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1. type of object graphical type style Individuals DefaultIndividualGT gray box Links DefaultLinkGT thin black line with label InstanceOf DefaultInstanceOfGT green line without label IsA DefaultisAGT blue line without label Attribute DefaultAttributeGT black line with label Class ClassGT turquoise box SimpleClass SimpleClassGT pink oval MetaClass MetaClassGT light blue oval MetametaClass MetametaGT bright green oval QueryClass QueryClassGT red oval Implicit In ImplicitInstanceOfGT dashed green line Implicit IsA ImplicitlsAGT dashed blue line Implicit Attribute ImplicitAttributeGT dashed black line The object DefaultJavaPalette has also some rules which define the default relationship be tween objects and graphical types e g all instances of Class have the graphical type ClassGT If you want to customize the graphical types for your model then you must define the new graphical types see below and then add them to a new graphical palette as instance of JavaGraphicalPalette Take the default graphical palette as a starting point since you may want to reuse some of the exist ing graphical types See file 03 ERD GTs sml athttp merkur informatik rwth aachen de pub bscw cgi 188651 for an example The safest way to define a correct graphical palette is to use the intermediate XPalette as superclass of the new palette It can be found within the CB Forum model for business model canvasses at http merkur inform
2. Figure 8 23 Adding an instantiation link between Address and Class the Telos Editor field as well as in the history window Figure 8 25 shows the CBIva with the query class and the answer We can also execute this query from CBGraph From the menu Current connection we select Query to server A dialog we ask for the name of query class If we have told the example query we can type AngusEmployees in the text field and hit on the Submit Query The query will be evaluated and the objects in the result will be shown in the list box We can select the objects which should be added to the graph multiple selection with the Shift key is possible and click on the Show objects button The 129 localhost4001 Individual Employee Employee in Class SimpleClass with attribute name String salary Integer dept Department boss Manager education String address Address Figure 8 24 The resulting graph after commit CBlva ConceptBase cc User Interface in Java File Edit Browse Options History Windows Help E Telos Editor Angus in AngusEmployees end 1 2 3 4 Robert in AngusEmployees 5 end 6 7 Edward in AngusEmployees c this boss Angus 8 end 4 end 9 5 10 Bill in AngusEmployees History Window 10 ASK i Now 2015 09 15 13 09 UTC Module oHome
3. lt deriveExpList gt lt label gt 1 gt plainArgList gt gt lt label gt SELECTORB lt label gt lt label gt SELECTORB lt selectExpB2 gt lt label gt SELECTORB lt restriction gt gt lt selectExpB gt lt restriction gt SELECTORB lt label gt lt restriction gt SELECTORB lt selectExpB2 gt lt restriction gt SELECTORB lt restriction gt gt lt label gt lt label gt lt label gt lt selectExpA gt lt label gt lt selectExpB gt lt label gt lt objList gt gt lt objectname gt lt objList gt lt objectname gt A 3 Syntax of active rules The event condition and actions of an ECArule are specified as a special assertion Therefore the syntax is an extension of the normal assertion language shown in the section before lt ecarule gt lt ifclause gt lt ecaevent gt lt eventop gt lt askop gt lt ecacondition gt lt condformula gt gt lt variableBindList gt ON lt ifclause gt lt eca DO lt actionlist gt lt optelseaction gt IF IFNEW TRANSACTIONAL lt ecaevent gt condition gt FOR ALPHANUM lt eventop gt lt literal gt lt eventop gt lt literal gt lt askop gt lt literalArg gt lt askop gt lt literalArg gt Tell tell Untell untell Ask ask lt condformula gt true false lt literal gt 136 lt actionlist gt lt
4. lt restriction gt gt restriction lt label gt lt selectExpB gt restriction lt label gt enumeration lt classlist gt restriction lt label gt lt object gt lt selectOperator gt gt dot bar lt labellist gt gt lt label gt lt labellist gt lt label gt lt label gt gt ALPHANUM LABEL NUMBER 138 lt object gt lt substlist gt lt singlesubst gt lt selectexp gt gt derive lt substlist gt lt selectexp gt lt singlesubst gt lt substlist gt lt singlesubst gt substitute lt object gt lt labe specialize lt label gt lt label lt label gt select lt selectexp gt SELEC select lt selectexp gt SELEC 139 LES gt OR1 OR2 lt label gt lt selectexp gt Appendix B O Telos Axioms O Telos is the variant of Telos originally defined by John Mylopoulos Alex Borgida Manolis Koubarakis and others that is used by the ConceptBase system This list is the complete set of pre defined axioms of O Telos and thus defines the semantics of a O Telos database without user defined rules and constraints The subsequent axioms are written in a first order logic syntax but all can be converted to Datalog with negation though there is some choice in the conversion wrt mapping to rules or constraints Axiom 1 Object identifiers are unique Vo 11 l1 y1 12 l2
5. amare contained in x1 xn In O Telos rules and constraints are defined as attributes of classes Use the category constraint for integrity constraints and the category rule for deductive rules The text of the formula has to be enclosed by the character The choice of the class for a rule or constraint is arbitrary except for query classes which use the special variable this Continuing our running example the following formula is a deductive rule that defines the boss of an Employee Note that the variables e m are fora11 quantified T Employee with rule BossRule forall e Employee m Manager exists d Department e dept d and d head m gt e boss m constraint SalaryBound forall e Employee b Manager x y Integer e boss b and e salary x and b salary y gt x lt y end The second formula is an integrity constraint that uses the boss attribute defined by the above rule The constraint demands a salary of an Employee does not exceed the salary of his boss Note that you can define multiple salaries for a given instance of Employee The constraint is on each individual salary not on the sum Also note that the arguments of the lt predicate are bound by the two predicates with attribute label salary 2 2 9 Meta formulas Some formulas violating the predicate typing condition can be re written to a set of formulas that do not violate the condition The s
6. lt label gt in lt selectExpB gt lt selectExpA gt in lt selectExpB gt lt selectExpB gt isA lt selectExpB gt lt selectExpB gt lt selectExpB gt lt infixSymbol gt gt INFIXSYMBOL lt label gt lt literalArgList gt gt lt literalArg gt lt literalArgList gt lt literalArg gt lt literalArg gt gt lt objectname gt lt arExpr gt gt lt arExpr gt lt arTerm gt lt arExpr gt lt arTerm gt lt arTerm gt lt arTerm gt gt lt arTerm gt x lt arFactor gt lt arTerm gt lt arFactor gt lt arFactor gt lt arFactor gt gt lt arExpr gt lt objectname gt lt funExpr gt lt selectExpA gt gt lt selectExpA gt lt selector gt lt selectExpA gt lt selectExpA gt lt label gt un T ECTOR1 SELECTOR2 lt selector gt gt lt deriveExp gt gt lt label gt lt deriveExpList gt lt label lt plainArgList gt lt funExpr gt 135 lt funExpr gt lt deriveExpList gt gt lt singleExp gt gt lt label gt lt label gt lt plainArgList gt lt singleExp gt lt singleExp gt gt lt literalArg gt lt label gt lt labe lt plainArgList gt gt lt literalArg gt lt lt selectExpB gt lt selectExpB2 gt lt restriction gt lt objList gt lt literalArg gt
7. In m Manager A m boss dst A srce boss m r2 vars m ground srce A src boss m A m boss dst r3 vars m ground dst var src A m boss dst A srce boss m end Note that the predicates var and ground are builtin predicates of PROLOG Thus this is also an example for calling PROLOG predicates in a query or rule 49 Chapter 3 Answer Formats for Queries The ConceptBase server provides an ASK command in its interface which allows to specify in which text based format the answer should be returned There are two pre defined formats one for returning a list of object names and one for returning a list of object frames These two formats can be extended by user defined answer formats To understand them we first look as the syntax of the ASK command at the programming interface We use here the syntax of CBshell section 7 since it can be tested directly in a command terminal ask lt query gt lt query format gt lt answer format gt lt roll backtime gt The query is typically a parameterized expression like O abc param1 In that case the query format is OBJNAMES The rollback time is typically Now i e the query refers to the current database state There are four options for the answer format LABI E the answer shall be returned as a comma separated list of object names e g bill mary john FRAME the a
8. An ECAassertion has the following structure the syntax is described in section A 3 x1 x2 C1 y1 C2 ON TRANSACTIONAL event FOR x IF IFNEW condition DO actionl action2 ELSE action3 The TRANSACTIONAL modifier cannot be used in combination with the FOR clause The ELSE part is optional The first line contains the declaration of all variables used in the ECAassertion The specified classes of the variables here C1 and C2 are only used for compilation of the rule during the evaluation of the rule it is not tested if the variables are instances of the specified classes If necessary include predicates like In z Class in the IF part of the ECArule The variables can occur in the ON IF DO and ELSE part of the ECArule When the IF part begins with IF NEW then the whole condition shall be evaluated against the newest database state See also new tag for conditions There is also a variant of ECArules without an IF part It is equivalent to the longer form on the right side The shortcut can also be used in combination with the TRANSACTIONAL modifier or the FOR clause x1 2 C1 y1 C02 ses x1 x2 C1 y1 C2 ON event ON event IF TRUE DO actionl action2 a DO actionl action2 4 1 2 Events Possible events are the insertion Tell or deletion Untell of attributes A instantiation links In or specialization links Isa For example if the rule should be executed if an object is in
9. Development of ConceptBase cc started in late 1987 in the context of ESPRIT project DAIDA Jark93 and was continued within ESPRIT Basic Research Actions Compulog 1 and 2 1989 1995 the ES PRIT LTR project DWQ Foundations of Data Warehouse Quality 1996 1999 and the ESPRIT project MEMO Mediating and Monitoring Electronic Commerce 1999 2001 Versions have been distributed for research experiments since early 1988 ConceptBase cc has been installed at more than eight hundred sites worldwide and is seriously used by about a dozen research projects in Europe Asia and the Americas The direct predecessor of O Telos is the knowledge representation language Telos specified by John Mylopoulos Alex Borgida Martin Stanley Manolis Koubarakis and others Telos was designed to rep resent information about information systems esp requirements Telos was based on CML Conceptual Modeling Language developed in the mid late 1980 ties A variant of CML was created under the la bel SML System Modeling Language and implemented by John Gallagher and Levi Solomon at SCS Hamburg CML itself was based on RML Requirements Modeling Language developed at the Univer sity of Toronto by Sol Greenspan and others Neither RML nor CML were implemented in 1987 They were regarded as theoretic knowledge representation languages with possible world semantics SML was implemented as a subset of CML using Prolog s SLDNF semantics In 1987 we decided to s
10. This operation will delete the object from the database As for the insertion of objects before the modification will be send to the server when you click on the Commit button Note that this operation has an effect on the database in contrast to the next operation Hide object from view The object will be removed from the current view This operation has no effect on the database i e the object will not be deleted from the database Display in Telos Editor This operation will load the frame of the object into the Telos editor If the Telos editor contains already some text then the frame is appended to the existing text e Show in new Frame A new internal window within CBGraph will be shown and the selected object will be shown in the new window 8 2 9 Editing of Telos objects CBGraph supports also the creation and deletion of Telos objects A Telos object in the context of CBGraph is a proposition as described in chapter 2 As described there there are four types of Telos objects 117 Individuals Instantiations InstanceOf Specializations IsA and Attributes 5 Create Object Attribute gt gt fF Create Object Individual Source label Destination Name ObjectName GraphType Defaultindividual E Aur Class Show Attribute Instantiation Ok Cancel Ok Cancel E Create Object Instantiation F Create
11. gt exists SUBC CLASS spec sub SUBC and x inSubRel SUBC So essentially we pass the meta variable to the condition of the intermediary rule The attribute inSubRel is just used to be able to specify a dedicated conclusion predicate for the intermediary de ductive rule It is defined as attribute of Proposition The complete example is at http merkur informatik rwth aachen de pub bscw cgi d3070600 mp ISA complete sml txt Many more re usable examples for meta formulas are in the ConceptBase Forum at http merkur informatik rwth aachen de pub bscw cgi 1042523 2 2 10 Further object references In addition to the so called select expressions gt gt already introduced above for directly refering to attributes specializations and instantiations as objects three other basic constructors may be used within frames and assertions e is the counterpart of and denotes the target of an attribute instead of the attribute object itself e g mary advi ses is the same as PR 29 e The set valued operator has the commonly used meaning as in paths in object oriented models and relates an object with the set of all attribute values of a certain category i e mary dept contains both PR and R amp D e As can be understood as the set variant of but employing the attribute category instead of the concrete attribute label the same holds for with respect to Thus mary dept is the set of all attributes as objects tha
12. lt classlist gt lt withspec gt gt lt empty gt with lt decllist gt lt decllist gt gt lt empty gt lt declaration gt lt decllist gt lt declaration gt lt declaration gt gt lt attrcatlist gt lt proplist gt lt attrcatlist gt gt lt label gt lt attrcatlist gt lt label gt lt proplist gt gt lt property gt 133 lt property gt gt l l l lt complexref gt gt lt enumeration gt gt lt pathexpression gt gt lt pathargument gt gt lt restriction gt gt lt endspec gt gt lt label gt gt lt proplist gt lt property gt lt label gt lt objectname gt lt label gt lt complexref gt lt label gt lt enumeration gt lt label gt lt pathexpression gt lt objectname gt lt withspec gt lt endspec gt lt classlist gt lt objectname gt SELECTORB lt pathargument gt lt label gt lt label gt SELECTORB lt pathargument gt lt restriction gt lt restriction gt SELECTORB lt pathargument gt lt label gt lt enumeration gt lt label gt lt pathexpression gt lt label gt lt objectname gt end ALPHANUM LABEL NUMBER Note ConceptBase represents internally object identifiers as id NUMBER where NUMBER is a se quence of digits For this reason labels matching this pattern are forbidden in the Telos frame syntax A 2 Syntax of the rule
13. 5 5 Setting user home modules When ConceptBase is used in a multi user setting it makes sense to automatically assign clients of Con ceptBase users to a dedicated module context their so called home module To use this feature the database of the ConceptBase server has to contain instances of the pre defined class CB_User This class is defined as follows CB_User with attribute homeModule Module end Assume that we have two users mary and john who need to be assigned to different modules when they log into the CBserver by their favorite user interface The system adminstrator should then include the following definitions to the database of the CBserver 75 Projectl in Module end Project2 in Module end mary in CB_User with homeModule ml Projectl end john in CB_User with homeModule ml Project2 end As a consequence the start module of the two users will be set accordingly when they log into the CBserver The home module feature is especially useful in a teaching environment The teacher can put some Telos models into the shared System module Students home modules would be assigned to sub modules e g based on group membership Each student group can then work on an assignment by working on their sub module without interfering with other student groups There is a subclass AutoHomeModule of Module which supports applications of ConceptBase where by default any user should work in her own module context Rather t
14. 7 and 9 Employee Manager and Department Analogously the attributes 4 5 6 and 10 are automatically regarded as instances of the class Attribute The instances are instances of the class Inst anceOf holding explicit instantiation objects and 8 is an instance of the class IsA explicit specialization objects Note that all relationships are declared by using the identifiers not the names of objects Thus Class denotes the identifier of the object Class etc The identifiers are maintained internally by ConceptBase s object store Externally the user refers to objects by their name A standard way to describe objects together with their classes subclasses and attributes is the frame syntax Frames are uniformly based on object names The next frames establish two departments labelled PR and RD and state that the individual object mary is an instance of the class Manager Mary has four attributes labelled hername earns advises and currentdept which are instances of the respective attribute classes of Employee with labels name salary and dept mary in Manager with na salary de end me hername earns pt advises PR currentdept RD 15000 Mary Smith PR in Department end RD in Department end 15 The corresponding propositions for the frame describing mary are P mary mary mary
15. Cascading UNTELE i ee ae ea ra be ea S Memory consumption and performance 02 00002020005 7 The CBShell Utility 7 1 Ta Ra 7 4 Tid 7 6 Ta 7 8 Syntax Options CODOS 0 2 daa A a Seok Ge ES Rae 7 3 1 Argument delirnitets sc o se ee a eR RE eR Ew Interactive use of CBShell 2p 4 sa hk ao BR OG Dee ae Ae 8 Positional parameters oos sc soreo e ep eo p a eA ee ee eS Executable CB Shell scripts ss lt c s 2 ee a A CBShell scripts within regular shell scripts o o ta A A ee ak S 8 The ConceptBase cc Usage Environment 8 1 8 2 8 3 CBlva 8 1 1 8 1 2 8 1 3 8 1 4 8 1 5 8 1 6 8 1 7 8 1 8 8 1 9 8 1 10 8 1 11 Telos editt gt ccoo e a e o e Oe a ee So History WIDAOW oo ee eal a ee el ee DIN meS oc OSLO a Gee dete bo eee ie de ees Brame DIOWEEP c k oe Rb GRE EER PEELE Soe BES ER EE EEE Display queries 5 o i ne See a eh ea See eae Seda eh hes Display IES se a eS A ee aoe ee E Ee AS rG cd os eS Ot Bae KS GEESE A DESO ES BESS Tree DIOWSED o koh ee RS RE Sa ee ARS Bk a a ee as The graph editor CBGraph lt se a ee ee ee he ee 8 2 1 82 2 8 2 3 8 2 4 8 2 5 8 2 6 8 2 7 8 2 8 8 2 9 8 2 10 8 2 11 a oes bk Gk SES ee OB Se pS eA He Oe a Starting CBGraph via CBlva ce ee eS The cbgraph command ce aoe A ae eh Bae aoe AS a Redirecting the CBserver location o o ee ee ee eee ed ii y i ee a eS ES ERAS ee ee Memi DAT e us o a ER A EA eee ee EA es
16. String source of module 1 String source of module 2 Gl IF HAS_IMAGE PNG image of the background image Since edges are also objects in Telos the nodes stored in the graph file include the edge node that represents the edge itself The graph file stores complex information about the nodes including the graphical types of the nodes their dimension and location By default the graph files stores the Telos module sources needed to manipulate the graph The graph file stores the sources of all modules that are on the path from the root module System to the current module the module that is active when the graph file is saved The module System is not saved since it is typically not updated Note that ConceptBase database can include a tree of module see section 5 3 Hence a graph file does in general not store the Telos sources of the complete database If you create graph files for all leave modules of a database then the combination of the graph files is completely containing the database as sources models The extraction of Telos sources uses the builtin query 1istModule see section 5 7 This is in most cases a faithful listing However there are rare cases when the extracted cannot be told to a CBserver For example if a module contains deductive rules that are essential for satisfying integrity constraints for objects defined in the same module then a single TELL operation could fail bacause ConceptBase require
17. 5 4 Exporting and importing objects In order to use objects which are not visible in a module ConceptBase offers the export import facility The Module object has two further attributes namely to objects exported from a module and to modules imported by a module Module with attribute contains Proposition exports Proposition imports Module end In order to allow other modules to import objects from a module we need to define an export attribute from the module object to those objects We call the set of objects exported by a module the export interface of a module In order to include the export interface of another module to a module we need to define an import s attribute from the module object to the module to be imported In our running example we would like to define a specialization of the Class Employee within the Work module It is desirable to reuse Employee from the Master module instead of redefining it in the Work module In order to import the class Employee to the Work module we have to define all objects belonging to the Employee class as exported objects First change the module context to Master Now TELL the following frame within module Master 74 Master with exports el Employee e2 Employee name end Now you have defined the objects Employee and Employee name as exported objects of the Master module Any module in your database which defines an import s attribute t
18. ConceptBase end the inconsistency is removed from the model To see the update of the graphical type in the Graph Editor you have to select the inconsistent link and select Validate and update selected objects from the Current connection menu EN ConceptBase Graphical Editor File Edit ae Current connection mProjkorEmp onnected with localhost Figure D 1 Graph Editor showing the example model with inconsistent link D 2 3 Limitations and final remarks Metaformulas extend the expressive power of defining rules and constraints for ConceptBase Objectbases The implementation of this mechanism is not complete at the moment but should enable the use of the most frequently requested concepts like single and necessary Some limitations are listed below e limited partial evaluation The partial evaluation procedure is limited to a conjunction of predicates preceeded by forall quantors 161 e no source to source transformation Formulas are not converted automatically into the form mentioned above supported by the meta formula mechanism even if they could be transformed If the class variables can t be bound using partial evaluation of the input formula the formula is rejected even if there exists an equivalent formula in which partial evaluation could be used to bind the class variables e not all classes are supported Generated formulas where variables are quantified over instances of the following classes or
19. Germany Jarke M Gallersdorfer R Jeusfeld M A Staudt M Eherer S ConceptBase A deductive object base for meta data management Journal of Intelligent Information Systems Vol 4 No 2 pp 167 192 March 1995 170 JIM 09 JIN 98 JIQV99 JJR88 JJR90 JJS 99 JMSV90 JQC 00 JQJ98 Lud2010 MaPr99 MBJK90 MW80 NJJ 96 Quix96 QSJ02 RaDh92 Jeusfeld M A Jarke M Mylopoulos J eds Metamodeling for Method Engineering Cambridge MA 2009 The MIT Press ISBN 10 0 262 10108 4 Jeusfeld M A Jarke M Nissen H W Staudt M ConceptBase Managing Conceptual Models about Information Systems In Bernus P Mertins K Schmidt G eds Handbook on Architectures of Information Systems Springer Verlag pp 265 285 1998 Jarke M Jeusfeld M A Quix C Vassiliadis P Architecture and Quality for Data Ware houses An Extended Repository Approach Information Systems Vol 24 No 3 pp 229 253 1999 Jarke M Jeusfeld M Rose T A KBMS for database software evolution documentation of first ConceptBase prototype Report MIP 8819 Universit at Passau Germany 1988 Jarke M Jeusfeld M Rose T A software process data model for knowledge engineering in information systems Information Systems 15 1 85 116 1990 Jeusfeld M A Jarke M Staudt M Quix C List T Application Experience with a Repository System for I
20. Is class synonym for listClass mkdir module synonym for newModule so we mimick the navigation within modules by commands known from Unix to manager directories showAnswer print the last result on standard output this can be useful if you employ the CBserver as a generator in a shell pipe see Graphviz case below showAnswer gt filename same as showAnswer but output is redirected to filename showUsers show the list of users that have at any time been enrolled to this database implemented by a query that displays the instances of the class CB_User who synonym for showUsers show name show the frame with the given name shortcut for ask get_object name objname echo string prints the string to standard output use double quotes if the string has multiple words a sequence n within the string is replaced by a newline character echo n string like the one argument variant but no newline is printed after the string newline prints a newline character on standard output nl synonym for newline exit exits the shell also stops a server which has been started in this shell quit same as exit 9999 Command arguments with white space characters have to be enclosed in double quotes arguments may span multiple lines Lines starting with are comment lines If an argument contains a string of the form PropName it will be replaced with the value of the corresponding Java property which may be defined using the D option of t
21. It contains numerous examples on how to solve certain modeling problems It is highly recommended to join the workspace More details are available at http conceptbase sourceforge net CB Forum html ConceptBase cc is mainly used for metamodeling and for engineering customized modeling languages The textbook JJM 09 Jeusfeld M A M Jarke and J Mylopoulos Metamodeling for Method Engineering Cambridge MA 2009 The MIT Press ISBN 10 0 262 10108 4 introduces into the topic and provides six in depth case studies ranging from requirements engineering to chemical device modeling The book and this user manual are complementary to each other 1 1 Background and history Proposals for next generation databases BMS84 stem from three traditions e Databases This stream is best typified by extended relational and object oriented databases The main extension is the addition of complex domains shared sub objects and procedures to the data base Examples include Postgres Damokles Cactis Iris DASDBS and many others e Programming languages The main goal is to provide persistence and sharing to one or more pro gramming languages ideally orthogonal to the type systems of these languages Examples include the O system for imperative programming languages and typed versions of Prolog such as LOGIN or PROTOS L Knowledge representation Some of these systems aim at providing database service to AI appli cations other
22. Random functions can be useful in the context of active rules section 4 e g to initiate the firing of a rule with an arbitrary candidate out of the set of candidates The code for select rnd is accessible via the ConceptBase Forum at http merkur informatik rwth aachen de pub bscw cgi 1694234 2 3 4 Reified query calls You might want to memorize certain query calls that you want to call over and over again ConceptBase provides a built in class QueryCa11 which you can instantiate by such query calls as ordinary objects i e reified query calls The following example defines the class count as a query call object COUNT Class class in QueryCall end Of course you can ask the query call COUNT Class class without having told it as an object Reifying COUNT Class class additionally allows you to use it as an attribute of another object or to browse it with the graph editor Examples for query calls in particular for using integer intervals as class attributes are available in the CB Forum at http merkur informatik rwth aachen de pub becw cgi 2571997 38 2 4 View definitions The view language of ConceptBase is an extension of the ConceptBase Query Language CBQL Besides some extensions that allow an easier definition of queries views can also be nested to express n ary rela tionships between objects The system class View is defined as follows Class View isA GenericQueryClass with attribute inherited_attribute Pr
23. boss Manager end 14 Manager in Class isA Employee end Department in Class with attribute head Manager end The label of the common source in the first frame is 1 Employee It is declared as instance of the class Class and has four attributes The class Manager is a subclass of Employee Oid s preceded by ff in our examples are generated by the system This leads to the following set of propositions corresponding to the frames above The belief time inserted by the system is denoted by omission marks U P U U U U U P U U U U U Pp F 17 T r T T T T 1 3 4 5 6 M 7 8 D 9 1 r r r name Employee E xinstanceof Class SEYING ees salary I1 dept HA e boss xisa D Departmen Did wee Manager M xinstanceof Class Ey ws nteger gt ES HD poe ee D instanceof tClass 0 D head Miss Instantiation to the pre defined class Individual is implicitly given by the structure of the three individual propositions named 1 3 of Attribute are also called attribution objects or explicit attributes Propositions 1 2
24. but including implicit attributes find_attribute_categories Lists all the attribute categories that may be used for objname This is a lookup of all attributes of all classes of ob jname find incoming attribute categories In contrast to the previous query this query returns all attribute cate gories that go into ob jname i e attribute categories for which ob jname can be used as an attribute value find_attribute_values Lists all objects that are attribute values of ob jname in the attribute category cat find_explicit_attribute_values Same as before but only for explicit attributes E 1 4 Links between objects find_incoming_links Lists the links that go into ob jname and are instance of category Note that all types of links are returned including attributes instance of links and specialization links find_incoming links_simple Same as before but without the parameter category find_outgoing_links Lists the links that come out of ob jname and are instance of category Note that all types of links are returned including attributes instance of links and specialization links find_outgoing_links_simple Same as before but without the parameter category get links2 Return the links between src and dst get_links3 Return the links between src and dst that are instance of cat E 1 5 Other queries find_object This query just returns the object given as parameter ob jname if it exists Thus it can be used to check
25. by their identifier Telos structurally object oriented framework generalizes earlier data models and knowledge represen tation formalisms such as entity relationship diagrams or semantic networks and integrates them with predicative assertions temporal information and in particular meta modeling This combination of fea tures seems to be particularly useful in software information applications such as requirements modeling and software process control A formal description of O Telos can be found in MBJK90 Jeus92 The following example is used throughout this section to illustrate the language A company has employees some of them being managers Employees have a name and a salary which may change from time to time They are assigned to departments which are headed by managers The boss of an employee can be derived from his department and the manager of that department No employee is allowed to earn more money than his boss This section is organized as follows first the frame and network representation of the O Telos language is explained Then the predicative sublanguage for deductive rules and integrity constraints are presented Subsection 2 3 presents a declarative query language which introduces queries as classes with optional predicative membership specification 2 1 Frame and network representation As a hybrid language O Telos supports three different representation formats a logical a graphical se mantic network an
26. decrement i il Tell In il EmployeeCounter end The files CB_HOME examples ECArules counter x 1pi contain the code for the Prolog predicates increment and decrement You must copy LPI files to the database directory before you start the ConceptBase server see also appendix F Note that all free variables of the PROLOG predicate must be bound in its call Furthermore the variables must be bound to object dentifiers if you want to use them in a Tell Untell or Ask action The effect of the increment and decrement procedures can also be achieved using the arithmetic expressions like 7 1 The simple solution with arithmetic expressions is available from http merkur informatik rwth aachen de pub bscw cgi d2773786 EmployeeCount sml txt The purpose of the example above is only to show that user defined PROLOG predicates can be called in the DO part of an ECArule You can define more interesting PROLOG predicates like sending an email to a user with content derived from the object base This requires however some knowledge of PROLOG and of the internal features of the ConceptBase server You should also note that the count of a class c can always and more correctly be computed by the function COUNT c That does even count inherited and deduced instances 4 2 3 Timestamps An often asked requirement in meta modeling applications is the recording of creation and modification dates ConceptBase stores the creation ti
27. gt why Syntax error 1 in line 1 parser message syntax error unexpected ENDOFINPUT expecting END or ENDMIT Syntax error Unable to parse Employee in Class ocalhost 4001 gt tel Employee in Class end yes localhost 4001 gt tell bill in Employee end yes localhost 4001 gt 1s Employee bill localhost 4001 gt show bill bill in Employee end localhost 4001 gt 1 2 localhost 4001 gt stop offline gt exit The term 1 2 is an example of a query that is not preceded by the ask command Note that such queries may no contain blanks since it would split it into several words Use quotes in such cases The prompt offline indicates that the CBShell is not yet connected to a CBserver Once connected it displays the hostname and port number of the connected CBserver as prompt The CBserver is started with disabled tracing The trace messages of the CBserver would otherwise be displayed in the output as well 7 5 Positional parameters A CBShell script can use variables 0 9 inside the script to refer to the positional parameters supplied via the call of cbshell Assume the following content of the script file File pascript startServer u nonpersistent t low port 1 tell 2 in Class end ask find_instances 2 class OBJNAMES ABEL Now ask find_instances 3 class OBJNAMI ABEL Now
28. in MinMax with end Attribute RelationshipType role with attribute minmax MinMax end The model defines the concepts of EntityTypes and RelationshipTypes Each entity that participates in a relationship plays a particular role This role is modelled as a Telos attribute link of the object Rela tionshipType The attributes describing the entities are modelled as Telos attribute links to a class Domain containing the value sets Roles can be restricted by the min max constraints 1 or 1 1 The next model contains a concrete ER model HEX ERE ERR RAKE RRA EE AA A Le x File Emp_ERModel x gt J HERAEAEEEEREDERAKH ARA Class Employee in EntityType with keyeAttr attribute ssn Integer eAttr attribute name String end Class Project in EntityType with keyeAttr attribute pono Integer eAttr attribute budget Real end Integer in Domain end Real in Domain end String in Domain end Class WorksIn in RelationshipType with role attribute emp Employee prj Project end WorksIn emp with minmax mProjForEmp 1 end WorksIn prj with minmax mEmpForProj 1 x end 155 ConceptBase in Project with pno cb_pno 4711 end Martin in Employee with ssn martinSSN 4712 end M_CB in WorksIn with emp mIsEmp Martin prj cbIsPrj ConceptBase end Hans in Employee with ssn hans_ssn 4714 end The entity types Employee an
29. l 0 be eS Re ee ee 22 Detault graphical pes qs kab cg ee ek da eS a ee ee Ee eR PS C3 Customizing the graphical types s sess 625 4 8666 2806 de 8 bo Psd os C3 1 Properties of CBladividual and CBLink gt e 6 eee ee ee RO Coma CERAIN 05 Saa ass ee eee wwe eH Ses 6 bees C 3 3 Providing a new implementation for a graphical type CIA SHAPES ceci eee bee de beh eda bea ae eb abe eae C33 IES eas eee be BS a Ee a eS a ly oe Examples D 1 Example model the employee model 0 2565 6 RES eee Ee ES Ee SS D 2 A Telos modeling example ER diagrams o 00200002 eee D1 The basicimodel oces ssp e A D22 Theus or mela To eo GS we EA wie Goes RES S D 2 3 Limitations and final remarks 2 55455 584 6 see eS RS EER RS Predefined Query Classes E 1 Query classes and generic query classes 2 o o eee ELI Unstances and Classes ok ba kG RE SORE a ae ES a E 1 2 Specializations and generalizations lt lt ee ietor Boles PANIES A CERES SE ee SS ELA PA Bel OMARE 24 4 6 eaa Siete is GREE BO re ee ts eee tes Bo WURCHOUS 4 564 04 40 oS eRe ee web ae Se ob oe ee es E 2 1 Comiptitation and counting coo oc ee ee ee E22 Sine mampulanon s c sce eta a a p oe ee A ee eo E3 Bilin quere Classes ooe s cer eree rra eea a Eee Pe E CBserver Plug Ins EL Defnmng the plugs ccor e tra te ee ii bw SG EZ Calling the pugan ws ec oe rena e Re e ERE PSS ER Ae F3 Programming mtertace for the
30. mary P E1 mary xinstanceof M P E3 mary hername Mary Smith P E4 E3 xinstanceof 3 P E5 mary earns 15000 P E6 E5 xinstanceof 4 P E7 mary advises PR P E8 E7 instanceof 5 P E10 mary currentdept RD P E11 E10 instanceof 5 The attribute categories name salary and dept must be defined in one of the classes of mary In this case mary is also instance of Employee due to the following axiom which defines the inheritance of class membership in O Telos and hence can instantiate these attributes Specialization axiom axiom 13 in appendix B The destination superclass of a specialization inherits all instances of its source sub class An example is the specialization 8 all instances of Manager including mary are also instances of Employee O Telos enforces typing of the attribute values by the following general axiom Instantiation axiom axiom 14 in appendix B If p is a proposition that is instance of a proposition P then the source of p must be an instance of the source of P and the destination of p must be an instance of the destination of P For example Mary Smith must be an instance of String The individual mary also shows another feature attribute classes specified at the class level do not need to be instantiated at the instance level This is the case for the boss attribute of Employee On the other h
