager s endpoints via properties A single property is used to configure the endpoints for a particular POA Manager The property value consists of a comma separated list of endpoints with the following syntax plugin id options plugin id options For example ooc orb oa endpoint iiop port 9998 iiop port 9999 ooc orb poamanager MyManager endpoint iiop This configuration creates two IIOP endpoints for the Root POA Manager on specific ports and one IIOP endpoint for the POA Manager named MyManager on an arbitrary port Technically the second property isn t necessary because this is the default configuration if no endpoints are specified for a POA Manager It is important to note that only those transport plug ins which were installed via the ooc oci server property can be used in endpoint configuration When experimenting with various endpoint configurations it can be very useful to enable connection tracing diagnostics With diagnostics enabled the ORB will display its endpoint information allowing you to confirm that the application s endpoints are configured correctly Diagnostics can be enabled using the orBtrace_connections command line option or using the equivalent property coc orb trace con
222. n message MinorAct iveConnect ionManagement Active connection management closed connection MinorForcedShutdown Forced connection shutdown because of timeout m MinorLocationForwardHopCountExceeded Forced connection shutdown because of timeout 393 CHAPTER 18 Exceptions and Error Messages INTF_REPOS Minor Exception Code 394 MinorNoInt fRepos Interface Repository is not available MinorLookupAmbiguous Search name for lookup is ambiguous MinorIllegalRecursion Illegal Recursion MinorNoEntry IFR is not populated with a required definition CORBA System Exceptions OBJECT NOT EXIST Minor Exception Code MinorUnregisteredValue Attempt to pass unactivated unregistered value as an object reference MinorCannotDispatch Unable to dispatch servant or POA not found 395 CHAPTER 18 Exceptions and Error Messages INV_POLICY Minor Exception Code 396 MinorCannotReconcilePolicy Cannot reconcile IOR policy with effective policy override MinorInvalidPolicyType Invalid PolicyType MinorNoPolicyFactory No PolicyFactory for the PolicyType has been registered Non Compliant Application Asserts Non Compliant Application Asserts If the Orbacus library was compiled without the preprocessor definition DNDEBUG defined Orbacus tries to detect common programming mistakes that lead to no
223. n t generate type codes and insertion and extraction functions for the Any type Use of this option will cause the translator to generate more compact code no virtual inheritance Don t use virtual C inheritance If you use this option you cannot use multiple interface inheritance in your IDL code and you also cannot use multiple C inheritance to implement your servant classes tie Generate tie classes for delegate based interface implementations Tie classes depend on the corresponding skeleton classes i e you must not use no skeletons in combination with tie fwd Generate separate header files for forward declarations impl Generate example servant implementation classes An input file Foo idl will generate the files Foo imp1 h and Foo_impl cpp These files will not be overwritten therefore you must first remove the existing files before new ones can be generated You must not use no skeletons in combination with this option impl all Similar to imp1 but function signatures are generated for all inherited operations and attributes You must not use no skeletons in combination with this option c suffix SUFFIX Use suFFIx as the suffix for source files The default value is cpp h suffix SUFFIX Use suFFIx as the suffix for header files The default value is h 30 Translating IDL to C stub suffix SUFFIX Use suFFIx as the suffix for stub files The default value is an empty suffix skel
224. n t see anything from the event channel but an object implementing the Pullconsumer interface The following example shows the basic layout of a pull supplier 1 Java 2 public Any pull 3 4 java util Date date new java util Date 5 String s PullSupplier says date toString 6 7 Any any orb create_any 8 any insert_string s 5 10 return any ii 1a 13 public Any 14 try _pull BooleanHolder has_event is 4 16 has_event value true 17 18 return pull 19 Date and time are inserted into the any In this example new event data can be provided at any time so try _pull always sets has event to true in order to signal that an event is available It then returns the actual event data Programming Example After examining the most important aspects of the event suppliers code we are now going to analyze the consumers code The push consumer with its push operation is shown first 1 Java 2 public void push Any any 3 d 4 try 5 6 String s any extract_string 7 System out println s 8 9 catch MARSHAL ex 10 LIL Ignore unknown event data 12 13 The push consumer s push operation is called with the event wrapped in a CORBA any In this code fragment it is assumed that the any contains a string with date and time information In case the any contains another data type a MARSHAL exception is thrown This exception can be ignored here b
225. n compliant CORBA applications If such a mistake is found an error messages like this will appear Non compliant application error detected Application used wrong memory allocation function After detecting such an error the Orbacus library dumps a core Unix only and prints the file and line number where the error was detected You can use the core dump in order to track down the problem with a debugger The following error messages can appear Application requested a feature that has not yet been implementedThis is not an application error This error message appears if an application attempts to use a feature that has not yet been implemented in Orbacus In this case the only thing that can be done is to wait for the next Orbacus version that has this particular feature implemented Application used a deprecated feature that is not implemented anymoreThis is not an application error This error message appears if an application attempts to use a feature that is no longer implemented in Orbacus In this case the only thing that can be done is to avoid using this particular feature Application used wrong memory allocation functionlf this message appears an incorrect memory allocation function has been used A common mistake that leads to this error is to use malloc strdup and free or the new and delete operator instead of CORBA string_alloc and CORBA string_dup and CORBA string_ free for string memory management Message
226. n is installed as shown below ooc oci server ID options bidir protocol ID The following options are supported protocol ID Specifies the identifier of the underlying plug in This parameter is required Because the bi directional plug in is layered on another plug in the underlying plug in must be installed first For example to install bi directional IIOP the IIOP plug in is installed first and then the bi directional plug in is installed ooc oci server iiop bidir protocol iiop Note that a bi directional application generally needs to install both the client and server side plug ins 371 CHAPTER 17 The Open Communications Interface Endpoint Configuration 372 There are two distinct types of bi directional endpoints one which creates a real endpoint using the underlying plug in and one which only listens for callbacks on existing outgoing bi directional connections The latter type will be referred to as a callback endpoint A server will typically create the first type of endpoint a security restricted client will only create the second type since listening on a real port is often forbidden or pointless if a firewall prevents incoming connections The implication of creating a callback endpoint is that a server wishing to call back to a client will only be able to do so if there is an existing bi directional connection from the client to the server If not the server wil
227. n new data is transferred to the clipboard the old clipboard contents are replaced Using Paste you can add the clipboard data into a naming context The clipboard contents are not changed by this operation i e you can Paste the same items several times Note that if naming contexts are transferred to the clipboard their contents are not evaluated before they are pasted It is during the Paste operation that the bindings of a context are duplicated This means that if new bindings are added to a context after a Cut or Copy operation these bindings will be present after pasting this context An item registered with the Naming Service has three modifiable attributes its ID its Kind and its IOR The ID and Kind attributes can be edited by simply double clicking the ID or Kind field in the table You can also change binding attributes with the corresponding menu operations Change ID Change Kind and Change IOR Entering a new IOR for an existing name effectively replaces an object registered with the Naming Service by another object with the same name Use Select all to select all of the entries in the binding table The current table selection can be inverted using Invert Selection 211 CHAPTER 9 Orbacus Names Console The View Menu The operations in this menu control the appearance of the console window as well as the presentation of the Naming Service data Toolbar Toggles the toolbar visibility Status Bar Toggles the statusbar
228. n on this policy The default value is o Value timeout gt 0 Sets the max attribute of the oB RetryPolicy at the ORB level See Appendix B for more information on this policy The default value is 1 Value true false Sets the remote attribute of the oB RetryPolicy at the ORB level See Appendix B for more information on this policy The default value is false Value none transport server target Sets the Messaging SyncScopePolicy at the ORB level The default value iS transport Value timeout gt 1 Sets the 0B TimeoutPolicy at the ORB level See Appendix B for more information on this policy The default value is 1 Value true false Determines whether system exceptions that occur during Dynamic Invocation Interface DII operations are raised immediately or are stored only in the CORBA Environment object This property is only available for Java applications The default value is true Note that specifying a value of false may result in unexpected behavior Value string ooc orb server_shutdown_timeou t ooc orb server_timeout ooc orb use_type_code_cache ooc orb service name Configuring the ORB and Object Adapter Specifies the name of the server as registered with the Implementation Repository IMR Note that you should not put this property in a configuration file that is shared by several IMR enabled servers Furthermore this property should not be specified fo
229. n page 14 Implementing the Example in C Implementing the Server Overview Hello_impl definition To implement the server we need to define an implementation class for the Hello interface To do this we create a class Hello _imp1 that is derived from the skeleton class POA Hello defined in the file Hello _skel h Create a file Hello _imp1 h and enter the class definition of Hello impl shown below 1 C 2 include lt Hello skel h gt 3 4 class Hello_impl public POA Hello public 5 PortableServer RefCountServantBase G 4 7 public 8 9 virtual void say_hello 10 throw CORBA SystemException iil fig Since our implementation class derives from the skeleton class POA Hello we must include the file Hello _skel h Here we define Hello _imp1 as a class derived from POA Hello and RefCountServantBase RefCountServantBase is part of the PortableServer namespace and provides reference counting Our implementation class must implement all operations from the IDL interface In this case this is just the operation say hello CHAPTER 1 Getting Started Hello_impl implementation Create a file Hello_impl cpp and enter the class implementation of Hello impl shown below 1 C 2 include lt iostream h gt 3 include lt OB CORBA h gt 4 include lt Hello_impl h gt 5 6 void Hello impl say_hello throw CORBA SystemException 7 1 8 cout lt lt Hello World
230. n the contents of the IMR have been changed from outside the console Note that clicking or expanding an item will refresh the item In addition to the operations offered by the menu bar some frequently needed functions are available by icons located in the toolbar The toolbar contains all of the items of the Edit menu and the Refresh item of the View menu The toolbar is shown below Coll Jee gt m fe o The Menus When selecting an OAD server or POA with the right mouse button a popup menu with a choice of operations will be displayed as shown below Create Modify Delete Cut Paste Start Stop Reset Refresh This popup menu provides the same operations as the toolbar 179 CHAPTER 7 The Implementation Repository Console 180 In this chapter CHAPTER 8 Orbacus Names A CORBA object is often represented by an object reference in the form of a Stringified IOR a lengthy string that is difficult to read and cumbersome to use It is much more natural to think of an object in terms of its name which is a core feature of the CORBA Naming Service In the Naming Service objects are registered with a unique name which can later be used to resolve their associated object references Orbacus Names is compliant with 10 This chapter does not provide a complete description of the service It only provides an overview suitable to get you started For more information plea
231. n the service Where lt strategy gt can be random round robin least load or min dispersion The least 1load strategy has the options tolerance tolerance load per client load_per_client critical load critical_load reject load reject_load dampening multiplier dampening multiplier The min dispersion strategy has the options tolerance tolerance load per client load per _ client reject load reject_load dampening multiplier dampening_multiplier 278 Making References Utilities The 1bmkref utility creates object references for use by clients of Orbacus Balancer Note that this can only be used to create object references when the service is configured to use the IIOP Its usage is shown below lbmkref H host port group id repository id object id host The host that the balancer server is running on The default value is the canonical hostname of the machine in which 1bmkref is executed port The forward port of the service group id The ID of the load balanced group repository id The Repository ID of the new object reference object id The Object ID of the new object reference 279 CHAPTER 13 Orbacus Balancer Utility Objects LoadAlert LoadCalculator LoadUpdater 280 To take advantage of the features of the adaptive load balancing strategies a load balanced server must send load updates to the appropriate load balanced groups and respon
232. n wishes to reject the connection CORBA NO_PERMISSION may be raised Parameters transport_info The TransportInfo for the new connection 459 CHAPTER E Open Communications Interface Reference Interface OCI AccFactory Attributes Operations 460 local interface AccFactory An interface for an AccFactory object which is used by CORBA servers to create Acceptors See Also Interface OCI Acceptor Interface OCI AccFactoryRegistry id readonly attribute PluginId id The plugin id tag readonly attribute ProfileId tag The profile id tag create_acceptor Acceptor create_acceptor in ParamSeq params raises InvalidParam Create an Acceptor using the given configuration parameters Refer to the plug in documentation for a description of the configuration parameters supported for a particular protocol Parameters params The configuration parameters Returns The new Acceptor Raises InvalidParam If any of the parameters are invalid change_key void change _key inout IOP IOR ior in ObjectKey key Change the object key in the IOR profile for this given protocol Parameters Module OCI ior The IOR key The new object key get_info AccFactoryInfo get_info Returns the information object associated with the Acceptor factory Returns The Acceptor 461 CHAPTER E Open Communications Interface Reference Interface OCI AccFactoryInfo
233. nd 3 on page 264 See load per client on page 272 See reject load on page 273 273 CHAPTER 13 Orbacus Balancer dampening multiplier See dampening multiplier on page 273 274 Connecting to the Service Connecting to the Service Servers that use Orbacus Balancer must be configured with the service s initial reference The object key of the service is Balancer hence a URL style object reference of the service running on host 1bhost at port 10000 would be corbaloc lbhost 10000 Balancer Using this object reference a server can configure the Orbacus Balancer initial reference with the property ooc orb service Balancer corbaloc lbhost 10000 Balancer An alternative to using the above property is to use the ORBInitRef command line option Refer to Chapter 5 for more information on URLs and configuring initial services 275 CHAPTER 13 Orbacus Balancer Load Balanced IMR enabled Servers Load balanced servers may also be IMR enabled servers For information on using the IMR refer to Chapter 6 Note that Orbacus Balancer and the IMR need no additional configuration Object references created by a member POA of an IMR enabled server will still refer to the associated load balanced group within Orbacus Balancer However when Orbacus Balancer selects a member implemented by a IMR enabled server to service a new connection the reference returned to the client will actually refer to
234. nding b boolean next_n in unsigned long how many out BindingList ieill void destroy he Make sure that you destroy the iterator object when it is no longer needed 193 CHAPTER 8 Orbacus Names Programming Example 194 Orbacus includes simple C and Java examples that demonstrate how to use the CORBA Naming Service These examples are located in the folder naming demo We will concentrate on the Java example but the C example works similarly The example expects a Naming Service server to be already running and that the server s initial reference can be resolved by the ORB Because of its volume we have split the code into several parts for the discussion below Initialization Programming Example The first code fragment deals with initializing the ORB oad anajunk WNP WWWWWWWNNNNNNNNNNKRFPRPRPRP RRR RP PB NOP WNHNRFPOOHOWAIAUHFWNHPRP OW WANA UNF WNEHE O Java java util Properties props System getProperties props put org omg CORBA ORBClass com ooc CORBA ORB props put org omg CORBA ORBSingletonClass com ooc CORBA ORBSingleton org omg CORBA ORB orb null try orb ORB init args props org omg CORBA Object poaObj null try catch org omg CORBA ORBPackage InvalidName ex POA rootPOA POAHelper narrow poa0bj POAManager manager rootPOA the POAManager poaObj orb resolve_ initial references RootPOA throw new R