31. mary dept currentdept RD So there are four attributes using four attribute categories Like an object can have multiple classes an attribute can have multiple categories In fact explicit attributes in O Telos are just objects and their attribute categories are their classes At the lowest abstraction level tokens the object labels of the at tributions frequently do not carry a specific meaning and can then be neglected when formulating logical expressions The attribution predicate x m y performs just this projection In the example the follow ing attributions facts are true mary name Mary Smith mary aliasname Mary Smith mary salary 15000 mary dept PR mary dept RD The class labels name aliasname etc are defined at an abstraction level where the meaning of some application domain is captured The class label attribute category of an attribute is defined as an object label of an attribute at the class level For example the name and aliasname attributes could be defined for the class Employee as follows Employee in Class with attribute single name String attribute aliasname String end Here the following predicate facts would be true Employee in Class Employee attribute name String Employee single name String Employee attribute aliasname String Employee attribute String Employee single String A AO TES TA 21 The mechanism for attribution is exact
32. object names must be unique within one module but different modules can contain different objects with identical names Tell Untell and Ask operations work relatively to a specified module The normal way of specifying the context in which a transaction takes place is using the Set Module function of CBlva See subsection 5 2 to learn how to change the module context of a transaction The basic set of predefined objects of ConceptBase such as Class Proposition QueryClass etc belongs to the predefined module System The default module of clients logging into a CBserver is oHome a direct submodule of System You can set the module context to your other modules in order to manipulate them 72 The contains attribute of the Module object is a derived attribute and is a link to all objects defined inside the context of a certain module This attribute is not stored explicitly but can be used anywhere in the O Telos assertion language Now we show how to create modules We introduce a small running example in order to demonstrate all module related facilities of ConceptBase Let s assume you ve started ConceptBase with a fresh database After telling the following two frames the server contains two new modules which are nested inside the pre defined oHome module Master in Module end Work in Module end 5 2 Switching between module contexts The standard way for changing the module context is to choose the select module menu entry fro
33. sequence of calls Each individual call from a ConceptBase client to the server comes with a certain latency time Thus if one would have to call the same query for dozens of arguments in a sequence most of the answer time would actually be the latency time To address this problem the CBserver offers a query call pattern for bulk queries bulk q x1 x2 x3 The query q stands for a query class with a single parameter The bulk query is converted by the CBserver into the following sequence of query calls q x1 q x2 q x3 The answers to the query call are collected into a single answer set and then transformed with the answer format of the query call Hence the answer format is applied to the whole answer and not to the part answers Example ask bulk Q abc def OBJNAMES MyFormatA Now Sorting of answers is disabled for bulk queries in order to return the answers in the sequence indicated by the arguments of the bulk query call Here the answer to the argument abc shall precede the answer to argument def Arguments that do not reference an existing object are removed from the argument list by the CBserver before answering the query Bulk queries are only supported for generic query classes with a single parameter The query class may not be a builtin query class The main prupose of bulk queries is to speed up the interaction between the ConceptBase clients such as CBGraph and the CBserver You can however use them with the
34. shall return the project budget of project P1 if existent You can also use the shortcut get Budget P1 like for any other query and the functional form getBudget P1 The latter is the preferred form for function calls Note that ConceptBase adopts the mathematical style for function calls rather that the object oriented one gt If your function has several arguments then use alphabetically sorted parameter names in the function definition f in Function isA D with parameter al Rl a2 R2 constraint Ct BS eae S end This corresponds to the mathematical function signature f Rix Ro gt D Functions without parameters are also possibe e g a function magicnumber that returns a fixed number magicnumber in Function isA Integer with constraint cmagic this 42 end You can call it with an empty argument list magicnumber ISAn object oriented style for the first function would be P1 getBudget rather than get Budget P1 41 2 5 2 Shortcuts for function calls and functional expressions Since functions require fillers for all parameters ConceptBase offers also the functional syntax f x to refer to function calls The expression f x is a shortcut for f x param1 where paraml is the only parameter of function f If a function has more than one parameter then they are replaced according their alphabetic order g in Function isA T with parameter xe TL y T2 constraint end A call like g b
35. 1 wn and the command line call cbshell pascript 4321 MyClass Integer The CBShell interpreter will then replace 1 with 4321 2 with MyClass and 3 with Integer If you supply less parameters than required by the script it will issue an error message and quit If the script had started a CBserver then this CBserver is stopped before quitting Likewise if the script had enrolled to an existing CBserver process it will unenroll before quitting The variable 0 is bound to the name of the script file CBShell uses the Java tokenizer to separate the positional parameters The tokenizer uses white spaces blanks tabs to separate tokens Use double quotes if one argument consists of several words e g cbshell otherscript MyClass isA Integer end An example of a script with positional parameters is provided in the CB Forum at http merkur informatik rwth aachen de pub bscw cgi d3364559 ticket307 cbs txt You can also call CBShell scripts within scripts batch files of the host operating system see section 7 7 98 7 6 Executable CBShell scripts A CBShell script can be made executable under Unix Linux and can then be used pretty much like any other shell script Assume that you have a CBShell script myscript that you want to execute directly from the command line As a first step create a link to the cbshell at a common directory for installed programs sudo ln s opt conceptbase cbshell usr bin cbshell As a second st
36. 1lpi there are two ways to plug it into the CBserver The first way is to copy the file into an existing database directory created by the CBserver cbserver g exit d MYDB cp myplugin swi lpi MYDB This option makes the definitions only visible to a CBserver that loads the database MYDB The second option is to instruct ConceptBase to load your LPI code to any database created by the CBserver To do so you just have to copy the LPI file into the directory with the system definitions cp myplugin swi lpi lt CB_HOME gt lib SystemDB where CB_HOME is the directory into which you installed ConceptBase The number of LPI files is not limited You may code zero one or any number of plug in files A couple of useful LPI plug ins are published via the CB Forum see http merkur informatik rwth aachen de pub bscw cgi 2768063 Note that these plugins are copyrighted typically come with their own license conditions that may be different to the license conditions of ConceptBase If you plan to use the plugins for commercial purposes you may have to acquire appropriate licenses from the plugin s authors Since we currently supply the CBserver for Linux only you need to run the CBserver on a local Linux computer in your network if you want to use the plug ins Note that we supply a ready to use virtual appliance that includes Linux and ConceptBase and that can be executed via a virtualization engine see http conceptbase sour
37. 33 head_of head this end The variable head_of in the constraint is prefixed with to indicate that it is a placeholder for the compted attribute with label head_of We recommend to use the prefix to avoid confusion of the place holder variable in query constraints and corresponding attribute label in the query definitions Analogously you can use the prefixed answer variable this instead of the plain version this ConceptBase will ac cept both the prefixed and the non prefixed version for the answer variable and the placeholder variable of computed attributes Non prefixed placeholders in constraints are replaced internally by the prefixed counterparts The generated deduction rules for above query would be forall this vl v2 this in SI_Manager and this union vl and vl in Union and v2 in Department and exists s s in HighSalary and this salary s and v2 head this gt Well_off_SI_Manager2 this vl v2 forall this vl v2 Well_off_SI_Manager2 this vl v2 gt this in Well_off_SI_Manager2 Computed attributes are treated differently from retrieved attributes The retrieved attribute union causes the inclusion of the condition this union v1 and vl in Union The corresponding variable v1 does not occur in the sub formula generated for the query class constraint The computed attribute causes the inclusion of the condition v2 in Department but typically also occurs in the query constraint Like retrieved a
38. 3613919 8 2 4 Redirecting the CBserver location You can use the command line argument host to override the hostname and portnumber encoded in the graph file Assume a graph file graph1 gel was created from a a CBserver connection at localhost 4001 Then loading this graph file in a subsequent call will also connect to localhost 4001 If you want to use another CBserver e g running on myhost acme com 4002 then call CBGraph from the command line as follows cbgraph rw host myhost acme com 4002 graphl gel Note that the CBserver must be running at the remote location before you enter the above command When you subsequently save the graph file it will have myhost acme com 4002 encoded as its connec tion The redirection also works in the reverse direction So assume that the graph file graph2 gel was created for a connection at myhost acme com 4002 Then the following command will redirect the con nection to localhost cbgraph rw host localhost graph2 gel The default port number is 4001 If no CBserver is running at localhost 4001 then CBGraph shall start it in the background 8 2 5 Moving objects All explicit information is a proposition is ConceptBase including attributes specializations and instan tiations You can move objects in the graph editor by pointing the cursor to the object s label and then dragging it while keeping the left mouse button pressed If a graph has ma
39. 8 6 displays the super classes classes and attributes of an object in a tree To start the tree browser you must mark an object in the Telos editor and select the item View Object as Tree from the popup menu or the Edit menu To expand an item just double click on the icon If you mark an object name in the tree you can load into the Telos editor with the Telos Editor button or open a new tree browser with the button View Object as Tree 108 Class N Individual gt jn O NISA gt Proposition gt Class SA N attribute Q N rule MSFOLrule gt in gt isA gt attribute gt mrule MRule gt constraint MSFOLconstraint Ok TelosEditor View Object as Tree Figure 8 6 Tree Browser 8 2 The graph editor CBGraph The CBGraph Editor is an advanced graphical modelling tool that supports the browsing and editing of Telos models It supports user definable graphical types i e objects may be visualized by dedicated graph ical layouts In addition to predefined graphical types the user can add his her own graphical types by modifying and adding certain objects in the knowledge base Furthermore the standard components can be replaced by own classes implementing specific application dependent behaviour In the following we first give an overview of CBGraph application and then present the main compo nents and functions of CBGraph Details about the use of
40. Field with the object Employee Editing Telos objects using CBGraph Telos objects can also be edited graphically in CBGraph In our example we want to add another attribute named address to the class Employee The attribute destination of this attribute should be a new class called Address First we select the object Employee and click on the Create Attribute button in the tool bar or select Add Attribute operation from the tool bar As we have selected the Employee object it should be already inserted as source of the attribute We have to type the label address and the destination of the attribute in the text fields see figure 8 22 As this attribute does not belong to a specific attribute category it is just an attribute we do not have to specify an attribute class By clicking on the Ok button CBGraph will create a new object for Address represented by the default graphical type a gray box Then it will create the attribute link from Employee to Address with the label address The result is shown in figure 8 23 Now we want to declare Address as an instance of Class Therefore we select Address hold down the Shift key and select Class Both objects should be selected now We click on the Create Instantiation button and a dialog as shown in figure 8 23 should appear As we have selected the objects in the correct way the dialog already specifies the object we want to create Address in Class and we can click dir
41. Figure 8 25 Query class and its answer selected objects will be added to the graph however with no connection to existing objects 130 8 4 Usage as applet Both applications CBIva and CB Graph Editor can be used as an applet within a web browser with a plugin for JDK 1 4 To start the applications as applet you have to specify inside the applet class of the program For CBlva the applet class is i5 cb workbench CBIvaApplet class and for the CB Graph Editor the main applet class is i5 cb graph cbeditor CBEditorApplet class For example to include the CB Graph Editor as applet inside your web page use the following applet tag lt applet archive cbh jar jg13 1 0 jar code i5 cb graph cbeditor CBEditorApplet class width 10 height 10 gt lt applet gt The archive parameter specifies the names of the archives to be loaded the code parameter is the name of the applet class to be startet As we have not specified a codebase parameter the JAR files have to be located in the same directory as the HTML file See http java sun com 3j2se 1 4 docs guide misc applet html for more information on the applet tag 8 5 Configuration file The configuration options are stored in a file CBjavalnterface in the home directory of the user The settings are stored automatically on exit You can edit the file manually with a normal text editor It contains name value pairs in the format variable value All variables can al
42. In p Proposition necessaryandP p c m d by this extension which results in the following substitution for the remaining formula c EntityType d Domain m keyeAttr Metaformulas defining sets of rules Another use of Metaformulas is the formulation of deductive rules Metaformulas defining deductive rules extend the possibilities of defining derived knowledge Assignment of graphical types This example first demonstrates the use of meta formulas to assign graphical types to object categories The minimal graphical convention for ER diagrams is to use rect angular boxes for entities and diamond shaped boxes for relationships In our modelling example these graphical types are assigned to objects which are instances of EntityType or RelationshipType and to in stances of these objects KOK KR ARA KA OK OK OK OK OK KKK KARA RARA RARA RARAS x KOK IK IK KK KK OK OK OK OK OK RK OK OK OK OK KK x File ERModelGTs x x Definition of the graphical palette for x ER Diagrams for use on color displays x x graphical type for inconsistent roles x Class InconsistentGtype in JavaGraphicalType with attribute property textcolor 0 0 0 edgecolor 255 0 0 edgewidth 2 implementedBy implBy i5 cb graph cbeditor CBLink priority p 14 end x graphical type for entities x Class EntityTypeGtype in JavaGraphicalType with property bgcolor 10 0 250 t
43. Preds Set finds all objects X that satisfy the condition in Preds and puts the result into the list Set Supported predicates in Preds are In A AL and Isa Example coserver askAl1 X In X Employee A X salary 1000 S cbserver tellFrames F tells all frames contained in the atom F The call will fail if there is any error in F Example cbserver tellFrames bill in Employee end cbserver makeName Id A converts an object identifier to a readable object name cbserver makeld A Id converts an object name Prolog atom into an object identifier used by the CB server to identify Telos objects If A is already an object identifier it is returned as well in Id cbserver arg2val E V transforms an argument either an object identifier or a functional expression to a value a number or a string The value can then be used in Prolog style computations such as arithmetic expressions cbserver val2arg V I transforms a Prolog value number string to an object identifier possibly by cre ating a new object for the value cbserver concat X Y concats the strings Prolog atoms contained in the list X The result is returned in Ys Note that ConceptBase internally manages concepts by their object identifier The programming in terface instead addresses concepts and objects by their name i e the label of the object or the Prolog value corresponding to the label You may have to use the procedure makeName and makelId to swi
44. Proposition p Proposition necessary x m VAR P p c m d and x in c gt exists y VAR y in d and x my end It reads as follows For each attribute with label m between the classes c and d which instantiates the attribute Proposition necessary and for each instance x of c there should exist an instance y of d which is destination of an attribute of x with category m One should notice that the predicates In x c and In y d cause this formula to be a meta formula The instantiation of x and m to the class VAR is just a syntactical construct Every variable in a constraint 156 has to be bound to a class This restriction is somehow contrary to the concept of meta formulas and the VAR construct is a kind of compromise The resulting In predicates are discarded during the processing of meta formulas The VAR construct is only allowed in meta formulas It enables the user to leave the concrete classes of x and m open without instantiating them to for example to Proposition The single constraint can be defined in analogy These constraints can be added to the system as if they were normal constraints Their effect becomes visible when declaring attributes as necessary or single This is done in the following model KK KK KKK KK KKK KKK KK KK KK File ERSingNec x KKK KKK KKK K KEK KKK KK KK KKK A x necessary constraint metaformula Class with constraint necConstraint forall c d Proposit
45. The Entity Relationship Model Towards a Unified View of Data ACM Trans act on Database Systems Vol 1 No 1 March 1976 pp 9 36 1976 Chen W Warren D S Tabled Evaluation with Delaying for General Logic Programs Vol 43 No 1 January 1996 pp 20 74 1996 Eberlein A Requirements Acquisition and Specification for Telecommunication Services PhD Thesis University of Wales Swansea UK 1997 Gallersdorfer R Realization of a Deductive Object Base by Abstract Data Types in German Diploma thesis Universit t Passau Germany 1990 Hahn U Jarke M Eherer S Kreplin K COAUTHOR a hypermedia group authoring en vironment In Benford J M Bowers S D eds Studies in Computer Supported Cooperative Work North Holland 79 100 1990 Jarke M ed Database Application Engineering with DAIDA Springer Verlag 1993 Jeusfeld M A Jarke M From Relational to Object Oriented Integrity Simplification Proc 2nd Intl Conf Deductive and Object Oriented Databases Munich Dec 1991 also as Aach ener Informatik Berichte 91 19 RWTH Aachen Germany 1991 Jeusfeld M Staudt M Query optimization in deductive object bases To appear in Frey tag Vossen Maier eds Query Processing for Advanced Database Applications Morgan Kaufmann 1992 also as Aachener Informatik Berichte 91 26 RWTH Aachen Germany Jeusfeld M A Anderungskontrolle in deduktiven Objektbanken Dissertation Universitit Passau
46. Y2 Plo 1 l1 Y1 A Plo 2 l2 yo gt 21 22 A l l2 A y1 y2 Axiom 2 The name of individual objects is unique V 01 02 1 P 01 01 1 01 A P 02 02 1 02 01 02 Axiom 3 Names of attributes are unique in conjunction with the source object Y 01 l y1 02 y2 P o1 2 1 y1 A P o2 2 1 y2 gt 01 02 V l in V l isa Axiom 4 The name of instantiation and specialization objects in isa is unique in conjunction with source and destination objects V 01 L Y 02 Plains l y A P 02 x l y A in V 1 isa gt 01 02 Axioms 5 6 7 8 Solutions for the predicates In Isa and A are derived from the object base Vo x c P o x in c gt In x c V o c d P o c isa d Isa c d Vo x n y p c m d P o x n y AP p c m d Aln o p gt AL x m n y V x m n y AL x m n y gt A z m y Axiom 9 An object x may not neglect an attribute definition in one of its classes Va y p c m d In x c A Alx m y A P p c m d gt Axioms 10 11 12 The isa relation is a partial order on the object identifiers V cIn c Obj gt Isa c c V e d e Isa c d A Isa d e Isa c e V c d Isa c d A Isa d c gt c d Axiom 13 Class membership of objects is inherited upwardly to the superclasses Y p x c d In x d A P p d isa c gt In x c Axiom 14 Attributes are typed by their attribute classes Vo l y p P o 1 y A In o p 3 c m d P p c m d A In x c A In y d
47. a terminal to see the output generated by it Now assume that you have started a CBserver on localhost with port number 4001 You should tell at least the following frame to the Cbserver to define the class File to which the above script refers to File in Class with attribute size Integer end Then execute in a terminal window printfiles4cbshell cbshell p It will tell the file size information to the CBserver At the end the end of file detection of the CBShell will trigger the CBShell to exit from the CBserver It is also possible to continue the pipe to a post processing program In this case the commands sent to CBShell should include ask commands in combination with showAnswer The following pipe shows the main idea generator cbshell p postprocessor An elaborate example of this usage is in the CB Forum at http merkur informatik rwth aachen de pub bscw cgi 3421289 The example shows how to extract module import statements from pro gram source files store them in ConceptBase and let ConceptBase produce a graph specification layed out by GraphViz 100 Chapter 8 The ConceptBase cc Usage Environment The ConceptBase cc User Interface consists of two main applications CBlIva is the ConceptBase cc Interface in Java that supports the editing of Telos frames displays instances of Telos objects etc CBGraph is a graphical editor for Telos models or modules Telos models can be represented by differ en
48. a graph displayed in CBGraph Since they are constructed from a ConceptBase database they are a materialized view on the database The view consists of the nodes and links displayed in the window their positions their graphical types the hostname portnumber and module from which the graph was created the size of the window its background color and image and the window s zoom factor You can thus save the current state of your graphical view in the gel file and load it in a subsequent session with CBGraph to continue editing it much like with a drawing tool The graph file stores serialized Java objects in the following sequence String title of the internal frame Dimension size of the graph editor Dimension size of the internal window Dimension size of the drawing area of the internal window Integer number of nodes incl edge objects nodel Rectangle bound of nodel node2 Rectangle bound of node2 Integer number of edges String source node of edge 1 String node object on the edge 1 String destination of edge 1 String source node of edge 2 String node object on the edge 2 String destination of edge 2 Color background color Float zoomfactor String hostname String port number 120 String module context as absolute path String long title of the graphical palette String name of the graphical palette Integer saveflag bit0 HAS_IMAGE bitl HAS_SOURCI IF HAS_SOURCE String saved modules e g modl mod2
49. after and priority before ensure that this ECArule is executed after or before some other ECArules if several rules can be fired at the same time There can be multiple values for each of these attributes As you may have noted one of the two attributes is redundant since r1 priority_after r2 is equivalent to r2 priority_before r1 Still ConceptBase provides both Furthermore ConceptBase does not automatically check the consistency of the priority declarations if r is before ra then r2 cannot be before r1 ConceptBase also does not provide for the transitivity of the priority You can however define this yourself via appropriate deductive rules 4 1 6 Coupling mode of an ECA rule The coupling mode of an ECArule determines the point of time when the condition and the action of the ECArule are evaluated and executed Possible values are Immediate The condition is evaluated immediately after the event has been detected If it evaluates to a non empty answer the DO action is executed immediately too If the answer is empty then the ELSE actions are executed provided that the ECArule has an ELSE part ImmediateDeferred The condition is evaluated immediately after the event has been detected If it eval uates to a non empty answer the actions of the DO part are executed towards the end of the current transaction Deferred The condition is evaluated towards the end of the current transaction If it evaluates to a non empty answer t
50. an explicit instance of class c 2 In_e x c or x in c The object x is an explicit instance of class c or of one of the sub classes of c or of the system class of x The system class of individual objects is Individual attribution objects have the system class Attribute instantiation objects the system class Inst anceOf and specialization objects have the system class IsA 3 A e x m y or x m y The objects x and y are linked by an explict attribute with attribute category m The attribute category is either explicitly assigned to the attribute or derived by a rule see subsection 2 2 3 4 Isa_e c d or c isA d The class c is a direct subclass of class d The above predicates can be used for example to define defaults values see http merkur informatik rwth aachen de pub bscw cgi 2396075 Since deduction should be transparent to the user one should avoid using the above predicates if the proper predicates In x c and A x n y can do the job 2 2 2 Notes on attribution The attribution of objects in O Telos axioms 7 and 8 in appendix B is more generic than in object oriented approaches in particular UML In O Telos an attribution relates two arbitrary objects In languages such as UML attributes are defined at classes to declare which states an object instance of the class may have This is well possible in O Telos as well e g by declaring the integer valued salary attribute of a class Employee and using it for i
51. and that the polygon line ends in its starting point here 0 0 The size of the bounding rectangle in the above example is 4x5 pixels If your shape is more complicated e g a curved shape then you should embed it into a bigger rectangle The polygon lines may not intersect each other Figure C 1 visualizes the pre defined graph shapes Note that by default the dimensions of a shape are adjusted from the area that the object label occupies This is fine for the shapes that are close to a rectangle The other shapes should be used in combination with the size resizable An example for the use of resizable shapes graphical types can be found in the CB Forum at http merkur informatik rwth aachen de pub bscw cgi 3596768 151 o BAS D Tri gt _ FolderL FolderR CS eee roe De SK Polygon Shape X Y Figure C 1 Some of the standard shapes You can extend the shapes by using the parameterized graph type PologonShape as shown in the previous subsection Use the align property to specify at which position the node s label should be displayed Default is center The above link also contains examples of user defined shapes C 3 5 Icons You can specify an image icon that is displayed instead of a shape to be drawn for the small compoment of a node CBIndividual The syntax for specifying an image icon is image lt image file location gt You can specify either the URL of the image file or the local path of
52. and the related links are redisplayed Selection and movement of multiple nodes and links is also possible Nodes and linkes are selected by clicking on its label e g Manager in figure 8 17 Some links like the blue specialization link in the figure have no label Then one can select the link by clicking on the small square dot in the middle of the link This square dot is by default invisible It becomes visible when you click on any other node or link label in the graph e g on Manager We can further experiment with CBGraph by showing the classes and attributes of Employee The classes of Employee are shown by selecting Instance of from the popup menu Attributes of an object can be shown by selecting Outgoing attributes from the menu The next submenu will show all attribute classes that apply for the current object In our example Employee is an instance of Class There fore it has the attribute classes constraint rule and mrule see figure 8 18 The attribute class Attribute applies to all objects as in Telos any kind of object can have an attribute Furthermore all attributes of an object are member of the attribute class Att ribute As we want to see all attributes we select this attribute class and select Show all from the next submenu All attributes and their values will be shown in CBGraph g localhost4001 PRIIP PPPRP PRIPP PIR RPPN AA PPPRP PRRP PRSA PNRP RANA AA RP LA ALL SALLE DLA EYED RAR RARA AAA PEAS ALLIED A
53. applied to objects in the graphical view that have been selected Change graphical palette The current graphical palette assignment of graphical types to nodes and links is replaced by another one 115 Change module Change the database module for the currently active internal window Querystring Well_off Manager v New query Show Objects I Cancel Figure 8 9 Query dialog 8 2 7 Tool bar The tool bar see figure 8 10 consists of a set of buttons that are mainly short cuts for some menu items The right half of the tool bar provides buttons for the creation of Telos objects Open new frame Hide selected NA without connection obj snow a i Create objects Commit P N f Y UB ME cea al i Fi Load amp Save graph doen Show links Show added connection between objects removed objects Figure 8 10 Tool Bar of CBGraph Open a new frame without connection Opens a new internal window without a connection to a server Within this internal window you can create new Telos objects load existing layouts and save new layouts Information about the graphical types is loaded from an XML file included in the JAR file S CB_HOME 1ib classes cb jar Load graph see File Menu gt Load Save graph see File Menu gt Save Hide selected objects Hides the selected objects from the current view This operation has no effect on the current database i e the objects will be not
54. as sub module of the module that contains the ERD semantics and university data as sub module of the university module A way out of this dilemma is to use the module feature of ConceptBase in a thoughtful way In this case define a module like ERnotation to which the ERD notation is told Within this module define a submodule like UMode1 to which the example ER model is told Finally define a submodule UData to hold the sample data By nesting the submodules in this way the sample data objects can see the definitions of the example ER model And the example ER model can see the objects of the ER notation 5 8 Saving and loading module sources The ConceptBase server see section 6 has two command line options save and load to synchronize with the content of database modules as Telos sources files in the file system of the CBserver The purpose of this feature is to allow an easy way to save reload the complete content of a database using a readable source format These sources can be modified with a regular text editor The source files generated by the save function include a set module directive that instructs the CBserver to load the file to the original module path when the load function is invoked or when the file is loaded manually via the load model function of CBlIva see section 8 The file names of the saved loaded module sources consist of a module path starting with the root module name System fol lowed by the f
55. at tributes of them will be ignored Those classes are Boolean Integer Real String TransactionTime MSFOLassertion MSFOLrule MSFOLconstraint metaMSF OLconstraint metaMSFOLrule BDMConstraintCheck BDMRuleCheck LTrule Evaluator ExternalReference QueryClass BuiltinQueryClass AnswerRepresentation GraphicalType X11_Color ATK_TextAlign ATK_Fonts ATK_LineCap ATK_ShapeStyle The justification is twofold Some of these generated formulas e g a formula beginning with S forall x l are regarded as redundant because the object as instance of Integer should have no instances Another justification is that the use of meta formulas should be restricted to user defined modeling tasks Manipulation of the most system classes is disabled for reasons of efficiency and safety In the case of deductive rules additional problems arise similar to the straticfication problem At the moment only monotonous transactions are allowed This means that generated formulas can only be inserted or deleted during one transaction both operations at the same time are not permitted The meta formula mechanism also influences the efficiency of the system every transaction has to be supervised wether it affects the meta formulas or one of the generated formulas If the preconditions of the generated formulas don t hold anymore e g if the instances of EntityType eAtt r are no longer instances of Proposition necessary in the previous model the correspondin
56. by ConceptBase to parse the arguments of the Foreach construct and similar answer formatting expressions They are not printed to the answer stream 3 2 4 Special characters If one wants a comma inside an expresssion that shall be visible in the answer then one has to escape it The same holds for the other special characters like etc Here is a short list of supported special characters Some require a double backslash Mn new line ASCII character 10 t tab character Mb backspace character 0 empty string no character left parenthesis right parenthesis Xy comma In principal any non alphanumerical character like Y F can be referred to by the back slash operator Note that the vanilla versions of these characters are used to denote expressions in answer formats Hence we need to escape them by the backslash if they shall appear in the answer 3 2 5 Function patterns The substitution mechanism for answer formats recognizes patterns such as F exprl expr2 as function calls An example is the ASKquery construct from from section 3 2 6 The mechanism is however very general and can be used to realize almost arbitrary substititions The parentheses and the commas separating the arguments of F are parsed by ConceptBase and not placed on the output The following simple function patterns are pre defined e OT expr puts the expr into dou
57. classes The idea is to com bine them like nested functional expressions e g f g x h y The problem is however that queries stand for predicates and nested query calls are thus formally higher order logic predicates occur as arguments of other predicates and consequently outside Datalog Still the feature is so useful that we provide it A nested query call is like an ordinary parameterized query call except that the parameters can themselves be query calls For example COUNT What_SI_ Manager 10000 salary class counts the in stances of the parameterized query call What_SI_Manager 10000 salary Syntactically query calls can be arbitrarily deep e g Union Intersec EmpMinSal 800 minsal X EmpMaxSal 1400 maxsal Y X Manager Y ConceptBase does perform the usual type check on the parameters by analyzing the instantiation of the core class of a query call For example the core class of EmpMinSal 800 minsal is EmpMinSal Thus ConceptBase will check whether EmpMinSal is an instance of the class expected for the parameter X Nested query calls are mostly used in combination with functional expressions i e nested query calls where queries are functions see section 2 5 A function in ConceptBase is a query class that has at most one answer object for any combination of input parameters Of particular interest for nested query calls are functions that do not operate on values suchs as integers but rather on classes such as the cl
58. compilation of logical expressions in particular for generating triggers that only evaluate the affected logical expressions when an update occurs The remaining axioms 18 28 are also specific to O Telos They define the five predefined objects in O Telos Axiom 29 takes care that objects cannot refer via its source destination parts to objects that were defined later than the object itself This virtually forbids to define an link between two objects when one of the objects is not yet defined Stanley and Greenspan axioms 2 3 4 10 12 13 14 Axiom 1 is probably also in an earlier Telos 141 While this sounds natural we need to posutlate it Otherwise we can t guarantee that we can refer to any object by a name Axioms 30 and 31 are used to transfer instantiation and attribution facts from the extensional databases to the intensional database They have more a technical purpose in the mapping of logical expressions to Datalog While O Telos has just five predefined objects and 31 predefined axioms the ConceptBase system has many more pre defined objects to provide a better modeling experience and for representing concepts like query classes active rules functions etc They are in a way also predefined but are less essential in understanding the foundations So O Telos is the foundation of ConceptBase but ConceptBase has more pre defined constructs than those mentioned in the axioms of O Telos ConceptBase allows to add user defined rule
59. deleted from the database Open connection Opens a new internal window with a new connection to a server See File menu gt Connect to server Show object This operation adds an object defined in the database to the graph You will be prompted to enter the object name of the object you want to add to the graph Show links between marked objects This operation will search for relationships between the selected objects Do not select too many objects for this operation n queries have to be evaluated for n objects Creation of objects The following four buttons open the Create Object dialog to create new individual objects attributes instantiations and specializations See section 8 2 9 for more details 116 Show added removed objects Shows the objects that have been added or removed since the last commit or since the window has been opened Here you can also select objects to undo the change i e remove added objects or re insert removed objects Commit Sends the changes to the server The list of objects to be added or removed is transformed into a set of Telos frames and transferred to the server 8 2 8 Popup menu The popup menu is activated by a click on the right mouse while the cursor is located over an object e Toggle component view switches the view of this object In the detailed component view you can either see the frame of this object or tree like representation of super and subclasses instances cla
60. ee EA ees AMBAS oye eee Bete Se eG es Ot tee we eet Se eee Popup MGM ss fa eset Yee be oe ee oh Ge eres de Editing of Telos objects lt oc oca ee be EAE ewe ESE ERS Caching of query results within CBGraph o Graph TES sos a AG a a a ee OR ee Re ele ode Y An example session with ConcepiBase 2 o occ s OD a 8 3 1 8 3 2 33 8 3 4 S20 Starting Concept Bast e soe ee eh a ee ee ee ee Connecting CBlIva to the CBserver Loading objects fram extemal ES cos cc cenere nt ee RS Displaying Objects cierne es RHR SEO De eH ee EE a a Browsing ODIER jcc eb de eRe ee ee be ee Ss 84 84 87 88 88 89 90 90 91 93 94 94 94 95 97 97 98 99 99 100 8 3 6 Editing Tel s objects o e essare a a ERA a e e So Using ihe query Tac lt lt ocio ew ee bead A BA WEBS as applet nc cue ee YAS Bla BE RR SAS oY eA Se EE Bee So Lonnie 2g ae eae PR eee ORES Se Cae Gees BBE eS Syntax Specifications A l Syntax specifications for Telos frames o e e A 2 Syntax of the rule and constraint language AA Syma olgers casa a A a AS AA Terminal symbols lt s ses hw hee A eee ee A 5 Syntax specifications for SML fragmentS e O Telos Axioms Graphical Types Cl The grapbical type model sco elk de BS Bed a A Se y 2 The standard praphical types s c e eses a a ee da ei 2 1 The extended praphicaliypemod
61. feel is enabled CBGraph is not yet compatible with all Java look and feels We thus recommend to stick to the default Metal look and feel Enable Click Actions Click actions automatically trigger an active rule see section 4 when nodes with a certain graph type are pressed see section C 3 2 You can enable and disable this feature If you want to move nodes inside a graph that has nodes with click actions then you may want to disable click actions until you have fnished the re arrangement of nodes If an object is displayed in component view one can switch back to the node view by double clicking its title section 114 CBGraph File Edit Options View Current connection OWED cee bol ae A e E DefaultjavaPalette oHome localhost4001 Individual Class c super classes E sub classes 9 E only explicit D QueryClass re QueryClass in Class isA Class with gt Hall attribute C instance of retrieved_attribute Proposition f lt a computed_attribute Proposition instances constraint MSFOLquery J outgoing attributes 4 lend Individual QueryClass Connected with localhost Figure 8 8 Component view of Telos objects tree and frame View menu CBGraph has an experimental layout algorithm that may be useful to reorganize the layout of a complex graph The heuristic of the layout algorithm is rather simple and does not minimize link crossings Enable auto
62. graphical palette is used to combine the set of graphical types that together form a notation Individual GraphicalPalette in Class with attribute contains GraphicalType default GraphicalType end 143 In such a setting the same object may participate in different perspectives ConceptBase offers the possibility to specify multiple graphical types for the same object A tool can then provide different graph ical views on the same object To get the desired graphical type of an object under a specific palette an application program specifies the name of the actual graphical palette as answer format when querying the ConceptBase server Although this mechanism is available for arbitrary application programs we restrict our description to the CBGraph Editor The default specification serves as a catch all an answer object for which none of the graphical types of the current palette is specified is presented using the default graphical type of that palette C 2 The standard graphical types CBGraph is implemented using the Java Programming Language It is entirely based on the Swing toolkit package javax swing The graphical objects shown in CBGraph are all instances of the class JComponent in the javax swing package User defined representations of objects can be provided by overwriting a specific class of CBGraph details are given below C 2 1 The extended graphical type model Based on our experience with a legacy graph browser fo
63. graphical types can be found in Appendix C An example for the definition of graphical types of the Entity Relationship model is given in Appendix D 2 8 2 1 Overview The CBGraph Editor is entirely written in Java It can therefore be used on any platform with Java 1 4 or compatible successors of Java 1 4 The use as applet is also possible wrt to the usual security restrictions of applets CBGraph is integrated with CBlva i e Telos frames of objects shown in CBGraph can be loaded directly into a Telos editor and vice versa CBGraph allows to open several internal windows in its main window Each internal window has a separate connection to a CBserver Thus within a CBGraph you can establish multiple connections to the same CBserver or even to different servers The communication with the CBserver is done using pre defined ConceptBase cc queries and a special XML based answer format CBGraph requests information about the objects names attributes etc but also about their graphical type Figure 8 7 gives an overview of the CBGraph Editor Three internal windows have been opened the two windows on the left have been connected with the same server running on localhost port 4001 The small window in the upper right corner is not connected to a server but a few objects have been created The title of the internal windows displays the graphical palette and the current module if connected to a ConceptBase server plus the connection sta
64. modules without requiring the user to employ the select module function from CBlva Let s set the module context to Master and then TELL the following frame Employee with attribute name String end The object Employee is now only visible in the module Master When you set the module context to Work or System and try to load the Employee object you should get an error message from the server stating that the object Employee is not visible in that module context 73 5 3 Using nested modules A nested module is a module defined in the context of a father module and therefore can only be seen in the context of the father After the definition of the Master and Work modules as nested modules to the oHome module let s define a nested module to the Work module We assume that the current module context is set to the Work module Now tell the following frame Test in Module end As a result we have defined the nesting hierarchy depicted in Figure 5 2 System oHome Master Work Test Figure 5 2 A simple nesting hierarchy of modules A nested module can see the content of all its fathers Therefore when you set the module context to Test you can reference all objects contained in the modules Test Work oHome and System When you set the module context to Work you can reference all objects contained in Work oHome and System
65. objects 6 4 Tracing and restarting The trace of the CBserver can be saved by redirecting its output e g cbserver r 10 port 4444 t high d MYDB gt gt mylogfile log 88 The CBserver can also be started directly from the ConceptBase cc User Interface see section 8 and most parameters can be specified interactively The command line version is recommended when one CBserver serves multiple users or when user interface and server shall run on different machines The parameter r 10 instructs the CBserver to restart after 10 seconds if a crash has occurred A special error message during the startup of the CBserver is the following FATAL ERROR Application is locked by hostname PID 1234 CBserver aborted This messsage is printed if there is still a file with the name OB lock in the database directory option d The OB lock file should avoid that two servers are using the same database directory The file may be left over of a previous CBserver if the server was not stopped correctly e g aborted by Ctrl C or it crashed If you get this error message make sure that there is no other server running that uses this directory and then delete the file OB lock Then the CBserver should start correctly 6 5 Public CBservers A public CBserver is a ConceptBase server that is accessible from the whole network As such this is a property that any CBserver has except when the multi user capability is disabled or when yo
66. on Very Large Data Bases October 1 3 1980 Montreal Quebec Canada Nissen H W Jeusfeld M A Jarke M Zemanek G V Huber H Managing Multiple Re quirements Perspectives with Metamodels IEEE Software pages 37 48 March 1996 Quix C Sichtenwartung und Anderungsnotifikation fiir Anwendungsprogramme in deduk tiven Objektbanken Diploma Thesis RWTH Aachen 1996 Quix C Schoop M Jeusfeld M A Business Data Management for Business to Business Electronic Commerce SIGMOD Record Vol 31 No 1 pp 49 54 March 2002 Ramesh B Dhar V Process knowledge based group support for requirements engineering Journal Intelligent Information Systems Vol 1 No 1 1992 171 RJG 91 SSW94 SIGA91 StJa96 Soir96 Stan86 Stau90 TKDE90 Wing90 Rose T Jarke M Gocek M Maltzahn C Nissen H A decision based configuration process environment Software Engineering Journal Special Issue on Software Environments and Factories July 1991 K Sagonas T Swift and D S Warren XSB as an e cient deductive database engine Pro ceedings of the ACM SIGMOD International Conference on the Management of Data pages 442 453 Minneapolis Minnesota May 1994 Rich C ed Special Issue on Implemented Knowledge Representation and Reasoning Systems SIGART Bulletin Vol 2 No 3 June 1991 Staudt M Jarke M Incremental Maintenance of Externally Materialized Views In Proc of th
67. on a different machine that the user clients The r option must be handled with great care since it can easily lead to an infinite loop of restarts e g when a database file is corrupted In such cases you might have to reboot the whole computer The r option is not available under Windows s securitylevel configures the access control mechanism of ConceptBase The value 0 means that no access control is employed Any user can ask tell untell retell any object in any module You can also untell objects defined in a super module Level 1 default provides a very basic protection one can only untell objects when the are defined in the current module This prevents in particular undesired deletions of objects defined in the System module Level 2 fully enables access control First untelling of objects must happen in the module where the object has been defined Second any transaction submitted by a user to the CBserver is checked against the permission rules as defined in section 5 6 Enable access control when you use ConceptBase in a multi user setting and you want to avoid errorneous interferences between different users 85 e maxerrors sets the maximum number of errors to be displayed to a ConceptBase cc client within one transaction The value 1 means that no restriction is applied Set to 0 to surpress any errors message and to a positive number to limit the displayed errors messages to that number A low positive number can speed up t
68. op CB_Operation end A user is allowed to perform the operation op on the resource res iff the constraint of the query is satisfied Then user is returned as answer of the query If not the answer is nil equals empty set Some fundamental definitions are pre defined objects of ConceptBase Resource with end Module isA Resource end CB_Operation end CB_ReadOperation isA CB_Operation end CB_WriteOperation isA CB_Operation end TELL in CB_WriteOperation end ASK in CB_ReadOperation end Hence at least two operations TELL and ASK are pre defined symbolizing write and read accesses to a resource Modules are the prime examples of resources to be access protected Currently only access to them is monitored by the CBserver When a user wants to switch to a new module then he must at least have the permission to execute the operation ASK on it i e read permission Otherwise the module switch is rejected This check is the main protection scheme offered to module owners Define the query class CB_Permitted in the module that needs protection Assume that there is a user jonny who wants to protect his module Mjonny To do so he would first define the module and set the module context to Mjonny Mjonny in Module end Then he would set the module context to Mjonny define his rights management policy for example CB_Group with attribute groupMember CB_User 77 permitted_read Resource permitted_write Resource owner
69. plugs 2 emoa Se hs BH ee a oe RES a 133 133 134 136 137 138 140 143 143 144 144 145 146 147 148 149 150 152 154 154 154 154 156 161 163 163 163 163 164 164 164 164 165 165 166 Chapter 1 Introduction ConceptBase cc is a deductive object base management system for meta databases Its data model is a conceptual modeling language making it particularily well suited for design and modeling applications Its underlying data model allows to uniformly represent data classes meta classes meta meta classes etc yielding a powerful meta CASE environment The system has been used in projects ranging from development support for data intensive applications JMSV90 JJQV99 JQC 00 requirements engineer ing RaDh92 Eber97 NJJ 96 electronic commerce QSJO2 and version amp configuration management RJG 91 to co authoring of technical documents HJEK90 The key features distinguishing ConceptBase cc from other extended DBMS and meta modeling sys tems are e Unlimited meta class hierarchy allowing to represent information at any abstraction level data class meta class meta meta class Uniform data structure called P fact for concepts their attributes their class memberships and their super and sub concepts all four types of information are full fledged objects e Clean formal integration of deductive and object oriented abstraction by Datalog logical theories e Complex computations can
70. querying past database states These principles are combined orthogonally e g deductive rules can be restricted to modules formulated for meta classes employed in active rules using functional definitions to compute properties and be revised without overwriting the earlier definitions The Java based user interface offers an extensible palette of graphical tabular and textual user interfaces The communication between the user clients and the object base is organized in a client server architecture using TCP IP Further clients can be connected by an API documented in the ConceptBase programmers manual Contributions to this manual were made by Lutz Bauer Rainer Gallersd rfer Michael Gebhardt Matthias Jarke Manfred Jeusfeld Thomas List Hans Nissen Christoph Quix Ren Soiron and Martin Staudt Contributions to the source code of ConceptBase were made by Masoud Asady Lutz Bauer mod ule system Markus Baumeister Ulrich Bonn Stefan Eherer Rainer Gallersd rfer object store Michael Gebhardt Dagmar Genenger Michael Gocek Rainer Hermanns Manfred Jeusfeld CB server logic foun dation function component David Kensche Andr Klemann Eva Kriiger integrity component Rainer Langohr Farshad Lashgari Tobias Latzke Xiang Li Yong Li Thomas List object store Andreas Mi ethsam Hans Nissen module system Martin P schmann Christoph Quix CB server view component Christoph Radig object base interface Achim Schloss
71. specific graphical type is defined as an instance of the object GraphicalType CBGraph uses the subclass JavaGraphicalType Instances of this class specify a graphical represenation of an object by defining graphical attributes such as shape color line thickness font etc Since the actual attributes and their admissible value depend on the used visualization tool the definition of GraphicalType looks very simple GraphicalType in Class end The declaration of a graphical type for a concrete object is done by using the attribute grapht ype which is defined for Proposition and therefore available for all objects Proposition with attribute graphtype GraphicalType end The attribute can be defined explicitely for an object or can be specified by using a deductive rule see section C 2 for an example One can attach a priority value to each graphical type If there multiple graphtype attributes defined for one object the graphical type with the highest priority value will be used by CBGraph Many applications employ multiple notations to provide different perspectives on the same set of ob jects Each perspective emphasizes on a specific aspect of the world such as the data oriented the process oriented and the behavior oriented viewpoint and uses an aspect specific notation A graphical notation as e g the Entity Relationship diagram typically consists of a set of different graphical symbols as e g diamonds rectangles and lines A
72. subse quently When terminating CBGraph it shall disconnect from the CBserver which then exits automatically 6 2 Database format A ConceptBase database is a directory that contains at least the following files e OB symbol a binary file that associates object names like MyClass with object identifiers 87 e OB telos binary file storing all propositions e OB rule text file containing the generated Prolog code for rules constraints and queries e OB ruleinfo text file containing argument information about queries and some formation for the cost based formula optimizer e OB ecarule text file containing the generated Prolog code for active rules The database files may only be updated via the ConceptBase server Their initial state is bootstrapped from textual Telos frames that define the pre defined objects of O Telos Since the pre defined objects can change from version to version we cannot guarantee binary compatibility of ConceptBase databases You can easily export the textual definitions from a databases via the save option Those definitions can then be imported to the new ConceptBase version The database directory may contain further text files with filetype Ipi These are Prolog plugins loaded at startup time see also section F 6 3 Modifying the system database A new database is created from the database lib SystemDB in your ConceptBase installation directory The System database contains exactly the object
73. switch to the module Mjonny If a second user like mary was to be granted read permission jonny would define within module Mjonny mary in CB_User with permitted_read rl Mjonny end In the above example rights can also be granted to groups of users and then inherited to its members via rules rr 4 to rr6 It should be noted that the definitions of owner_resource permitted_read and permitted_write are just for illustrating what is possible ConceptBase only requires the query class CB_Permitted in the module where the access rights need to be enforced If such a query class or a local version as explained below is not defined then any access is permitted for any user When a user attempts to switch to new module context ConceptBase checks whether the user has at least read permission i e permission for executing the operation ASK on the module If permission is not granted the user cannot switch the module context and an error message is presented The definition of the query CB_ Permitted is visible in the module where it is defined and in all sub modules of this module One can also define a local version of the query by appending the module name to its name e g CB_PermittedMjonny This version is only tested for access to the module Mjonny The local overrides the general version CB Permitted and its function is not inherited to sub modules The subsequent definition prevents updates to the Test module if it is visible in the Test modul
74. that are frequently used and are also available in the menu The operations apply to the Telos Editor which has currently the focus e Quick Connect if connected to a CBserver then disconnect otherwise try to connect either to the public CBserver if configured or to a running local CBserver if the connection to a running local CBserver fails then attempt to start one in the background e Clear e Cut Copy Paste e Tell Untell The objects specified in the active Telos Editor will be added or removed from the object base e Retell A new window will popup and ask you to enter the frames that should be untold and told The contents of the current Telos Editor will be inserted as default into the two text areas e Ask Evaluate the query specified in the Telos Editor gt If you specify the name of an ordinary class i e not a query class then ConceptBase cc will interpret this as a query call to find all instances of that class You can also enter an arithmetic expression like 100x COUNT QueryClass COUNT Class e List module List the content of the current module as Telos frames e Exit The preferred way to start a CBserver from CBlva is to use the Start CBserver from the File menu It provides an output window for the trace messages of the CBserver but this window is only visible if the trace mode is set to minimal or higher Disconnecting from the CBserver will not stop it It has to be stopped explictly or CBlIva
75. the database in particular module listings The parameter has the default value none which disables the saving function Currently the CBserver only saves module listings Each module is stored in one file with file type sml The directory dir must exist The module listing is performed when the CBserver is shut down complete module tree is listed or when a client tool logs out home directory tree of the client tool is listed The module listings uses the set module directive to enable the import of the file to the right module location See also section 5 8 for details views dir specifies the directory into which the results of certain queries are materialized See section 5 9 for details rl rlmode controls the way how the CBserver creates labels for generated formulas The default value is on instructing the CBserver to find a readable label for the generated formula It typically consists of the labels of the participating metaclass attributes occuring in the metaformula If set to of f the CBserver will just take a system generated label that contains a unique identifier This is slightly less readable if you want to inspect the generated formulas but safe against certain possibilities of assigning the same label twice sm servermode sets the server mode Possible values are master default and slave In slave mode the last client that leaves the CBserver will also shutdown the CBserver provided that the CBserver and the client
76. the usual notation for function expressions The last query class is thus equivalent to QueryClass EmployeeWithMoreRichCoworkersThanWilli isA Employee with constraint c2 COUNT RichCoworker this gt COUNT RichCoworker Willi end Since the COUNT function is frequently used ConceptBase provides the shortcut c for COUNT c Consequently the shortest form of the above query would be QueryClass EmployeeWithMoreRichCoworkersThanWilli isA Employee with constraint c2 RichCoworker this gt RichCoworker Willi end The shortcut is also applicable to the Union example above The expression below computes the numbers of instances of the set expression Union Intersec EmpMinSal 800 EmpMaxSal 1400 Manager The definitions for Union and Intersec can be found in the ConceptBase Forum at http merkur informatik rwth aachen de pub bscw cgi 896920 Besides COUNT ConceptBase supports aggregation function for finding the minimum maximum and average of a set Aggregation functions are not limitered to numerical domains For example one can define a function that returns an arbitrary instance of a class selectrnd in Function isA Proposition with parameter class Proposition end The membership constraint has to be provided as so called CBserver plug in see chapter F A call selectrnd RichCoworker Willi worker would then return an arbitrary instance of RichCoworker Willi worker
77. untell all instantiations to 1t Use the CBserver option s 1 to prevent such undesired deletions 6 9 Memory consumption and performance ConceptBase cc stores objects in a dedicated object store maintained in main memory A P fact P o x n y consumes about 800 bytes of main memory That means that one can store roughly 1 million P facts in 1 GB of main memory A typical Telos frame is stored with roughly 10 P facts Hence 1 GB of main memory allows you to store around 100 000 Telos frames On 32 bit CPUs this results in a maximum of roughly 400 000 frames that can fit into 4 GB of addressable main memory This restriction virtually vanishes with 64 bit CPUs A single TELL UNTELL operation submitted to the CBserver should not contain more than about 2000 frames at about 5 attributes per frame Otherwise the compiler can run out of stack memory The raw performance of the object store i e the time needed to reconstruct a frame for a given object identifier is virtually independent from the number of P facts that it stores However if you have defined many rules or integrity constraints the performance may well degrade significantly with the number of stored P facts The same holds for queries We tested the response times for standard queries such as computing the transitive closure in relation to varying database sizes Results indicate that ConceptBase apparently approximates in many cases the theoretic optimum The performance of the ac
78. usually told together with the employee In contrast the IF part of the second tule is checked against the old database state i e where the employee was still defined The third rule checks if the employee is an instance of the view class when the attribute salary was inserted Again the fourth rule does the same for deletion of the attribute If the number of employees is large it is more efficient to ask for the instances of materialized than to evaluate the view However if updates occur quite often materialization is not good because materialized view must be maintained for every update transaction 4 2 2 Counter This example shows how to call prolog predicates with an ECArule It implements a counter for a class Employee The counter is stored as an instance of the object EmployeeCounter Whenever an employee is inserted or deleted from the object base the counter is incremented or decremented Class Employee end EmployeeCounter end ECArule EmployeeCounterRule with ecarule er x Employee i il Integer ON Tell In x Employee IF i in EmployeeCounter DO Untell In i EmployeeCounter Call increment i il Tell In i1 EmployeeCounter 67 ELSE Tell In 1 EmployeeCounter end ECArule EmployeeCounterRule_del with ecarule er x Employee i il Integer ON Untell In x Employee IF i in EmployeeCounter DO Untell In i EmployeeCounter Call
79. version V5 2 4 ConceptBase cc features a new query evaluation method which uses a so called tabling cache to store intermediate results of predicates that are called during the top down SLDNF query evaluation Assume for example that an employee bill has two projects p1 and p2 Then the result of a predicate bill hasProject x with variable x would be the set bill hasProject p1 bill hasProject p2 consisting of facts We call this fact set also the extension of the predicate After a completed predicate evaluation the tabling cache of the predicate holds its extension Tabling speeds up query evaluation and prevents infinite loops when ConceptBase cc evaluates recursive queries and deductive rules Essentially the tabled evaluation allows to compute dynamically stratified semantics of the Datalog database underlying ConceptBase cc Plenty of examples for recursive rules and queries are provided in the online ConceptBase Forum The CBserver provides three tabling cache modes to control the behavior during query evaluation c off In this mode the cache is completely disabled Use this mode when your models do not include recursive rules The mode is only provided for backward compatibility and has no advantages c keep The cache is only emptied when necessary i e when the cache has been invalidated by an update to the database or when the maximum number of facts in the cache is exceeded The maximum number is cur
80. we will explain more details about answer formats using the following example An answer object A to a query class QC has by default a frame structure A in QC with catl labelll v11 label12 v12 cat2 label21 v21 Piga end In case of a complex view definition VC the values vij can be answer objects themselves e g B in VC with catl label11 v11 label12 v12 cat2 label21 v21 with cat21 label211 v211 ET end ss end 3 2 Constructs in answer formats 3 2 1 Simple expressions in patterns We first concentrate on the pattern attribute i e they are not applicable in the head or tail attribute of an answer format The pattern of an answer format is applied to each answer object of a given query call effectively transforming it according to the pattern The following expressions are allowed Capital letters in the list below indicate that the term is a placeholder for some label occuring in the query definition or the answer objects 52 this denotes the object name of an answer object e g A The syntax for object names is defined in section 2 1 In particular attribution objects have names like mary earns this ATTRIBUTE_CAT denotes the value s of the attribute ATTRIBUTE_CAT of the current answer object this The attribute must be defined in the query class retrieved_attribute computed _attribute or view inherited_attribute Note that some att
81. whether ob jname exists but there is a builtin query exists which does the same The query is mainly useful in combination with a user defined answer format e g the Graph Editor is using this query to retrieve the graphical representation of the object AvailableVersions Lists the instances of Version with the time since when they are know This query is used by the user interface to use a different rollback time Options gt Select Version listModule Lists the the content of a module as Telos frames see also section 5 7 E 2 Functions Functions may also be used within other queries You may define your own functions see section 2 5 164 E 2 1 Computation and counting COUNT counts the instances of a class this may be also a query class SUM computes the sum of the instances of a class must be reals or integers AVG computes the average of the instances of a class must be reals or integers MAX gives the maximum of the instances of a class wrt the order of lt and gt see section 2 2 MIN gives the minimum of the instances of a class wrt the order of lt and gt see section 2 2 COUNT Attribute counts the attributes in the specified category of an object SUM _ Attribute computes the sum of the attributes in the specified category of an object must be reals or integers AVG Attribute computes the average of the attributes in the specified category of an object must be reals or integers MAX Attribut
82. will stop it if it is shut down itself The Quick Connect button of the toolbar provides a simplified way to start a local CBserver It does not ask for CBserver parameters Instead the default values are used for all parameters except that the server mode is set to slave and multi user mode is disabled This causes the CBserver to shutdown whenever the last connected client disconnects from it You can move the tool bar outside the main window or display it in vertical form if you click on the leftmost area of the tool bar and drag it to another place 5The query can either be a query call referring to an existing query or a frame representing a new or existing query definition 104 8 1 3 The status bar The status bar contains some fields that display general information about the status of the application e Connection status either connected or disconnected from server e Short message usually the result of the last action e Current version i e the rollback time see section 2 1 specified for queries default Now e Current module the database module to which TELL ASK operations are applied The field for the current version shall display the current time if the version is set to Now If set toa rollback time in the past it displays both the version name and the time associated to the version It will then also hight the background of the text field to make the user aware that queries are evaluated against a past
83. y Employee es Employee salary ON Tell es in Employee salary IFNEW From es y and y in EmpWithoutLastModified and Known es t DO Tell y lastModified t end ECArule LastModified_change with mode m ImmediateDeferred ecarule er t1 t2 TransactionTime y Employee i Integer es Employee salary lab Label ON Tell es in Employee salary IFNEW From es y and y lastModified t1 and Known es t2 DO Untell y lastModified t1 Tell y lastModified t2 end Both ECArules are evaluated against the new database state The first ECArule is for the case where the object y has not yet a lastModified attribute Then it has to be initialized The second rule takes care for the updating case Note that the transaction time is represented as string of the form tt year month day hour minute sec millisec A deprecated solution is available from http merkur informatik rwth aachen de pub bscw cgi d2936786 ECA lastmodified sml txt It uses the Ask action in the DO and ELSE parts to query perform different actions depending on whether an object already has a filler for the attribute lastModi fied 4 2 4 Simulation of Petri Nets ECArules are a powerful tool to express semantics of concepts that are not expressible by deductive rules For example the semantics of petri nets in particular the firing of an enabled transition can be expressed by a single ECArule ECArule UpdateConnecte
84. 1 fib n 2 gt fib this ConceptBase employs a bottom up query evaluator to evaluate the recursive function Thus the result of a function call fib n shall only be computed once and then re used in subsequent calls If the recursion is not inside a single function definition but rather a property of a set of function query definitions then you must use so called forward declarations They declare the signature of a func tion query before it is actually defined A good example is the computation of the length of the shortest path between two nodes spSet in GenericQueryClass isA Integer with parameter x Node y Node end sp in Function isA Integer with parameter x Node y Node constraint csp x y and this 0 or x nexttrans y and this MIN spSet x y 1 end spSet in GenericQueryClass isA Integer with 45 parameter x Node y Node constraint csps exists xl Node x next xl and this sp xl y end Here the query class spSet computes the set of length of shortest path between the successors of a node x and a node y The length of the shortest path is then simply 0 if x y or the minimum of the spSet x y plus if there is a path from x to y and undefined else The signature of spSet must be known for compiling sp and vice versa ConceptBase has a single pass compiler Hence it requires the forward declaration The query spSet is not a function because it returns in general several numbers The co
85. 106 CBiva ConceptBase cc User Interface in Java ca als File Edit Browse Options History Windows Help 20428 BRAAF a Display Queries j DoNotSave_LM changeAttributeValue listModule Answer Format ask cance Telos Editor Cancel omea Preprocessing Telos object names Version Now Module oHome 11 56 UTC 0 08 Figure 8 4 Display queries dialog parameter or as a specialization of the parameter class see section 2 3 You can select a value for the parameter from the drop down list if you have clicked on the Show Values button Note that this list might be very long Especially for the predefined queries it usually returns all objects in the database as any object can be used as a parameter for these queries 8 1 9 Display functions This dialog is similar to the previous dialog but displays instances of Function Note that functions are formally special queries Consequently the dialogs for functions and queries are pretty much the same The separation into two dialogs serves quicker handling 8 1 10 Query editor The Query Editor see figure 8 5 allows the interactive definition of queries The name of the query is entered in the upper left text field the super class in the upper right field After you have entered this information the list box Retrieved Attributes will be filled with all available att
86. 140 Axiom 15 Subclasses which define attributes with the same name as attributes of their superclasses must refine these attributes YV c d a1 a2 M f Isa d c A P a1 c m e A P a2 d m f Isa f e A Isa a2 a1 Axiom 16 If an attribute is a refinement subclass of another attribute then it must also refine the source and destination components V c d a1 a2 M1 M2 6 f Isa az a1 A P a1 c m1 e A Plaz d ma f gt Isa d c A Isa f e Axiom 17 For any object there is always a unique smallest attribute class with a given label m V T M Y C d Q1 Q2 f Un z c A In x d A P ax C M e A P az d m f 39 43 h In x g A Pas g m h A Isa g c A Isa g d Axioms 18 22 Membership to the builtin classes is determined by the object s format Yo 2 l y P o x 1 y In o Obj Vo l Plo o l 0 A l in A L isa In o Indiv Vo x c P o 2 in c 04 x A o 4c gt In o Inst Vo c d Plo c isa d A 0 4c A 0 4 d amp In o Spec VYo az l y Plo 2 l y 042 A oA y A LF in A l isa gt In o Attr Axiom 23 Any object falls into one of the four builtin classes V o In o Obj In o Indiv V In o Inst V In o Spec V In o Attr Axioms 24 28 There are five builtin classes P 0bj 0bj Proposition Ob7 P Indiv Indiv Individual Indiv P Attr Obj attribute 4 0b5 P Inst 0bj InstanceOf 0b P Spec 0bj ISA 0bj EE S
87. BIva and CBGraph see section 8 The distribution also contains a client CBShell that can be used to interact with a ConceptBase cc server using a command shell window The CBShell client can also be used to run non interactive scripts e g for loading a sequence of files with Telos source models into the CBserver Access to a CBserver via a web interface is also supported Required software is made available via the ConceptBase cc Forum 1 4 Overview of this manual This manual provides detailed information about using ConceptBase cc Information about the installation procedure can be found in the Installation Guide in directory doc TechInfo New users are advised to follow the installation guide for getting the system started and then to work through the ConceptBase cc Tutorial More information about the knowledge representation mechanisms the applications and the implementation concepts can be found in the references Chapter 2 describes the ConceptBase cc version of the Telos language and gives some examples for its usage Chapter 6 discusses the parameters that can be set when starting the CBserver Finally section 8 describes the ConceptBase cc Usage Enviroment All trademarks are property of their respective owners 3ConceptBase cc now relies on SWI Prolog ht tp www swi prolog org Formerly ProLog by BIM had been used Appendices contain a formal definition of the Telos syntax and internal data structures A Appendix C summa