235. nections See Configuring the ORB and Object Adapter on page 51 for more information on configuration properties For a complete description of the available transport plug ins and their options see Chapter 17 Using POA Managers Command line Options and Endpoints Transport plug ins may support command line options and it is important to understand the effects of using those options They can be summarized as follows e Using a plug in s command line options will always add a new endpoint configuration i e command line options do not override an existing endpoint configuration e Command line options only configure endpoints for the Root POA Manager The first item is the most significant Let s consider some examples which will serve to explain this issue First assume that there is no endpoint configuration property for the Root POA Manager and that we use the following command line options IIOPhost host abc com IIOPport 1234 The IIOP plug in will convert these command line options into the following configuration property ooc orb oa endpoint iiop host host abc com port 1234 Now let s consider a more complicated example Suppose that we have an existing endpoint configuration property defined and we also use command line options The existing endpoint configuration is ooc orb oa endpoint iiop port 5555 And the command line options are IIOPport 5556 After the command line options are proc
236. ng table in ascending alphabetical order with naming contexts being listed at the top You can change this order with the options available in the Sort menu Bindings can be sorted by their ID or Kind fields If the extended attributes are displayed items can also be sorted by date and time You can reverse the sort order by 212 The Menus selecting the current sorting mode a second time in the View menu or by clicking on the table header cells In this case the display switches from ascending to descending order and vice versa If the contents of a naming context have been changed by a third party and you want to update the information displayed in the console window selecting Refresh updates the display If the console is connected to Orbacus Names a refresh is done automatically each time a change occurs 213 CHAPTER 9 Orbacus Names Console The Tools Menu 214 The operations available in this menu are meant as tools for your everyday work Ping Checks the accessibility of the selected items Clean up Unbinds inaccessible objects from the current context Sometimes it is useful to check if an object bound to a name still exists or if the object reference associated with it has become invalid for example because of a server crash To perform such a check select all the objects you want to check and start the Ping operation The console tries to contact each of the selected objects and displays the time it took to get
237. ng the s option which configures the service for automatic start up Windows NT Native Service ntimrservice s If you want to remove the service run ntimrservice u Note If the executable for the service is moved it must be uninstalled and re installed Any trace information provided by the service is be placed in the Windows NT Event Viewer with the title impservice To enable tracing information add the desired trace configuration property i e one of the coc imr trace properties or one of the ooc orb trace properties to the HKEY LOCAL MACHINE NT registry key with a rREc_sz value of at least 1 161 CHAPTER 6 The Implementation Repository Configuration Properties In addition to the standard configuration properties described in Chapter 3 the IMR also supports the following properties Property Value Description ooc imr mode master slave dual Specifies the mode in which the imr server will be started ooc imr administrative true false If set to true then run the IMR in administrative mode For details refer to the a command line option ooc imr dbdir directory Equivalent to the d command line option ooc imr admin_endpoint info Equivalent to the a command line option ooc imr forward_endpoint info Equivalent to the F command line option ooc imr slave_endpoint info Equivalent to the s command line option ooc imr locator_endpoint info Equivalent to the u command line o
238. nge the instance denoted by the tie 1 C 2 template lt class T gt 3 class POA I tie public POA I a 5 public 6 VE are 7 T tied object 8 void _tied_object T amp obj 9 void tied object T obj CORBA Boolean release true 10 HE eee iil 7 9 The _tied object function permits you to retrieve and change the implementation instance that is currently associated with the tie The first modifier function calls delete on the current tied instance before accepting the new tied instance if the release flag is currently true the release flag for the new tied instance is set to false The second modifier function also calls delete on the current tied instance before accepting the new instance but sets the release flag to the passed value Delegation using Java For every IDL interface the IDL to Java mapping generates an operations interface containing methods for the IDL attributes and operations This operations interface is also used to support delegation based servant implementation For an interface 1 the following additional class is generated IPOATie java the tie class that inherits from rroa and delegates all requests to an instance of Ioperations 94 Implementing Servants To implement our servant class using delegation we need to write a class that implements the toperations interface 1 Java 2 3 4 5 6 7 8 9 10 1i 12 13 14 15 The servant class I_i
239. nitRef URL For example starting an application as shown below will enable the client to resolve the NameService initial reference myclient ORBInitRef NameService corbaloc nshost 10000 NameService The orBconfig option is an alternative method for defining a list of initial services and is often preferable when a number of services must be defined See Configuring the ORB and Object Adapter on page 51 for more information on these command line options Also refer to the INS specification 10 for detailed information on the standard options ORBInitRef and ORBDefaultInitRef In addition to using command line parameters a program can add to the list of initial services using the ORB operation register initial reference Jf Tits module CORBA interface ORB void register_initial_ reference in ObjectId id in Object obj raises InvalidName a he For example in C 1 C 2 CORBA Object_var obj Get a name service reference somehow 3 orb gt register initial reference NameService obj 1 This will become part of the ORB interface when the Portable Interceptor specification is adopted 145 CHAPTER 5 Locating Objects 146 Get a reference to the naming service for example by reading a stringified object reference and converting it with string to object or by any other means Add the reference to the ORB s list of initial references Or in Java 1 Java 2 org omg CORB
240. nitions of the IDL interfaces please refer to the official Event Service specification In this chapter CHAPTER 12 The Interface Repository A CORBA Interface Repository IFR is essential for applications using the dynamic features of CORBA such as the Dynamic Invocation Interface and DynAny The IFR holds IDL type definitions and can be queried and traversed by applications The Orbacus Interface Repository is compliant with 4 This chapter does not provide a complete description of the IFR For more information please refer to the specification This chapter contains the following sections Usage page 252 Connecting to the Interface Repository page 256 Configuration Issues page 257 Interface Repository Utilities page 258 Programming Example page 259 251 CHAPTER 12 The Interface Repository Usage The Orbacus Interface Repository is currently only provided with Orbacus for C irserv h help v version d debug i ior DNAME DNAME DEF UNAME IDIR case sensitive FILE h Display the command line options supported by the server help v Display the version of the server version d Print diagnostic messages This option is for Orbacus internal debug debugging purposes only i Print the stringified IOR of the server to standard output ior DNAME Defines NAME aS DEF Or 1 if DEF is not provided This option is DN
241. nstructor accepts a POA reference and remembers that reference in a private member variable The _default_poa function returns the servant s POA In Java the approach is very similar Factory Objects Java public class Product_impl extends ProductPOA private org omg PortableServer POA poa_ public Product_imp1 org omg PortableServer POA poa poa_ poa public org omg PortableServer POA _default_POA return poa_ 115 CHAPTER 4 CORBA Objects Getting the POA for a Currently Executing Request The ORB provides access to an object of type PortableServer Current Jif TDI module PortableServer interface Current CORBA Current exception NoContext POA get_POA raises NoContext ObjectId get_object_id raises NoContext Ihe hs This interface provides access to the POA and the object ID for an executing request Note that these operations must be invoked only from within the context of an executing operation inside a servant otherwise they raise NoContext The current object provides a useful way to obtain access to a servant s POA and object ID without having to store the POA reference in a member variable at the cost of being accessible only from within an operation implementation You can obtain a reference to the current object from resolve_initial references In C the code looks something like this c ii Cee CORBA ORB var orb Get the O
242. nt is instantiated the RefCountServantBase constructor sets this reference count to 1 When the servant is activated with the POA the POA increases the reference count by at least 1 When the ServantBase_ var we assigned the servant to goes out of scope the reference count is decremented by 1 This means that when createProduct returns only the POA is holding a reference to the servant Later when the servant is deactivated in destroy the POA decrements the reference count by exactly the same number it used to increment the reference count upon activation This causes the reference count to drop to zero in which case the servant will be implicitly deleted Note that whenever the ORB starts to dispatch a request on the servant the reference count is incremented After request dispatching is finished the count is decremented by the same amount This ensures that a reference counted servant cannot be deleted while a request is executing 111 CHAPTER 4 CORBA Objects Factory Objects using Java Here is our Java implementation of the Product interface 1 Java 2 public class Product_impl extends ProductPOA 31 4 public void destroy s d 6 byte id _default_POA servant_to_id this y _default_POA deactivate_object id 8 2 Servant class Product_imp1 is defined as an implementation of the Product interface 6 7 The destroy operation deactivates the servant with the POA As long as no other r
243. nt of every symbol that needs an explicit DLL import statement 31 CHAPTER 2 Generating Code with Orbacus with interceptor args Generate code with support for arguments result and exception list values for interceptors no local copy To ensure strict compliance with CORBA s location transparency semantics the default behavior of the translator is to generate code that copies valuetype argument and result values for collocated invocations Specify this option to disable strict compliance and generate more efficient code case sensitive The semantics of OMG IDL forbid identifiers in the same scope to differ only in case This option relaxes these semantics but is only provided for backward compatibility with non compliant IDL 32 Translating IDL to Java Translating IDL to Java Synopsis Description Options for jidl jidl options idl files Translates IDL files into Java files For every construct in the IDL file that maps to a Java class or interface a separate class file is generated Directories are automatically created for those IDL constructs that map to a Java package e g a module jidl can also add comments from the IDL file starting with to the generated Java files This allows you to use the javadoc tool to produce documentation from the generated Java files See Using javadoc on page 43 for additional information h help v version d debug DNAME DNAME
244. o manager pl 23 24 Hello _impl helloImpl new Hello impl hel1loPOA 25 PortableServer ServantBase_var servant helloImpl 26 PortableServer ObjectId_var oid 27 PortableServer string_to_ObjectId hello 28 helloPOA gt activate_object_with_id oid servant 29 Hello var hello helloImpl gt _this 30 3 CORBA String_var s orb gt object_to_string hello 32 ofstream out Hello ref 33 out lt lt s lt lt endl 34 out close 35 36 manager gt activate 37 orb gt run 38 39 return 0 14 22 Create a new POA using PERSISTENT life span policy and the usER_1p object identification policy 24 25 Create the Hello servant Programming Example 26 27 Using the string hello create an object id 28 Activate the servant with the new POA The remainder of the code is unchanged 173 CHAPTER 6 The Implementation Repository 174 In this chapter CHAPTER 7 The Implementation Repository Console The Orbacus Implementation Repository IMR includes a graphical client for administering the service called the Orbacus IMR Console The Orbacus IMR Console provides complete control over the IMR OADs and servers in a domain This chapter contains the following sections Usage page 176 The Menus page 177 175 CHAPTER 7 The Implementation Repository Console Usage com ooc IMRConsole Main look CLASS
245. o the pool where it waits to be promoted again While in the waiting state the thread is said to be a follower In this model it is possible to have multiple threads in the processing state at the same time However as stated above there can only ever be one leader The main advantage of this model is scalablilty It allows tight control over the number of threads used by each POAManager 337 CHAPTER 16 Concurrency Models The Reactor What is a Reactor Available Reactors 338 In reactive mode see Single Threaded Concurrency Model on page 328 Orbacus uses a so called Reactor for event dispatching 141 Simply speaking the Reactor is an instance in Orbacus a singleton where special objects so called event handlers can register if they are interested in specific events These events can be network events such as an event signaling that data are ready to be read from a network connection Again this chapter only applies to Orbacus when used with reactive concurrency models If you use Orbacus with any other concurrency model for example any of the multi threaded models the following examples are not applicable Also since Orbacus for Java currently doesn t support the reactive model at all the following only applies to Orbacus for C Currently there are three Reactors supported by Orbacus e The standard select Reactor which relies on the Berkeley Sockets select function
246. oad alerts to overload members When a member receives a load alert it forwards the next client request back to the service There are two types of strategies adaptive and non adaptive When using an adaptive strategy a load balanced group must receive load updates from the members These loads are then used by the strategy to determine the next member to be used for a client connection Adaptive strategies can also provide load re balancing When using non adaptive strategies the service does not require load updates from the members and load re balancing is not possible Member selection and load re balancing are discussed in the following sections The advantages and disadvantages of the different types of load balancing strategies is also presented Non adaptive member selection does not use load information from the members Hence non adaptive member selection will only correctly balance connections under a certain set of conditions These conditions are as follows Dedicated hosts e Homogeneous hosts e Clients generate the same load and are connected for the same amount of time or clients are connected for short periods of time While adaptive member selection can be used in more situations than non adaptive member selection it is not without problems The problems with adaptive member selection are highlighted below 1 Using a polling technique to retrieve member loads does not scale Hence it is decided that lo
247. object and server POA needs this policy set to BOTH for BiDir communication to take place OB ACMTimeoutPolicy This policy determines whether the ORB performs active connection management ACM on the connection associated with an object reference The policy specifies a time after which idle connections are shutdown A value of O means no timeout The default for this policy is the value of the ooc orb client_timeout property see ooc orb client_timeout on page 53 OB ConnectionReusePolicy This policy determines whether the ORB is permitted to reuse a communications channel between peers If this policy is false then each object will have a new communications channel to its peer The default for this policy is true OB ConnectTimeoutPolicy If an object has this policy and a connection cannot be established after value milliseconds a CORBA NO_RESPONSE exception is raised 303 CHAPTER 15 Using Policies 304 Table 4 Orbacus policies Policy Description OB InterceptorPolicy This policy determines whether client side interceptors will be called Client side interceptors are enabled by default To disable client side interceptors this policy can be set on an ORB or object reference with a value of false OB LocateRequestPolicy This policy determines whether the ORB sends GIOP LocateRequest messages This policy exists to avoid an interoperability issue re
248. objects must be narrow d to an info object for this protocol for example in the case of an IIOP plug in a OCI TransportInfo must be narrow d to OCI IIOP Transport Info 343 CHAPTER 17 The Open Communications Interface Class Diagram 344 Figure 15 shows the classes and interfaces of the OCI except for the Buffer and Info interfaces lt O 1 ORB OA 1 Connector Acceptor Factory Factory Registry Registry Connector C t Transport A t Acceptor Factory onnector ranspor cceptor Factory creates creates lt creates creates pi Protocol Protocol Protocol oo Specific Specific Specific pecitic Connector Acceptor Factory Connector Transport Acceptor Factory Figure 15 OC Class Diagram Orbacus provides abstract base classes for the interfaces Connector Factory Connector Transport Acceptor Factory and Acceptor The protocol plug in must inherit from these classes in order to provide concrete implementations for a specific protocol Orbacus also provides concrete classes for the interfaces Buffer Connector Factory Registry and Acceptor Factory Registry Instances of Connector Factory Registry and Acceptor Factory Registry can be obtained via the ORB operation resolve initial references using the identifiers OCIConFactoryRegistr