88. Base will apply various heuris tics to re order the predicates in the condition This can result in several orders of magnitude better per formance Currently the optimization only applies to conditions that are conjunctions of predicates and whose predicates are all referring to the same database state 4 4 Limitations of the current implementation The current implementation of active rules in ConceptBase has several limitations e The dependency graph of ECA rules may contain cycles i e rule R1 executes an action which fires the rule R2 and R2 has an action which fires R1 The current algorithm for detecting cycles tests the dependency graph during compile time The cycle checker prints a warning message on the console if it has detected a possible cycle but the compilation of the rule is not aborted because it is still 70 possible that the cycle does not occur during the execution of the rule The user must take care that endless loops are avoided The ON part of an ECArule consists of a single atomic event ConceptBase does not support complex events such as event 1 occurs after event 2 Instantiations and specializations of system classes Proposition Attribute InstanceOf are not detected in the event manager Adding those events would affect the performance Like QueryClasses ECArules can not be modified after they have been told e g change the event condition or actions The only updateable attribute of
89. CBShell 59 Chapter 4 Active Rules Active rules specify certain actions that have to be executed if an event occurs and a condition is fulfilled at this time Because active rules consists of an Event a Condition and an Action they are abbreviated as ECArule Events ON part of ECArules are insertions and deletions of objects Tell Untell and queries Ask The events are detected during the processing of the input frames for a Tell or Untell or Ask operation For example if you tell 2 frames at a time and the first frame matches an event for an ECArule then the ECArule is executed before the second frame is processed You can also control the sequencing of the firing of ECA rules by the so called ECAmode and by priority orderings in the set of defined ECArules The condition of the ECArule IF part is a logical expression over the database It will bind free variables occurring in the condition if any and these bindings together with the bindings of the event are passed to the action part of the ECArule The action DO part of an ECArule is evaluated for each evaluation of the IF part that has is true in the database The elements in a DO part can be Tell Untell Retell Ask and Call actions Call actions can call any Prolog predicate for example a Prolog predicate defined as a CBserver plug in see appendix F Retell actions are combining an Untell and a Tell in particular for assigning a new attribute value e g Retell e sala
90. CE Same as before but returns TRUE only if obj is an explicit instance of class find_classes Lists all objects of which ob jname is an instance find_instances Lists all instances implicit and explicit of class find_explicit_instances Same as before but only explicit instances are returned E 1 2 Specializations and generalizations ISSUBCLASS Checks whether sub is subclass of super The result is either TRUE or FALSE IS_EXPLICIT_SUBCLASS Same as before but returns TRUE only if sub is an explicit subclass of super find_specializations Lists the subclasses of class If ded is TRUE then the result will also include implicit subclasses if ded is FALSE only explicit information will be included find_specializations Same as before but for super classes 163 E 1 3 Attributes IS_ATTRIBUTE_OF Returns TRUE if src has an attribute of the category att rCat which has the value dst IS_EXPLICIT_ATTRIBUTE_OF Same as before but only for explicit attributes find_all_explicit_attribute_values Lists all attribute values of ob jname that are explicitely defined find_iattributes Lists the attributes that go into class find_referring_objects Lists the objects that have an explicit attribute link to class find_referring_objects2 Lists the objects that have an explicit attribute link to ob jname and for which the attribute link is an instance of cat find_all_referring_objects2 Same as before
91. ConceptBase cc ConceptBase cc User Manual Version 7 8 Manfred A Jeusfeld Christoph Quix Matthias Jarke University of Sk vde 54128 Sk vde Sweden RWTH Aachen Ahornstr 55 52056 Aachen Germany 2015 09 11 Copyright 1987 2015 by The ConceptBase Team All rights reserved See http conceptbase sourceforge net cbteam html for details This report is published by its authors via http conceptbase cc You can use this report for private and academic purposes Unless you are member of the ConceptBase Team you may not alter this report and you may not republish it neither electronically nor as hardcopies Rather point to the original location of this report at http conceptbase sourceforge net CB Resources html Abstract ConceptBase cc in short ConceptBase is a multi user deductive object manager intended for conceptual modeling metamodeling and coordination in design environments The system implements O Telos a dialect of Telos integrating deductive and object oriented paradigms It uniformly represents all information regardless of its abstraction level data class meta class meta meta class etc in a single data structure called P facts The deductive query language is seamlessly integrated into the meta class hierarchy Modeling is supported by meta classing deduction and integrity checking active rule speci fication functional definition of computation a module concept and a rollback mechanism for
92. ConceptBase cc users as unnatural be havior They expect that an UNTELL is also supposed to affect the objects themselves not just their instantiation to classes To support those users we provide a so called untell mode see parameter U in the list of CBserver command line parameters The untell mode is verbatim will cause ConceptBase cc to behave as explained above The mode cleanup default will take care to remove the objects themselves provided that they have no other instantiations to classes except instantiation to the four builtin classes Individual Attribute InstanceOf and IsA Furthermore no other object may be linked to the object subject to be untold 4 Deleted objects can however be recovered by setting the so called roll back time before an ASK transaction is issued Only ASK transaction are allowed on historical database state It makes little sense to update a historical state That would be falsifying the history of stored P facts 92 6 8 1 Cascading UNTELL You can use ECArules to realize a cascading UNTELL i e if an object is deleted then all its links to other objects are deleted as well leading to potential follow up deletions The required ECArules are provided in http merkur informatik rwth aachen de pub bscw cgi 3260276 You only need to add the ECArules to your database to enact the cascading UNTELL You should be careful with using the cascading UNTELL For example untelling a system class will also
93. ECArule is act ive If you set this attribute to FALSE you can deactivate the rule for a certain time Deleting or setting the attribute to TRUE re activates the ECArule If you don t want to use an ECArule anymore you can untell it as a whole The ECArule evaluator is not very efficient Response times may be long in case that an ECArule leads to many updates to the object base ECArules that update the database will temporarily disable the cache based predicate evaluator By this certain recursive deductive rules called in the IF part of ECArules may not terminate if you activate the CBserver parameter unsafe see section 6 The unsafe mode disables checks on the presence of recursion This leads to faster execution time since the safe mode would refresh the predicate cache after each update to the database 71 Chapter 5 The Module System The module concept provides the facility to divide a ConceptBase database into an arbitrary number of autonomous clusters We use the term module for such a cluster A module is autonomous in the sense that the visibility of objects and validity of deductive rules and integrity constraints is limited to the scope of a certain module This implies that for each server operation TELL UNTELL ASK the user has to define a module in whose context he wants the operation to be executed One useful application of modules in ConceptBase are modelling situations where different objects are l
94. EmployeeWithHighSalary contains all employees who earn more than 100 000 The class EmployeeWithHighSalary_Materialized will contain the same employees This imple mented by the following ECArules 66 ECArule EmployeeWithHighSalary_Materialized_Ins with ecarule er x Employee ON Tell x in Employee IF x in EmployeeWithHighSalary DO Tell x in EmployeeWithHighSalary_Materialized end ECArule EmployeeWithHighSalary_Materialized_Del with ecarule er x Employee ON Untell x in Employee IF x in EmployeeWithHighSalary DO Untell x in EmployeeWithHighSalary_Materialized end ECArule EmployeeWithHighSalary_Materialized_Ins_salary with ecarule er x Employee y Integer ON Tell x salary y IF x in EmployeeWithHighSalary DO Tell x in EmployeeWithHighSalary_Materialized end ECArule EmployeeWithHighSalary_Materialized_Del_salary with ecarule er x Employee y Integer ON Untell x salary y IF x in EmployeeWithHighSalary DO Untell x in EmployeeWithHighSalary_Materialized end The first rule checks if the employee belongs to the view when the employee was inserted Note that we don t use the constraint of the view in the ECArules we just reuse the view definition here The second tule does the same for deletion of employees The first rule checks the IF part on the new database state since the employee s salary is
95. F part Originally the predicates in the IF part were not re ordered by ConceptBase to gain a better performance Instead they were executed exactly in the sequence in which they were defined This is still the case when the CBserver parameter eo is set to of f Consider the following example as a variant of UpdateConnectedPlaces discussed in the previ ous subsection ECArule UpdateConnectedPlacesV1 with mode m Deferred ecarule er fire FireTransition t Transition p Place m Integer ON Tell fire transition t IF p in Place and m M p IM p t and t in Enabled and p in ConnectedPlace t DO Retell p marks m end UpdateConnectedPlacesV1 is equivalent to UpdateConnectedPlaces but it results in sig nificantly longer execution times The reason is that the condition of UpdateConnectedPlacesV1 starts with a predicate with an unbound variable p In contrast the condition of UpdateConnected Places starts with a predicate whose variable t is bound by the ON part of the ECArule In cases where the IF part does not contain a mixture of quoted new database state and unquoted old database state one can outsource the condition to a query class The advantage is that the constraint of the query class is automatically optimized by ConceptBase The extended example is in the CB Forum at http merkur informatik rwth aachen de pub bsow cqi 3242537 When the CBserver parameter eo is set to on default then Concept
96. IV f m 3 The whole expression returns a real number 2 5 3 Example function calls and definitions 1 The following three variants all count the number of instances of Class COUNT Class class COUNT Class Class The result is an integer number e g 42 119 The operator is a special shortcut for COUNT 2 The subsequent query sums up the salaries of an Employee SUM_Attribute bi11 ob3jname Employee salary attrcat SUM_Attribute Employee salary bill Note that the parameter label att rcat is sorted before objname for the function shortcut The result is returned as a real number even if the input numbers were integers 2 5001000000000e 04 You can also use functions also in query class to assign a value to a computed _attribute QueryClass EmployeesWithSumSalaries isA Employee with computed_attribute sumsalary Real constraint c sumsalary SUM_Attribute Employee salary this end 3 Complex computations can be made by using multiple functions in a row This query returns the percentage of query classes wrt the total number of classes Function PercentageOfQueryClasses isA Real with constraint c exists i1 i2 Integer r Real 11 COUNT QueryClass class and 12 COUNT Class class and r DIV il r1 i2 r2 and this MULT 100 r1 r r2 end The query can be simplified with the use of function shortcuts to Function PercentageOfQueryClasses isA Re
97. Ipicall picall executes the LPI call only for debugging purposes prolog prologstatement executes the Prolog statement only for debugging purposes getErrorMessages gets error messages for the last transaction and prints them on stdout why synonym for getErrorMessages result completion result compares the given result with the last result which has been received this com mand hence can be used to check whether the CBserver produces the expected completion ok error and result use this command in combination with the option 1 setModule mod changes the module context of this shell if the parameter module is omitted it will set the module to oHome l There is a small syntactic restriction for the retell command You need to avoid a line consisting just of a double quote to terminate the untellFrames Instead start the tellFrames in the same line that terminates the untellFrames 95 Gl cd mod synonym for setModule getModulePath display the current absolute module path e g System oHome MyModule pwd synonym for getModulePath newModule mod creates a new module with the given name within the current module implemented by a tell operation modin Module end listModule mod list all frames defined in a module shortcut for ask listModule mod module uses currentmodule if called without parameter Im mod synonym for listModule listClass class display the instances of class uses Individual as class if called without parameter
98. LLA A EH Employee ary 8 4b rail e Employee m Mana Toggle component view super classes sub classes instance of instances outgoing attributes Attribute gt only explicit incoming attributes constraint gt all Add Instance rule Add Class graphtype gt Add SuperClass Add SubClass Add Attribute Add Individual Delete Object from Database Figure 8 18 The graph after expanding it with the classes and the attributes of the class Employee CBGraph can also show implicit relationships between objects e g relationships deduced by rules or the Telos axioms For example if we select the object John and select Instance of from the popup menu we can display the implicit classes of John by selecting All from the next submenu As John is an instance of Manager and Manager is a subclass of Employee John is also an instance of Employee As there is no explicit object John gt Employee the instantiation link between John and Employee will be represented as an implicit link i e a dashed line see figure 8 19 The same applies also to attribute links For example the employee Herbert has an implicit boss attribute to Phil This can be shown by selecting Outgoing attributes boss All Phil from the popup menu Note that the submenu All for the attribute class Attribute will be always empty as only explicit attributes can be displayed in th
99. Object Specialization ObjName in lObjName isA Class Class Ok Cancel Ok Cancel Figure 8 11 Create Object dialogs for Individuals Attributes Instantiations and Specializations For each object type we provide a dialog to create this object type as shown in figure 8 11 This dialog is opened by clicking on one of the Create buttons in the tool bar or by selecting an Add item from the popup menu e g Add instance or Add subclass If there are some objects selected in the current internal window then the object names of these objects will be inserted into the text fields of the dialog in the order they have been selected i e the first text field will contain the name of the object which has been selected first Furthermore if you move the cursor into a text field in the Create Object dialog and select an object in the graph then the name of this object will be inserted into the text field As changes might lead to a temporary inconsistent state of the database we do not execute the changes directly on the database They are stored in an internal buffer in CBGraph and executed when you hit the Commit button in the tool bar Creating Individuals If you want to create a new individual object you just have to specify the object name You have to enter a valid Telos object name for example it must not contain spaces In addition you can sel
100. S Axiom 29 Objects must be known before they are referenced The operator lt is a predefined total order on the set of identifiers Vo z l y P o x 1 y x lt 0 A y 30 Axioms 30 31 axiom schemas For any object P p c m d in the extensional object base we have two formulas for rewriting the Jn and A predicates The Jn is mapped to a unary predicate where the class name is forming part of the predicate name and the A predicates is mapped to a binary predicate that carries the identifier of the class of the attribute in its predicate name Internally user defined deductive rules that derive Jn and A predicates will also be rewritten accordingly This extends the choices for static stratification V o In o p gt In p o Vo 1 l y P o x l y Aln o p gt A plz y The following axioms are taken from papers on Telos i e formulated by Mylopoulos Borgida Kouba rakis paper though we could not immediately find it there The axioms 15 and 16 are similar to the structural ISA constraint of Taxis MW80 for attributes In O Telos we do however not inherit attributes downward to subclasses but rather constrain refined attributes at subclasses in the sense of co variance Moreover attributes in O Telos are objects as well hence the notion of specialization is more complicated than for the Taxis case Axiom 17 is needed to be able to uniquely match an attribution predicate to a most specific attribute This is utilized in the
101. _resource Resourc end CB_User isA CB_Group end CB_Group in Class with rule rrl forall p Resource u CB_User u owner_resource p gt u permitted_write p rr2 forall p Resource u CB_User u permitted_write p gt u permitted_read p rr3 forall u CB_User u groupMember u rr4 forall u CB_User p Resourc exists g CB_Group g groupMember u and g owner_resource p gt u owner_resource p rr5 forall u CB_User p Resourc exists g CB_Group g groupMember u and g permitted_write p gt u permitted_write p rr6 forall u CB_User p Resourc exists g CB_Group g groupMember u and g permitted_read p gt u permitted_read p end CB_ Permitted in GenericQueryClass isA CB_User with parameter user CB_User res Resource op CB_Operation constraint cperm not exists u CB_User u owner_resource res and not u user or op in CB_ReadOperation and user permitted_read res or op in CB_WriteOperation and user permitted _write res and UNIFIES user this end In the above example access rights are granted to groups of ConceptBase users The owner of a resource will always have full access via rules rr1 and rr2 Then the user would claim ownership to the module via jonny in CB_User with owner_resource rl Mjonny end 78 Then only jonny can
102. a clear semantics and of better capabilities for meta modelling Since we wanted to be able to manage large knowledge bases millions of concepts rather than a few hundred we decided to select a semantics that allowed efficient query evaluation Telos included already features for deductive rules and integrity constraints Thus the natural choice was DATALOG with perfect model semantics The deductive rule evaluator and the integrity checker were ready in 1990 A query language query classes followed shortly later O Telos exhibits an extreme usage of DATALOG e There is only one base relation P o x l y called P facts used for all objects classes meta classes attributes class membership relationships and specialization relationships as well as for deductive rules integrity constraints and queries e The semantics of class membership specialization and attribution is encoded by around 30 axioms which are either deductive rules or integrity constraints e Deductive rules ranging over more than one classification level instances classes meta classes etc are partially evaluated to a collection of rules or constraints ranging over exactly one classification level O Telos should be regarded as the data modeling language of a meta database It is capable to represent semantic features of other data modeling languages like entity relationship diagrams and data flow dia grams Once modeled as meta classes in O Telos one simply h
103. a parameter of the CBserver e g 1A side effect of the server method ENROLL_ME is that the user of the registering client will automatically be defined as an instance of class CB_User The definition is be made in the context of module oHome 76 cbhserver g public new MYNEWDB This will instruct the CBserver to tell oHome in AutoHomeModule end when it sets up the new database See also section 6 5 The home module definitions need to be made within module oHome because they will be evaluated upon client registration server method ENROLL_ME in this module context Please note that the module context is only dependent on the user name not on the client and not on the network location of the user It could well be that a user mary is defined on multiple computers on the network and that different natural persons are identified by mary ConceptBase currently cannot detect such cases 5 6 Limiting access to modules When multiple users work on the same server their workspaces not only need to be separated in a controlled way by means of the module feature Users are also interested in controlling who has which rights on their workspace module ConceptBase includes basic support for rights definition and enforcement via a user definable query class CB_Permitted The signature of this query class has to conform the following format CB_Permitted in GenericQueryClass isA CB_User with parameter user CB_User res Resource
104. abeled with identical names In earlier versions of ConceptBase this was prohibited by the Naming Axiom which demands that different objects have different names Now objects with identical names can be stored in different modules without interferences As another application users can manage alternative conceptual models of the same domain in different modules The set of visible objects in a module context is not limited to the set of objects defined for the module The ConceptBase module concept permits to reuse existing objects from different modules via import and export interfaces Furthermore modules can be nested a nested module is only visible within the context of its father module Objects that are visible in a father module are visible and can be reused to all its child modules ConceptBase users can be assigned to so called home modules i e the module they start working with when registering with the ConceptBase server So called auto home modules force every user in her own module to further reduce potential unwanted interferences A flexible access control mechanism allows to define access rights of users simply by query classes defined either globally or locally to a module 5 1 Definition of modules A Module is a standard O Telos object which defines the content of a module Module in Class with attribute contains Proposition end In ConceptBase a module is a container of objects Modules create a name space
105. action gt lt actionop gt lt optelseaction gt not lt condformula gt lt condformula gt and lt condformula gt lt condformula gt or lt condformula gt lt condformula gt lt action gt lt actionlist gt lt action gt lt actionop gt lt literal gt lt actionop gt lt literal gt noop reject Tell tell Untell untell Retell retell Ask ask Call call Raise raise CALL ELSE lt actionlist gt lt empty gt A 4 Terminal symbols ALPHANUM LABEL NUMBER BOOLI FUNCTOR COMP SYMBOL INFIXSYMBOL SELECTOR1 SELECTOR2 SELECTORB gt La 2A 20 9 gt everything except gt newlines tabs everything enclosed in except and which must be escaped with everything enclosed in except and which must be escaped with gt REAL INTEGER gt 0 9 0 9 0 9 0 9 Ee 0 9 gt 0 9 gt TRUE FALSE gt From To A Ai AL In Isa Label P LT GT LE GE EQ IDENTICAL UNIFIES Known ES ES A AS gt COMPSYMBOL in isA gt non gt gt n gt gt 137 A 5 Syntax specifications for SML fragments This format is only internally used to represent Telos frames as Prolo
106. ad the definition of a view into the Telos Editor the complex structure of it is lost During compilation of the view the view is translated into several classes and some additional contraints are generated so the resulting objects might look quite strange if you reload them 2 5 Functions Functions are special queries which have mandatory input parameters and return at most one result for a given input Functions can either be user defined by a membership constraint like for regular query classes or they may be implemented by a PROLOG code which is defined either in the OB builtin file this file is part of every ConceptBase database or in a LPI file see also section 4 2 2 A couple of aggregation functions are predefined for counting summing up and computing the min imum maximum average Furthermore there are functions for arithmetic and string manipulation See section E 2 for the complete list Since functions are defined as regular Telos objects you can load their definition with the Telos editor of the ConceptBase User Interface Unlike as for user defined generic query classes you have to provide fillers for all parameters of a function We will refer to any query expression whose outer most query is a function as a functional expression The intrinsic property of a function is that it returns at most one answer object for a given combination of input parameters This property allows to form complex functional expressions includin
107. al with constraint c this MULT 100 DIV COUNT QueryClass COUNT Class end and with arithmetic expressions to Function PercentageOfQueryClasses isA Real with constraint c this 100 QueryClass Class end The function PercentageOfQueryClasses has zero parameters You can use it as follows in logical expressions PercentageOfQueryClasses gt 25 5 So a function call F calls a function F that has no parameter Functions that yield a single numerical value can directly be incorporated in comparison predicates For example the following query will return all individual objects that have more than two attributes 43 ObjectWithMoreThanTwoAttributes in QueryClass isA Individual with attribute constraint cl COUNT_Attribute Proposition attribute this gt 2 end The functional expression used in the comparison can be nested See section 2 3 3 for details You can also re use the above query to form further functional expressions e g for counting the number of objects that have more than two attribute You find below all three representations for the expression COUNT ObjectWithMoreThanTwoAttributes class COUNT ObjectWithMoreThanTwoAttributes ObjectWithMoreThanTwoAttributes 2 5 4 Programmed functions If your application demands functional expressions beyond the set of predefined functions you can extend the capabilities of your ConceptBase install
108. alent to the first call using FRAME Subsequently the specification of such user defined answer formats is presented 50 3 1 Basic definitions By default ConceptBase displays answers to queries in the FRAME format see A and B below For many applications other answer representations are more useful For example relational data is more readable in a table structure Another important example are XML data If ConceptBase is integrated into a Web based information system then answers in HTML format are quite useful For this reason answer format definitions are provided Answer formats in ConceptBase are based on term substitutions where terms are evaluated against substitution rules defined by the answers to a query A substitution rule has the form L gt R with the intended meaning that a substring L in a string is replaced by the substring R The object of a term substitution is a string in which terms may occur for example this is a string called a with aterm b Assume the substitution rules e a gt string no x e b gt that was subject to substitution e x gt 123 The derivation of a string with terms proceeds from left to right First the term occurence a is dealt with The next term in the string is then x which is evaluated to 123 Finally b is substituted and the result string is this is a string called string no 123 with a term that was subject to substitution We denote a s
109. and they may be instantiated more than once as e g dept In some cases for attribute categories occuring in a frame the corresponding objects which are instanti ated by the concrete attributes can not uniquely be determined This multiple generalization instantiation problem is solved by the following condition which must hold for O Telos object bases Multiple generalization instantiation axiom axiom 17 in appendix B If pl and p2 are attributes of two classes c1 and c2 which have the same label component 1 and iis a common instance of cl and c2 which has an attribute with category 1 then there must exist a common specialization c3 of cl and c2 with an labelled attribute p3 which specializes pl and p2 and i is instance of c3 Particularly if cl is specialization of c2 and p1 is specialization of p2 cl and p2 already fulfill the conditions for c3 and p3 O Telos treats all three kinds of relationships att ribute isa in as objects Thus each attribute instantiation or generalization link of Employee may have its own attributes and instances For example each of the four Employee attributes is an instance of an attribute class denoted by the label attribute but can also have instances of its own The attribute with label earns of mar y is an instance of attribute salary of class Employee Syntactically attribute objects are denoted by appending the attribute label with an exclamation mark to the name of some individual The relat
110. and asks for the parameters to start a CBserver If the information has been entered the server will be started and its output will be captured in a separate window The workbench will be automatically connected to that server Stop CBserver Stops the CBserver only allowed for the person who started the server Close Same as Exit if CBIva was not started from CBGraph If it was started from CBGraph and CBGraph is still running then the Close option only hides the CBIva window Exit Exit CBlva if a CBGraph windows was opened via CBIva it shall be closed as well Likewise a CBserver started via CBIva will be closed Edit Clear Clears the text area of the currently activated Telos editor This is not the standard way to start the CBserver Normally the CBserver is started in a separate shell command window as explained in section 6 The standard way offers more options and control over the CBserver See also the installation guide for a discussion on the various ways to start ConceptBase 102 Cut Copy Paste Cut copy or paste text to from clipboard Tell Untell Un Tells the text in the currently activated Telos editor Retell A new window will popup and ask you to enter the frames that should be untold and told The contents of the current Telos Editor will be inserted as default into the two text areas Ask Frame Temporarily tells the content of the Telos editor extracts the query names from the frames asks them as qu
111. and constraint language In the definitions below the term literal is a synonym for predicate lt assertion gt gt l lt rule gt gt lt constraint gt gt lt formula gt gt lt rule gt lt constraint gt forall lt variableBindList gt gt lt literal gt lt formula gt gt lt literal gt lt literal gt lt formula gt lt formula gt exists lt variableBindList gt lt formula gt forall lt variableBindList gt lt formula gt not lt formula gt lt formula gt lt gt lt formula gt lt formula gt lt formula gt and lt formula gt lt formula gt or lt formula gt lt formula gt lt literal gt lt literal2 gt gt lt formula gt lt variableBindList gt gt lt variableBind gt lt variableBindList gt lt variableBind gt 134 lt variableBind gt gt lt varList gt lt objectname gt lt varList gt lt objList gt ALPHANUM lt selectExpB gt lt varList gt gt ALPHANUM lt varList gt ALPHANU lt objectname gt gt lt label gt lt selectExpA gt lt deriveExp gt lt label gt gt ALPHANU LABEL NUMBER lt literal gt gt FUNCTOR lt literalArgList gt lt literalArg gt lt infixSymbol gt lt literalArg gt lt arExpr gt COMPSYMBOL lt arExpr gt lt literalArg gt lt label gt lt label gt lt literalArg gt BOOLEAN lt literal2 gt gt
112. as to tell the meta classes to ConceptBase cc 1 The acronym SML survived in ConceptBase as the filetype sm1 for source models to get an evironment where one can manipulate models in these modeling languages Since all abstraction levels are supported the models themselves can be represented in O Telos and thus be managed by Con ceptBase ConceptBase s implementation of O Telos provides a couple of features beyond the core O Telos First of all there is a dedicated query language CBL which provides a class based interpretation for queries Secondly modules have been introduced to structure the search space Essentially the module identifier is added to the object identifier Thirdly ConceptBase cc supports a limited version of active rules to react to internal and external events Finally ConceptBase cc supports recursively defined functions and arithmetic expressions 1 2 The architecture of ConceptBase cc ConceptBase cc 7 8 follows a client server architecture Clients and servers run as independent processes which interact via inter process communication IPC channels Fig 1 1 Although this communication channel was initially meant for use in local area networks it has been used successfully for nationwide and even transatlantic collaboration of clients on a common server The ConceptBase cc server CBserver offers programming interfaces that allow to build clients and to exchange messages in particular for updating and que
113. ass of all employees with more than two co workers ConceptBase provides a collection of aggregate functions that operate on classes For example the COUNT function returns the number of instances of a class The input of such a function can be any nested query call QueryClass EmployeeWith2RichCoworkers isA Employee with constraint c2 COUNT RichCoworker this worker class 2 end The outer predicate here COUNT is an instance of Function i e delivers at most one value for the given argument It is also possible that both operands of a comparison predicate are nested expressions QueryClass EmployeeWithMoreRichCoworkersThanWilli isA Employee with constraint c2 COUNT RichCoworker this worker class gt COUNT RichCoworker Willi worker class end 37 ConceptBase supports shortcuts for query calls and function calls see section 2 5 in case that all pa rameters of a query or function have fillers in the query call In such cases one can write Q x1 x2 instead of O x1 p2 x2 p2 ConceptBase shall replace the actual parameters x1 x2 etc for the parameter labels p1 p2 in the alphabetic order of the parameter labels For example the expression RichCoworker this is equivalent to RichCoworker this worker since worker is the only parameter label of the query Likewise COUNT c is a shortcut for COUNT c class Since COUNT is also a function we support COUNT c as well to match
114. at See subsection C 3 5 for more details textposition Relative position of the node s text label to the image icon This property is only evaluated if a graphical type defines an image icon Possible values are center left right top and bottom default label The label to be used for this object instead of the object name align Alignment of the label possible values are center left right topright bottomleft and bottomright default is center o top bottom topleft size Initial size of the node in pixels e g 20x20 the non numeric value resizable is allowed as well If set the user can also resize the element via mouse actions default undefined then the size is fixed by the Java LayoutManager font Name of the font to be used for the shape e g Arial default Default font of Java fontsize Size of the font in pixels default default font size of Java fontstyle The style of the font e g bold italic underlined bold italic clickaction The name of a query class that shall be called directly when an object with this graphical type 1s clicked See section C 3 2 for details Edges with empty label anonymous edge are displayed with a square dot in the middle of the edge The color of the square dot is by default the edgecolor and its size is set to 6 pixels If the gra
115. ates three labels arguments may not be expressions ConcatenateStrings4 concatenates four labels arguments may not be expressions concat same as ConcatenateStrings StringToLabel removes the quotes of a string and returns it as a label not an object useful if labels should be passed as a parameter of a query 165 toLabel evaluates the argument and that creates an individual object with the canonical representation of the argument result the canonical representation is an alphanumeric where special characters are replaces by substrings like C30_ for special characters For example the expression toLabel concat 1 2 will return C42_3 The substring C42_ is the canonical representation ASCII number of x The subexpression 1 2 is evaluated to 3 E 3 Builtin query classes These queries must not be used within other queries as they do not return a list of objects They may only be used directly from client programs exists Checks whether ob jname exists and returns yes or no get_object Returns the frame representation of objname This query may be either called with just one parameter ob jname or with four parameters ob jname dedIn dedIsa dedWith The dedx parameters are boolean flags that indicate whether implicit deduced information should also be included in the frame representation Note that the order of the parameters hast to be the same as listed above get_object_star Returns the frame representation
116. atik rwth aachen de pub bscw cgi 3594885 With XPalette you can define a new palette without having to worry about values for required default graphical types BMG_Palette in JavaGraphicalPalette isA XPalette with palproperty bgimage http conceptbas longtitle Business Model contains bmgl Customer_GT bmg2 Revenue_GT bmg3 CustomerRelationship_GT bmg4 Channel_GT sourceforge net CBICONS bgimages bmgcolor png end C 3 Customizing the graphical types To support the user in defining his own graphical types we provide some examples and documentation of the properties There are two ways to customize the graphical types e Defining new graphical types with different properties using the provided implementations i5 cb graph cbeditor CBIndividual and i5 cb graph cbeditor CBLink e Defining new graphical types with a different implementation class which extends i5 cb graph cbeditor CBUserObject or CBIndividual or CBLink Both possibilities will presented in the next two subsections 146 C 3 1 Properties of CBIndividual and CBLink The easiest way to modify the representation of an object in the CBGraph Editor is to load an existing graphical type modify its properties and store it as a new graphical type The properties available and there meaning are given in the following Note that colors have to be given as RGB color value e g 0 0 0 is black 255 0 0 is red 255 255 255 is white etc Fu