249. ofiles adding profiles to ORs or extracting object keys from profiles Acceptor and Connector Factories are used by clients to create Acceptors and Connectors Acceptors are created infrequently usually only when POA Managers are created Connectors however need to be created by clients whenever a new connection to a server has to be established The only component of the OCI that is configurable by applications is the Acceptor When creating a new Acceptor an Acceptor Factory takes a sequence of protocol specific parameters which are used to configure the Acceptor Each plug in implementation should document these configuration parameters The configuration parameters for the plug ins included with Orbacus are described later in this chapter The ORB provides Acceptor and Connector Factory Registries These registries allow the plugging in of new protocols Transport Connector Connector Factory Acceptor Factory and Acceptor must be written by the Interface Summary plug in implementers The Connector Factory must then be registered with the ORB s Connector Factory Registry and the Acceptor Factory must be registered with the ORB s Acceptor Factory Registry The Info Objects Info objects provide information on Transports Acceptors and Connectors A Transport Info provides information on a Transport an Acceptor Info on an Acceptor and a Connector Info on a Connector To get information for a concrete protocol these info
250. ol has the following structure corbaloc iiop versione host port object key The components of the URL are as follows iiop This is the default protocol for corbaloc URLs and therefore is optional e version The IIOP version number in major minor format The default iS 1 0 host The hostname of the server port The port on which the server is listening The default is 2089 e object key A stringified object key The specification allows a URL to contain multiple addresses but the semantics are vendor specific In Orbacus each address is used in turn until one is found that works or until the ORB has tried them all and failed to contact the object The rir protocol is a shortcut for the ORB operation resolve initial references The corbaloc URL for the rir protocol has the following structure corbaloc rir id The components of the URL are as follows e rir The protocol e id The identifier of the service to be resolved The identifier NameService is used if id is not supplied Some examples of corbaloc URLs are corbaloc nshost 10000 NameService corbaloc myhost 10000 MyObjectId corbaloc rir NameService 133 CHAPTER 5 Locating Objects See The BootManager on page 138 for information on how a server can support corbaloc URLs 134 Object Reference URLs corbaname URLs A corbaname URL provides additional flexibility by incorporating use of th
251. olicy The location transparency policy This policy is used to control how strict the ORB is in enforcing location transparency This is useful for performance reasons Attributes value readonly attribute short value LOCATION TRANSPARENCY STRICT ensures strict location transparency is followed LOCATION_TRANSPARENCY RELAXED relaxes the location transparency guarantees for performance reasons Specifically for collocated method invocations the dispatch concurrency model will be ignored and policy overrides are not removed The default value is LOCATION TRANSPARENCY RELAXED 412 Module OB Interface OB ProtocolPolicy Attributes Operations local interface ProtocolPolicy inherits from CORBA Policy The protocol policy This policy specifies the order in which profiles should be tried value readonly attribute OCI PluginIdSeq value If a ProtocolPolicy is set then the value specifies the list of plugins that may be used The profiles of an IOR will be used in the order specified by this policy If no profile in an IOR matches any of the plugins specified by this policy a CORBA TRANSIENT exception will be raised By default the ORB chooses the protocol to be used contains boolean contains in OCI PluginId id Determines if this policy includes the given plugin id 413 CHAPTER B Orbacus Policy Reference Interface OB RequestTimeoutPolicy local interface RequestTimeoutPolicy inherits from COR
252. ons for a UDP endpoint are shown below udp bind ADDR buffer size N host ADDR ADDR message timeout SEC multicast no loopback ttl N numeric port N transport timeout SEC bind ADDR Specifies the hostname or dotted decimal address of the network interface on which to bind the socket If not specified the socket will be bound to all available interfaces This option is useful in situations where a host has several network interfaces but the server should only listen for connections on a particular interface buffer size N Sets the size of the socket s receive buffer Note that this is only a hint to the operating system To determine the actual size use the trace option when installing the plug in The default value is operating system dependent host ADDR ADDR Specifies a list of one or more hostnames and or dotted decimal addresses representing the addresses that should be advertised in ORs Multiple addresses are represented as multiple tagged profiles If host is not specified the canonical hostname is used This option must be specified if multicast is used message timeout SEC Specifies the expiration time in seconds for incomplete messages Because the plug in may fragment a request into multiple packets it is possible for some packets to be lost If no more packets have arrived for an incomplete message after the specified timeout the message is discarded
253. operations that can subsequently return references to other objects 10 Implementing the Example in C Implementing the Client Overview Client code 7 12 16 20 In several respects the client program is similar to the server program The code to initialize and destroy the ORB is the same Save the following code in a file Client cpp ONIN AHH FWD HP PRR P wo WNHO 14 15 16 Ty 18 19 20 21 22 23 24 25 26 27 C include lt OB CORBA h gt include lt Hello h gt include lt fstream h gt int run CORBA ORB ptr int main int argc char argv Same as for the server int run CORBA ORB ptr orb const char refFile ifstream in refFile char s 2048 la SS ys CORBA Object_var obj Hello ref orb est ngmt OnObs ech Ss ir Hello var hello Helllo _ narrow obj hello gt say aello p return 0 In contrast to the server the client does not need to include Hello impl h Only the generated file Hello h is needed This code is the same as for the server The stringified object reference written by the server is read and converted to a CORBA Object object reference It s not necessary to obtain a reference to the Root POA or its POA Manager because they are only needed by server applications 11 CHAPTER 1 Getting Started 12 22 24 The narrow operation generates a Hello object reference from the CORBA Objec
254. operty If present the ORB loads the configuration file Next the ORB loads the configuration file specified by the ORBconfig option Therefore the properties loaded from the file specified by ORBconfig will override any existing properties including those loaded by a configuration file specified in the environment variable or system property See Precedence of Properties on page 68 for more information Configuration files are only loaded during ORB initialization Changes made to a configuration file after an ORB has been initialized have no effect on that ORB 1 Orbacus for Java also accepts a URL specification as the filename Configuring the ORB and Object Adapter Using the Windows NT Registry RegUpdate Synopsis Example Another convenient mechanism for use with C applications under Windows NT is to use the system registry Properties can be stored in the registry under the following registry keys HKEY LOCAL MACHINE Software 00C Properties HKEY CURRENT _USER Software 00C Properties Individual properties are defined as sub keys of the base For example the property ooc orb trace connections 5 is stored in the registry as the following key containing a value named connections with a REG_SZ data member equal to 5 Software 00C Properties ooc orb trace The Orbacus distribution includes a utility called RegUpdate The tool first removes all sub keys defined under the specified registry key Next all
255. option only available for C servers This option is used for server registration and can only be used when starting the server for the first time ii Use the orBServerrd command line option iii Use the coc orb server_name configuration property This configuration property is equivalent to the orBServerId command line option and may be set in a configuration file or programmatically prior to initializing the ORB in a server In this example the IMR is responsible for starting the servers Hence when the server is started the orBServerid option is automatically added to the argument list 8 Create object references for use by the clients A server can always be used to create references for its objects However if an object is created by a POA that uses the usER_1p object identification policy then the mkre utility can also be used to create a reference for the object Using the mkreg utility is discussed below Assume each server has a single primary object Server uses Object1 for its Object ID and server2 uses Object2 Also each server creates a persistent POA called Main to hold its objects To create object references for these objects run the following on master mkref P 10001 Serverl Object1 Main gt Objectl ref mkref P 10001 Server2 Object2 Main gt Object2 ref After all OADs servers and POAs are registered it is recommended to restart the IMR in non administrative mode This will prevent any accidental
256. or and the Interface Repository The IDL to C Translator and the Interface Repository Private Versus Global Interface Repositories Steps Example The Orbacus IDL to C and IDL to Java translators internally use the Interface Repository for generating code That is these programs have their own private Interface Repository that is fed with the specified IDL files All code is generated from that private Interface Repository However it is also possible to generate C code from a global Interface Repository To generate C code from a global Interface Repository 1 Start the Interface Repository using the command irserv 2 Feed the Interface Repository the IDL code using the command irfeed 3 Finally use the irgen command to generate the C code For example irserv ior gt IntRep ref amp irfeed ORBrepository cat IntRep ref file idl irgen ORBrepository cat IntRep ref file By comparison the IDL to C translator idl performs all these steps at once in a single process using a private Interface Repository Thus you only have to run a single command idl file idl See Chapter 12 for more information on the Interface Repository 39 CHAPTER 2 Generating Code with Orbacus Include Statements Using include statements If you use the include statement in your IDL code the Orbacus IDL to C translator id1 does not create code for included IDL files Instead the translato
257. orBadSchemeName Bad scheme name MinorBadAddress Bad address MinorBadSchemeSpecificPart Bad scheme specific part MinorOther Other MinorInvalidAbstract InterfaceInheritance Invalid abstract interface inheritance MinorInvalidValueInheritance Invalid valuetype inheritance MinorInvalidServiceContextId Invalid service context ID MinorObject IsNull Object parameter to object_to_ior is null MinorInvalidComponentId Invalid component ID MinorInvalidProfileId Invalid profile ID MinorDuplicatePolicyType Duplicate policy types MinorDuplicateDeclarator Duplicate declarator MinorInvalidValueModifier Invalid valuetype modifier MinorDuplicateValueInit Duplicate valuetype initializer MinorAbstractValueInit Abstract valuetype cannot have initializer 383 CHAPTER 18 Exceptions and Error Messages MinorDuplicateBaseType Base type appears more than once MinorSingleThreadedonly ORB does not support multiple threads a ogs MinorNameRedefinitionInImmediateScope Invalid name redefinition in an immediate scope MinorInvalidValueBoxType Invalid type for valuebox MinorInvalidLocalInterfaceInheritance Invalid local interface inheritance MinorConstantTypeMismatch Constant type doesn t match definition 384 CORBA System Exceptions NO MEMORY Minor Exception Code
258. orbaloc myhost 2098 TelemetryData To obtain the object reference of a channel factory use a corbaloc URL with the object key as shown in Table 2 on page 237 For example assuming the untyped Event Service is running on host myhost at port 2098 here is how a C application can obtain the object reference of the channel factory and create a channel with the identifier TelemetryData C CORBA Object var obj orb gt string to object corbaloc myhost 2098 DefaultEventChannelFactory OBEventChannelFactory EventChannelFactory var factory OBEventChannelFactory EventChannelFactory _ narrow obj CosEventChannelAdmin EventChannel var channel factory gt create channel TelemetryData 245 CHAPTER 11 Orbacus Events 246 Here is the same example in Java Java org omg CORBA Object obj orb string to object corbaloc myhost 2098 DefaultEventChannelFactory com ooc OBEventChannelFactory EventChannelFactory factory com ooc OBEventChannelFactory EventChannelFactoryHelper narrow obj org omg CosEventChannelAdmin EventChannel channel factory create_channel TelemetryData Programming Example Programming Example In the Event Service example that comes with Orbacus two supplier and two consumer clients demonstrate how to use an untyped event channel to propagate information The pieces of information transferred by this example are strings containing the current date and tim
259. orld servers This section covers the following topics Non adaptive Load Balancing page 283 Adaptive Load Balancing page 288 Running the Load Balanced Servers page 292 Programming Example Non adaptive Load Balancing 15 The Hello World server presented in Chapter uses the Root POA to activate its Hello servant However a member POA must have a member policy the usER_rp ID assignment policy value and the PERSISTENT lifespan policy value Hence the Hello World server must be modified so that the Hello servant is activated using a POA with the above policies Furthermore the Hello servant is no longer activated under the Root POA so it becomes necessary for it to override the _default_Poa method The modified servant s class declaration is shown below 1 C 2 include lt Hello skel h gt 3 4 class Hello impl public POA Hello 5 public PortableServer RefCountServantBase 6 7 PortableServer POA_var poa_ 8 oP public 10 ial Hello _impl PortableServer POA_ptr 12 13 virtual void say hello throw CORBA SystemException 14 15 virtual PortableServer POA ptr _default_POA 16 Private member to store the servant s default POA A constructor must be defined to allow the assignment of the servant s default POA Declaration of the default_poa method 283 CHAPTER 13 Orbacus Balancer The remainder of the class declaration is unchanged The de
260. ository IMR works and how to use it In this chapter This chapter contains the following sections Background page 153 Information Managed by the IMR page 154 IMR Security page 157 Usage page 158 Windows NT Native Service page 160 Configuration Properties page 162 Connecting to the Service page 163 Utilities page 164 Getting Started with the Implementation Repository page 167 CHAPTER 6 The Implementation Repository 152 Programming Example page 170 Background Overview How It All Works Background The Orbacus Implementation Repository IMR provides support for the indirect binding of persistent object references The key advantage of indirect binding is that it loosens the coupling between clients and servers so that the location of the server can change without affecting the client In practical terms this is accomplished by providing the client with an IOR that actually refers to the IMR rather than to the server itself The IMR also provides the ability to start servers on demand using the Object Activation Daemon OAD The CORBA specification does not standardize how servers and the IMR interact it only suggests functionality for vendors to implement Hence the interface between servers and the IMR is strictly proprietary Due to the proprietary interface between servers and the IMR servers using the IMR must be developed using Orbacus for C or Java Howev
261. ot always equal because of TypeCode compaction However if the cache is enabled two TypeCode objects received over the wire with the same repository id will always be equal For more information on the semantics of the equal and equivalent TypeCode operations see 3 Value ior 57 CHAPTER 3 ORB and Object Adapter Initialization ooc orb trace connections ooc orb trace retry 58 Adds an initial service to the ORB s internal list This list is consulted when the application invokes the ORB operation resolve_initial_references name is the key that is associated with an IOR or URL For example the property ooc orb service NameService adds NameService to the list of initial services See The BootManager on page 138 for more information Value level gt 0 Defines the output level for diagnostic messages printed by Orbacus that are related to connection establishment and closure A level of 1 or higher produces information about connection events and a level of 2 or higher produces code set exchange information The default level is O which produces no output Value level gt O Defines the output level for diagnostic messages printed by Orbacus that are related to transparent re sending of failed messages A level of 1 or higher produces information about re sending of messages and a level of 2 or higher also produces information about use of individual IOR profiles The default level is O wh