117. ation by adding more functions There are two ways first you can extend the capabilities of a certain ConceptBase database or secondly you can add the new functionality to your ConceptBase system files We will discuss the first option in more details using the function sin as an example and then give some hints on how to achieve the second option A function like any builtin query class has two aspects First the ConceptBase server requires a regular Telos definition of the function declaring its name and parameters This can look like Sin in Function isA Real with parameter x Real comment c computes the trigonometric function sin x end The super class Real is the range of the function i e any result is declared to be an instance of Real The parameters are listed like for any regular generic query class The comment is optional We recommend to use short names to simplify the constructions of functional expressions The above Telos frame must be permanently stored in any ConceptBase database that is supposed to use the new function The second aspect of a function is its implementation The implementation can be in principal in any programming language but we only support PROLOG because it can be incrementally addded to a Con ceptBase database An implementation in another programming language would require a re compilation of the ConceptBase server source code The syntax of the PROLOG code must be conformant to the Prolog compi
118. attribute with label m Deductive rules for x m n y are introduced with ConceptBase V7 1 They allow to simulate multi sets i e derived attributes where the same value can occur multiple times Examples are available in the CB Forum http merkur informatik rwth aachen de pub bscw cgi 2330042 2 2 3 Assigning attribute categories to explicit attributes The instantiation of an explicit attribute to an attribute category can be explicit see above or via inheri tance or via a user defined rule Explicit instantiation is typically established when telling a frame like the Employee example to the database Instantiation by inheritance is more rarely used but is in fact just the application of the specialization principle to attribution objects Employee with attribute salary Integer end Manager isA Employee with attribute bonus Integer end Manager bonus isA Employee salary end Here the bonus attribute is declared as specialization of the salary attribute Any instance of the bonus attribute will then be an instance of the salary attribute via the usual class membership inheritance of O Telos For example mary in Manager with bonus bon1 10000 end shall make the following attribution facts true mary bonus bonl 10000 mary bonus 10000 A_e mary bonus 10000 mary salary bonl 10000 22 mary salary 10000 A_e mary salary 10000 mary attribute bonl 10000 mary attribute 10000 A_e mary attribu
119. ay not document them in this user manual or its sources You rather should write a companion report that lists the differences of your version of ConceptBase cc to the one distributed via the home page of ConceptBase cc http conceptbase cc We sometimes use the short form ConceptBase We then always refer to ConceptBase cc 11 Chapter 2 O Telos by ConceptBase cc ConceptBase cc is an implementation of the O Telos data model O Telos is derived from the knowledge representation language Telos as designed by Borgida Mylopoulos and others MBJK90 While Telos was geared more to its roots in artificial intelligence O Telos is more geared to database theory in par ticular to deductive databases Nevertheless O Telos is to a large degree compatible to the original Telos specification In some respects it generalizes Telos for example by removing the requirement to classify objects into the levels for tokens simple classes and meta classes In O Telos we have just five predefined objects see appendix on the axioms of O Telos Telos and O Telos as well also have strong links to the semantic web in particular to the triple predicates used for defining RDF S statements The main difference is that O Telos is based on quadruples where the additional components identifies the statement While RDF S has to use special link types to reify triple statements i e to make statements about statements O Telos statements are simply referred to
120. be defined Thus the default attribute defined in Graphical Palette will not be used anymore The contains attribute has still to be used i e a graphical type will only be used if it is also contained in the current graphical palette Although the attributes are not IColors are given as RGB color value e g 210 210 210 is light grey and 0 0 0 is black 144 declared as single and necessary each graphical palette should have exactly one value for the each of the default and implicit attributes Class JavaGraphicalPalette isA GraphicalPalette with attribute defaultIndividual JavaGraphicalType defaultLink JavaGraphicalType implicitIsA JavaGraphicalType implicitInstanceOf JavaGraphicalType implicitAttribute JavaGraphicalType palproperty String end The attribute palpropert y 1s used for declaring any number of properties of a palette The properties are passed to the CBGraph Editor when it loads the palette at startup time CBGraph supports the following properties for palettes bgcolor sets the background color of the windows that displays the graph format should be r g b e g 255 255 255 for white bgimage sets the background image for the graph windows the image shall be specified by the URL to a PNG GIF or JPG image it is scaled by the CBGraph editor to fit into the internal window showing a graph of this palette longtitle used for setting the title of the graph windows employing this palette i
121. be shown Note that the list will be empty if the source object does not yet exist in the database If you have specified the attribute category you can also select the attribute value from a listbox by clicking on the Select button next to the text field for the attribute value The listbox will show all instances of the destination of the attribute category e g all instances of Department for the category Employee dept If you select the radio button Show Attribute Instantiation then CBGraph will also show the in stantiation link for the attribute For example if you create a new attribute for John with the la bel JohnsDept in the attribute category Employee dept then the instantiation link between John JohnsDept and Employee dept will also be shown As the graph gets quite confusing with too many links this radio button is not selected by default Deletion of objects is also possible As this operation should not be mixed up with the removal of an object from the current view this operation is just available from the popup menu item Delete Object from Database As you might make mistakes while editing the model there is the possibility of undoing changes The button Show added removed objects list all objects that have been added or removed since the last succesful commit or since the connection has been established A screenshot of the dialog is shown in figure 8 12 The left list shows the objects
122. be user defined by recursive function definitions e g the length of the shortest path between two nodes Queries are defined as classes with user defined membership constraints queries can range over any type of object at any abstraction level Active rules can be used to define the system s reaction to events active rules can change the state of the database and can trigger each other e Client server architecture with wide area Internet access ConceptBase cc implements the version O Telos Object Telos of the knowledge representation lan guage Telos MBJK90 O Telos integrates a thoroughly axiomatized structurally object oriented kernel with a predicative assertion language in the style of deductive databases A complete formal definition can be found in JGJ 95 Jeus92 O Telos is viewed as a hybrid knowledge representation language integrat ing ideas from frame like concept description languages and deductive databases This hybrid character suggests a hypertext style combination of graphical semantic network views and textual frame repre sentations at the user interface Both O Telos views are based on the common logical representation so that they can be treated in a completely symmetrical way both for purposes of querying browsing and of editing manipulation This manual is integrated with the ConceptBase cc Forum The ConceptBase cc Forum is an Internet based workspace where ConceptBase cc developers and users share knowledge
123. bination with the f option It shall instruct CBShell to confirm each command in the script file before it is executed i This option modifies the startServer command by invoking a CBserver compiled directly from its sources For developers only a This options instructs CBShell not to directly show the answer to each command in interactive mode instead you have to manually call showAnswer p Disables the display of the command prompt in interactive mode This may be useful when CBShell is used in a Unix pipe where the preceding program generates the commands and feeds them into CBShell q Instructs CBShell to convert single quotes in positional parameters into escaped double quotes This option is useful when a parameter contains special characters and still shall be regarded as a valid object label by ConceptBase Useful when calling CBShell scripts within regular scripts e g bash that pass parameters with special characters to the CBShell scripts See also section 7 7 94 params At most nine user defined positional parameters can be supplied The are bound to the CBShell variables 1 to 9 The CBShell variable 0 is bound to the name of the scriptfile 7 3 Commands startServer serveroptions starts a CBserver with the specified options and connects to it cbserver serveroptions same as startServer enrollMe host port connects to an already running CBserver i e not using the startServer command if a public CBserver is configure
124. bjects The database is maintained as a directory Setting the database is mandatory except when the update mode is set to nonpersistent see below You cannot start two concurrent servers which use the same database directory To avoid this case a file OB lock is created in the database directory when the first server is started If the server crashes during its execution the file OB lock will still exist in the directory Before you restart the server you might have to remove this file manually db dbdir Like d but also sets the load save views directories to dbdir i e the CBserver will automat ically maintain the module sources in dbdir and also materialize the selected queries in the same directory See section 5 9 for details new dbdir Like d but deletes any existing database at location dbdir before it creates and initializes it u updatemode controls update persistency The allowed values are persistent and nonpersi stent If no database is provided by parameter d then the default update mode is set to non persistent Otherwise the default is persistent In nonpersistent mode all updates are lost after the ConceptBase server is stopped In persistent mode updates are stored in the files of the database and will be available for future sessions lYou can also start the CBserver from within the ConceptBase cc user interface CBlva Details are in the installation guide distributed with ConceptBase cc and in secti
125. ble quotes e UQ expr removes double quotes from expr e ALPHANUM expr outputs an alphanumeric transcription of expr This is useful when an object names contains special characters but the output format requires an alphanumeric label If expr already evaluates to an alphanumeric label then it is inserted unchanged e From expr inserts the source object of expr The source object is computed by the predicate From x 0 of section 2 2 This pattern is useful for printing attributes ConceptBase will first apply pattern substitution to expr and then to the whole term From expr e To expr inserts the destination object of expr The destination object is computed by the predicate To x 0 of section 2 2 e Label expr inserts the label of the object referenced by expr The label is computed by the predicate Label x 1 of section 2 2 e Oid expr inserts the identifier of the object referenced by expr Note that the argument expr can be another pattern such as this Specifically the expression Oid this is equivalent to this oid However the Oid pattern is also applicable to patterns not including this 55 Examples are available from the CB Forum see http merkur informatik rwth aachen de pub bscw cgi 2502545 The above set of patterns can be extended by user defined functions via LPI plugins In princi ple any routine that can be called from the ConceptBase server can also be called in an a
126. ble this refers to the instances of this class If the query has parameters or computed attributes variables with the names of the parameters or computed attributes will be predefined In a DatalogInRule the variable this refers to the instances of the concerned class In a DatalogAttrRule the variables src and dst refer to the source and destination object of the attribute Note that all predefined variables have to be prefixed with and must be encoded in single quotes e g this src param e existential variables These variables must be declared in a special predicate vars list which has to be the first predicate of the code For example the predicate vars x y defines the variables x and y A query expression of the form query q may be also used as predicate or as second argument of an In predicate q may be any valid query expression e g just the name of a query class or a derive expression including the specification of parameters for example find_instances Class class In addition PROLOG predicates can be used as predicates You can define your own PROLOG predi cates in a LPI file see section 4 2 2 for an example 2 7 3 Examples This section defines a few datalog queries and rules for the standard example model of Employees Depart ments and Managers see SCB_HOME examples QUERIES The first example defines a more efficient version of the recursive MetabossQuery DatalogQuer
127. by a double click on the object It shows the Telos frame of the object By a double click on the title bar of this component one can switch back to the default view of this object Thus each object can be shown by a small component the default view and a large component which gives more detailed information Components are in this context specific Java objects namely instances of javax swing JComponent Thus different components can be provided to represent an object e g tables buttons text fields You can implement your own component and integrate into CBGraph by extending a specific Java class Details about the customization of CBGraph using graphical types and other components can be found in appendix C CBGraph can be used to edit Telos models see section 8 2 9 It can also display implicit relation ships between objects which have been derived by rules or Telos axioms For each type of relationship instanstation specializations and attributes one can choose to see only the explicit relationships or to see all relationships 8 2 2 Starting CBGraph via CBIva CBGraph can be invoked from CBlva via the menu item Browse gt Graph Editor If CBlIva is connected with a CBserver CBGraph will be connected to the same server and you will be prompted to enter the object name you want to start with the name of a graphical palette and the database module The graphical palette 1s a Telos object which represents a set of graphical type
128. ce the test is done only on the user name a malicious attacker could use your user name for an account on another computer and then successfully log into your CBserver Use Internet firewalls to protect against such attacks y vmode controls whether view maintenance rules are generated vmode on or not vmode of f View maintenance rules are used to keep a ConceptBase cc view up to date upon changes to the object base Default value for vmode is of f mc maxcost this parameter defines the maximum cost level for a predicate in a binding path that is used to compile a meta formula see section 2 2 9 The evaulation of a binding path yields fillers for the meta variables Set maxcost to 10 if such a predicate should have about one free variable Set it to 100 if if may have two free variables Default is 100 The higher the number the more candidate paths are generated increasing the likelihood that a binding path is found On the downside a high value increases the compile time of meta formulas pl pathlen sets a maximum length for binding path candidates In principle the number of candidates can explode with the path length Like the previous parameter the path length influences the ability of ConceptBase cc to compile meta formulas The default value is 5 If you set the value to 0 then no meta formula can be compiled im imax sets the maximum number of iterations used to re order attribution predicates with one free variable Evaluatin
129. ceforge net import cb appliance html for details 167 F 2 Calling the plug in There are two ways to trigger the call of a procedure implemented by an LPI plugin 1 By explicitely calling a builtin query class or function whose code has been implemented by the LPI plugin The LPI code would then look similar to the code in SYSTEM SWL builtin and you must have defined an instance of Built inQueryClass that matches the signature of the LPI code The call to the builtin query class may be enacted from the user interface or it may be included as an ASKquer y call in an instance of AnswerFormat Refer for more information to section 3 2 5 and to the directory Examples BuiltinQueries in your ConceptBase installation directory 2 By calling the implemented function as a CALL action of an active rule See section 4 2 2 for an example In that case there does not need to be a definition of a builtin query class or function to declare the signature of the procedure If the code of an LPI plugin realizes a ConceptBase function e g selecting the first instance of a class then you can use that function whereever functions are allowed As an example consider the definition of the LPI plugin select first swi lpi from http merkur informatik rwth aachen de pub bscw cgi d2984654 selectfirst swi lpi txt compute_selectfirst _res _class _cl nonvar _class cbserver ask In _res _class tell selectfirst in Function isA Pro
130. ces super classes subclasses outgoing and incoming attributes is used If you select Frame then the Telos frame of the object will be shown in a text area see figure 8 8 Invalid Telos Objects CBGraph can validate objects that are currently shown in the graph i e it checks whether the object is still valid in the database or it is has already been removed see Current Con nection menu If you select Mark here then the objects will be marked with a red cross as invalid Remove from display instantly will remove the objects directly from the view Popup Menu These options control the behaviour of the Popup Menu see section 8 2 8 The delay is the time in milliseconds an item of the popup menu has to be selected before the submenu is shown Note that the construction of a submenu might require a query to the CBserver If the option Popup Menu blocks while waiting for server is activated then the editor will block the UI while it waits for an answer of the CBserver Otherwise the query to the server will be executed in a separate thread and interaction with the UI will be possible If you have the problem that some submenus are still shown after you have used the popup menu set the delay to 0 and activate the option Popup Menu blocks while waiting for server Look amp Feel This option allows you to adapt the look and feel of CBGraph windows to your desktop environment By default the Metal look and
131. ch are subject to substi tution The ASKquery construct allows to introduce recursive calls during the derivation of a query since there can and should be an answer format for Q which may contain expressions ASKquery itself In principle this allows infinite looping However the answer format evaluator prevents such loops by halting the expansion when a recursive call with same parameters has occured The answer then contains an character at the position where the loop was detected Additionally an error message is written on the console window of the ConceptBase server tracemode must be at least low A simple example for use of ASKquery is given in recursive answers sml The example uses a view instead of a query class in order to include also answers into the solution which not have a filler for 56 the requested attribute i e hasChild is inherited_attribute not retrieved attribute It is common practice to combine the ASKquery construct with Foreach in order to display an iteration of objects in the same way The user should define an answer format for the iterated query Q as well Do not mix the use of ASKquery with the view definitions in ConceptBase The nesting depth of a view is determined by the view definition The nesting depth of an answer generated by expansion of ASKquery is only limited by the complexity of the database For example one can set up an ancestor database and display all descendants of a person and rec
132. ch might be useful for implement ing new graphical types 149 String toString returns the full object name of the Telos object which is represented by this user object TelosObject getTelosObject returns the Telos object which is represented by this user object see docu mentation of package 15 cb telos object for more details on TelosObject CBFrame getCBFrame returns the frame in which this object is presented a CBFrame is an extension of a JInternalFrame ObjectBaseInterface getObi returns the ObjectBaselnterface i e a connection to the server of the cur rent frame This is useful if you want to execute your own queries to retrieve additional information from the server see documentation of package i5 cb telos object and i5 cb api for more details String getProperty String property returns the value of a property boolean hasProperty String property returns true if the property is defined for this graphical type JPopupMenu getPopupMenu returns the popup menu for this object By using this method you can extend the popup menu with own operations If you overwrite this method the operations in the default popup menu will not be available Example The following example defines a graphical type that uses a JButton to visualize the object Only the method getSmallComponent is overwritten The background color of the button will be changed if the property bgcolor has been defined The example shows that the implementation o
133. changes to the database or add new objects from the database The CBGraph editor displays the connection status in the title of its internal window containing the graph The hostname of a CBserver in a graph file is by default localhost Consequently the graph editor will try to establish a connection to a CBserver running on localhost If you want to connect to a remote CBserver then you should specify in CBlIva the full domain name of the CBserver e g myhost acme com This long name will then be stored in the graph file that is created from a graph editor started via CBIva Such graph files can then be copied to other computers and can be loaded with CBGraph to auto connect to the remote CBserver specified in the graph file provided that CBserver is running and accessible If no CBserver is accessible CBGraph will attempt to start a local CBserver in the background provided that the graph file specifies localhost as hostname and the graph file contains module sources In other cases CBGraph switches to the offline mode You can still change location and size of the graphical elements and store it back to the graph file But you cannot delete objects and you cannot add objects to the database The menus to show attributes instances and subclasses shall also not work An example on how to create and use graph files containing materialized database views is available in the CB Forum at http merkur informatik rwth aachen de pub bscw cgi
134. classes and deductive integrity checking ConceptBase regards query classes as ordinary classes with the only exception that class membership cannot be postulated via a TELL but is derived via the class membership constraint formulated for the query class A consequence of this equal treatment is that a constraint formulated for an ordinary class can refer directly or indirectly to a query class e g Unit in Class with attribute sub Unit end BaseUnit in QueryClass isA Unit with constraint cl not exists s Unit sub From s this end SimpleUnit in Class isA Unit with constraint c forall s SimpleUnit s in BaseUnit end Here the constraint in the class SimpleUnit refers to the query class BaseUnit ConceptBase supports references to query classes without parameters in ordinary class constraints and rules A prerequisite is that the the query class is an instance of the builtin class MSFOLrule Mem bership to this builtin class is necessary to store the generated code for an integrity constraint or a rule that an integrity constraint might depend upon and to enable the creation of a dependency network between the query class and the integrity constraints There are two simple methods to achieve membership to MSFOLrule Method 1 Make sure that any query class is an instance of MSFOLrule This can simply be achieved be telling the following frame prior to your model QueryClass isA MSFOLrule end Method 2 Decide for eac
135. classes like get_object Class objname may only occur as a singleton 4 Under Linux with Gnome the default web browser is used to display the content Otherwise a Java window capable of displaying HTML is opened Due to unknown reasons the mechanism works for Linux only if at least two browser tools are installed You may want to install Chromium as second browser besides Firefox to fulfill the constraint 103 ConceptBase Tutorial I II Opens a window with the online version of the respective tutorial CB Forum Opens a window to the public version of the ConceptBase Forum with lots of examples About Shows a dialog with information about this program License Displays the license of ConceptBase cc in a new window CB Team Displays a page about the ConceptBase Team History Load History Load previously saved contents of the history window Save History Save contents of the history window to a file Redo History Redos certain operations which are currently in the history The operations can be selected from a list Set History Options Select the type of operations that should be displayed in the history window 8 1 2 The tool bar The tool bar is the button panel below the menu bar All buttons have tool tips 1 e small messages that show the meaning of these buttons The tool tips appear if you move your mouse pointer over the button and do not move your mouse for about one second The buttons are shortcuts for some operations
136. code defines the executable code of the query as string Datalog rules have to be defined as an instance of DatalogInRule or DatalogAttrRule de pending on whether their conclusion should be an In predicate or an A predicate 16 Older releases of ConceptBase provided a prototype of a query evaluation strategy based on the magic set method We no longer support this strategy 47 Class DatalogRule with attribute concernedClass Proposition code String end Class DatalogInRule isA DatalogRule end Class DatalogAttrRule isA DatalogRule end The attribute concernedClass specifies the class for the In predicate or the attribute class for the A predicate 2 7 2 Datalog code The datalog code is a list of predicates separated by commas As in Datalog or Prolog this will be interpreted as a conjunction of the predicates To use disjunction the code attribute has to be specified multiple times All predicates that may be used in standard rules and queries may also be used in datalog queries see section 2 2 for a list An argument of a predicate may be one the following e an object name If the object name starts with an upper case letter or includes special characters such as or it must be written in single quotes This also holds for string object e g a string must be written as a string e a predefined variable defined by the context of the query or rule If the query has a super class the varia
137. comment coml This is a comment to an instantiation between attributes end mary learns gt Employee salary coml with comment com2 This is a comment to the the previous comment attribute end The labels InstanceOf IsA and Attribute for the three Telos system classes are indeed alias names for the following object expressions Attribute lt gt Proposition attribute InstanceOf lt gt Proposition gt Proposition IsA lt gt Proposition gt Proposition Hence Attribute as the alias name for the attribute with label attribute of Proposition InstanceOf is the alias name for the instantiation link between Proposition and Proposition The object Proposition is indeed an instance of itself because it has the shape of an individual object which is a special case of the shape of a proposition Finally I sA is an alias name for the specialization link between Proposition and Proposition This representation is deviates slightly from the axioms in appendix B because it was originally implemented in ConceptBase in this way The reflexive definition of InstanceOf IsA as instantiation specialization links is redundant since O Telos axioms 18 22 derive these instantiations anyway Figure 2 1 shows as the second view on propositions the graphical semantic network representation of mary and her relationships to the other example objects Individual objects are denoted as nodes of the graph instantiation specialization and attrib
138. ction part of the ECArule Note that ECArules without any free variable are also possible By default predicates are evaluated against the old state of the object base i e before the transaction started If a predicate has to be evaluated on the new database state i e the intermediate state representing the updates processed so far during the transaction then it has to be quoted by the backward apostrophe for example x in Class instead of x in Class The syntax new x in Class is supported as well and equivalent to the use of the backward apostrophe Note that only conditions of ECA rules can see intermediate database states If the whole condition shall be evaluated against the new database state the use the clause IFNEW instead IF 4 1 4 Actions Actions are specified in a comma separated list The syntax is similar to that one of events except that you can also ask queries Ask and call Prolog predicates Ca11 The standards actions are as follows Tell predicate The predicate fact is told to the system The predicate must be either an attribution instantiation or specialization predicate All arguments of the predicate must be bound at execution time of the action Untell predicate The predicate fact is untold from the system Retell predicate Old facts are first untold and then the new predicate fact is told See below for restric tions Ask predicate The predicate is evaluated possibly binding free variab
139. ctive rules could loop infinitely but also shall not change your file system and shall not interact with the operating system unless you call such code explicitely in the active rule You can disable the loading of LPI plugins with the CBserver option g nolpi The CBserver will then not load LPI plugins upon startup This option might be useful for debugging or for disabling loading LPI plugins that are configured in the 1ib SystemDB sub directory of your ConceptBase installation F 3 Programming interface for the plug ins The CBserver plug ins need to interface to the functionalities of the CBserver the Prolog runtime and possibly the operating system To simplify the programming of the CBserver plug ins we document here the interface of the module coserver We assume that the code for the plug ins is written in SWI Prolog and the user is familiar with the SWI Prolog system 168 cbserver ask Q Params A asks the query Q with parameters Params to the CBserver The answer is returned as a Prolog atom in A The atom holds the answer represented in the answer format of Q see also chapter 3 Example cbserver ask find_classes bill objname A cbserver ask Preds evaluates the predicates in list Preds The predicate can backtrack and will bind in case of success the free variables in Preds We currently support only the following predicates In A AL and Isa Example cbserver ask In X Employee A X salary 1000 cbserver askAll X
140. ctory into which 2A full list of all parameters is described in section 6 Note that the script CBserver must be in the search path It is available in the subdirectory bin of your ConceptBase cc installation directory 121 the CBserver internally stores objects persistently Then we start the usage environment with the command cbiva in the other window It is also possible to start the CBserver from the user interface To do so choose Start CBserver from the File Menu of CBIva see section 8 1 1 and specify the parameters in the dialog which will be shown see figure 8 13 The option Source Mode controls whether the CBserver accessing the database via the d parameter database maintained in binary files or via the db parameter database maintained both in binary files and in source files See section 6 for more details Once the information has been entered via the OK button the server process will be started and its output will be captured in a window This output window provides also a button stop the server If you started the server this way then you can skip the next section as the user interface will be connected to the server automatically Start CBserver Parameters CBserver out gt Includes plugins selectfirst Port 4001 Database home jeusfeld db gt This is ConceptBase cc CBserver 7 6 10 Skovde 2014 01 31 m gt Copyright 1987 2014 by The ConceptBa
141. d Project participate in a binary relationship WorksIn The attributes Employee ssn and Project pno are key attributes of the respective objects D 2 2 The use of meta formulas The above model distinguishes attributes and key attributes One important constraint on key attributes is monovalence In the previous releases of ConceptBase it was possible to declare Telos attributes as instance of the attribute categories single or necessary but the constraint ensuring this property could not be formulated in a general manner because the use of variables as placeholders for Telos classes e g in an Jn Literal was prohibited To overcome this restriction meta formulas have been integrated into the system An assertion is a meta formula if it contains such a class variable The system tries to replace this meta formula by a set of semantic equivalent formulas which contain no class variables In previous releases properties as single or necessary had to be ensured manually by adding a constraint for each such attribute This job is now performed automatically by the system Example necessary and single The following meta formula ensures the necessary property of attributes which are instances of the cat egory Proposition necessary The semantics of this property is that for every instance of the source class of this attribute there must exist an instantiation of this attribute Class with constraint attribute necConstraint forall c d
142. d a frame representation The two latter formats are based on the logical one As explained in the next subsections the logical representation also forms the base for integrating a predicative assertion language for deductive rules queries and integrity constraints into the frame representation We start with the so called P fact representation of a O Telos object base An O Telos object base is a finite set of interrelated propositions P facts objects OB P oid x 1 y tt oid x y tt ID 1 LABEL 12 where oid has key property within the knowledge base ID is a non empty set of identifiers with a non empty subset LABEL of names The components cid x 1 y tt are called identifier source label or name destination and belief time of the proposition We read them as follows The object x has a relationship called 1 to the object y This relationship is believed by the system for the time tt As shown below there is a natural interpretation of a set of propositions as a directed graph semantic network We distinguish four patterns of propositions and give them the following names Individual objects P oid oid 1 oid tt oid is an object with name 1 believed tt InstanceOf relationships instantiations P oid x instanceof y tt x is an instance of class y believed tt IsA relationships specializations P oid x isa y tt and x is a specialization of y believed tt Attribute links all other pro
143. d add it to your source models when needed The definition below shows the use of immutable attributes The spouses are created when the source object marriagel is created Afterwards they shall not be updated for the whole time span of marriagel Marriage in Class with immutable spousel Person spouse2 Person end marriagel in Marriage with spousel sl mary spouse2 s2 bill end The immutable attribute category instructs the integrity constraint compiler to prune unnecessary in tegrity checks on updates of these attributes This feature can be disabled by setting the CBserver parameter o to a value smaller than 4 see also section 6 1 31 2 3 Query classes ConceptBase realizes queries as so called query classes whose instances fulfill the membership constraint of the query Stau90 This section first defines the structural properties of the query language CBQL and then introduces the predicative component Queries are instances of a system class QueryClass which is defined as follows QueryClass in Class isA Class with attribute retrieved_attribute Proposition computed_attribute Proposition attribute single constraint MSFOLquery end A super classes of query class imposes a range condition of the set of possible instances of the query class any instance of the query class must be an instance of the superclass Example socially interested are those managers that are member of a union Union in Class e
144. d answer representations one can specify user defined answer formats In our case it is a parameterized answer format AFParameter somevalue somevar This means that the result of the query will be for matted according to the answer format AFParameter and the variable somevar will be replaced with somevalue The variable can be used like any other expression i e it must be enclosed in The following definition of AFParameter is an example how the parameter can be used in the pattern If the parameter is not specified the string somevar will not be replaced Individual AFParameter in AnswerFormat with attribute head hd lt result gt attribute tail tl lt result gt attribute pattern pi lt object gt lt type gt somevar lt type gt lt name gt this lt name gt lt object gt end Note that you can use any answer format with or without parameters as answer representation in the ASK method 58 3 4 File type of answer formats The optional fileType attribute of answer formats is used by the server side materialization of query results section 5 9 ConceptBase will use the specified file type when storing the query results in the file system The default value is txt The attribute is single valued though single valuedness is not enforced 3 5 Bulk query calls It is sometimes useful to call the same query class with multiple arguments in a single call rather than in a
145. d then it is the default host for enrollMe otherwise localhost is default host 4001 is default port number connect host port synonym to enrollMe cancelMe disconnects from a CBserver disconnect synonym to cancelMe stopServer stops the CBserver which is currently connected stop synonym to stopServer tell frames tells frames to the CBserver enclose the frames in double quotes untell frames untells frames from the CBserver enclose the frames in double quotes retell untellFrames tellFrames untells and tells frames to a CBserver in one transaction enclose both ar guments in double quotes tellModel file file2 tells files to the CBserver the files can have file types sml and txt if no file type is specified ConceptBase cc will append the default file type sml to the file name ask Query QueryFormat AnswerRep RollbackTime asks a query possible query formats are OBJNAMI and FRAMES the answer representation can be LABEL FRAME default or a user defined an swer format the rollback time should be Now If the query format is OBJNAMES then Query is a string in double quotes containing a query call or a comma separated list if query calls It the query format is FRAMES then Query is a string of Telos frames including a query definition The answer representations are discussed in section 3 hypoAsk frames Query QueryFormat AnswerRep RollbackTime tells frames temporarily and asks a query
146. d to the insertion of the P fact The right boundary ta specifies the time point after which the CBserver assumes the P fact to be not true anymore It is initialized with Now when the P fact is created This symbolic value is interpreted as the current time You may also interpret such a time interval to be right open The UNTELL operation terminates the belief time of P facts specified in an O Telos frame The value Now is replaced by the time when the UNTELL operation is executed 3ConceptBase takes the system time using timezone Coordinated Universal Time UTC of the computer on which it is running and rounds it to milliseconds The time is captured when the transaction is initiated i e all P facts told or untold in the transaction will use that transaction time 91 From the user s perspective a TELL operation is about creating some objects and the UNTELL op eration is about deleting them Many users expect the UNTELL operation to be symmetric to the TELL operation i e untelling a frame that has been told before should remove the frame completely This is however not the case for the following reasons e An O Telos frame being argument of a TELL or UNTELL operation is not necessarily all the infor mation about an object but just some e Other objects might refer to an object told previously An UNTELL operation would then be rejected to preserve referential integrity e ConceptBase cc adds instantiation to the built
147. dPlaces with mode m Deferred rejectMsg rm The last firing of a transition failed Check whether the transition was enabled ecarule er fire FireTransition t Transition p Place m Integer ON Tell fire transition t IF t in Enabled and p in ConnectedPlace t and m M p IM p t DO Retell p marks m ELSE reject end 69 The example shows that the condition can also be a complex logical expression Note that the event ON part binds the two variables fire and t The condition IF part additionally binds the free vari ables p and m Each binding of the free variables is passed to the DO part leading to some update of the tokenFi11 attribute In case that the IF part cannot be evaluated to true the ELSE part is executed That will lead to an abortion of the current transaction rolling back all updates and issuing the error message listed under re jectMsg A complete specification of modeling petri nets is in the CB Forum http merkur informatik rwth aachen de pub bscw cgi 1419080 Further examples of ECA rules can be found at http merkur informatik rwth aachen de pub bscw cgi 1747992 It should be noted that one can also ask queries in the DO part and ELSE part of an ECArule Other than for the IF part such queries are only evaluated once 4 3 Optimization of ECA rules ECArules can be configured to follows various execution semantics A particular issue is the evaluation of the ECA condition I
148. database The actual directory name of the database is supplied as the d parameter of the command CBserver The u parameter of the CBserver specifies whether updates are made persistent or are just kept in system memory temporarily Use u persistent for a update persistence or u nonpersistent for a non persistent update mode 10 Historically we used the terms application or object base instead database We now believe that database is a much better term ln nonpersistent update mode the database is actually copied to a temporary directory This copy will be removed when you shutdown the server 122 The database can be modified interactively using the editor commands TELL UNTELL Another way of extending ConceptBase cc databases is to load Telos objects expressed in frame syntax stored in plain text files with the extension sml Call the menu item Load Model from the File Menu to add these objects to the database In our example the database directory Employee was built interactively and can be found together with files containing the frames constituting the example in the directory CB_HOME examples QUERIES where you have to replace CB_HOME with the ConceptBase installation directory The following files contain the objects of the Employee example expressed in frame syntax Employee_Classes sml Employee_Instances sml Employee Queries sml An alternative to interactively building a database is to s
149. depends on the database state at a certain point of time The global rule of dynamic stratification is that the answer to a predicate call A x may not depend on its negation not A x Such a clash can be detected by maintaining a stack of active predicate calls ConceptBase reports a violation of dynamic stratification in the log window of the CB client with a message STRATIFICATION VIOLATION indicating the predicate that participated in the violation Two flavors of error messages can occur e STRATIFICATION_VIOLATIONI The evaluation of a predicate P leads to a cyclic call to itself where in between a negated predicate Q occurs Hence P depends on Q and Q depends on P Consequently P indirectly depends on its negation e STRATIFICATION_VIOLATION2 While evaluating a predicate P a the system derives that P a would be true i e the fact P a is in the extension of the variable free predicate call P a This evaluation occurs in the context of a matching positive call P x where the system cannot prove that P a would be in the extension The matching call P x has the same arguments as P a except for certain variable positions In practice most rule sets are already statically stratified i e no violation can occur regardless of the data in the database Counter examples are in the CB Forum see http merkur informatik rwth aachen de pub bscw cgi 888832 in the models Russel sml and Win sml These examples are neither statically
150. discussed in section 2 5 As legacy support ConceptBase provides the pre defined classes Token SimpleClass Meta Class and MetametaClass to structure the object base into objects that have no instances tokens objects that have only tokens as instances simple classes objects that have only simple classes as instances meta classes and finally objects that have only meta classes as instances meta meta classes These classes are provided only for compatibility with older Telos specifications In fact an absolute hierarchy from tokens to simple classes to meta classes etc is not an essential ingredient of O Telos and in many situations too restrictive Instead meta class levels are implicitely expressed via instantiation If an object x is an instance of object c and object c is an instance of object mc then mc is also called a meta class of x and c a class of x Being a class or a meta class is relative to the object x that we consider For example mc is the class of c This implicit definition of the meta class concept is far more flexible than a fixed structure 1 There is virtually no limit in the meta class hierarchy there can be meta classes meta meta classes meta meta meta classes etc 2 A class can have object from different meta class levels as instances This is in particular important for extending the capabilities of the O Telos language An example of a class that has objects from different levels as instances is Proposi
151. ds some variables in the rule r Actions of an ECArule can update the database They will then lead to new entries in the event list that are processed just like described above The events are generated per action Tell Untell Retell and then followed by a delimiter i e ConceptBase will start processing the events after each Tell Untell Retell action 4 1 8 Switching Queues You can control the execution order of ECA triggers via coupling modes precedence priority and via a feature called queue switch The queue switch utilizes seperate trigger queues for ECA triggers Main queue q0 The main queue is the default queue It is processed under a first in first out regime When all triggers of the main queue are processed ConceptBase will stop with the ECA execution Sub queue q1 The sub queue q1 is initially empty and is filled by triggers from actions following a queue switch As soon as q1 is empty the system will resume processing of q0 Hence the end of the sub transaction is detected by running out of triggers in the sub queue User defined queues The FOR clause allow to generate dedicated trigger queues on the fly see below There are two ways to specify a queue switch The first is by including the keyword TRANSACTIONAL in the ON part of an ECArule e g ON TRANSACTIONAL Tell x in A As soon as an event e is matched against the event clause of a transactional ECArule the trigger queue is switched to q1 Subseque
152. e Layouts of CBGraph are stored with all information about graphical types true false InvalidObjectsMethod Specifies whether objects that have been identified as invalid should be marked or deleted mark delete DiagramDesktopBackgroundColor Background color of the desktop of CBGraph comma separated representation of an RGB value DebugLevel Level for debug messages Possible values are SEVERE WARNING INFO CON FIG FINE FINER FINEST according to the java util logging package Default is WARN ING 132 Appendix A Syntax Specifications A 1 Syntax specifications for Telos frames lt object gt gt lt objectname gt lt objectname gt lt inspec gt lt isaspec gt lt withspec gt lt endspec gt lt objectname gt lt inspec gt lt isaspec gt lt withspec gt lt endspec gt lt objectname gt gt lt objectname gt lt label gt lt bindings gt lt objectname gt SELECTOR1 lt label gt lt objectname gt SELECTOR2 lt objectname gt lt bindings gt gt lt empty gt lt bindinglist gt lt bindinglist gt gt lt singlebinding gt lt bindinglist gt lt singlebinding gt lt singlebinding gt gt lt objectname gt lt label gt lt label gt lt objectname gt lt inspec gt gt lt empty gt in lt classlist gt lt isaspec gt gt lt empty gt isA lt classlist gt lt classlist gt gt lt objectname gt lt objectname gt
153. e gives the maximum of the attributes in the specified category of an object wrt the order of lt and gt see section 2 2 MIN Attribute gives the minimum of the attributes in the specified category of an object wrt the order of lt and gt see section 2 2 PLUS computes the sum of two reals or integers MINUS computes the difference of two reals or integers MULT computes the product of two reals or integers DIV computes the quotient of two reals or integers IPLUS computes the sum of two integers result is an integer number IMINUS computes the difference of two integers result is an integer number IMULT computes the product of two integers result is an integer number IDIV computes the quotient of two integers and then truncates the quotient to the largest integer number smaller than or equal to the quotient ConceptBase realizes the arithmetic functions via its host Prolog system SWI Prolog Integer num bers on Linux are represented as 64 bit numbers yielding a maximum range from 2 1 to 264 1 SWI Prolog supports by default under Windows and Linux64 arbitrarily long integers Real numbers are implemented by SWI Prolog as 64 bit double precision floating point numbers ConceptBase uses 12 decimal digits E 2 2 String manipulation ConcatenateStrings concatenates two labels typically strings the two arguments can be expressions that are concatenated after their evaluation ConcatenateStrings3 concaten
154. e 22th VLDB Conference Bombay India 1996 Soiron R Kostenbasierte Anfrageoptimierung in deduktiven Objektbanken Diploma Thesis RWTH Aachen 1996 Stanley M T CML a knowledge representation language with application to requirements modeling M S thesis University of Toronto Ontario 1986 Staudt M Anfragereprdsentation und auswertung in deduktiven Objektbanken Diploma thesis Universitat Passau 1990 Stonebraker M ed Special Issue on Database Prototype Systems IEEE Trans on Knowl edge and Data Engineering Vol 2 No 1 March 1990 Wing J M A Specifier s Introduction to Formal Methods IEEE Computer No 9 pp 8 24 Sept 1990 172
155. e and access control is enabled by the CBserver GenericQueryClass CB_PermittedTest isA CB_User with parameter user CB_User res Resource op CB_Operation constraint cperm op in CB_ReadOperation and UNIFIES user this end There are plenty of ways to combine general and local versions of CB_Permitted yielding different access policies When using access control at least the module System should be protected Otherwise users could change essential definitions affecting all other users Examples for access control policies are in the HOW TO section of the ConceptBase Forum http merkur informatik rwth aachen de pub bscw cgi 2281940 It is very well possible to make access to a ConceptBase database completely impossible by errors in the definition of CB_Permitted For example one could deny access to any operation by the following simple rule CB_Permitted in GenericQueryClass isA CB_User with parameter user CB_User res Resource op CB_Operation constraint cperm FALS end E Ur In such cases one has to start the CBserver with disabled access control and repair the definition of the query CB_Permitted Access control is by default set to level 1 which just constrains the scope of an UNTELL to the local module You need to set the CBserver option s to 2 to fully enable access control see option s in section 6 79 5 6 1 Access to System module The access definition via the query CB_Permi
156. e evaluation of negated predicates but rather re order them at compile time to guarantee that all variables are bound at call time Tabled evaluation is also implemented in XSB http xsb sourceforge net and DES http www fdi ucm es profesor fernan des 6 7 Database persistency The default update mode is persistent In persistent mode all changes to the database are written to the file system at the directory specified in the parameter d Persistent mode is suitable when a CBserver runs for a longer period of time and is directly updated by application programs If ConceptBase cc is used for testing and modeling purposes the update mode nonpersistent is an interesting alternative We discuss two scenarios for the nonpersistent mode and one for the persistent mode Scenario 1 Single user modeling When a user needs to model a certain application domain with classes and meta classes he usually works with external Telos files aka source models file extension 90 sml These files can include comments like usual with program source code The recommended mode here is u nonpersistent without specifying a database The user can load the source models into such a non persistent server and make corrections to the source files in case of errors or design changes Here ConceptBase is mostly used to check and analyze the models Recommended options cbserver u nonpersistent mu disabled Scenario 2 Lab assig
157. e literature on deductive databases For the purposes of this manual consider the following rule forall p Position exists pl Position p moveTo pl and not pl in Win gt p in Win ConceptBase internally compiles such rules into a representation where Position moveTo and Win are predicate symbols forall p exists pl Position p and Position pl and moveTo p pl and not Win pl gt Win p Static stratification requires that one can consistently assign stratification levels numbers to the set of predicate symbols such that 1 If there is a rule with conclusion predicate A and positive condiction predicate B not negated then the level of A must be greater or equal the level of B 2 If there is a rule with conclusion predicate A and negated condiction predicate B then the level of A must be strictly greater the level of B In the example above the conclusion predicate Win depends on the condition predicate not Win Since we only can assign one level to Win we cannot find a static stratification for the above rule The same argument also works in case of multiple inter dependent rules Static stratification can be tested at compile time of a rule 46 Dynamic Stratification is an extension of static stratification i e any statically stratified rule set is also dynamically stratified It is not only considering predicate symbols but also the arguments with which a predicate is called at run time Obviously this
158. e of class ClassName is created The new instance carries the label ClassName as prefix with a system generated suffix appended to it The identifier of the created object is returned in the argument ID newLabel Prefix L A new label that is not yet used as object name is created The prefix must be an existing object name The 2nd argument should be a variable The type of the variable can be Label or a more specific class name CreateA ttribute AttrCat x y ID This predicate creates a new attribute for object x with value y in the given attribute category e g Employee salary The attribute will get a system generated label In contrast to the action Tel 1 A x ml y the attribute is also created if another attribute with the same attribute category already exists Other predicates to be invoked via Cal1 can be defined in a LPI file see Counter example below Events and actions may also be specified in a prefix syntax e g Tell x in Class instead of the longer form Tell x in Class Furthermore there are two simple builtin actions noop is not doing anything except that is succeeds and re ject aborts the current transaction If the execution of an ECArule leads to an update to the database i e via Tell or Unte11 then the updated database is subject to integrity checking If a violation is detected then the whole transaction is rolled back including the updates done by ECArules 4 1 5 Priorities The attributes priority
159. e query fireTransition t1 It is assumed that the ConceptBase server includes an active rule that is triggered by the query call Hence such calls can result in an update to the database CBGraph shall refresh its graph after performing the query call to show the effect of the database update to the graph You can also specify a click action with arity zero clickaction fire 0 In this case the name of the clicked object is not included as a parameter of the query call A click action like fireTransition is equivalent to fireTransition 1 Click actions let a graph directly interact with the ConceptBase server Each click on a node whose graphical type has a click action will result in a corresponding query call that triggers active rules as suming that there are active rules matching the query call The active rule in the CBserver can change the database state but it can also trigger calls to external programs You can also specify clickactions with two arguments like in clickaction playMove 2 In such cases CBGraph will prepend the username before the object name of the node that has been clicked The generated query call would look like playMove Jonny m1 Note that the query must have two arguments in this case e g GenericQueryClass playMove isA Position with parameter argl CB_User arg2 Move end Note that the first argument for the username must have a label arg1 that is lexicographically ordered before the lab
160. e state of an object base at a specific time By default all queries are evaluated on the current state of the object base version Now By selecting another version queries are evaluated wrt to a previous state of the object base Pre Parse Telos Frames If enabled the user interface parses the contents of a Telos editor before it is send to the server Thus syntax errors might be already detected at the client side Show Line Numbers Enables the display of line numbers in the Telos Editor window Use Save Options to memorize this setting for the next session of CBlIva Use Query Result Window If enabled the result of a query is shown in a separate window in a table view Look and Feel You can switch the look and feel to an other style Default and preferred is Metal Save Options Saves the current options for subsequent sessions of CBlva Edit Options Manually Complete and editable list of options for CBIva The contents is main tained in a file CBjavalnterface of the user home directory Help ConceptBase cc Manual Opens a window with the online version of this ConceptBase cc man ual 3Usually one only asks a single query call like Q v1 p1 However ConceptBase cc also supports comma separated lists of query calls like 01 v1 p1 02 c1 p2 Such lists of query calls are evaluated one after the other The results is merged into a single answer For technical reasons calls to builtin query
161. e which holds the Telos definition of sin You will have to restart the ConceptBase server after you have copied the LPI file into the directory of the ConceptBase database If you want the new function to be available for all databases you construct then you have to copy the file sin swi 1pi to the subdirectory 1ib SystemDB of your ConceptBase installation Note that your code might be incompatible with future ConceptBase releases If you think that your code is of general interest you can share it with other ConceptBase users in the Software section of the CB Forum http merkur informatik rwth aachen de pub bscw cgi 2768063 2 5 5 Recursive function definitions Some functions like the Fibonacci numbers are defined recursively ConceptBase supports such recur sive definitions If the function is defined in terms of itself then express the recursive definition in the membership constraint of the function fib in Function isA Integer with parameter n Integer constraint cfib S n 0 and this 0 or n 1 and this 1 or n gt 1 and this fib n 1 fib n 2 end The variable this stands for an answer object that fulfills the constraint cf ib Note that ConceptBase regards integers also as objects ConceptBase shall internally compile the disjunction into three formulas forall n this Integer n 0 and this 0 gt fib this forall n this Integer n 1 and this 1 gt fib this forall n this Integer n gt 1 and this fib n
162. e x You can use the db option for activating the saving loading of module sources and the materialization of query results within the database directory cbserver db MYDB This creates a single directory with both the binary database files the module sources and the material ized query results Further examples are available from the CB Forum athttp merkur informatik rwth aachen de pub bscw cgi 3097259 5 9 1 Post export command ConceptBase can only export textual query results Some output formats such as program source code can be further processed by calling appropriate tools This can be initiated manually or one can configure the directory specified in the views option with a command file postExport sh This command file shall then be executed by the CBserver whenever a saving operation on the views directory has taken place You have to regard that the command is executed in the context of the CBserver Hence it is executed in the directory in which the CBserver was started You should therefore change to the views directory inside the post export command file like shown in this example of postExport sh bin sh cd dirname 0 cp xml home meee public The second line changes to the views directory The third line does the specific processing of the materialized query results Here we just copy the file More interesting are calls to transformation routines You should remove the write permission
163. ect it with the current server and load the Employee object The CBGraph Editor described in detail in section 8 2 allows you to display arbitrary objects from the current onceptBase server Then we select the Employee object and choose the Sub classes option from the context menu available via the right mouse button We choose to only display explicit subclasses from the submenu and select the Manager object The displayed graph is now expanded figure 8 16 Now we expand the node Manager a subclass of Employee by choosing the menu item Instances from the popup menu for Manager We select the menu item Show all to display all instances of Manager The resulting graph is shown in figure 8 17 123 localhost4001 Figure 8 17 The resulting graph after expanding with the instances of Manager Note that different object types are represented by different graphical objects The instances of Manager are shown only as grey rectangles because they are normal individual objects The nodes Manager Salesman Employee etc are shown as ovals since these nodes are instances of the system class 124 SimpleClass see for a full description of graphical object semantics Appendix C One can move nodes and links by selecting a node or a link and then holding down the left mouse button while moving the cursor to a different position When the button is released the selected object will be located at the current position
164. ect a graphical type for the object Note that the selection of the graphical type has no effect in the database e g by selecting the graphical type of a class ClassGT the object will not declared as an instance of Class If you have performed the commit operation the object will get the correct graphical type from the server Creating Instantiations In the dialog for instantiations you have to enter the name of the instance and the name of the class in the two text fields If the object entered does not yet exist it will be created and represented in the default graphical type Creating Specializations This dialog is similar to the one before except that you specify here the name of the subclass and the name of the superclass Objects that do not exist yet will be created and represented in the default graphical type Creating Attributes This is the most complex dialog as you have to specify the source the label the value and the category of the attribute The source and the value or destination of the attribute are normal object names The label may be any valid Telos label The attribute category has to be a 118 select expression specifying an attribute category e g Employee salary see chapter 2 The attribute category can be selected from a listbox by clicking on the Select button next to the text field of the attribute category All attribute categories that apply to the current source of the attribute will
165. ect base As an example consider the following formula forall x Emplye not x boss Mary With the example object base of section 2 1 we find two errors There are no objects with names Emplye and Mary There are two possible cases to violate the second part of the restriction The first case is illustrated by an example forall x Proposition y Integer x salary y gt y lt 10000 In this case the classes of x Proposition and any of its superclasses have no attribute labelled salary Therefore the predicate x salary y cannot be assigned to an attribute of the object base Instead one has to specify forall x Employee y Integer x salary y gt y lt 10000 or forall x Manager y Integer x salary y gt y lt 10000 depending on whether the formula applies to managers or to all employees The second clause of the predicate typing condition is closely related to multiple generalization instan tiation Suppose we add new classes Shop Guest and Guest Employee to the given class Employee Shop in Class end Since any object is an instance of Proposition ConceptBase will include this class when searching the concerned class of an attribution predicate 25 Guest in Class with attribute dept Shop end GuestEmployee in Class isA Guest Employee end The following formula refers to objects of class GuestEmployee and their dept attribute The prob lem is that t
166. ectly on Ok The new instantiation link will be added to the graph Now we are satisfied with our changes and want to commit them in the server So far the changes have been stored in an internal buffer of CBGraph and have not been sent to the server We click on the Commit button in the upper right corner CBGraph generates now Telos frames for the added objects and sends them to the server If we did not make an error all changes should be consistent and accepted by the server This is shown by the appearing message box Changes committed If an error occurs an error 127 CBlva ConceptBase cc User Interface in Java File Edit Browse Options History Windows Help mer Tells content of Telos Editor Telos Editor 1 Employee in Class SimpleClass with 2 attribute 3 name String 4 salary Integer 5 dept Department 6 7 8 boss Manager education String rule 9 bossrule forall e Employee m Manager 10 exists d Department e dept d and d head m ial gt ebossm 12 constraint 13 SalaryBound forall e Employee b Manager x Integer y Integer History Window 6 ERROR Version Now 2015 09 11 09 45 UTC Module oHome Figure 8 21 Trying to add an attribute to the class Employee with the resulting error report message will displayed instead The graphical editing is an alternative to the textual editing via the Telos Editor It is appropria
167. ed as parameter substitutions In ConceptBase an answer format is an instance of the new pre defined class AnswerFormat Individual AnswerFormat in Class with attribute forQuery QueryClass order Order orderBy String head String pattern String tail String fileType String end 51 The first attribute assigns an answer format to a query class a query may have at most one answer format The second and third attribute specify the sorting order of the answer i e one can specify by which field an answer is sorted and whether the answer objects are sorted ascending or descending much like in SQL The head pattern and tail arguments are strings that define the substring substitution when the answer is formatted They contain substrings of type expr that are replaced The head and tail strings are evaluated once independent form the answer to the query Usually they do not contain expressions but only text The response to a query is a set of answer objects A1 A2 The pattern string is evaluated against each answer object For each answer object the derivation of the pattern is put into the answer text Hence the complete answer consists of derivation of head string derivation of pattern string for answer object Al derivation of pattern string for answer object A2 derivation of tail string The fileType attribute is explained in section 3 4 In the next sections
168. ed libraries Under Linux Unix can check whether all required libraries are installed by export PATH CB_HOME bin SPATH ldd CB_HOME CBvariant bin CBserver The installation of ConceptBase cc requires about 50 MB of free hard disk space The main memory requirements depend on the size of the object base loaded to the ConceptBase cc server The initial main memory footprint is just about 8 MB We recommend about 20 MB of free main memory for small appli cations and 200 MB and higher for large applications of ConceptBase cc The server can handle relatively large databases consisting of a few million objects Response times depend on the size of the database and even more on the structure of the query Since clients connect to a CBserver via Internet the server requires the TCP IP protocol to be available on both the client and the server machine can be the same computer for single user scenarios Note that a firewall installed on the path between the client and the server machine might block remote access to a CBserver The default port number used for the communication between server and client is 4001 It can be set to another port number by a command line parameter The CBserver is by default multi user capable i e multiple clients can connect to the same CBserver This feature is by default disabled when you start the CBserver from within the user interface See section 6 for more details The standard ConceptBase cc client are C
169. el of the second argument arg2 The username is the same that is used by the CBGraph tool to register to the CBserver That user is then stored as instance of the predefined class CB_User Another option with click actions is to limit the scope of nodes and links in the current diagram that are refreshed after calling the click action The click action can invoke an active rule which changes the database state Consequently certain objects in the diagram may get a new graphical type By default CBGraph shall refresh all nodes and links in the diagram after executing a click action This can be rather 148 slow when the displayed graph is large The option n allows to limit the refresh to the neighborhood of the selected object The neighborbood is defined as the set consisting of the selected object the direct neighbors object of the selected object the direct neighbors of those neighbors and all the links in between Note that this only refers to the objects displayed in the graph You can enable the neighbor refresh by adding the string n to a click action like in clickaction fireTransition n The n option is not guaranteed to work correctly since some objects outside the neighborhood may be affected by the click action Hence only use this when you know that the effect is bound to the neigh borhood and when the displayed diagram has all the required links displayed to compute the neighborhood You can enable a
170. elow are allowed The effect of ASKquery in an answer format is that the above query call is evaluated and the AS Kquery expression is replaced by the complete answer to the query In terms of the substitution the following rule is applied ASKquery Q subst1 subst2 FRAME gt X where X is the result of the query call O subst1 subst2 after derivation of the arguments subst1 subst2 etc This sequencing is important since an ASKquery call can contain terms that are subject to substitution e g ASKquery MyQuery this catl paraml this x1l x2 FRAME ConceptBase will always start to evaluate left to right and the innermost terms before evaluating the terms that contain inner terms Hence the derivation sequence is ASKquery MyQuery this catl paraml this xl x2 FRAME L gt ASKquery MyQuery alpha paraml this xl x2 FRAME 12 gt ASKquery MyQuery alpha paraml this name x2 FRAME rl gt ASKquery MyQuery alpha paraml smith x2 FRAME 13 gt ASKquery MyQuery alpha paraml smith param2 FRAME 14 The answer is 15 where we assume the following example substitution rules rl x1 gt name 12 this catl gt alpha 13 this name smith r4 x2 gt param2 r5 ASKquery MyQuery FRAME gt The answer is This guarantees that the query call is groung i e does not contains terms whi
171. emented in Java which supports editing ad hoc querying and browsing CBlIva The tool CBGraph supports editing diagrams extracted from the database and CBShell is a command line shell for interacting with the database Although ConceptBase cc provides multi user support and an arbitrary number of clients may be con nected to the same server process ConceptBase cc does not yet support concurrency control beyond a forced serialization of messages 1 3 Hardware and software requirements The ConceptBase cc server CBserver can be compiled on at least the following platforms including e 1386 CPUs under Linux Kernel 2 4 or higher e 164 AMD64 CPUs under Linux Kernel 2 4 or higher Pre compiled binaries are provided for Linux Compilation from the ConceptBase cc sources on Mac OS X and Windows and other platforms should be possible as well though we cannot provide support for them See instructions distributed with the ConceptBase cc source files for further details Implementation languages for the CBserver are Prolog in particular for logic based transformation and compilation tasks and C C in particular for persistent object storage and retrieval The ConceptBase cc usage environment CBIva CBGraph CBShell executes on any platform with a compatible Java Virtual Machine Java 6 Java 7 or Java 8 should all work We recommend the most recent stable version of Java 7 or Java 8 The CBserver is dynamically linked with a couple of shar
172. ep include the following comment as the first line of myscript usr bin cbshell Then make the script executable chmod u x myscript You can then directly call the script by simply typing its name myscript The direct call is equivalent to the call cbshell myscript 7 7 CBShell scripts within regular shell scripts CBShell offer the basic commands to interact with a ConceptBase server However it lacks control struc tures such as loops and conditions It also cannot invoke arbitrary programs Regular shell scripts such as the Bourne shell of Unix Linux do provide these capabilities and thus it is a natural idea to integrate CBShell scripts within regular scripts to accomplish more sophisticated automation tasks As a first step you should make the CBShell script executable and declare in its first line usr bin cbshell q This allows to pass parameters that include special characters to the CBShell script Assume that the CBShell script ascript was declared that way Then it can be called in a Bourne shell like ascript Jet 400 MyClass The option q prepares the CBShell to treat parameters with single quotes in a special way Assume further that ascript has the following content usr bin cbshell q File ascript tell 1 in 2 end CBShell will internally expand the quoted parameter Jet 400 to Jet 400 and then execute tell Jet 4001 in MyClass end The res
173. er Tobias Sch neberg Ren Soiron optimizer Martin Staudt CB server query component Kai von Thadden query component Hua Wang anwer formatting Claudia Welter Thomas Wenig and others If you ever contributed to the ConceptBase source code and you are not listed here then give us a note Contents 1 Introduction 1 1 Background sad ISO sostenerse ROE ES OLR EE ES LLL Telos nds EOS oi ii ia a da 12 The srchitecture at ConcepiBaseho cors sp ke a ER Bee 1 3 Hardware and software requirements 00000000 eee 14 Overview ol this miatial lt so sc he eR RR a a AS a 15 Ditlerences to catlier Versions se cou we ew e l License fmGenie SS SE ee SEA Re wo 1 7 Diselaumer and rights oe eR a ee eae eS 2 O Telos by ConceptBase cc 21 Frame and network representation s o s co ta bbe oS ade ee ee eS 242 Wales and COMSHAINIS cg a cS a ee ae Ee eR eS ER ee ee Ba 22 1 Basse predicaies su eite rert pew ee beans Bade ES Yea o 222 NOTES ODA HEDUC N lt es 2c Ge ER eS SRS EEE SRS S 2 2 3 Assigning attribute categories to explicit attributes 22A Reserved WORMS s ec coe eones ea bb we ee he eee eS ee ae 22 5 Comparison predical s ooo ee ee ewe vow VI a i oo oe Sg ae DGS oe Bes Se ete eee Pe ee oe ees 2 2 7 Semantic restrictions on formulas ee eee eR 22 8 Rule and constraint Syntax o e o cee ee Re SRA ey ee E S 229 NGA TORMMISE lt lt 5 a e Dew ee eS ER ee EY Re 2 210 PFurtherobject ref