262. ote_port The remote port 466 Module OCI IIOP Interface OCI IIOP ConnectorInfo Attributes local interface ConnectorInfo inherits from OCI ConnectorInfo Information on an IIOP OCI Connector object See Also Interface OCI Connector Interface OCI Connector nfo remote_addr readonly attribute InetAddr remote_addr The remote IP address to which this connector connects remote_port readonly attribute unsigned short remote_port The remote port to which this connector connects 467 CHAPTER E Open Communications Interface Reference Interface OCI IIOP ConFactoryInfo 468 local interface ConFactoryInfo inherits from OCI ConFactoryInfo Information on an IIOP OCI Connector Factory object See Also Interface OCI ConFactory Interface OCI ConFactory nfo Module OCI IIOP Interface OCI IIOP AcceptorInfo Attributes local interface AcceptorInfo inherits from OCI AcceptoriInfo Information on an IIOP OCI Acceptor object See Also Interface OCI Acceptor Interface OCI Acceptor nfo hosts readonly attribute CORBA StringSeq hosts Hostnames used for creation of IIOP object references addr readonly attribute InetAddr addr The local IP address on which this acceptor accepts port readonly attribute unsigned short port The local port on which this acceptor accepts 469 CHAPTER E Open Communications Interface Reference Inte
263. ou can get this list by calling get_all_property_ names Wi sews void get_all property names in unsigned long how many out PropertyNames property names out PropertyNamesIterator rest As with get_all_properties a list of names as well as an iterator is returned This iterator implements the PropertyNamesIterator interface ji Ib interface PropertyNamesIterator void reset boolean next _one out PropertyName property name boolean next_n in unsigned long how many out PropertyNames property names void destroy he The iterators should always be destroyed when they are no longer needed Sometimes it is useful to know of how many properties a PropertySet consists of This information is provided by get_number of properties IDL unsigned long get number of properties Note that you have to be careful if you intend to use the return value of get_number of properties as the input value for the how_many parameter of get_all_properties in order to get a complete property list You always have to check the PropertiesIterator for properties that were not returned as part of the Properties sequence returned by get_all_properties otherwise you might miss a property that was defined by another process between your calls to get_number of properties and get_all_ properties 225 CHAPTER 10 Orbacus Properties Deleting Properties If a property has become obsolete it can be deleted from the PropertySet
264. p_id raises GroupNotFound Register a load balanced group member unregister_member void unregister_member in MemberId member _id in GroupId group_id Unregister a load balanced group member References 1 2 3 4 5 6 7 8 10 Buschman F et al 1996 Pattern Oriented Software Architecture A System of Patterns New York Wiley Gamma E et al 1994 Design Patterns Reading MA Addison Wesley Henning M and S Vinoski 1999 Advanced CORBA Programming with C Reading MA Addison Wesley Object Management Group 1999 The Common Object Request Broker Architecture and Specification Revision 2 3 1 ftp www omg org pub docs formal 99 1 0 07 pdf Framingham MA Object Management Group Object Management Group 1999 C Language Mapping ftp www omg org pub docs formal 99 07 45 pdf Framingham MA Object Management Group Object Management Group 1999 DL Java Language Mapping ftp www omg org pub docs formal 99 07 53 pdf Framingham MA Object Management Group Object Management Group 1999 Portable Interceptors ftp ftp omg org pub docs orbos 99 12 02 pdf Framingham MA Object Management Group Object Management Group 1998 CORBA Messaging ftp ftp omg org pub docs orbos 98 05 06 pdf Framingham MA Object Management Group Object Management Group 1998 CORBAservices Common Object Services Specification ftp www omg org pub docs for
265. pboard under the selected OAD Start Start the selected server Stop Stop the selected server Reset Reset the state of the selected server The Create menu item creates a child object under the selected object OADs are created under the IMR Domain root object servers are created under OADs and POAs are created under servers The Modify menu item applies to all objects However servers are currently the only objects that have attributes that can be modified To delete an object the Delete menu item is used This operation recursively deletes all children under the selected item 177 CHAPTER 7 The Implementation Repository Console The View Menu The Toolbar and the Popup Menu 178 The Cut and Paste menu items only apply to servers and are used to move servers to different hosts Note that OAD for the desired host must be selected when using Paste In very rare circumstances it s possible for the IMR and OAD to become confused as to the state of a server In this case it might be necessary to manually reset the state of the server using the Reset menu item It also necessary to use this item if the server continually crashes on startup and has reached the maximum number of retries specified by its max_spawns attribute This prevents the OAD from continually starting the same broken server The View menu contains the Refresh menu item The Refresh menu item is used to update the console whe
266. pecifies the delay in milliseconds between packets In some cases sending packets too quickly can cause more packets to be dropped The default value is O packet size N Sets the size of a packet in bytes If necessary the plug in splits a single request into multiple packets of the specified size and reassembles them on the server Note that there are hard operating system limits on the size of a datagram The default size is 1472 which is the largest portable size no loopback Specifies that loopback mode of the socket shall be disabled for multicast communication This prevents sending multicast packets back to the local socket For Java this functionality is only available from JDK 1 4 0 on ttl N Specifies the time to live value 0 255 of multicast packets sent System defaults apply if not specified trace N Sets the level of diagnostic output The default value is O Note The no loopback option for multicast communication is to be specified on the client side for Unix systems and on the server side for Windows systems 359 CHAPTER 17 The Open Communications Interface Server Installation 360 The server side UDP plug in is installed as shown below ooc oci server udp trace N The following options are supported trace N Sets the level of diagnostic output The default value is O The UDP OCI Plug in Endpoint Configuration The configuration opti
267. perty ReadOnlyProperty As a property consists of a name value pair both the name and the value are the parameters to this operation 223 CHAPTER 10 Orbacus Properties Querying for Properties As soon as a property is defined the PropertySet can be queried for the property s value with the get_property value operation Ai TED any get_property value in PropertyName property name raises PropertyNotFound InvalidPropertyName For a particular property name this call either returns the any associated with that name or throws an exception if a property with the name does not exist You can not only query for a particular property value but also for a list of all the properties defined within a PropertySet The get_all_ properties operation serves this purpose IDL void get_all properties in unsigned long how many out Properties nproperties out PropertiesIterator rest This operation works similar to the list call offered by the Naming Service In both cases the maximum number of items to be returned at once is specified An iterator implementing the PropertiesIterator interface gives access to the remaining items if any IDL interface PropertiesIterator void reset boolean next_one out Property aproperty boolean next _n in unsigned long how many out Properties nproperties void destroy 224 Querying for Properties If you are only interested in a list of property names y
268. pertySetDefFactoryHelper narrow obj 2355 24 catch org omg CORBA BAD PARAM ex 25 i 26 This object does not implement the Property Service 27 28 29 PropertySetDef set factory create_propertysetdef Ww fo 227 CHAPTER 10 Orbacus Properties 5 27 228 31 32 38 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 Bs 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 va 74 RS Any anyLong orb create_any Any AnyString orb create_any Any anyShort orb create_any anyLong insert_long 12345L anyString insert_string Foo anyShort insert_short short 0 try set define property LongProperty anyLong set define property StringProperty anyString set define property ShortProperty anyShort catch ReadOnlyProperty ex Bn error occurred catch ConflictingProperty ex An error occurred catch UnsupportedProperty ex An error occurred catch UnsupportedTypeCode ex An error occurred catch InvalidPropertyName ex An error occurred PropertiesHolder ph new PropertiesHolder PropertiesIteratorHolder ih new PropertiesIteratorHolder set get_all properties 0 ph ih PropertyHolder h new PropertyHolder while ih value next_one h The next property is now stored in h value ih value destroy Get a Property Servic
269. pl For USER_ID you must provide the Object ID I impl impl new I _impl org omg PortableServer POA poa impl default _POA byte id MyObjectName getBytes poa activate_object_with _id id impl BWDY HP 105 CHAPTER 4 CORBA Objects Deactivating Servants Deactivation of Servants using C Deactivation of Servants using Java Transient and Persistent Objects 106 A servant can be deactivated Deactivating a servant breaks the association between the CORBA object and the servant requests that arrive from clients thereafter result in an OBJECT _NOT_EXIST exception or a TRANSIENT exception if the server is down at the time a request is made To deactivate a servant call the deactivate object member function on the servant s POA C PortableServer POA var poa impl default POA PortableServer ObjectId_var id poa gt servant_to_id amp impl1 poa gt deactivate object id BwWDhY HP The code obtains a reference to the servant s POA by calling default Poa This assumes that _default_pPoa is correctly overridden to return the appropriate POA if the servant is not activated with the Root POA The call to servant_to_id on the servant s POA returns the object ID with which the servant is activated The call to deactivate _object breaks the association between the CORBA object and the servant Note that deactivate object returns immediately even though the servant
270. platforms the exec attribute may refer to an executable or a shell script with interpreter as its first line 155 CHAPTER 6 The Implementation Repository POAs 156 However if a batch file or shell script is used then it should accept the ORBServerld option since it is automatically appended to the args attribute by the IMR In the case of Java servers a batch file or shell script should be created to start the server An alternative is to set the exec attribute to the Java interpreter and to use the args attribute to specify the class implementing the server The IMR allows implicit registration of POAs when the server is started This can be enabled or disabled for each server using the activate_poas server attribute If implicit registration is enabled then the user does not have to register any of the POAs instead the server transparently notifies the IMR whenever a Call to create_Poa is made by the application code If the user disables implicit registration then the user must register all persistent POAs i e POAs with the PERsIsTENT life span policy POAs are registered using the name of its server and the name of the POA Note that any transient POAs POAs with the TRANSIENT life span policy created by the server are not registered with the IMR The IMR also maintains the status for each POA which indicates the state of its POA Manager The valid values are inactive active holding and discarding
271. policies new org omg CORBA Policy 1 11 org omg BiDirPolicy BidirectionalPolicyValueHelper insert 12 any Org omg BiDirPolicy BOTH value 13 policies 0 orb create_policy 14 org omg BiDirPolicy BIDIRECTIONAL POLICY TYPE value 15 any 16 17 org omg PortableServer POA myPOA 18 rootPOA create_ POA MyPOA manager policies This is equivalent to the C version BidirectionalPolicy Client This example shows how to create an object reference with the Implementation BidirectionalPolicy enabled to signal connection reuse is allowed over connections established with this object reference The C example is presented first followed by the Java version C CORBA Object_var obj orb gt string tonobiject rel file Hello rer CORBA PolicyList policies 1 policies length 1 CORBA Any any any lt lt BiDirPolicy BOTH policies 0 orb gt create _policy 10 BiDirPolicy BIDIRECTIONAL POLICY TYPE 1 any 12 Iob ob set policy overrides 14 policies CORBA ADD OVERRIDE 15 16 Hello var hello Hello _narrow obj vonon AeA WDNR 322 5 11 13 14 16 Programming Examples Obtain the object reference from some means here using a file Create the BidirectionalPolicy with a value of BOTH to enable BiDir Add the Bidirectional Policy to the object and make sure to catch the return object reference Narrow the object to the specific type for me
272. ption ooc imr trace peer_status level gt 0 Defines the output level for IMR diagnostic messages related to communications with the OADs The default level is O which produces no output ooc imr trace process_control level gt 0 Defines the output level for IMR diagnostic messages related to the forking and death of server processes The default level is O which produces no output ooc imr trace server_status level gt 0 Defines the output level for IMR diagnostic messages related to the status of servers and POAs The default level is O which produces no output 162 Connecting to the Service Connecting to the Service Servers that use the IMR must be configured with the IMR initial reference The object key of the IMR is mmr hence a URL style object reference of the IMR service running on host imrhost at port 10000 would be corbaloc imrhost 10000 IMR Using this object reference a server can configure the IMR initial reference with the property ooc orb service IMR corbaloc imrhost 10000 IMR An alternative to using the above property is to use the ORBInitRef command line option Refer to Chapter 5 for more information on URLs and configuring initial services 163 CHAPTER 6 The Implementation Repository Utilities Implementation Repository Administration 164 The imradmin utility provides complete control over the IMR OADs and servers in a domain Its command interfac
273. quests so that threads have to be created only once and can then be reused for other requests Figure 14 shows an example with one client and a thread pool server with three threads in the pool Sender and receiver threads are not shown fO g ho iQ lt IO Client Thread Pool Server Figure 14 Thread Pool Server The first three operation calls g and h can be carried out immediately since there are three threads in the pool However the fourth request i is delayed until at least one of the other requests returns Since there is no time consuming thread creation the thread pool concurrency model performs better than the thread per request model The thread pool is a good trade off if on the one hand frequent thread creation and destruction result in unacceptable performance but on the other hand delaying the execution of concurrent method calls is also not desired Leader_Follower Multi Threaded Concurrency Models In the Leader Follower concurrency model each thread from the thread pool will transition between the following states e leader e processing e follower The leader thread of which there can only be one at any given time waits for incoming requests When a request is received the leader thread will promote a new leader while it goes into the processing state to handle the received requests Once processing is complete the thread is absorbed back int
274. r struct PropertyError PropertyName name PropertyErrorCode code J A load balancing strategy configuration property error MemberData struct MemberData MemberId member _id LoadAlert alert i The member data MemberPolicyValue struct MemberPolicyValue GroupId group_id MemberId member _id i The member policy value Module LoadBalancing MemberExists exception MemberExists i A MemberExists exception indicates that a member with the specified id is already exists in the load balanced group MemberNotFound exception MemberNotFound J A MemberNotFound exception indicates that the specified member does not exist in the load balanced group GroupExists exception GroupExists 475 CHAPTER F Orbacus Balancer Reference 476 i A GroupExists exception indicates that a load balanced group with the specified id already exists GroupNotFound exception GroupNot Found 1 A GroupNotFound exception indicates that the specified load balanced group does not exist StrategyNotFound exception StrategyNotFound i A StrategyNotFound exception indicates that the specified strategy is not supported by the Balancer StrategyNotAdaptive exception StrategyNotAdaptive Jz A StrategyNotAdaptive exception indicates that the strategy is not an adaptive strategy and does not require load updates InvalidProperties exception InvalidPropert
275. r each operation invocation Portable Object Adapter provides high scalability for servers that contain very large numbers of objects Objects by Value reduce network traffic by turning a remote interaction into a local invocation Dynamic Invocation and Dynamic Skeleton Interface send and receive requests without compile time knowledge of interface types and operation signatures Implementation Repository start servers on demand and migrate servers to different hosts without adversely affecting clients Interface Repository build IDL to anything translators easily Support for Local Interfaces standard way to implement locality constrained objects Platform support About this Document Getting Help Additional resources PREFACE For platform availability please refer to the Orbacus home page at http www orbacus com support new_site platforms jsp This manual is except for the Getting Started chapter no replacement for a good CORBA book This manual also does not contain the precise specifications of the CORBA standard which are freely available on line A good grasp of the CORBA specifications in 4 5 and 6 is absolutely necessary to effectively use this manual In particular the chapters in 4 covering CORBA IDL and the IDL to C mapping should be studied thoroughly For C users we also highly recommend 3 This book contains by far the best treatment of CORBA programming wi
276. r inserts the appropriate include statements in the generated header files Restrictions There are several restrictions on where to place the include statements in your IDL files for this feature to work properly include may only appear at the beginning of your IDL files All include statements must be placed before the rest of your IDL code e Type definitions such as interface or struct definitions may not be split among several IDL files In other words no include statement may appear within such definitions If you do not want these restrictions to be applied you can use the translator option a11 with ial With this option the IDL to C translator treats code from included files as if the code appeared in your IDL file at the position where it is included This means that the compiler will not place include statements in the automatically generated header files regardless of whether the code comes directly from your IDL file or from files included by your IDL file Note that when generating code from an Interface Repository using irgen the translator behaves identically to ial with the a11 option In other words the irgen command does not place include statements in the generated files but rather generates code for all IDL definitions in the Interface Repository 1 Preprocessor statements like define or ifdef may be placed before your include statements 40 Documenting IDL Files Documenting IDL
277. r servers that are not registered with the IMR Value timeout gt 0 If the server is not able to gracefully disconnect from the client in timeout seconds a connection shutdown is forced If this property is set to zero then the server will not force a connection shutdown If the property is not set a default timeout value of two seconds is used Value timeout gt 0 The server actively closes a connection that has been idle for timeout seconds once that connection has no more outstanding replies Note that the application must use one of the threaded server side concurrency model if connection timeouts are desired If this property is set to zero or not set at all then the server does not close idle connections Value true false Determines whether the ORB caches TypeCodes When the TypeCode cache is disabled the ORB creates a new TypeCode object for each TypeCode received over the wire including those associated with Any values When the TypeCode cache is enabled only one TypeCode object is instantiated for each TypeCode with a unique non empty repository id The default value is true Note that there is one rare case where the cache may not work as expected if an application requires the received TypeCode to be equal to the one that was transmitted where equal implies a successful result from the TypeCode equal operation Although TypeCodes with the same repository id are always equivalent they are n
278. r the wire The default is false only retry on locally generated exceptions Note Many TCP IP stacks do not provide a reliable indication of communication failure when sending smaller requests therefore the failure may not be detected until the ORB attempts to read the reply In this case the ORB must assume that the remote end has received the request in order to guarantee at most once semantics for the request The implication is that when using the default setting of RETRY_STRICT most communication failures will not cause a retry This behavior can be relaxed using RETRY ALWAYS retry_remote readonly attribute boolean retry remote 415 CHAPTER B Orbacus Policy Reference Interface OB TimeoutPolicy Attributes 416 local interface TimeoutPolicy inherits from CORBA Policy The timeout policy This policy can be used to specify the default timeout for connection establishment and requests If an object also has Connect ionTimeoutPolicy Of RequestTimeoutPolicy set those values have precedence See Also Interface OB ConnectTimeoutPolicy Interface OB RequestTimeoutPolicy value readonly attribute unsigned long value If an object has a TimeoutPolicy set and a connection cannot be established or no response to a request is available after value milliseconds a CORBA NO_RESPONSE exception is raised The default value is 1 which means no timeout Module OBPortableServer Module OBPortableSer
279. rReadStringOverflow Overflow while reading string MinorReadStringZeroLength Encountered zero length string MinorReadStringNul1lChar Encountered null char in string CORBA System Exceptions Minor ReadStringNoTerminator Terminating null char missing in string Minor ReadWStringOverf low Overflow while reading wstring Minor ReadWStringZeroLength Encountered zero length wstring Minor ReadWStringNul1lWChar Encountered null char in wstring ReadWStringNoTerminator Minor Terminating null char missing in wstring a MinorReadFixedOverflow Overflow while reading fixed MinorReadFixedInvalid Invalid encoding for fixed value MinorReadBooleanArrayOverflow Overflow while reading boolean array Minor ReadCharArrayOverflow Overflow while reading char array Minor ReadWCharArrayOverflow Overflow while reading wchar array Minor ReadOctetArrayOverflow Overflow while reading octet array Minor ReadShortArrayOverflow Overflow while reading short array Minor ReadUShortArrayOverf low Overflow while reading ushort array Minor ReadLongArrayOverflow Overflow while reading long array Minor ReadULongArrayOverflow Overflow while reading ulong array Minor ReadLongLongArrayOverf low Overflow while reading longlong array Minor
280. rategy get_properties PropertySeq get_properties Get the property set of the strategy push_load void push_load in MemberId member_id in unsigned long load raises MemberNotFound StrategyNotAdaptive Update the load of a member 479 CHAPTER F Orbacus Balancer Reference Interface LoadBalancing Group Operations 480 interface Group Represents a load balanced group get_id GroupId get_id Get the id of the load balanced group get_ior Object get_ior in string repository id in ObjectId oid Get an IOR for use by a client of this load balanced group get_strategy_proxy StrategyProxy get_strategy proxy Get the strategy proxy of the load balanced group set_strategy void set_strategy in string name in PropertySeq properties raises StrategyNot Found InvalidProperties Use the specified built in load balancing strategy set_custom_strategy void set_custom_strategy in Strategy the_strategy Use the given custom load balancing strategy add_member void add_member in MemberId member_id raises MemberExists Add a member to the load balanced group remove_member void remove _ member in MemberId member_id raises MemberNotFound Remove a member of the load balanced group set_load_alert void set_load_alert in MemberId member_id Module LoadBalancing in LoadAlert alert raises MemberNot Found Set the LoadAlert object for a member list_m
281. ration file for the IMR and OADs First create a configuration file for the IMR containing the following imr conf ooc imr admin_endpoint iiop port 10000 ooc imr forward_endpoint iiop port 10001 ooc imr slave endpoint iiop port 10002 ooc imr mode master ooc imr dbdir usr local Orbacus db This file is placed in the usr local orbacus etc directory on host master Second create a configuration file for the OADs containing the following oad conf ooc orb service IMR corbaloc master 10000 IMR ooc imr slave_endpoint iiop port 10002 ooc imr mode slave ooc imr dbdir usr local Orbacus db This files is placed in the usr local Orbacus etc directory on hosts slavel and slave2 Start the IMR in administrative mode On host master run 167 CHAPTER 6 The Implementation Repository 168 imr ORBconfig usr local Orbacus etc imr conf administrative Start the OADs On host slavei run imr ORBconfig usr local Orbacus etc oad conf On host slave2 run imr ORBconfig usr local Orbacus etc oad conf Each OAD automatically registers itself with the IMR Note that an OAD can also be registered manually using the imradmin utility For example to register the OAD on host slavei run imradmin ORBInitRef IMR corbaloc master 10000 IMR add oad slavel Add each server to the IMR In our example we will run one server on each OAD The server names are Serverl and Server2 and are located in usr loca
282. rb poamanager manager co nc_model ooc orb poamanager manager en dpoint ooc orb poamanager manager lea der_follower_pool ooc orb poamanager manager ver sion Configuring the ORB and Object Adapter Specifies the GIOP version to be used in object references The default value is 1 2 This option is useful for backward compatibility with older ORBs that reject object references using a newer version of the protocol Value reactive threaded Specifies the communications concurrency model used by the POA Manager with name manager The default value is determined by ooc orb oa conc_model See Chapter 16 for more information on concurrency models Value string Specifies a comma separated list of endpoints for the POA Manager with name manager The default value is iiop See Endpoints on page 78 for more information Value n gt 0 Determines the number of threads in the pool used by the leader_follower concurrency model The default value is 10 This property is only effective when the ooc orb poamanager Manager conc_model property has the value leader follower Value 1 0 1 1 or 1 2 Specifies the GIOP version to be used in object references generated by a particular POA Manager This option is useful for backward compatibility with older ORBs that reject object references using a newer version of the protocol The default value is determined by the value of ooc orb oa version 61 CHAPTER 3 ORB and
283. rceptors will be disabled Create a new POA using the policy set created above 313 CHAPTER 15 Using Policies 314 And now the same example in Java wont OAN BAe WN PH ae H NFO 13 Java org omg CORBA Object obj orb resolve initial references Root POA org omg PortableServer POA rootPOA org omg PortableServer POAHelper narrow obj org omg PortableServer POAManager manager rootPOA the POAManager org omg CORBA Any any orb create_any org omg CORBA Policy policies new org omg CORBA Policy 1 any insert_boolean false policies 0 orb create_ policy com ooc OBPortableServer INTERCEPTOR CALL POLICY ID value any 14 15 16 org omg PortableServer POA myPOA rootPOA create_ POA MyPOA manager policies 1 16 This is equivalent to the C version Programming Examples CommunicationsConcurrencyPolicy This example shows how to create a new POA Manager with the concurrency model set to threaded The C version is presented first followed by the Java version Au PF WN HB 7 8 9 10 IL 12 T3 14 15 16 T7 18 ie 20 21 C CORBA Object_var poaObj orb gt resolve_initial references RootPOA OBPortableServer POA_var rootPOA OBPortableServer POA _ narrow poaObj POAManagerFactory var factory rootPOA gt the POAManagerFactory OBPortableServer POAManagerFactory var pmFactory OBPortableServer POAManagerFa
284. requests to other 328 Single Threaded Concurrency Model servers or receive and buffer replies This is very useful for oneway operations or the Dynamic Invocation Interface DII operation send deferred in combination with get_response or poll_response However the main advantage of a reactive client becomes apparent if it is used together with a reactive server in mixed client server applications A mixed client server application is a program that is both a client and server at the same time Without the reactive concurrency model it is not possible to use nested method calls in single threaded applications which are absolutely necessary for most kinds of callbacks Consider two programs A and B both mixed client server applications First A tries to call a method on B Before this method returns B calls back A by invoking method g This scenario is quite common and for example is used in the popular Model View Controller pattern 1 Using the reactive concurrency model for the client A can dispatch incoming requests while waiting for B s reply for This is shown in Figure 10 f0 gt dispatch g0 i dispatch lt aai p T T Client Server Client Server Figure 10 Reactive Client Server The reactive concurrency models are also very fast There is no overhead for thread creation or context switching Only an additional call to an operation like sele
285. responding to the IOR specified on the command line or the initial Naming Service as provided to the ORB with options like ORBservice or ORBconfigby You can make another naming context the root context using Switch Root Context The new root context s IOR is specified in the Enter The Menus IOR dialog window as shown in Figure 5 The IOR can be entered directly Enter IOR x TargetlOR From File Browse Figure 5 Entering an IOR or can be read from a file If an IOR is entered manually you usually either use the URL style notation as described in Chapter or you copy a stringified object reference into the dialog box using Cut amp Paste After selecting Browse a file containing an IOR can be selected Sometimes it is not desirable to completely replace the currently visible root context by another root context For example you may need to copy bindings from one context to another If this is the case simply open an additional window for the new root context using New Window You can then switch the root context in only one window without affecting the information displayed in the other one Using two windows you can easily transfer bindings from one context to another using Cut amp Paste Complete naming contexts can be loaded from a special file with naming context information Such a file which was previously created with Save Context As is loaded with Load Context The bindings saved to
286. rface OCI IIOP AccFactoryInfo local interface AccFactoryInfo inherits from OCI AccFactoryInfo Information on an IIOP OCI Acceptor Factory object 470 In this appendix APPENDIX F Orbacus Balancer Reference This appendix describes the interfaces for the Orbacus Balancer This appendix contains the following sections Module LoadBalancing page 472 Module LoadBalancing Util page 483 471 CHAPTER F Orbacus Balancer Reference Module LoadBalancing Aliases 472 The definitions in this module provide the interface of the Orbacus Balancer Groupld typedef string GroupId A load balanced group ID GroupIdSeq typedef sequence lt GroupId gt GroupIdSeq A sequence of load balanced group IDs Memberld typedef string MemberId A member ID MemberldSeq typedef sequence lt MemberId gt MemberIdSeq A sequence of member IDs Objectld typedef PortableInterceptor ObjectId ObjectId An object ID PropertyName typedef string PropertyName A load balancing strategy configuration property name PropertyValue typedef any PropertyValue A load balancing strategy configuration property value PropertySeq typedef sequence lt Property gt PropertySeq A sequence of load balancing strategy configuration properties PropertyErrorSeq typedef sequence lt PropertyError gt PropertyErrorSeq A sequence of load balancing strategy configuration property errors Constants Module LoadB
287. rface to access Transport and Acceptor information objects related to the current request get_oci_transport_info TransportInfo get_oci_transport_info This method returns the Transport information object for the Transport used to invoke the current request get_oci_acceptor_info AcceptorInfo get_oci_acceptor_info This method returns the Acceptor information object for the Acceptor which created the Transport used to invoke the current request Module OCI IIOP Module OCI IIOP Aliases Constants This module contains interfaces to support the IIOP OCI plug in InetAddr typedef string InetAddr Alias for an IP address This alias will be used for address information from the various information classes It can be an IPv4 or IPv6 address string PLUGIN_ID const PluginId PLUGIN ID iiop The identifier for the lt SmallCaps gt ORBacus IIOP plug in 465 CHAPTER E Open Communications Interface Reference Interface OCI IIOP TransportInfo local interface TransportInfo inherits from OCI TransportInfo Information on an IIOP OCI Transport object See Also Interface OCI Transport Interface OCI TransportInfo Attributes addr readonly attribute InetAddr addr The local IP address port readonly attribute unsigned short port The local port remote_addr readonly attribute InetAddr remote_addr The remote IP address remote_port readonly attribute unsigned short rem
288. rgen Generates C from an Interface Repository 28 Translating IDL to C Translating IDL to C Synopsis idl options idl files Description Translates IDL files into C files For each IDL file four C files are generated For example idl MyFile idl produces the following files MyFile h Header file containing MyFile idl s translated data types and interface stubs MyFile cpp Source file containing MyFile idl s translated data types and interface stubs MyFile_skel h Header file containing skeletons for MyFile idi s interfaces MyFile_skel cpp Source file containing skeletons for MyFile idl s interfaces Options h help Show a short help message v version Show the Orbacus version number d debug Print diagnostic messages This option is for Orbacus internal debugging purposes only DNAME Defines Name as 1 This option is directly passed to the preprocessor DNAME DEF Defines Name as DEF This option is directly passed to the preprocessor UNAME Removes any definition for Name This option is directly passed to the preprocessor IDIR 29 CHAPTER 2 Generating Code with Orbacus Adds the directory pir to the include file search path This option is directly passed to the preprocessor Runs the source files through the preprocessor without generating code no skeletons Don t generate skeleton classes no type codes Do
289. s Properties The CORBA Property Service permits you to annotate an object with extra attributes called properties that were not defined by the object s IDL interface Properties can represent any value because they make use of the CORBA any data type Orbacus Properties is compliant with 10 This chapter does not provide a complete description of the service It only provides an overview suitable to get you started For more information please refer to the specification This chapter contains the following sections Usage page 220 Connecting to the Service page 221 Using the Property Service with the IMR page 222 Creating Properties page 223 Querying for Properties page 224 Deleting Properties page 226 Programming Example page 227 1 Note that the Property Service has nothing to do with the properties used for configuration purposes Configuration properties are described in ORB Properties on page 52 219 CHAPTER 10 Orbacus Properties Usage Orbacus includes functionally equivalent implementations of the Property Service in C and Java C propserv h help v version i ior Java com ooc CosPropertyService Server h help v version i ior Options h Display the command line options supported by the help server v Display the version of the server version i Prints the stringified IOR of the server to standard