174. er is updated Graphical Palette and Graphical Types When a connection to a server is established CBGraph loads the graphical palette and all its graphical types including their properties and other information If an object has to be shown the server sends only the name of the graphical type the information about the properties are taken from the cache Thus if you change the graphical palette or a graphical type after CBGraph has established the connection this change will not be visible in CBGraph There is currently no method implemented to update the cache manually Graphical Types of Objects When an object is loaded from the server also the graphical type for this object is retrieved The graphical type of the object is updated when you invoke the Validate and Update operation from the Current Connection menu Lists of super sub classes classes instances attributes The lists in the popup menu or in the tree like view of an object are produced by evaluating queries To reduce the communication between client and server each query will only be evaluated once when the corresponding popup menu should be shown or when the part of the tree should be shown The result will be stored in a cache for each object This cache is emptied when you invoke the Validate and Update operation from the Current Connection menu 8 2 11 Graph files Graph files extension gel are binary files that store the current state of
175. erentes a s Ck eee SE eee Ee PE SEES EMAL S 2 2 11 User definable error messages for integrity constraints 22 12 Immutable properties 20 6 6 edb eae erp kih eee eR eas Za Query CIOS oc ec rs Eee eS ss OS 2 3 1 Query definitions versus query calls s scree ee ee ee 2 3 2 Query classes and deductive integrity checking 2 3 3 Nested query calls and shoricuts 5 544 566 2 bc eee ee bees zoe Remedauers calls cocidos E SHES RDS EAE SE wR ES 2a View EMMONS 6 saa e eS RO OR RE Ee OS eR E Se Re 2 TUMON cis ay a AA As ts e dee 23 1 Puncions ae Special guernes socorro e ds 2 5 2 Shortcuts for function calls and functional expressions 2 5 3 Example function calls and definitions o 204 Programmed imcioDs i lt e es es irse e eoe e E e a o eE 2 5 5 Recursive function definitions gt s sss srep A a A 26 Query evaluation strategies o lt oo ceras sa ee ee 2 7 Datalop quemes andiules s coco 2 05544 255 Be RR Re rr e Zi Betended quer model ooo epe d ee eee EERO Se ee E AA a ee Pe ERO EER OS DEER eS EH HE AS oS Zoe Beampley ob ees a b desea ath poe es Gas be ee 4 3 Answer Formats for Queries al BASICAS IIED Go eee A A Oe ee EPS SSS 3 2 Conseils in answer ON S ii ek E Se OG OPER ee EE eS 321 Simple expressions m Paes ok Oe ee hee eee APR eS 322 Pr denned variables III 32 3 Tterationsoverexpressions ce eee Pe eS ewe SEPA A 324A Special charac
176. ery calls without parameters and returns the result in the Telos editor window Ask Query Call The query calls see section 2 3 1 listed in the Telos editor are asked and the result is returned in the Telos editor window Load Object Load the Telos frame of an object into the Telos editor View Object as Tree Opens a new window and shows the object in tree browser Browse New Telos Editor Opens a new Telos editor see section 8 1 4 Display Instances Opens the display instances dialog see section 8 1 6 Frame Browser Opens the frame browser window see section 8 1 7 Display Queries Shows all queries stored in the current database and provides a facility to call these queries see section 8 1 8 Display Functions Shows all functions stored in the current database see section 8 1 9 Query Editor Opens the query editor see section 8 1 10 Graph Editor Opens the CB Editor graphical browser see section 8 2 If the interface is con nected to a server CBGraph will also establish a connection to this server and ask for the graphical palette the initial object to be shown and the module context see section 5 Other wise CBGraph will start with no connection Options Set Timeout Set the number of milliseconds the user interface waits for a response of the server Select Module Select the current module see section 5 Select Version Select or create a new version A version is a special object that represents th
177. esteolor OD 0 linecolor 0 525 144 shape i5 cb graph shapes Rect implementedBy implBy i5 cb graph cbeditor CBIndividual priority pz e end x graphical type for relationships Class RelationshipGtype in JavaGraphicalType with 158 property bgcolor 255 0 0 textcolor 0 0 0 linecolor 3 0 0205 shape i5 cb graph shapes Diamond implementedBy implBy i5 cb graph cbeditor CBIndividual priority p 13 end x graphical palette Class ER_GraphBrowserPalette in JavaGraphicalPalette with contains defaultIndividual cl DefaultIndividualGT contains defaultLink c2 DefaultLinkGT contains implicitIsA c3 ImplicitIsAGT contains implicitInstanceOf c4 ImplicitInstanceOfGT contains implicitAttribute c5 ImplicitAttributeGT contains c6 DefaultIsAGT c7 DefaultInstanceOfGT c8 DefaultAttributeGT c14 EntityTypeGtype c15 RelationshipGtype cl6 InconsistentGtype end EntityType with rule EntityGTRule forall e EntityType A e graphtype EntityTypeGtype EntityGTMetaRule forall x VAR exists e EntityType In x e gt A x graphtype EntityTypeGtype end RelationshipType with rule RelationshipGTRule forall r RelationshipType A r graphtype RelationshipGtype RelationshipGTMetaRule forall x VAR exists r RelationshipType In x r gt A x graphtype RelationshipGtype end To activa
178. f graphical types is quite simple Place the source code of your Java implementation of a grahical type in the subdirectory Product POOL java i5 cb graph cbeditor of your CBPOOL import i5 cb graph cbeditor x import javax swing x import java awt Component xx x An example for a user defined CBUserObject public class CBButton extends CBUserObject public Component getSmallComponent JButton jButton new JButton this getTelosObject toString if hasProperty bgcolor jButton setBackground CBUtil stringToColor getProperty bgcolor return jButton The source code of the above example is included in the cbeditor directory in file CBButton java So you can indeed use i5 cb graph cbeditor CBButton instead i5 cb graph cbedi tor CBIndividual in graphical types to see the effect C 3 4 Shapes The package i5 cb graph shapes contains several shapes which might be useful for the ConceptBase CB Graph Editor To use these shapes you can either specify the full path e g i5 cb graph shapes Cloud or just the last part like Cloud as value of the property shape of a graphical type 150 class name graphical representation Arrow2 ArrowL ArrowR DoubleArrow DownArrow various arrows Banner a banner Circle a circle Cloud a cloud shape Cross a cross like the red cross Diamond a diamond rhombus DiRect DiRectL DiRectR direction sig
179. f no long title is specified then CBGraph uses the name of the palette itself for forming the window title if the longtitle is set to the empty string then it will cause CBGraph not to include it in the title of the graph windows The purpose of the background image is to highlight regions of a graph e g regions for instances classes and meta classes Another typical use is to support canvasses like the business model canvas http merkur informatik rwth aachen de pub bscw cgi d3595098 bmg egadget png used in the Telos models described in the CB Forum at http merkur informatik rwth aachen de pub bsew caids 5950987 If a background image is specified for a palette shown in an internal window of CBGraph then CB Graph links it with the size and zoom factor of the internal window Initially the zoom factor is set to 100 and the internal window size is set to display the image in its original resulution provided that it fits well to the screen size You can then resize the internal window and the background image shall be resized accordingly Analogously the image is resized when the zoom factor changes The background image is also stored in the GEL file see section 8 2 3 C 2 2 Default graphical types For the standard objects there are a number of predefined graphical types There are contained in the graphical palette Default JavaPalette which is used by default by the CBGraph Editor 145
180. f the current transaction typically has the structure name address transactiontime the time when the current transaction was started has format Y Y Y Y MM DD hh mm ss and is based on Coordinated Universal Time UTC formerly known as Greenwhich Mean Time cb_version the version number of ConceptBase cb_date_of release the version number of ConceptBase currentmodule is expanded to the name of the current module currentpath is expanded to the complete module path starting with root module System that was active when starting the transaction database is expanded to relative or absolute path of the database that was specified with the d option of the CBserver section 6 if no database was specified the variable is expanded to lt none gt ConceptBase also adds those command line parameters that deviate from their defaults to the set of pre defined variables The most common ones are see also section 5 9 loadDir directory from which the CBserver loads Telos source files at start up command line param eter load saveDir directory into which the CBserver saves Telos sources of modules at shut down or client logout command line parameter save viewDir directory into which the CBserver materializes results of certain queries command line pa rameter views Moreover if the current transaction was a call of a query like MyQuery vl paraml then param1 will be evaluated to v1 This makes all parameter sub
181. false when the first frame has been processed The predicate IS1ASTFRAME is true when ConceptBase starts with processing the last answer frame for a given query Otherwise it is false An example for conditional expressions is provided in the CB Forum see file csv sml in http merkur informatik rwth aachen de pub bscw cgi 861803 In most cases the IF THENELSE construct can be avoided by a more elegent query class formulation e ISLASTERAMI Gl 3 2 9 Views and path expressions If the answer format is defined for a complex view then path expressions like this cat2 cat21 for the parts of the complex answer can be defined An example for use of answer formats for views is given in views sml The reader should note that complex path expressions can only refer to components that were de fined as retrieved computed or inherited attributes in the view definition For example one cannot refer to this dept budget in the example view EmpDept in views sml since it is not a retrieved attribute of the dept component of the view definition EmpDept The second expression of the answer format EmpDeptFormat uses the builtin procedure UO It removes the quotes from a string Analogously a procedure QT can be used to put quotes around a term 57 3 3 Parameterized answer formats The general way to use an answer format for a query is to define the attribute forQuery Another possibil
182. for all objects with a label that match the given wildcard expression Only simple wildcards with a star at the end are allowed rename Renames an object from oldname to newname This is a low level operation directly on the symbol table that works directly on the symbol table It only checks whether newname is not already used as label for a different object no other consistency checks are performed The parameters have to be given in the order newname oldname 166 Appendix F CBserver Plug Ins An LPI plug in logic plug in is essentially a small Prolog program that is attached to the CBserver at startup time It extends the functionality of the CBserver for example for user defined builtin queries A plug in can also interface to the services of the operating system You can create a file like myplugin swi 1pi to provide the implementation for your user defined builtin queries or for action calls in active rules see section 4 You can use the full range of func tions provided by the underlying Prolog system here SWI Prolog http www swi prolog org and the functions of the CBserver to realize your implementation You may consult the the CB Forum for some examples at http merkur informatik rwth aachen de pub bscw cgi 2768063 You find there examples for sending emails from active rules and for extending the set of builtin queries and functions F 1 Defining the plug in Once you have coded your file myplugin swi
183. for the post export command to prevent that it can be over written by the materialization function Under Unix Linux this can be achieved via the command chmod u w postExport sh This setting must be done once within the views directory 2Overwriting the post export command file may be a desired feature You can then generate it from within the CBserver like any other file in the views directory This is however a major security hole and we strongly discourage to use this feature 83 Chapter 6 The ConceptBase cc Server The ConceptBase cc server CBserver offers its services via a TCP IP port to client programs The main services are to TELL or UNTELL O Telos objects and to ASK queries to the database The operations are called by clients for example the user interfaces described in section 8 An arbitrary number of clients can connect to a CBserver The CBserver is started by a command line cbhserver lt params gt assuming that the installation directory of ConceptBase cc is added to the search path of executable programs If it is not on the search path then simply change the current directory to the installation directory of ConceptBase cc or use its absolute path of the cbserver script 6 1 CBserver parameters The following parameters are available for the cbserver command d dbdir Set database dbdi r to be loaded If the database does not exist it is created and initialized with the O Telos pre defined o
184. g arithmetic expressions Functions are also special query classes hence you you use them whereever a query class is expected Subsequently we introduce first how to define and use functions like queries Then we define the syntax of functional expressions and the definition of recursive functions such as the computation of the length of the shortest path between two nodes 2 5 1 Functions as special queries Assume that an attribute either explicit or derived has at most one filler For example a class Project may have attributes budget and managedBy that both are single valued A third attribute projMember 1s multi valued 14A function returns the empty set nil if itis undefined for the provided input values 40 Project with attribute single budget Integer managedBy Employee attribute projMember Employee end The two functions get Budget and getManager return the corresponding objects getBudget in Function isA Integer with parameter proj Project constraint cl proj budget this end getManager in Function isA Employee with parameter proj Project constraint cl proj managedBy this end The two functions share all capabilities of query classes except that the parameters are required one cannot call a function without providing fillers for all parameters and that there is at most one return object per input value Function can be called just like queries for example get Budget P1 pro3
185. g generated formula has to be deleted If additional attributes are instantiated to Proposition necessary additional formulas have to be created The process of supervising the transactions is quite expensive and if it slows down the overall performance too much some of the meta formuals can be disabled temporarily Untelling a meta formula removes all the code generated Many more examples for meta formulas e g for defining transitivity of attributes are available from the CB Forum http merkur informatik rwth aachen de pub bscw cgi 1042523 162 Appendix E Predefined Query Classes This chapter gives an overview of the query classes which are predefined in a standard ConceptBase in stallation The names of parameters of the queries are set in typewriter font Most of the queries listed here are used by the ConceptBase user interface CBlIva to interaction with the CBserver A normal user typically formulates queries herself In fact most queries listed below are very simple and directly representation as query class An exception are the functions for computation and counting They cannot be expressed by simple query classes but extend the expressiveness of the system E 1 Query classes and generic query classes These queries can also be used in the constraints of other queries E 1 1 Instances and classes ISINSTANCE Checks whether obj is instance of class The result is either TRUE or FALSE IS_EXPLICIT INSTAN
186. g such predicates first can lead to faster elimination of free variables and thus lead to better query and ECA performance The default value is 3 eca emode controls the ECA sub system Possible values are unsafe ECArules are evaluated without safeguarding recursive deductive rules of f ECArules are not evaluated even if some are defined and safe ECA rules are evaluated with safeguarding recursive rules this is the default Use the mode unsafe if none of your ECArules calls recursive predicates on the newest database state This may lead to a limited speed up eo eomode controls the optimization of conditions of ECArules Possible values are on default and off The optimization is done by a re ordering of predicates in the condition Hence you only want to turn of optimization to gain full control over the order of evalution in ECA conditions The concerned class is a consequence of the predicate typing condition of section 2 2 You can roughly compare it to typing of variables in programming languages 86 load dir specifies the directory from which the CBserver will load module sources at start up time The module sources must have file names starting with System and file type sm1 Typically they are generated via the save flag in the preceding session of the CBserver The default is none i e no module sources are loaded at CBserver start up save dir specifies the directory into which to save certain textual excerpts of
187. g terms It is included only for historical reasons lt SMLfragment gt gt SMLfragment lt what gt lt in_omega gt lt in gt lt isa gt lt with gt lt what gt gt what lt object gt lt in_omega gt gt in_omega nil in_omega lt classlist gt lt in gt gt in nil in lt classlist gt lt isa gt gt isa nil isa lt classlist gt lt with gt gt with nil with lt attrdecllist gt lt classlist gt gt class lt object gt lt classlist gt class lt object gt lt attrdecllist gt gt attrdecl lt attrcategorylist gt lt propertylist gt lt attrdecllist gt attrdecl lt attrcategorylist gt lt propertylist gt lt attrcategorylist gt gt nil lt labellist gt lt propertylist gt gt nil lt propertylist2 gt lt propertylist2 gt gt property lt label gt lt propertyvalue gt lt propertylist2 gt property lt label gt lt propertyvalue gt lt propertyvalue gt gt lt object gt lt selectExpB gt enumeration lt classlist gt lt SMLfragment gt lt selectExpB gt gt selectExpB selectExpB selectExpB selectExpB lt restriction gt lt selectOperator gt lt selectExpB gt lt restriction gt lt selectOperator gt lt object gt lt object gt lt selectOperator gt lt selectExpB gt lt object gt lt selectOperator gt lt object gt
188. h query class individually You tag only those query classes that are used in rules or constraints This individual treatment saves some code generation at the expense of being less uniform Such an individual tagging would look like BaseUnit in QueryClass MSFOLrule isA Unit with constraint cl not exists s Unit sub From s this end ConceptBase will reject an integrity constraint or rule if it refers to a query class that is not an instance of MSFOLrule If a query class is defined as instance of MSFOLrule then it should not have a meta formula as constraint This is a technical restriction that can easily be circumvened by using normal deductive rule For example instead of the query class 13Tf the CBserver option cc is set to off we also allow calls to generic query classes in rules and constraints In such cases incremental integrity checking will be incomplete and thus potentially wrong Only experienced users should employ them 36 UnitInstance in QueryClass MSFOLrule isA Proposition with constraint cl this in Unit end you should define UnitInstance in Class with rule rl forall x VAR x in Unit gt x in UnitInstance end The example uses the macro predicate x in Unit explained earlier in this section It is equiv alent to the sub formula exists c x in c and c in Unit 2 3 3 Nested query calls and shortcuts ConceptBase has capabilities to form nested expressions from generic query
189. han having to define separate modules for each user explicitely you can just define a certain module to be an instance of Aut oHomeModule LectureModule in AutoHomeModule with exception el mary end mary in CB_User with homeModule ml LectureModule end john in CB_User with homeModule ml LectureModule end You can also define a rule to assign all or a subset of users to this module CB User in Class with rule homeRule forall u CB_User u homeModule LectureModule end Here user john a student will be automatically be assigned to a new module M_john that is created as sub module of LectureModule User mary presumably a teacher is defined to be an exception to this rule and she will get the home module LectureModule By this one can reduce the chances of unwanted interferences between users of the module LectureModule Still all users can read the definitions in the module Lect ureModu1e and its submodules unless access restrictions are defined see section 5 6 The simplest way to separate the workspaces of any user is to define oHome in AutoHomeModule end In this case no user needs to be defined explicitely as instance of CB_User and still will get assigned her own sub module to work in The auto home module becomes active as soon as the module is declared as instance of AutoHomeModule If you want to enable oHome as auto home module from the very beginning when a database is created then you can activate it by
190. hat only objects that match the query constraint are in the answer Particularly the categories computed_attribute and retrieved_attribute require that at least one filler for the respective attribute is present in an answer object Use ConceptBase views View and inherited attribute in case that zero fillers are also allowed for answers There are few other simple expressions that may be useful They just list attributes without having to refer to specific attributes this attrCategory denotes all attribute categories that are present in an answer object Example For answer object A this attrCategory evaluates to cat1 cat2 this attribute lists all attribute labels occuring in an answer object Example for answer object A this attribute evaluates to Llabel11 label12 label21 this attribute lists all attribute values occuring in an answer object Example for answer object A this attribute evaluates to v11 v12 v21 this oid displays the internal object identifier of the answer object this For the answer object A these expressions induce the following additional substitution rules this attrCategory Catl cat2 this attribute gt labelll labell2 label21 this attribute vl1 v12 v21 53 3 2 2 Pre defined variables The following variables can be used in the head tail and pattern of an answer format They do not refer to the variable this user outputs the user name o
191. he Java Virtual Machine if the property is defined The CBShell utility can be used in Unix pipes to extract textual output The CBserver and pass it to subsequent programs as input To do so you should start the CBserver with tracemode no and using the showAnswer command of CBShell to specify the elements to be written to standard output The CBShell script below realizes the extraction of Graphviz http graphviz org specifications from ConceptBase cc Command The last line of a CBShell script file should not be a comment line Otherwise CBShell fails to recognize the end of file correctly 96 File myscript startServer u nonpersistent t no tellModel ERD graphviz2 tellModel UniversityModel ask ShowERD UniversityModel erd OBJNAMES FRAME Now showAnswer exit Gl The complete example is available from the CB Forum at http merkur informatik rwth aachen de pub bscw cgi 2519759 Another resource for CBShell scripts is the list of test scripts at http merkur informatik rwth aachen de pub bscw cgi 2596438 7 3 1 Argument delimiters If an argument to a CBShell command spans multiple lines or contains several words separated by blanks then you have to enclose it in double quotes being the default argument delimiter Double quotes are also used for St ring objects in Telos frames These have to be escaped like in the following example tell Peter with comment ab
192. he actions of the DO part of the ECArule are executed immediately after the evalu ation of the condition Otherwise the ELSE actions are executed provided that the ECArule has an ELSE part Earlier ConceptBase releases used the keyword commit instead of noop The semantics was the same We continue to support the use of commit in legacy ECArules 63 The answer to the evaluation of the condition of an ECArule is the set of all combinations of variable fillers that make the condition true The modes Immediate and ImmediateDeferred differ considerably from the mode Deferred the condition of the ECArule is evaluated while not all frames of the current transaction are told resp untold So a quoted predicate like x in Class will be evaluated against a database state in which only those frames of the current transaction are visible resp invisible that were told resp untold before the ECArule was triggered The default is Immediate ConceptBase shall enforce a first in first out sequencing of ECArules with modes ImmediateDeferred and Deferred This sequence will enforce the complete execution of a triggered ECArule before the next rule triggering is handled The strict sequencing avoids intertwining of action executions of multiple ECArule threads So if the answer to a condition of an ECArule has multiple entries then the actions belonging to the respective answers are executed in a sequence in which no action of another ECArule is ca
193. he communication between ConceptBase client and server if a lot of error messages are generated The default is 20 cc ccmode predicate typing controls to which extent the CBserver applies strict typing of attribution predicates x m y occurring in the membership constraints of query classes If the mode is set to strict default attribution predicates without a unique concerned class shall not be accepted If the mode is set to extended the search for concerned classes shall include subclasses see section 2 2 7 If the mode is set to of f ConceptBase cc also accepts queries with unstrictly typed attribution predicates The strict mode is preferable since it avoids certain semantic errors Deduction rules and integrity constraints may never violate the predicate typing condition even if the mode is set to off An example for a query using non strict predicate typing is available from the CB Forum see http merkur informatik rwth aachen de pub bscw cgi 1270138 mu mumode multi user mode specifies whether the CBerver should run in multi user mode value enabled or in single user model value disabled By default the multi user mode is en abled allowing multiple users with different user names to connect to the CBserver In single user mode only clients started by the same user identified by her name can connect to the CBserver The single user mode is recommended if you want to block other users from logging into your CBserver Sin
194. he user An example violation is bill in Person with marriedTo ml eve end ve in Person end One can also define a hint for the meta level constraint that refers only to a non empty subset of the meta variables If a hint for a meta formula cannot be substituted as shown avove ConceptBase will not issue the hint but rather the text of the generated formula Examples of user defined error messages can be found in the ConceptBase Forum at http merkur informatik rwth aachen de pub bscw cgi 1543277 2 2 12 Immutable properties Immutable attributes cannot be changed retold once they are defined for their respective source object For example the two spouses in a marriage contract cannot be changed once the marriage contract object has been created Key attributes in the entity relationship model are another example Once an entity gets its key the key may never be changed Of course the object as a whole can be removed ConceptBase provides an attribute category for such objects Proposition with attribute immutable Proposition end The semantics cannot be expressed by a static integrity constraint but by an active rule that guards the deletion of immuntable attributes See also http merkur informatik rwth aachen de pub bscw cgi d3452001 Immutable sml txt in the CB Forum The immutable attribute category is pre defined in ConceptBase but the active rule implementing its semantics is not Include it from the CB Forum an
195. her query class This is the second way of query recombination Retrieved attributes and super classes already offer a simple way of querying a knowledge base pro jection and set intersection For more expressive queries there is an predicative extension the so called query constraint We use the same many sorted predicative language as in section 2 2 for deductive rules and integrity constraints and introduce a useful abbreviation Let Q be a query class with a constraint F that contains the predefined variable this Then the query class is essentially an abbreviation for the two deduction rules forall this F gt Q this forall this Q this gt this in Q The deduction rules are generated by the query compiler and only listed here for discussing the meaning of a query class The variable this stands for any answer object of Q We call this also the answer variable The sub formula F is combined from the query constraint F and the structural properties of the query in particular the super classes and the retrieved attributes Each super class C of O contributes a condition this in C to the sub formula F Each retrieved attribute like a D contributes a condition this a v and v in D toF Moreover each retrieved attribute add the new argument v to the predicate O The following example shows the translation QueryClass Well_off_SI_Managerl isA SI_Manager with retrieved_attribute union Union constraint we
196. iews parameter If the view is extracted from a module different to oHome then the filename includes the module name as a prefix The file type of the file is taken from the optional fileType attribute of the answer format of Q1 The default file type is txt The result of queries with no parameter is stored in files carrying the name of the query The materialization of query results is executed at the same events when the saving of module sources takes place see section 5 8 To enable the materialization you need to specify the target directory with the views option cbserver d MYDB views home meee MyViews You can also use the CBShell utility section 7 to extract the query results and materialize them on the client side This method is more flexible but you need to program the CBShell scripts for to extract all required views For example the CBShell script enrollMe alpha 4001 ask 01 x param OBJNAMES FRAME Now showAnswer exit 82 will enroll to the CBserver running on a host named alpha with port number 4001 and will extract just the answer to 01 x param If there are more answers to be extracted one has to employ separate scripts for each of them and execute them one after the other to save the results in separate files The server side method using the views option will determine all possible fillers x for the parameter param and automatically save the results of Q1 x param ina separate file with filenam
197. ile type sm1 For example a filename System oHome AB sm1 will hold the contents of the module AB that is a submodule to oHome that is a submodule of System The save function is activated when the option save savedir is specified The parameter savedir must be the path to an existing directory If activated the save function is invoked when one of the following events occurs 1 The CBserver is shutdown In this case the complete module tree starting from root module System is saved 2 A client disconnects from the CBserver Here the module tree starting at the home module of the user associated to the client tool is saved 3 A user changes the module context In this case the old module is saved In all cases the save function is executed with the rights of the user who started the CBserver The save function requires at least read permission for the module to be saved The above rules are also applicable to the server side materialization of query results see section 5 9 The load function gets activated when the option load loaddir is specified The directory loaddir should contain files with file names being formed just like with the save function It load the files in alphabetic order which makes sure that the sources of super modules are loaded before the sources of their sub modules The import is executed once at CBserver startup with the rights of the user who started the CBserver If a file contains an error the loading of thi
198. ill 1000 is a shortcut for g bi11 x 1000 y because x is occurs before y in the ASCII alphabet The shortcut can be used to form complex functional expressions such as f g bill getBudget P1 There is no limitation in nesting function calls Function calls are only allowed as left or right side of a comparison operator They are always evaluated before the compari son operator is evaluated For example the equality operator f g bill getBudget P1 f g mary 1000 will be evaluated by evaluating first the inner functions and then the outer functions Note that the parameters must be compliant with the parameter definitions As a special case of functional expressions ConceptBase supports arithmetic expressions in infix syn tax The operator symbols and are defined both for integer and real values ConceptBase shall determine the type of a sub expression to deduce whether to use the real valued or integer valued variant of the operation Examples of admissable arithmetic expressions are a 2x b 15 n m 3 Provided that a and b are variables holding integers the first expresssion is equivalent to the function shortcut IPLUS a IMULT 2 IMINUS b 15 and to the query call IPLUS a il IMULT 2 il IMINUS b il 15 i2 i2 i2 The second arithmetic expression includes a division which in general results in a real number Hence the function shortcut for this expression is PLUS n D
199. in classes Individual Attribute Instance Of and IsA depending on the type of the object The last reason is most significant in preventing symmetry As an example consider the O Telos frame referred to as frame 1 bill in Employee with name bname William end ConceptBase cc will recognize that bi11 is an individual and that bil1 bname is an attribute This information is attached internally to the P facts more precisely it is derivable from the structure of the corresponding P facts When you ASK the system for the frame of bi11 after the TELL operation on frame 1 you will get frame 2 Individual bill in Employee with attribute name bname William end Hence the instatiation to the four builtin classes is added to the frame If we submit the original frame 1 to an UNTELL operation ConceptBase cc assumes by default that only two facts should be untold 1 The instantiation of bill to Employee 2 The instantiation of the attribute bi11 bname to its attribute category Employee name As a consequence the object bi11 and its attribute continue to exist after the UNTELL on frame 1 It would look like frame 3 Individual bill with attribute bname William end Only by untelling this frame 3 as a second operation or by untelling the completed frame 2 the object bill and its attribute bi11 bname shall be made historical This assymmetry of TELL and UNTELL is regarded by some
200. ingle derivation step of a string S to a string S2 by S gt So It is defined when there occurs a substring L in Sy i e S1 V L W and a substitution rule L Rand S2 V R 4 W The substrings V and W may be empty A string S is called ground when no substition rule can be applied A sequence S S1 pis Sn is called a derivation of S A complete derivation of S ends with a ground string In our example the complete derivation is this is a string called a with a term b gt this is a string called string no x with a term b this is a string called string no 123 with a term that was subject to substitution An exception to the left to right rule are complex terms like do y Here the inner term y is first evaluated e g to 20 and then the result do 20 is evaluated In general term substitution can result in infinite loops This looping can be prevented either by re stricting the structure of the substitution rule or by terminating the substitution process after a finite number of steps The end result of a substitution process of a string is called its derivation In ConceptBase the substitution rules are guaranteeing termination except for the case of external procedures The problem with the exception is solved by prohibiting cyclic calls of the same external procedure during the substi tution of a call A cyclic call is a call that has the same function name e w query class and the same arguments express
201. ion p Proposition necessary x m VAR P p c m d and x in c gt exists y VAR y in d and xm y end x every Entity has a key x Class EntityType with necessary keyeAttr Domain end x single constraint metaformula Class with constraint singleConstraint forall c d Proposition p Proposition single x m VAR P p c m d and x in c gt forall al a2 VAR al in p and a2 in p and Ai x m al and Ai x m a2 gt al a2 end x every Entity key is monovalued necessary and single Class EntityType with rule keys_are_necessary Sforall a EntityType keyeAttr In a Proposition necessary keys_are_singl Sforall a EntityType keyeAttr In a Proposition single end The effects of this transaction can be shown by displaying the instances of instances of the class metaMSFOLconstraint The single and necessary constraints are inserted into this class after adding them to the system These constraints themselves can have specializations constraints which are added automatically to the system when inserting objects into the attribute category single resp necessary For the ER example one of the created formulas reads as forall x EntityType exists y Domain x keyeAttr y 157 We observe the relationship to the necConstraint formula the formula has been generated by computing one extension of In p Proposition necessary and P p c m d and replacing the predicates