290. s are shared only one server process is created which is used by all clients and persistent the server process is started when the IMR starts and is used by all clients activate poas If this attribute is set to true default then all persistent POAs will be registered automatically If set to false then persistent POAs are not registered automatically update timeout The amount of time in milliseconds to wait for server status updates failure timeou The amount of time in seconds to wait for the t server to start max spawns The maximum number of tries to start the server The IMR also maintains various state information for each server e The internal ID of the server e The status of the server process The valid values are forked starting running stopping and stopped e Whether or not the server was started manually e The number of times that the server process has been spawned Server processes inherit environment settings from the environment in which the OAD was started Hence path library path and class path environment variables can be used by the server application This is especially useful in the case of shared library and class path settings Note that the class path may also be set in the args attribute On Windows platforms the exec attribute may refer to an executable or batch file Make sure that the first line of the batch file contains echo off On UNIX
291. s object that is passed to the ORB init method to provide Orbacus property definitions 1 Java 2 java util Properties props new java util Properties 3 props put ooc orb oa conc_model thread pool 4 props put ooc orb oa thread_pool 20 5 org omg CORBA ORB orb orb omg CORBA ORB init args props Create a java util Properties object to hold our properties Define Orbacus properties Initialize the ORB using the java util Properties object Properties in C 2 3 Configuring the ORB and Object Adapter In C the Orbacus specific class OB Properties can be used to define properties C class Properties public Properties Properties Properties ptr p Properties static Properties ptr duplicate Properties ptr p static Properties ptr nil static Properties ptr getDefaultProperties void setProperty const char key const char value const char getProperty const char key const Ul sec i For example to add the threaded concurrency model to a property set that is used to initialize the ORB 1 C 2 OB Properties var dflt OB Properties getDefaultProperties 3 OB Properties var props new OB Properties dflt 4 props gt setProperty ooc orb conc_model threaded 5 CORBA ORB var orb OBCORBA ORB init argc argv props Create an oB Properties object that is based on the default properties This is import
292. s the directory in which the service maintains its database files If not specified then the current working directory is used A INFO admin endpoint INFO Specifies the service s administrative public endpoint settings This is the endpoint that the load balanced servers use to communicate with the service For security reasons access to this endpoint can be restricted F INFO forward endpoint INFO Specifies the services s public endpoint settings which is used by clients for server requests 267 CHAPTER 13 Orbacus Balancer Windows NT Native Service 268 The balancer server is also available as a native Windows NT service ntbalancerservice h help i install s start instal1 u uninstall d debug h help Display the command line options supported by the service i install Install the service The service must be started manually s start install Install and start the service u uninstall Uninstall the service d debug Run the service in debug mode In order to use Orbacus Balancer as a native Windows NT service first add the desired configuration properties to the HKEY_LOCAL MACHINE NT registry key see Using the Windows NT Registry on page 65 for more details For example add the ooc balancer admin endpoint and ooc balancer forward_endpoint properties so that the service will use non defau
293. se refer to the specification This chapter contains the following sections Usage page 183 Windows NT Native Service page 185 Configuration Properties page 187 Persistence page 188 Connecting to the Service page 189 Using the Naming Service with the IMR page 190 Bindings page 191 181 CHAPTER 8 Orbacus Names Name Resolution page 193 Programming Example page 194 182 Usage Usage Orbacus includes functionally equivalent implementations of the Naming Service in C and Java C nameserv h help v version i ior n no updates s start d database FILE 1l limit COUNT t timeout MINS c callback timeout SECS Java com ooc CosNaming Server h help v version i ior n no updates s start d database FILE 1l limit COUNT t timeout MINS c callback timeout SECS Options h Display the command line options supported by the help server v Display the version of the server version i Prints the stringified IOR of the server to standard ior output n Disables automatic updates i e callbacks that no updates notify interested clients of changes to the naming service sS start Use this option only when starting a persistent server using a new database d FILE database FILE Enables persistence for the server All of the bindings
294. shows how to set properties for C and Java applications Register ORB initializer for watson Orbacus Java org omg PortableInterceptor ORBInitializerClass com ooc watson R IORBInitializer_impl Load module watson Orbacus C Disable if module was build statically to avoid error message from the ORBs ModuleManager ooc orb modules watson On Windows enable one of the following properties if you built with DLLs For debug builds ooc orb module watson watson412d dl11 For non debug builds ooc orb module watson watson412 d11 Set request tracing levels more specific settings in and out override the general setting in the first of these lines ooc watson trace requests 3 ooc watson trace requests in 1 ooc watson trace requests out 2 In this chapter CHAPTER 15 Using Policies This chapter describes the policies used to configure the ORB and to create a new POA These policies are derived from the interface CORBA Policy This chapter contains the following sections Overview page 302 Supported Policies page 303 Programming Examples page 306 301 CHAPTER 15 Using Policies Overview 302 The ORB and its services may allow the application developer to configure the semantics of its operations This configuration is accomplished in a structured manner through interfaces derived from the interface CORBA Policy
295. smitted in any form or by any means photocopying recording or otherwise without prior written consent of IONA Technologies PLC No third party intellectual property right liability is assumed with respect to the use of the information contained herein IONA Technologies PLC assumes no responsibility for errors or omissions contained in this book This publication and features described herein are subject to change without notice Copyright 2001 2004 IONA Technologies PLC All rights reserved All products or services mentioned in this manual are covered by the trademarks service marks or product names as designated by the companies who market those products Updated 27 Oct 2004 Contents List of Figures Preface Chapter 1 Getting Started The Hello World Example Application Defining the Example in IDL Implementing the Example in C Implementing the Server Writing the Server Program Implementing the Client Compiling and Linking Running the Application Implementing the Example in Java Implementing the Server Implementing the Client Compiling Running the Application Summary Where To Go From Here Chapter 2 Generating Code with Orbacus Orbacus Translators Translating IDL to C Translating IDL to Java Translating IDL to HTML Translating IDL to RTF Generating C from an Interface Repository The IDL to C Translator and the Interface Repository Include Statements Documenting IDL Files Using javadoc xiii
296. st that the imr server is running on The default value is the canonical hostname of the machine in which mkref is executed 165 CHAPTER 6 The Implementation Repository port The forward port of the imr server If not set then mkref will use 9998 server name The name of the server as registered in the IMR object id The Object ID used by the object poal poa2 poan The POA which creates the object where poal is a child of the Root POA poa2 is a child of poal and so on Upgrading the IMR Database 166 The imrdbupgrade utility is used to upgrade an earlier version of the IMR database Command line usage is as follows imrdbupgrade database directory The database directory parameter is used to specify the IMR database directory Getting Started with the Implementation Repository Getting Started with the Implementation Repository To use the IMR several steps must be taken These steps are presented below and are explained by way of example In this example we assume that Orbacus has been installed in the directory usr local orbacus and the executables imr imradmin and mkref all exist in a directory that is in the search path 1 Determine the physical architecture In this example we have a network with three hosts master slavel and slave2 The host master is used to run only the IMR The hosts slavel and slave2 are used to run individual CORBA servers Create a configu
297. suffix SUFFIX Use suFFIX as the suffix for skeleton files The default value is _skel all Generate code for included files instead of inserting include statements See Include Statements on page 40 no relative When generating code idl assumes that the same 1 options that are used with ial are also going to be used with the C compiler Therefore ia will try to make all include statements relative to the directories specified with 1 The option no relative suppresses this behavior in which case id will not make include statements for included files relative to the paths specified with the x option header dir DIR This option can be used to make include statements for header files relative to the specified directory this header dir DIR Like the header dir option this option can be used to make include statements for header files relative to the specified directory However this option only applies to include statements for the header files of this IDL file other header dir DIR Like the header dir option this option can be used to make include statements for header files relative to the specified directory However this option only applies to include statements for the header files corresponding to IDL files that were included in this IDL file output dir DIR Write generated files to directory DIR file list FILE Write a list of all generated files to file FILE dll import DEF Put DEF in fro
298. system rp policy value directs the ORB to assign a unique object identifier to the CORBA object represented by the servant the usER_ID policy value requires the server application code to supply an ID that must be unique within the servant s POA Servants can be activated implicitly or explicitly Implicit activation takes place when you create the first object reference for a servant Explicit activation requires a separate API call Typically you will use implicit activation for transient objects and explicit activation for persistent objects The ImplicitActivationPolicy controls whether explicit or implicit is in effect Explicit activation requires the No_IMPLICIT ACTIVATION policy value on the servant s POA whereas implicit activation requires the IMPLICIT ACTIVATION policy value 101 CHAPTER 4 CORBA Objects Implicit Activation of Servants using C The following code shows how to implicitly activate a servant T Ge 2 I impl impl 3 I ve aby mal s _iclouis y A new servant imp1 is created 3 The new servant is activated implicitly by calling _this Note that implicit activation as shown requires the RETAIN IMPLICIT ACTIVATION and SYSTEM ID policies on the servant s POA The servant is activated with the POA that is returned by the servant s _default_Poa member function The default implementation of _default_poa returns the Root POA if you want servants activated on a different POA you must override
299. t remoteAdadr iil CORBA UShort remotePort iiopInfo gt remote port T2 13 cout lt lt Will connect to 14 lt lt remoteAddr 0 lt lt lt lt remoteAddr 2 lt lt as lt lt remoteAddr 2 lt lt lt lt remoteAddr 3 16 lt lt lt lt remotePort lt lt endl 7 ij 4 6 Get the OCI connector info and narrow to an IIOP connector info 8 The if block is only executed if this really was an IIOP connector info 10 16 The address and port are obtained and displayed on standard output 351 CHAPTER 17 The Open Communications Interface 352 9 12 14 16 23 The Java version looks as follows 1 Java 2 org omg CORBA Object obj Get an object reference somehow 3 4 org omg CORBA portable ObjectImpl objImpl 5 org omg CORBA portable ObjectImp1l obj 6 com ooc CORBA Delegate objDelegate 7 com ooc CORBA Delegate objImpl get delegate 8 9 com ococ OCI ConnectorInfo info 10 objDelegate get_oci_connector_info 11 com ooc OCI IIOP ConnectorInfo iiopInfo 12 com ooc OCI IIOP ConnectorInfoHelper narrow info ils 14 if iiopInfo null 1s 16 int remoteAddr Converter addr iiopInfo remote_addr 7 int remotePort Converter port iiopInfo remote_port 18 iS System out print1n Will connect to 20 remoteAddr 0 21 remoteAddr 1 22 remoteAddr 2 23 remoteAddr 3 remotePort
300. t configuration Specifically each anonymous POA Manager will create a single IIOP endpoint on a port chosen by the operating system Consequently object references created by POAs managed by an anonymous POA Manager are inherently transient 2 Applications which require configurable POA Managers in addition to the Root POA Manager can use the proprietary POA Manager factory described in the next section 1 IONA has proposed adding support for POA Manager identity For details see http cgi omg org issues orb revision html Issue4297 2 Unless of course an indirect persistence mechanism such as the Implementation Repository is in use 73 CHAPTER 3 ORB and Object Adapter Initialization The POA Manager Factory To allow an application to easily configure POA Managers Orbacus provides the standard CORBA 3 0 factory interface for creating named POA Managers iff TDI module PortableServer local interface POAManagerFactory typedef sequence lt POAManager gt POAManagerSeq exception ManagerAlreadyExists he POAManager create POAManager in string id in CORBA PolicyList policies raises ManagerAlreadyExists CORBA PolicyError POAManagerSeq list POAManager find in string id local interface POA readonly attribute POAManagerFactory the POAManagerFactory 74 Using POA Managers Creating a POA Manager The example below illustrates how to create a new POA Manager using the P
301. t object reference Although narrow for CORBA objects works similar to dynamic_cast lt gt for plain C objects dynamic_cast lt gt must not be used for CORBA object references That s because in contrast to dynamic_cast lt gt narrow might have to query the server for type information The say_hello operation on the hello object reference is invoked causing the server to print Hello World Implementing the Example in C Compiling and Linking Overview Dependencies For more details Compiling Hello cpp results in an object file with the following name e UNIX Hello o e Windows Hello obj You must link both the client and the server with the file for your platform The compiled Hello _skel cpp and Hello impl cpp are only needed by the server Compiling and linking is to a large degree compiler and platform dependent Many compilers require unique options to generate correct code To build Orbacus programs you must at least link with the Orbacus library for your platform e UNIX liboB a e Windows ob lib Additional libraries are required on some systems such as libsocket a and libns1 a for Solaris or wsock32 1ib for Windows The Orbacus distribution includes various README files for different platforms which give hints on the options needed for compiling and the libraries necessary for linking Please consult these README files for details 13 CHAPTER 1 Getting Started Running the
302. t_ulong 1000 4 org omg CORBA Policy policies new org omg CORBA Policy 1 5 policies 0 6 orb create_policy com ooc OB TIMEOUT POLICY ID value 7 ULongAny 8 org omg CORBA Object newObj 9 obj _set_policy_override policies 10 org omg CORBA SetOverrideType ADD OVERRIDE This is equivalent to the C version Note that you can also set the timeout policy at the ORB level Interceptor Call Policy This example shows how to create a new POA with server side interceptors disabled The C version is presented first followed by the Java version 2 7 9 15 17 18 woaAarNdIaunFwWNH PRPPRPHP HP HBB OID UH KRWNHO Programming Examples C CORBA Object_var obj orb gt resolve_initial references RootPOA PortableServer POA_var rootPOA PortableServer POA _narrow ob PortableServer POAManager var manager rootPOA gt the POAManager CORBA Any any CORBA PolicyList policies 1 policies length 1 any lt lt CORBA Any from_ boolean false policies 0 orb gt create policy OBPortableServer INTERCEPTOR CALL POLICY ID any PortableServer POA_var myPOA rootPOA gt create POA MyPOA manager policies Obtain references to the root POA and its POA manager Create a policy set consisting of the OBPortableServer InterceptorCallPolicy policy The OBPortableServer InterceptorCallPolicy policy is given a value of false so that server side inte
303. tart If the service is to be started automatically when the machine is booted select the Orbacus Interface Repository Service entry then click Startup Next select Startup Type Automatic and press ox Alternatively the service could have been installed using the s option which configures the service for automatic start up ntirservice s If you want to remove the service run 253 CHAPTER 12 The Interface Repository 254 ntirservice u Note If the executable for the Interface Repository is moved it must be uninstalled and re installed Any trace information provided by the service is placed in the Windows NT Event Viewer with the title Irservice To enable tracing information add the desired trace configuration property i e one of the ooc orb trace properties to the HKEY LOCAL MACHINE NT registry key with a REG_sz value of at least 1 Configuration Properties Usage In addition to the standard configuration properties described in Chapter 3 the Orbacus Interface Repository also supports the following properties ooc ifr options OPTS Allows command line options to be passed to the Windows NT Native service at start up Note that absolute pathnames should be used when specifying include directives IDL files etc ooc ifr endpoint ENDPOINT Specifies the endpoint configuration for the service Note that this property is only used if the ooc orb oa endpoint property is not set 255
304. ted item Selects all items in the object table Inverts the current selection New contexts and bindings are created with the operations New Context and New Binding respectively If one of these functions is selected a new context or object binding with a unique name is added to the current context For new object bindings an IOR can be specified Use Delete to remove the selected items from a naming context Deleting Naming Service entries removes all selected bindings from their parent context The objects belonging to these bindings are not affected Destroying Naming Service information only affects the actual Naming Service data not the objects themselves Use Link to create a new binding for an existing naming context where the naming context is specified by an IOR The operation Unlink unbinds the selected items For objects Unlink is equivalent to Delete but for contexts Unlink differs in that the context is not destroyed Since a context is not destroyed using Unlink it should only be used when there are multiple bindings to a context in order to avoid orphaned contexts The Menus The console supports a clipboard that you can use to move bindings between different contexts Data is transferred to the clipboard using the Cut or Copy commands Cut moves the currently selected items to the clipboard and deletes the original entries whereas Copy simply creates a copy in the clipboard but keeps the source entry unchanged Whe
305. tempt to replace the content of an Any by its own value For example char s CORBA string dup Hello world CORBA Any any any lt lt S w N Be 4 any lt lt S Inserting s into any twice will result in a dangling pointer because any will free its own value which is s on assignment Invalid union discriminator type used This message appears if the discriminator type argument to CORBA ORB create_union_tc denotes a type invalid for union discriminators Valid types have a CORBA TCKind that is one of CORBA tk_short CORBA tk_ushort CORBA tk_long CORBA tk_ulong CORBA tk_char CORBA tk_boolean Or CORBA tk_enum Union discriminator mismatch This message either indicates an attempt to set a union discriminator to an invalid value with the _a modifier function or the use of a wrong accessor function i e an accessor function that does not correspond to the type of the union s actual value Uninitialized union used If this message appears an uninitialized union i e a union that was created with the default constructor and that was not set to any legal value was used 399 CHAPTER 18 Exceptions and Error Messages 400 Message Description CORBA Any operator lt lt Exception cannot be used with no type codes This message indicates that CORBA Any operator lt lt Exception was invoked for an exception for which no TypeCode
306. tes attrib mode com ooc OB RETRY_STRICT value attrib interval 500 attrib max 5 attrib remote true org omg CORBA Any any orb create_any com ooc OB RetryAttributesHelper insert any attrib org omg CORBA Policy policies new org omg CORBA Policy 1 policies 0 orb create policy com ooc OB RETRY POLICY ID value any org omg CORBA Object newObj obj _set_policy override policies org omg CORBA SetOverrideType ADD OVERRIDE 1 16 This is equivalent to the C version Note that you can also set the retry policy at the ORB level 311 CHAPTER 15 Using Policies Timeout Policy 312 2 6 7 8 1 10 This example shows how to configure timeouts at the object level As usual the C version is presented first followed by the Java version C CORBA Any ULongAny ULongAny lt lt CORBA ULong 1000 CORBA PolicyList policies 1 policies length 1 policies 0 orb gt create policy OB TIMEOUT_POLICY_ID LongAny CORBA Object_var newObj obj gt _set_policy overrides policies CORBA ADD_OVERRIDE oINIGnAuUAWNHR We want to set the timeout to a value of 1000 milliseconds Set the policy on the object by using the set_policy overrides method This method returns a new object that has the set of policies applied And now the same example in Java 1 Java 2 org omg CORBA Any ULongAny orb create_any 3 ULongAny inser
307. text is used In addition to the object s IOR both operations expect a unique binding name If a name already exists an AlreadyBound exception is thrown There are also other exceptions you might encounter at this stage e g I1legalName if an empty string was provided as part of a NameComponent 199 CHAPTER 8 Orbacus Names Exceptions This code fragment deals with exceptions that may be thrown by the Naming Service operations 1 Java 2 catch NotFound ex 3 d 4 System err print Got a NotFound exception 5 switch ex why value 6 7 case NotFoundReason missing node 8 System err print missing node 9 break 10 11 case NotFoundReason _not_context 12 System err print not context 13 break 14 15 case NotFoundReason not_object 16 System err print not object 17 break 18 19 20 System err print1n Dl ex printStackTrace 22 throw new SystemException 23 24 catch CannotProceed ex 25 26 System err print1n Got a CannotProceed exception 27 ex printStackTrace 28 throw new SystemException 29 30 catch InvalidName ex 31 32 System err println Got an InvalidName exception 33 ex printStackTrace 34 throw new SystemException 200 Programming Example 25 36 catch AlreadyBound ex 37 38 System err println Got an AlreadyBound exception 39 ex printStackTrace 40 throw new
308. th C to date What this manual does contain however is information on how Orbacus implements the CORBA standard A shortcoming of the current CORBA specification is that it leaves a high degree of freedom to the CORBA implementation For example the precise semantics of a oneway call are not specified by the standard To make it easier to get started with Orbacus this manual contains a Getting Started chapter explaining some Orbacus basics with a very simple example The latest updates to this guide can be found at http www orbacus com support new_site support manual jsp Should you need any assistance with Orbacus please visit our Frequently Asked Questions FAQ list at http www orbacus com support new_site faqs html or consult the Orbacus community resources at http www orbacus com support new_site community Customers with a support agreement can contact us at support orbacus com For more information on support go to http www orbacus com support new_site support The IONA knowledge base http www iona com support knowledge_base index xml contains helpful articles written by IONA experts about Orbacus and other products Comments on IONA documentation can be sent to docs support iona com xvii PREFACE Typographical conventions This guide uses the following typographical conventions Constant width Constant width courier font in normal text represents portions of code and literal nam
309. the IMR instead of the member s server When the client makes a request using this reference the IMR receives the request activates the member s server if necessary using the OAD and returns a new object reference to the client that refers the server 276 Utilities Utilities In this section This section describes various load balancing utilities Service Administration page 278 Making References page 279 Utility Objects page 280 Utility Object Configuration Properties page 281 277 CHAPTER 13 Orbacus Balancer Service Administration The lbadmin utility provides complete control over Orbacus Balancer Its command interface is shown below h help Display this information list groups List the load balanced groups create group group id Create a load balanced group destroy group group id Destroy a load balanced group get group info group id Get the attributes of a group get group ior group id repository id object id Get the IOR for use by a client set strategy group id lt strategy gt Use the specified built in strategy set custom strategy group id ior Use the given custom strategy list members group id Enumerate the members of the group add member group id member id Add a member to the group remove member group id member id Remove a member from the group shutdown Shutdow
310. the replica of one member to the replica of another causes the target member to become overloaded This situation is what we will call system instability In some cases the system may remain instable indefinitely For example if a single client is solely responsible for causing a high load then the client will likely be bounced from member to member Yet another source of load re balancing errors comes from the fact that a member cannot redirect a client until it receives a request When this occurs the member may no longer be overloaded This can be alleviated by associating an expire time with a load alert Some important things to note when choosing between adaptive and non adaptive load balancing strategies are e _Non adaptive strategies impose very little overhead compared to adaptive strategies e Adaptive strategies will produce a more balanced system when the assumptions for the non adaptive strategies are not satisfied Under certain conditions load re balancing will be error prone In such a case adaptive strategies which take an aggressive approach to re balancing may result in many load re balancing errors Furthermore load re balancing can be an expensive operation making these errors even more severe On the other hand if the system is such that load re balancing errors seldom occur and the expense of re balancing is minimal then adaptive strategies that take an aggressive approach to load re balancing should result in
311. the underlying ORB uses GIOP minor The minor version number of the ORB s protocol For example the minor GIOP version if the underlying ORB uses GIOP id The id of the profile that contains this information index The position index of this profile in an IOR components A sequence of tagged components FactoryAlreadyExists exception FactoryAlreadyExists i A factory with the given plugin id already exists PluginId id Module OCI Members id The plugin id NoSuchFactory exception NoSuchFactory E No factory with the given plugin id could be found PluginId id Members id The plugin id InvalidParam exception InvalidParam i A parameter is invalid string reason Members reason A description of the error 433 CHAPTER E Open Communications Interface Reference Interface OCI Buffer Attributes Operations 434 local interface Buffer An interface for a buffer A buffer can be viewed as an object holding an array of octets and a position counter which determines how many octets have already been sent or received The IDL interface definition for Buffer is incomplete and must be extended by the specific language mappings For example the C mapping defines the following additional functions octet data Returns a C pointer to the first element of the array of octets which represents the buffer s contents octet rest
312. this file are added to the current naming context When saving a naming context the console checks each context for accessibility If a context cannot be accessed i e if its contents cannot be saved a message is displayed in the error window You also get an error message if the console detects a recursion The bindings contained in the naming context leading to the recursion is not saved Use Save IOR to File in order to create a file that contains the stringified IOR of the currently selected binding or context With Close Window the current window is closed Closing the last window causes the application to terminate Exit can be used to terminate the application regardless of how many windows are open 209 CHAPTER 9 Orbacus Names Console The Edit Menu The operations in this menu provide the means for creating and deleting objects and for changing the Naming Service structure 210 New Context New Binding Delete Link Unlink Cut Copy Paste Change ID Change Kind Change IOR Select all Invert Selection Creates a new naming context Creates a new binding for an object Deletes the selected items Creates a new binding for an existing naming context Unbinds the selected items Moves the selected items to the clipboard Copies the selected items to the clipboard Inserts the clipboard contents Edits the ID field of the selected item Edits the Kind field of the selected item Edits the IOR of the selec
313. thod invocation And now the Java version Java org omg CORBA Object obj orb string to object relfile Hello re org omg CORBA Any any orb create_any org omg BiDirPolicy BidirectionalPolicyValueHelper insert any org omg BiDirPolicy BOTH value org omg CORBA Policy policies new org omg CORBA Policy 1 policies 0 orb create_policy 10 org omg BiDirPolicy BIDIRECTIONAL POLICY TYPE value any TI 12 obj obj _ set policy override policies 13 org omg CORBA SetOverrideType ADD OVERRIDE 14 15 Hello hello HelloHelper narrow obj owon An AUNE This is equivalent to the C version 323 CHAPTER 15 Using Policies 324 In this chapter CHAPTER 16 Concurrency Models This chapter describes how an Object Request Broker handles communication and request execution using single and multi threaded concurrency models This chapter contains the following sections Concurrency Models page 326 Single Threaded Concurrency Model page 328 Multi Threaded Concurrency Models page 331 The Reactor page 338 325 CHAPTER 16 Concurrency Models Concurrency Models What is a Concurrency Model Why different Concurrency Models Orbacus Concurrency Models Overview 326 A concurrency model describes how an Object Request Broker ORB handles communication and request execution There are two main categories of concurrency models single threaded concurren
314. tial Services 142 The CORBA specification provides a standard way to bootstrap an object reference through the use of initia services which denote a set of unique services whose object references if available can be obtained using the ORB operation resolve_initial_references which is defined as follows Ait TDI module CORBA interface ORB typedef string ObjectId exception InvalidName Object resolve initial references in ObjectId identifier raises InvalidName Ja i Initial services are intended to have well known names and the OMG has standardized the names for some of the CORBAservices 9 For example the Naming Service has the name NameService and the Trading Service has the name TradingService Initial Services Resolving an Initial Service 5 12 19 26 An example in which the ORB is queried for a Naming Service object reference will demonstrate how to use resolve_initial_ references The example assumes that the ORB has already been initialized as usual First the Java version 1 Java 2 org omg CORBA Object obj null 3 org omg CosNaming NamingContext ctx null 4 By exes S q 7 obj orb resolve _initial_references NameService 8 9 catch org omg CORBA ORBPackage InvalidName ex 10 bal An error occured service is not available 12 T3 14 ake esa null 15 16 The object reference is invalid iy 18 19 try 20 21 ctx org omg CosN
315. tic Linking The Bi directional OCI Plug in When statically a C application an explicit reference must be made to the bi directional plug in as well as to the underlying plug in in order to include the plug in s modules Shown below is the technique used by the sample programs in the bidir demo subdirectory Note that the code below is enclosed in guard macros that are only activated when statically linking These macros are appropriate for both Unix and Windows First extra include files are necessary if defined HAVE SHARED amp amp defined OB DLL include lt OB OCI_init h gt include lt OB OCI_BiDir init h gt endif Next the plug in must be registered prior to calling oRB_ init if defined HAVE SHARED amp amp defined OB DLL When linking statically we need to explicitly register the plug in prior to ORB initialization CCl Beguisize rag ugin uioachitalias Cilgeerelitem Ora endif 375 CHAPTER 17 The Open Communications Interface URL Support 376 The bi directional plug in supports corbaloc URLs with the following protocol syntax corbaloc bidir_ ID peer object key corbaloc bidir ID peer options object key The first form indicates a callback endpoint whereas the second form indicates an endpoint using an underlying plug in The components of the URL are as follows bidir I D This selects the bi directional plug in using the underlying plug in identified by
316. to a Hello object A simple Java cast is not allowed here because it is possible that the client will need to ask the server whether the object is really of type Hello The say_hello operation is invoked causing the server to print Hello World on standard output 21 CHAPTER 1 Getting Started Compiling Steps To compile the application Ensure that your CLASSPATH environment variable includes the current working directory as well as the Orbacus for Java classes i e the oB jar file as shown below Platform Command UNIX CLASSPATH your_orbacus_directory 1lib OB jar SCLASSPATH export CLASSPATH Windows set CLASSPATH your_orbacus_directory lib OBE jar sCLASSPATH 22 Replace your _orbacus directory with the name of the directory where Orbacus is installed To compile the implementation classes and the classes generated by the Orbacus IDL to Java translator use javac or the Java compiler of your choice javac hello java Implementing the Example in Java Running the Application Steps To run the application complete the following steps 1 Start the Hello World Java server by entering the following command in a command prompt java hello Server 2 Start the Hello World Java client by entering the following command java hello Client Again make sure that your CLASSPATH environment variable includes the oBE jar file You might also want to use a C s
317. tr 13 14 virtual void say_hello throw CORBA SystemException I5 16 virtual PortableServer POA ptr _default_POA iy jhe Private member to store the servant s default POA A constructor must be defined to allow the assignment of the servant s default POA Declaration of the _default_poa method Programming Example The remainder of the class declaration is unchanged The definition of the constructor and _default_poa method follow 0 r LONAN PWD HP C Hello_impl Hello impl PortableServer POA ptr poa poa_ PortableServer POA duplicate poa PortableServer POA_ptr Hello _impl _default_POA return PortableServer POA duplicate poa 171 CHAPTER 6 The Implementation Repository 172 The modified portion of the server program is shown below 1 C 2 SNE 4 run CORBA ORB ptr orb int argc 5 6 CORBA Object_var poaObj 7 orb gt resolve initial references RootPOA 8 PortableServer POA var rootPoa 9 PortableServer POA _ narrow poa0bj 10 alae PortableServer POAManager_var manager 12 rootPoa gt the _POAManager 13 14 CORBA PolicyList pl 2 15 pl length 2 16 pl 0 rootPOA gt create lifespan policy 17 PortableServer PERSISTENT 18 pl 1 rootPOA gt create_id_ assignment policy 19 PortableServer USER_ID 20 21 PortableServer POA var helloPOA 22 rootPOA gt create_POA hell
318. ty is only available in Java applications and is equivalent to the orBAcUS_CONFIG environment variable in C See Using a Configuration File on page 64 for more information on configuration files Value string Specifies a comma separated list of client side transport plug ins to be installed The plug ins are installed in the order they appear in the list The default value is iiop Value string Specifies a comma separated list of server side transport plug ins to be installed The plug ins are installed in the order they appear in the list The default value is iiop Value string Specifies a plug in s shared library C or initialization class Java In most cases this property is not necessary because the ORB attempts to locate the library or class using a well known name In C the well known name is 1ibocr_name so UNIX 1ibocr_name s1 HP UX or OcI_name d11 Windows where name is the plug in name e g iiop The ORB searches for this shared library in the library search path Similarly in Java the ORB searches the class path for a class named com ooc OCI name Value timeout gt 0 If the client is not able to gracefully disconnect from the server in timeout seconds a connection shutdown is forced If this property is set to zero then the client will not force a connection shutdown If the property is not set a default timeout value of two seconds is used ooc orb client_timeout ooc
319. uest timeout policy Structs Module OB RETRY_ALWAYS const short RETRY ALWAYS 2 The RETRY ALWAYS RetryPolicy value RETRY_NEVER const short RETRY NEVER 0 The RETRY_NEVER RetryPolicy value RETRY_POLICY_ID const CORBA PolicyType RETRY POLICY ID 1330577412 This policy type identifies the retry policy RETRY_STRICT const short RETRY STRICT 1 The RETRY _stTRIcT RetryPolicy value TIMEOUT_POLICY_ID const CORBA PolicyType TIMEOUT POLICY ID 1330577413 This policy type identifies the timeout policy RetryAttributes struct RetryAttributes short mode unsigned long interval unsigned long max boolean remote i The retry information 407 CHAPTER B Orbacus Policy Reference Interface OB ConnectTimeoutPolicy local interface ConnectTimeoutPolicy inherits from CORBA Policy The connect timeout policy This policy can be used to specify a maximum time limit for connection establishment See Also Interface OB TimeoutPolicy Attributes value readonly attribute unsigned long value If an object has a connect TimeoutPolicy set and a connection cannot be established after value milliseconds a CORBA NO_RESPONSE exception is raised The default value is 1 which means no timeout 408 Module OB Interface OB ConnectionReusePolicy local interface ConnectionReusePolicy inherits from CORBA Policy The connection reuse policy This policy determines whether conne
320. uld use the standard operation unchecked_narrow instead This operation assumes that the application is operating correctly and allows the narrow to succeed without using is a 1 Object references created from corbaloc URLs always have empty repository IDs The Bi directional OCI Plug in The Bi directional OCI Plug in Note This Bidir implementation is deprecated with the addition of the CORBA 3 compliant version of BiDir GIOP New users requiring BiDir functionality should use the new BiDir GIOP interface as described in Chapter 15 Overview The Orbacus Bi directional plug in offers a solution for distributed systems where security restrictions interfere with a client s ability to receive callbacks This capability is especially useful in two common situations e Firewalls prevent the server from establishing a separate connection back to the client e Browser restrictions prevent an applet from accepting connections Note This plug in does not implement the Bi directional IIOP standard defined by CORBA 2 3 This plug in uses a proprietary protocol that is not interoperable with other ORBs In this section This sections covers the following topics How Does it Work page 368 Peers page 369 Client Installation page 370 Server Installation page 371 Endpoint Configuration page 372 Command line Options page 373 Configuration Properties page 374 Static Linking page 375 URL Support page 376
321. untimeException org omg CORBA Object obj null try catch org omg CORBA ORBPackage InvalidName ex De oD mall obj orb resolve_ initial references NameService throw new RuntimeException throw new RuntimeException 195 CHAPTER 8 Orbacus Names 196 10 22 24 32 34 47 37 38 39 NamingContextExt ne null 40 try 41 42 nc NamingContextExtHelper narrow obj 43 44 catch org omg CORBA BAD PARAM ex 45 46 throw new RuntimeException 47 Usually the application is initialized in the main method For more information on ORB initialization see Chapter 3 In the next step we try to connect to the Naming Service by supplying NameService to resolve_initial references If InvalidName is thrown there is no Naming Service available because the ORB doesn t know anything about this service If calling resolve _initial_references was successful the object reference is checked and narrowed in order to verify that it supports the interface CosNaming NamingContextExt If the narrow operation raises CORBA BAD PARaM the object does not support the interface This is considered to be an error because we explicitly asked for a Naming Service instance Binding Programming Example In the next step some sample bindings are created and bound to the Naming Service 1 Java 2 Named _impl implA new Named impl 3 Named _impl implAl
322. ure 1 Documentation generated with the IDL to HTML translator Figure 2 Servants Proxies and the Object Adapter Figure 3 Class Hierarchy for Delegation Implementation in C Figure 4 Class Hierarchy for Inheritance and Delegation Implementation in Java Figure 5 Entering an IOR Figure 6 The Ping Window Figure 7 A closer look at the toolbar Figure 8 A popup menu offers important operations Figure 9 Reactive Server Figure 10 Reactive Client Server Figure 11 Threaded Server Figure 12 Thread per Client Server Figure 13 Thread per Request Server Figure 14 Thread Pool Server Figure 15 OCI Class Diagram Figure 16 Connection Requirements 41 86 93 95 209 214 216 217 328 329 332 334 335 336 344 368 xiii LIST OF FIGURES xiv Preface What is Orbacus Orbacus is an Object Request Broker ORB that is compliant with the Common Object Request Broker Architecture CORBA specification as defined in The Common Object Request Broker Architecture and Specification 4 C Language Mapping 5 IDL Java Language Mapping 6 and Portable Interceptors 7 The following sections highlight some of the features of Orbacus Ease of Use e Configuration and bootstrapping is simple Daemon less servers e Servers started automatically by the Implementation Repository r URL style object references e Watson diagnostics and analysis method tracing within the ORB e Extensibl
323. urns The Acceptor information object Module OCI Interface OCI AcceptorInfo Attributes Operations local interface AcceptorInfo Information on an OCI Acceptor object Objects of this type must be narrowed to an Acceptor information object for a concrete protocol implementation for example to OCI IIOP AcceptorInfo in case the plug in implements IIOP See Also Interface OCI Acceptor id readonly attribute PluginId id The plugin id tag readonly attribute ProfileId tag The profile id tag describe string describe Returns a human readable description of the transport Returns The description add_accept_cb void add_accept_cb in AcceptCB cb Add a callback that is called whenever a new connection is accepted If the callback has already been registered this method has no effect Parameters cb The callback to add remove_accept_cb void remove_accept_cb in AcceptCB cb Remove an accept callback If the callback was not registered this method has no effect Parameters 457 CHAPTER E Open Communications Interface Reference cb The callback to remove 458 Module OCI Interface OCI AcceptCB local interface AcceptCB An interface for an accept callback object See Also Interface OCI Acceptor nfo Operations accept_cb void accept_cb in TransportInfo transport _info Called after a new connection has been accepted If the applicatio
324. us Balancer also supports the following properties Value true false If set to true then run the service in administrative mode For details refer to the a command line option Value directory Equivalent to the d command line option Value info Equivalent to the a command line option Value info Equivalent to the F command line option Value level gt O Defines the output level for database diagnostic messages printed by the service The default level is O which produces no output A level of 1 or higher produces database information e g loading adding and removing group records in the database Value level gt O Defines the output level for lifecycle diagnostic messages printed by the service The default level is O which produces no output A level of 1 or higher produces lifecycle information e g creation and destruction of load balanced groups adding and removing members and setting load balancing strategies Value level gt O Usage Defines the output level for diagnostic messages related to the load balancing of members The default level is O which produces no output Levels greater than O produce different degrees of output 271 CHAPTER 13 Orbacus Balancer Built in Load Balancing Strategies In this section we present the load balancing strategies that are provided with Orbacus Balancer Note that the default strategy is the round robin strategy
325. us provides the iordump utility to decode stringified IORs and to print out their components in human readable format It is available in a C and a Java version Its usage is shown below iordump options f FILE IOR com ooc OB IORDump options f FILE IOR 1 h help Show available options V version Show Orbacus version f FILE Read IORs from file instead of command line IOR List of ORs The Java version is available in op jar Sample output for the demo hello The following command example iordump f Hello ref 148 The IORDump utility prints IOR 1 byteorder little endian type id IDL Hello 1 0 Profile 1 iiop iiop_version 1 2 host 192 168 0 1 port 17000 object_key 37 17L 172 171 49 49 48 50 48 11020 5E BS TSI ISa S648 ORS S77 S68 OFma ee e l DE a a iil eea S SIS 0 RootPOA 0 202 254 186 190 60 215 205 lt 0 0 0 0 0 Wea ae n Native char codeset ISO 8859 1 1987 Latin Alphabet No 1 Char conversion codesets ISO 646 1991 IRV International Reference Version X Open UTF 8 UCS Transformation Format 8 UTF 8 Native wchar codeset ISO IEC 10646 1 1993 UCS 2 Level 1 Wchar conversion codesets ISO IEC 10646 1 1993 UTF 16 UCS Transformation Format 16 bit form 149 CHAPTER 5 Locating Objects 150 CHAPTER 6 The Implementation Repository This chapter describes how the Orbacus Implementation Rep
326. values defined in an Orbacus configuration file are transferred to the registry RegUpdate HKEY LOCAL MACHINE HKEY CURRENT USER config file RegUpdate HKEY LOCAL MACHINE ob conf This command reads the properties defined in the file ob conf and writes the values under the following registry key HKEY LOCAL MACHINE Software 00C Properties 1 Use caution when defining Orbacus properties in the registry as they become global properties that will be used in every Orbacus for C application For example subtle errors can occur if the coc iiop port property is defined on a global basis 65 CHAPTER 3 ORB and Object Adapter Initialization Defining Properties Properties in Java 66 3 4 3 4 Java applications can use the standard Java mechanism for defining system properties because Orbacus will also search the system properties during ORB initialization For example 1 Java 2 lt java util Properties props System getProperties 3 props put ooc orb oa conc_model thread pool 4 props put ooc orb oa thread_pool 20 5 org omg CORBA ORB orb org omg CORBA ORB init args null Obtain the system properties Define Orbacus properties Initialize the ORB Java virtual machines typically allow you to define system properties on the command line For example using Sun s JVM you can do the following java Dooc orb oa thread_pool 20 MyServer You can also use the java util Propertie
327. vent retry_timeout 235 ooc event trace events 236 ooc event trace lifecycle 236 ooc event typed_ service 236 ooc ifr options 255 ooc ifr port 255 ooc imr dbdir 162 270 281 ooc imr trace oad 162 270 281 490 ooc naming callback_timeout 187 ooc naming database 187 ooc naming no_updates 187 ooc naming port 187 ooc naming timeout 187 ooc naming trace_level 187 ooc oci client 52 ooc oci plugin 52 ooc oci server 52 ooc orb client_timeout 53 ooc orb conc_model 53 ooc orb default_init_ref 53 ooc orb default_wcs 53 ooc orb extended_wchar 53 ooc orb giop max_message size 53 ooc orb id 54 ooc orb module name 54 ooc orb modules 54 ooc orb native_cs 54 ooc orb native_wces 54 ooc orb oa conc_model 59 ooc orb oa endpoint 60 ooc orb oa numeric 61 ooc orb oa thread_pool 60 ooc orb oa version 60 ooc orb poamanager manager conc_model 61 ooc orb poamanager manager endpoint 61 ooc orb poamanager manager version 61 ooc orb policy connection_reuse 55 ooc orb policy connect_timeout 55 ooc orb policy interceptor 55 ooc orb policy locate_request 55 ooc orb policy location_ transparency 55 ooc orb policy protocol 55 ooc orb policy rebind 55 ooc orb policy request_timeout 55 ooc orb policy retry 56 ooc orb policy retry interval 56 ooc orb policy retry max 56 ooc orb policy retry remote 56 ooc orb policy sync_scope 56 ooc orb policy timeout 56 ooc orb server_name 56 ooc orb server_shutdown_timeout 57 ooc orb server_timeout 57 ooc orb service
328. ver Constants INTERCEPTOR_CALL _POLICY_ID const CORBA PolicyType INTERCEPTOR CALL POLICY ID 1330577667 This policy type identifies the interceptor call policy 417 CHAPTER B Orbacus Policy Reference Interface OBPortableServer InterceptorCallPolicy local interface InterceptorCallPolicy inherits from CORBA Policy The interceptor call policy This policy controls whether the server side interceptors are called for a particular POA Attributes value readonly attribute boolean value The InterceptorCallPolicy value If a POA has an InterceptorCallPolicy set and value iS FALSE then any installed server side interceptors are not called for requests on this POA Otherwise interceptors are called for each request The default value is TRUE 418 BiDirPolicy Constants Typedefs BiDirPolicy BIDIRECTIONAL _POLICY_TYPE const CORBA PolicyType BIDIRECTIONAL POLICY TYPE 37 This policy type identifies the BiDirectional GIOP CORBA 3 compliant protocol policy NORMAL const BidirectionalPolicyValue NORMAL 0 This value indicates normal disabled BiDir GIOP functionality BOTH const BidirectionalPolicyValue BOTH 1 This value indicates enabled BiDir GIOP functionality typedef unsigned short BidirectionalPolicyValue 419 CHAPTER B Orbacus Policy Reference 420 In this appendix APPENDIX C Reactor Reference This appendix describes the Orbacus Reactor interfaces This append
329. vior of the Orbacus Watson module is controlled by the following properties Property Description ooc watson trace requests lt level gt This property sets the indicated tracing level for the in and out direction The default value is O ooc watson trace requests in lt level gt This property sets the indicated tracing level only for the in direction The default value is O ooc watson trace requests out lt level gt This property sets the indicated tracing level only for the out direction The default value is O The information displayed in the in and out directions differ for the different roles an application takes in CORBA For a client application making a CORBA request the out direction corresponds to the request sending direction and the results are received in the in direction For a server application requests from clients are coming in and replies with results or exceptions are sent out Setting one of the more specific properties ooc watson trace requests in and ooc watson trace requests out overrides the corresponding value for this direction set by coc watson trace requests 299 CHAPTER 14 Orbacus Watson Sample Configuration File 300 Applications using Orbacus Watson can simply be started by specifying a configuration file with appropriate property settings with the orBconfig command line option server ORBconfig watson cfg The following example file
330. xele rqbia p return 0 A reference to the Root POA is obtained using the ORB reference and the Root POA is used to obtain a reference to its POA Manager A servant of type Hello _imp1 is created and is used to incarnate a CORBA object The CORBA object is released automatically when it is not used anymore The object reference is stringified and written to a file The server enters its event loop to receive incoming requests 19 CHAPTER 1 Getting Started Implementing the Client Client java Save this to a file with the name Client java in the directory hello 1 Java 2 package hello 3 4 public class Client 5 6 public static void main String args z7 i 8 Same as for the server 9 10 sil static int run org omg CORBA ORB orb 12 L3 org omg CORBA Object obj null 14 try 15 16 String refFile Hello ref 17 java io BufferedReader in new java io BufferedReader 18 new java io FileReader refFile 19 String ref in readLine 20 Obi og emine cO AIEEE ESEN y 2m 22 catch java io IOException ex 23 24 ex printStackTrace 25 return 1 26 27 28 Hello hello HelloHelper narrow obj 29 30 hello say_hello 31 32 return 0 33 aya 6 9 This code is the same as for the server 14 26 The stringified object reference is read and converted to an object 20 28 30 Implementing the Example in Java The object reference is narrowed to a reference
331. y and OClAccFactoryRegistry respectively Concrete implementations of Connector Factory must be registered with the Connector Factory Registry and concrete implementations of Acceptor Factory must be registered with the Acceptor Factory Registry OCI Reference OCI for the Application Programmer OCI Reference This chapter does not contain a complete reference of the OCI It only explains OCI basics and in the remainder of this chapter how it is used from the application programmer s point of view for the most common tasks For more information on how to use the OCI to write your own protocol plug ins and for a complete reference please refer to Appendix E The following sections only apply to the standard Orbacus IIOP plug in For other plug ins please refer to the plug in s documentation A Converter Class for Java page 346 Getting Hostnames and Port Numbers page 347 Determining a Server s IP Address page 351 345 CHAPTER 17 The Open Communications Interface A Converter Class for Java As you will see in the following examples the OCI info objects return port numbers as IDL unsigned short values and IP addresses as an array of 4 IDL unsigned octet values This works fine for C but in Java this causes a problem because there are no unsigned types in Java The Java mapping simply maps unsigned types to signed types Consider for example the IP address 126 127 128 129 In J

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