202. ions menu We correct the error by adding a semicolon to the previous line and choose the Tell symbol again This time since there are no further mistakes the additional attribute is added to the class Employee Now we can choose again the item Outgoing Attributes from the popup of the Graph Editor window for the node Employee If we select Show all attributes of the attribute class Attribute the new attribute will NOT be shown CBGraph uses an internal cache which will only be updated on request Therefore we select the object Employee and select Validate and update selected objects from the menu Current connection The cache for the object Employee will be emptied Now showing all attributes should add the new attribute education to the graph 126 CBlva ConceptBase cc User Interface in Java File Edit Browse Options History Windows Help E oree Me E Telos Editor 1 Employee in Class SimpleClass with 2 attribute 3 name String E Display Instances 4 salary Integer zi dept Department 6 7 8 boss Manager rule bossrule forall e Employee m constraint EmployeeSalaries SalaryBound forall e EmployediFunction GenericQueryClass GetJavaGraphicalPalette GetJavaGraphicalType History Window 5 ASK Cancel Version Now 2015 09 11 09 36 UTC Module oHome Figure 8 20 The TelosEditor
203. ionship between salary and earns could be expressed as 3Subsection 2 2 contains an example for this problem in the context of linking logical formulas to O Telos objects 4For specialization relationships between two objects we need an axiom similar to the instantiation axiom which requires special ization relationships between their sources and destination components Jeus92 contains the complete axiomatization 5These instantiations were left out in the set of propositions for the employee example above 16 mary earns in Employee salary end Instantiation links are denoted by the operator gt and specialization links by gt They should always be enclosed in parentheses mary gt Manager end Manager gt Employee end The operators can be combined to form complex expressions The next example shows how to reference the instantiantion link between the attribute mary earns and its attribute class Employee salary The second frame shows that arbitrarily complex expressions are possible The parentheses have to be used to make the operator expressions unique The attribution operator has a stronger binding than the instantiation and specialization operators According to our own experience complex expressions for denoting objects are rare in modeling It is good to know that any object in O Telos can be uniquely referenced in the frame syntax mary learns gt Employee salary with
204. is category 125 E tocathost4001 SimpleClass Figure 8 19 The graph showing implicit instantiation and attribute links 8 3 6 Editing Telos objects Editing Telos objects with the Telos editor Before we are able to edit a Telos object we have to load its frame representation in to the Telos Ed itor field first For loading a Telos object to the Editor field we choose the Telos Editor Button from either the Display Queries oder Display Instances Browsing facilities or the Load Frame button from the ConceptBase Workbench window see Figure 8 20 Now we add an additional attribute e g education to the class Employee for the description of the Telos syntax see Appendix A We have added the line education String as shown in figure 8 21 To demonstrate error reports from the ConceptBase cc user interface and how to correct them we have made mistakes in the syntax notation of the added attribute By clicking the left mouse button on the Tell icon the content of the editor is told to the ConceptBase server Syntactical and semantical correctness is checked and the detected errors are reported to the Protocol field The report resulting from our mistakes by specifying the new attribute is also shown in figure 8 21 Note that this syntax error would have been already detected at the client side without interaction with the server if we would have enabled the option Pre parse Telos Frames in the opt
205. ise names of predicates such as A Ai In should not be used as object names or variable names The same holds for the keywords with and end which are used in the frame syntax 8Ror the example of subsection 2 1 among others the ground predicates mary in Manager Manager isA Employee and mary earns 15000 are valid facts describing the contents of the object base We suggest to choose verbs e g earns in our example for attribute labels to get more natural and readable predicates 23 2 2 5 Comparison predicates The next predicates are second class citizens in formulas In contrast to the above predicates they cannot be assigned to classes of the O Telos object base base Consequently they may only be used for testing i e in a legal formula their parameters must be bound by one of the predicates 1 8 1 x lt y x gt y x lt y x gt y x and y may be instances of any class If they are instance of Integer or Real they are or dered numerically If they are instance of TransactionTime they are ordered according to the time they are representing newer times are greater than older times Otherwise they are ordered alphabetically 2 x y The objects x and y are equal 3 x lt gt y or x y The objects x and y are not the same All comparison predicates may use functional expressions as operands They are evaluated before the comparison predicates is evaluated See section 2 3 3 for examples The p
206. isplayed A checkbox lets to select whether you want to load the module sources from the graph file and tell them to the CBserver Print Print the current graph If the graph is larger than the page size it will be automatically reduced to fit into the page Thus all printouts will be on one page Save image of graph Saves an image of the current graph as PNG or JPG file The PNG file format should be preferred as it delivers better results For technical reasons the image saving has to set the background color of the node edge labels This can overlap with the node shapes when they are not rectangles If so then use the screenshot function of your operating system to get better results Close Closes CBGraph A CBlIva window will be still available if it has not been closed before Exit Exit CBGraph and CBlva This operation will close both windows of the ConceptBase cc User Interface CBlIva if they were started in combination and exit the program 7 Tf you load a graph file that was created with different graphical types than the ones defined in the CBserver module that CBGraph might be connected to then the graph file is inconsistent with the current CBserver module You may be able to repair the inconsistency via the menu option Current connection change graphical palette Likewise some objects displayed in the graph could be undefined in the database You can validate them by one of the validation tabs in the menu Current c
207. it information in O Telos is represented as proposition ConceptBase allows to derive instantiation of an object to a class and attributes relations between objects This derived information has no object property i e it is not identified and it is not represented as a proposition Additional to the above predefined classes there are the builtin classes Class Integer Real and String Class contains all so called classes including itself as instances the only special property IWe will see in section 2 2 that the predicative language operates on a snapshot of the object base i e on those propositions that are believed at a specified reference time called rollback time This time is an interval The of the interval is the time when the object has been told created The end of the interval is either the time when the object was untold deleted or it is a special symbol Now indicating that the object is currently believed i e it is not deleted Strictly speaking we should better use the term predefined object or predefined proposition 13 of Class is the definition of two attribute categories rule and constraint Hence instances of classes can have deductive rules and integrity constraints Integer and real numbers are written in the usual way strings are character sequences e g this is a string These three classes are supported by comparison predicates like x lt y discussed in section 2 2 and by functions like PLUS MINUS
208. itor is now a stand alone tool and has the ability to store connection details plus a snapshot of the module sources in its graph files The graph files are then self contained and can be viewed and updated without having to maintain the module sources elsewhere It also can display a background image in the graph window Nodes can now be configured to be resizable Lines are now drawn with anti aliasing yielding much better graph images The CBShell utility now behaves more like a Linux Unix shell It provides easy shortcuts like cd for changing the module context It also allows the use of positional parameters hence making it a better companion to Linux Unix scripts The release notes to ConceptBase cc 7 8 lists all major changes and issues You find the release notes in the subdirectory doc TechInfo of your ConceptBase cc installation directory or via the web site http conceptbase cc The system still has about the same memory footprint as it used to be 10 years ago You can easily install the complete system for all supported platforms on a 32 MB memory stick 1 6 License terms ConceptBase cc is distributed under a FreeBSD style copyright license since June 2009 Both binary and source code are available via http sourceforge net projects conceptbase files The FreeBSD style copyright license of ConceptBase cc reads like follows The ConceptBase cc Copyright Copyright 1987 2015 The ConceptBase Team All rights reserved Redist
209. ity is to specify the answer format for a query is to use the answer representation field of the ASK method in the IPC interface The following code is an example for specifying a user defined answer in the ASK method This example is written in Java and uses the standard Java API of ConceptBase see the Programmer s Manual for details import i5 cb api public class CBAnswerFormat public static void main String argv throws Exception CBclient cbh new CBclient localhost 4001 nul1l null CBanswer ans cb ask find_specializations Class class TRUE ded OBJNAMES AFParameter bla somevar Now System out println ans getResult cb cancelMe In the example a connection is made to a ConceptBase server on localhost listening on port 4001 The ask method of the CBclient class sends a query to the server The first argument is the query the second argument is the format of the query in this example it is just one object name the third argument is the answer representation and the last argument is the rollback time The third argument is the the answer representation There are three predefined answer representations FRAME returns the answers as Telos frames including retrieved and computed attributes LABEL returns only the names of the answer objects as a comma separated list Thirdly default lets the CBserver choose between LABEL for function calls and FRAME otherwise Besides these pre define
210. k Meta formulas are a natural extension to classical meta modeling They allow to specify the meaning of modeling constructs at the meta class level The mapping to simple formulas allows an efficient evaluation It also allows to retrieve the specialized semantics definition of a model instance of a meta model since the generated simple formulas are attached to the constructs of the model in the example above they are attached to classes Person and City The meta formula compiler is fully incremental i e if the object base is updated then the set of generated simple formulas is also updated if necessary For example if one removes the category transitive from the connection attribute of City then the generated simple formula will also be removed Meta formulas that contain meta variables under existential quantification cannot be compiled directly but there is an elegant trick to circumvene this restriction Consider for example the formula forall x VAR SC CLASS spec ISA_complete spec super SC and x in SC gt exists SUBC CLASS spec sub SUBC and x in SUBC The meta variable SUBC is under an existential quantifier To circumvene the problem we write an intermediary rule replacing the predicate x in SUBC forall x Proposition spec ISA SUBC CLASS spec sub SUBC and x in SUBC gt x inSubRel SUBC and then re write the original constraint to forall x VAR SC CLASS spec ISA_complete spec super SC and x in SC
211. ler with which ConceptBase was compiled This is in all cases SWI Prolog www swi prolog org For our sin example the PROLOG code would look like compute_sin _res _x _C cbserver arg2val _x _v number _v _vres is sin _v cbserver val2arg _vres _res tell sin in Function isA Real with parameter x Real end The first argument _res is reserved for the result then for each parameter of the function there are two arguments The first is for the input parameter _x the second holds the identifier of the class of the parameter here _C It has to be included for technical reasons The clause tell instructs ConceptBase to tell the Telos definition when the LPI file is loaded Instead of this clause you may also tell the frame manually via the ConceptBase user interface There are a few ConceptBase procedures in the body of the compute_sin that are of importance here The procedure cbserver arg2val converts the input parameter to a Prolog value ConceptBase internally always uses object identifiers They have to be converted to the Prolog representation in order to 44 enter them into some computation The reverse procedure is coserver val2arg It converts a Prolog value e g a number into an object identifier that represents the value If necessary a new object is created for holding the new value The above code should be stored in a file like sin swi lpi This file has to be copied into the ConceptBase databas
212. les Note that this action can fail if the predicate is not true in the database Call proc The Prolog predicate matching procedure is called This can bind free variables You can define your own Prolog code as CBserver plugin You may also use CALL as keyword deprecated Raise query The query call query is raised as event The query is not evaluated This action can be used to trigger other ECArules that have a matching Ask event All parameters should be bound The query may not be a builtin query class or function noop This action stands for no operation i e nothing is done It can be useful for certain constructions with empty DO parts reject The current transaction is aborted and the database state is rolled back Instead of the capitalized action names Te11 you can also use the small caps variant te 11 The same tule is applicable for Untell Retell Ask Raise and Call Analogously the event statements in the ON part of an ECArule can laso use the small caps variants All variables in Tell Untell and Retell actions must be bound The insertion of an attribute A x ml y is only done if there is no attribute of category m1 with value y for object x Then a new attribute with a system generated label is created If an attribute A x m1 y should be deleted then all attributes of category ml with value y for object x are deleted If the argument of Retell is a fact AL x m1l n y then there will be at most one st
213. les will be replaced by the correct fillers when the meta level constraint is utilized in some modeling context Assume for example we want to have a symmetry category and attach a readable hint to it Proposition with attribute symmetric Proposition end RelationSemantics in Class with constraint symm_IC forall AC Proposition symmetric C Proposition x y VAR M VAR P AC C M C and x in C and y in C and x My gt y Mx end RelationSemantics symm_IC with comment hint The relation M of C must be symmetric i e x M y implies y M x end Note that the references to the meta variables M and C are surrounded by curly braces and that these meta variables are also occurring in the meta level constraint Now use the symmet ric concept in some modeling context e g to define that the marriedTo attribute of Person should be symmetric 12Meta variables are those variables that occur in the class position of x in c or in the label position of x m y or Label x m In the running example C and M are meta variables 30 Person with attribute symmetric marriedTo Person end At this point of time ConceptBase will find the hint text for the symmetric constraint and will adapt it to the context of C Person and M marriedTo When an integrity violation occurs the substituted hint The relation marriedTo of Person must be symmetric i e x marriedTo y implies y marriedTo x will be presented to t
214. ll_off_rule exists s HighSalary this salary s end The generated deduction rules for this query class are forall this v this in SI_Manager and this union v and v in Union and exists s s in HighSalary and this salary s gt Well_off_SI_Managerl this v forall this v Well_off_SI_Managerl this v gt this in Well_off_SI_Manager1 Classes occuring in a query constraint may be query classes themselves e g HighSalary This is the third way of query recombination The next feature introduces so called computed attributes i e attributes that are defined for the query class itself but not for its super classes The assignment of values for the solution is defined within the query constraint Like retrieved attributes computed attributes are included in the answer predicate so that the proper answer can be generated from it The following example defines a computed attribute head_of that stands for the department a man ager is leading The attribute head_of is supposed to be computed by the query It is not an attribute of SI_Manager or its super classes We expect that and answer to the query includes the computed attribute Note that a reference head_of to the computed attribute occurs inside the query constraint QueryClass Well_off_SI_Manager2 isA SI_Manager with retrieved_attribute union Union computed_attribute head_of Department constraint well_off_rule exists s HighSalary this salary s and
215. lled 4 1 7 Execution Semantics The coupling mode of an ECArule influences its execution semantics There are three basic steps First a Tell Untell Ask transaction is translated in a sequence of atomic events In case of a Tell Untell each frame inside the Tell induces a delimiter in the event list that is used later for the event processing A typical event list might look like El ea e3 o e4 e5 o Siok Here the events ej e3 were generated for the first frame of a Tell Untell the events ex es were generated for the second frame The diamond separates the events generated for subsequent frames of the same Tell Untell operation The event list is right open since the execution of actions from ECArules can lead to further events Each event has one of the forms Tell lit Untell lit or Ask q where lit is an attribution instantiation or specialization predicate and q is a query call ConceptBase will scan the event list and process events as soon as it detects a delimiter denoted by the diamond above For example when ConceptBase sees the delimiter between ez and e4 it will start to process e to ez one after the other Processed events are removed from the event list The first step is to determine the matching ECArules for a given event e This yields a working set of rules for each processed event e ws e Set of all ECArules whose ON part matches e The matching of the ON part of the ECArule and the event typicall
216. llfill revNec property RelationshipType with rule attribute revNecRule forall ro RelationshipType role A ro minmax 1 gt In ro Class revNec end definition of Class Inconsistent x x forall instances p of Class revNec If there exists a destination class d there must be a source class c with an attribute instantiating p otherwise p is inconsistent Class Inconsistent with rule attribute revNecInc forall p Class revNec exists c m d VAR y VAR P p c m d and In y d and not exists x VAR In x c and A x m y gt In p Inconsistent end To activate the different graphical representation of inconsistent roles the definition of the graphical type for attributes has to be modified Tell the following frame Inconsistent with rule attribute incRule forall e Attribute In e Inconsistent gt e graphtype InconsistentGtype end The effect of these transactions can be shown when starting the Graph Editor and displaying the at tributes of the RelationshipType instance Works In Be sure to switch the graph editor to the palette ER_GraphBrowserPalette before doing so see section 8 2 The attribute WorksIn emp is dis played as red link like in figure D 1 If you had already started the graph editor before telling the last frame you should synchronize it with the CBserver via the menu Current connection By telling H_CB in WorksIn with 160 emp hIsEmp Hans prj cbIsPrj
217. luated in combination with an icon image If a graphical type has no image ocon then any text position specified for it would be ignored In most cases the default value bottom is just fine You can also combine shapes with image icons In such cases the image icon plus the label are the inner content and the shape is drawn around it In the example below the label is placed left of the image icon Both are aligned in the center of a circular shape with gray background and black line color CBGraph shall compute the required size of the surrounding shape from the dimensions of the image icon and its label An exception holds when the size property is set to a fixed dimension like 50x40 image file home jonny images AgentIcon png textposition left shape i5 cb graph shapes Circle align center bgcolor 200 200 200 linecolor 0 0 0 The location specified in the image and bgimage property can either be a URL to an image file starting with http or file or a relative file location such as diaicons icon1 png In the latter case CBGraph shall first check if local directory CBICONS exists in the ConceptBase installation directory environment variable CB_HOME If that exits it shall expand the relative path to and absolute path using the location of CB_HOME If the local directory does not exist CBGraph shall expand the relative path to a URL starting with htt
218. ly attached to its so called concerned class Guest Employee dept The predicate typing condition holds for all formulas regardless whether they occur as constraints or rules of classes or within query classes 2 2 8 Rule and constraint syntax A legal integrity constraint is a CBL formula that fulfills predicate typing condition A legal deductive rule 1s a CBL formula fulfilling the same condition and having the format forall x1 c1 forall xn cn R gt lit al am where e lit isa predicate of type 1 or 3 and 10The enforcement of the restriction has been extended to query classes as of ConceptBase release 6 1 To support applications that were written for earlier releases a CBserver option cc predicate typing has been introduced to disable the check for query classes Details are in section 6 With ConceptBase 7 2 March 2010 the predicate typing has been further extended and now will scan subclasses of of the classes of x in attribution predicates x m y in case that superclasses do not provide a matching attribute class You need to set the CBserver option cc to extended to activate this behavior The extended mode creates more cases that the predicate type concerned class is found It should be noted that objects like x that are not instance of a class that defines and attribute with label m will lead to a failure of the predicate x m y i e its negation is then true 26 e the variables in al
219. ly the same as for instances like mary Note that the 3 argument attribution predicate expressing mary name Mary Smith represents a meaningful statement for some reality to be modeled On the other hand the predicate fact Employee attribute String is much less significant because the label attribute does not transport a specific domain meaning Here the 4 argument attribution predicate such as used for the fact Employee attribute name String is required Still from a formal point of view there is no different treatment of predicates at the class and instance level This uniformity is the basis for meta modeling i e the definition of modeling languages by means of meta classes The class labels attribute and single need to be defined at the classes of Employee Those are Class and the pre defined class Proposition to which any object including Employee and mary is instantiated In this case both attribute and single are defined for Proposition Proposition attribute attribute Proposition Proposition attribute single Proposition Note that attribute has itself as category This is the most generic attribute category and applies to any explicit attribution Both the attribution predicate x m y and its long form x m n y can be derived i e occur as conclusion of a deductive rule In such cases there are no explicit attribute objects between x and y ConceptBase demands that in such cases one of the classes of x has an
220. m the Options menu in the user interface A dialog with a listbox containing all known modules in the current context are shown Double clicking a module entry in the listbox sets the current module context to the selected module and lists all modules that are visible in this module i e its submodules and supermodules F Change Module Current Module is oHome Change Cancel Figure 5 1 The module context selection window In our example you should get a window displaying the modules Master System Work and oHome in alphabetic order see Figure 5 1 Now double click the entry Work As a result the module context of the CBserver is set to the module Work As the Work module has got no nested modules there are no additional modules displayed in the listbox i e all modules that are visible in the oHome module are also visible in the Work module Alternatively you can specify the module context using the load model operation and placing a Sset module MODNAME inline command placed before the first Telos frame of a source model file MODNAME stands for the name of the module in which you wish to define the content of the source model file Module paths like System oHome Work are allowed as well Please note that only one inline command is allowed within one source model file Specifying module contexts using inline commands is a facility for automatically loading Telos frames of large applications which are spread over different
221. matic layout Call a layout algorithm everytime the graph is changed e g by expanding the attributes Disabled by default Enabling it is not recommended Undo last layout operation Undo the last change of the graphical layout This option is only available when automatic layout is enabled Layout graph Call the layout algorithm Zoom Set the zoom factor of the graph e g 120 20 percent enlarged 200 100 75 50 25 Set the zoom factor accordingly Current connection menu These operations have effect on the current connection i e the connection of currently activated internal window Query to server This operation will open a dialog which prompts you to enter the name of a query see figure 8 9 The query can also be parameterized If you click on the Submit Query button the query will be sent to the server and the result will be displayed in the listbox You can select the objects that should be added to the graph Selection of multiple objects is possible Validate and update shown objects This operation will check for every object if it is still valid i e if it still exists in the database update the graphical type of the object and the internal cache of the object is deleted see below section 8 2 10 Depending on the option Invalid Telos Objects see above the objects will be either marked or removed from the current view Validate and update selected objects Similar to the previous option but is only
222. me of an object in its object base primary for the use of Rollback queries With the predicate Known x t the time of the creation of x can be made visible in rules or queries The following frames shows how to use it Class Employee with attribute salary Integer createdOn TransactionTime lastModified String rule createdOnRule forall t TransactionTime Known this t gt this createdOn t end EmpWithoutLastModified in QueryClass isA Employee with constraint noLM not exists t String this lastModified t end 5Since ConceptBase 6 2 LPI plug ins can be defined in two different formats A file with the suffix bim Ipi is intended to be used by a CBserver based on MasterProlog formerly BIM Prolog If the CBserver is based on SWI Prolog the server reads files with the suffix swi lpi Both Prolog Environments used a slightly different syntax which requires different implementations ConceptBase 7 0 and later only supports SWI Prolog hence providing the swi variant is sufficient 68 The limitation of this approach is that it just records the creation date of an object and not the time when it was modified i e the value of an attribute was changed To overcome this restriction one can use ECArules to update the attribute LastModified of the above example whenever an attribute of the category salary is inserted ECArule LastModified_init with mode m ImmediateDeferred ecarule er t TransactionTime
223. me time Each connection will be represented in one internal window with the graphical palette database module host name and port number in the title bar of the window The connection dialog consists of two tabbed panes In the first one Address you can enter the host address name or IP number and the port number In the second pane Initial Object you can specify the initial object to start the browsing process the graphical palette and the database module Start CBlva Workbench Start a CB workbench aka CBlva If you started CBGraph directly or if you have already closed the workbench window you can re start the workbench by this menu item If connected to a CBserver the new CBlva will list the content of the current module in its Telos editor window Save Save the current graph into a file The current nodes their location and the links will be saved into a file which can be reloaded later The graphical types will also be saved into the file By default the file will get the extension gel Graph Editor Layout A checkbox lets to select whether you want to save the module sources into the graph file It overrides the rw options of the cbgraph command Load Load a graph that has been saved with the previous menu item Existing nodes and links in the current window will be erased If the graph file was previously created to include module sources then the module sources are told to the CBserver before the graph is d
224. mes in the CBserver database Hence a persistent database is containing more information than the saved module tree and is also faster to start up compared to loading module sources Still the load save function offers a simple way to keep a textual representation synchronized with the evolving database state or to back up re load a database state The CBserver parameter db combines the function of d load save and views Hence all files will be accessed updated in the database directory 5 9 Server side materialization of query results Similar to the saving of module sources the CBserver parameter views enables the materialization of certain query results in the file system of the CBserver To do so one has to specify the queries to be materialized Only queries with a single parameter or with no parameter can be materialized The queries need to be listed with the module that contains the objects that match the query Example MyModule with saveView vi Ol v2 02 end You can also use deductive rules deriving the values for the saveView attribute The queries Q1 and Q2 need to be visible in the module MyModule The queries need to have an answer format section 3 defined for them attribute forQuery Assume that the query Q1 has the single parameter param C1 ConceptBase will then call the query 01 x param for each instance x of class C1 The result is stored in a file with name x in the directory specified with the v
225. mplete example for computing the length of the shortest path is in the CB Forum see http merkur informatik rwth aachen de pub bscw cgi 1694234 Recursive function definitions require much care Deductive rules shall always return a result after a finite computation This does not hold in general for recursive function definitions when they use arith metic subexpressions These subexpressions can create new objects numbers on the fly and thus force ConceotBase into an infinite computation On the other hand they are more expressive than pure deductive rules and thus useful to analyze large models in a quantitative way 2 6 Query evaluation strategies ConceptBase employs an SLDNF style query evaluation method i e query predicates are evaluated top down much like in standard Prolog This is known to cause infinite loops for certain recursive rule sets To overcome this the SLDNF evaluator is augmented by a tabling sub system SSW94 which detects recursive predicate calls and answers them from the cached results of a query the so called table rather than entering an infinite loop This tabled evaluation computes the fixpoint answer of a query provided that the overall rule set is stratified Even more dynamically stratified rule sets are supported as well Other than with the static stratification test a violation is detected at run time of a query rather than at compile time For a precise definition of stratification we refer you to th
226. n of ECA rules srie eee eS RR eR eR PO 4 4 Limitations of the current implementation 0 0 0000 eee The Module System 21 Detnmomat modules sc A GR mee ES AS a 5 2 Switching between module contexts o e o Using nested modules 2 3 6 cs ee eS a BEES RSS 3A Exporting and importing ODJOO S es compe A OS RRR SE ES EE ROS SS seine User home moduls lt a eR EROS ee ee Sb eed id 36 Limi ng access to modules lt o spoar oe a RE ee ee ae be ee 56 1 Accessto System module 2 24 465 sr bebe eee Sew 5 7 Listing the module content 2 0 ee bee eR ER RR ee eR 3 2 1 Restrichons ol ListModule sest eses eee a ee RE asra Kere 5 8 Saving and loading module somrces 2 eR ee 5 9 Server side materialization of query results o 339 1 Post exporicommand so 66 45 5 58 Bee Se RA DES wo 60 60 61 61 61 62 63 63 64 65 66 66 66 66 66 66 68 69 70 70 6 The ConceptBase cc Server C Berryer PARMO 2 vf oe Bee ES Shee Oe eee OS e ES Database WINER 5 ce cd Gok ee es ERG Sere he a RE eS Be eX Modifying The system database lt oe c ee OS ee OY ee dee ee OS AHS YS 6 1 6 2 6 3 6 4 6 5 6 6 6 7 6 8 6 9 Tracing BOULVESIANEING is ce ee EER RS SERS RE RRR ER Pupme CESE ik ea be eS ae ER He See CaS eee Sh PAS we The tabling subeysiem 4 045 246 e624 42 bo eek bee bea eee Bk hoo Database persistency o ee BAe ea bee es The UNTELL perO cocinas he RRR Re S SSS Bae Se eS 6 8 1
227. nd UnionMember in Class with attribute union Union end SI_Manager_0 in QueryClass isA Manager UnionMember end QueryClass SI_Manager in QueryClass isA Manager UnionMember with retrieved_attribute union Union salary Integer end Super classes themselves may be query classes which is the first kind of query recombination The second frame shows the feature of retrieved attributes which is similar to projection in relational algebra Example one wants to see the name of the union and the salary of socially interested managers The attributes must be present in one of the super classes of the query class In this example the union attribute is obviously inherited from the class UnionMember and salary is inherited from Manager CBQL demands that retrieved attributes are necessary each answer must instantiate them If an object does not have such an attribute then it will not be part of the solution As usual with attribute inheritance one may specialize the attribute value class e g QueryClass Well_off_SI_Manager isA SI_Manager with retrieved_attribute salary HighSalary end HighSalary in Class isA Integer with rule highsalaryrule forall m Integer m gt 60000 gt m in HighSalary end 32 The new attribute value class HighSalary is a subclass of Integer so that each solution of the restricted query class is also a solution of the more general one It should also be noted that HighSalary also could have been anot
228. nd disable click actions by a checkbox in the options menu of CBGraph The setting is also stored in the configuration file CBjavalnterface The entry is called ClickActions there See http merkur informatik rwth aachen de pub bscw cgi 3762781 for examples C 3 3 Providing a new implementation for a graphical type If you got the sources of ConceptBase then you can add your own implementation for graphical types The sources are in files CBPOOL zip downloadable via http conceptbase sourceforge net CB Download html Its subdirectory AdminPOOL contains instructions on how to compile the Con ceptBase system under Linux Unix Adapting the source code requires considerable programming skills in Java Hence this section is only meant for the programmers among you The implementedBy attribute of a graphical type specifies the class name of a Java class imple menting this graphical type This class has to be a subclass of i5 cb graph cbeditor CBUserObject If you are going to implement your own class it is most useful to extend CBIndividual or CBLink in the package i5 cb graph cbeditor i e in directory Product POOL java i5 cb graph cbeditor of the CBPOOL The class CBUserObject provides several methods which can be overwritten to implement your own graphical types Component getSmallComponent returns the small component i e the component which is shown first The return value should be an instance of javax swing JComponen
229. ndows and a status bar The first sub window a Telos editor can not be closed because it also contains the history window which records all operations for later reuse In the following each component of the user interface is explained Note that you might have to edit these files so that the correct Java Virtual Machine is used and the environment variable CB_HOME is set correctly See Installation Guide for details 101 Copy Paste Tell Untell Retell Ask List Module Exit CBiva Concept Base cc User Interface in Java Quick Connect E Telos Editor Class in Class with attribute constraint MSFOLconstraint rule MSFOLrule mrule MRule lend Main Telos Editor History Window Query successful Status Bar m 11 08 UTC Module oHome Figure 8 1 Main Window of CBlva 8 1 1 The menu bar File Connect Connect to a ConceptBase cc server CBserver started in another shell command window see section 6 Disconnect Disconnect from a CBserver Load amp Save Telos Editor Load or Save the contents of the current Telos Editor Load Model Load a source model file sml sml txt to the server As client and server are not supposed to share the same file system this method is now implemented as a normal Tell method The client reads the contents of the file into a string and sends the string to the server Start CBserver Opens a dialog
230. nformation Systems Development In R Kasckek ed Proceedings Entwicklungsmethoden fuer Informationssysteme und deren Anwendung EMISA 99 Reihe Wirtschaftsinformatik Teubner Verlag Stuttgart Germany pp 147 174 1999 Jarke M Mylopoulos J Schmidt J W Vassiliou Y Information systems development as knowledge engineering a review of the DAIDA project Programirovanie Vol 17 No 1 Academy of Sciences Russia also appeared as technical report MIP 9010 Universit t Passau Germany 1990 Jarke M Quix C Calvanese D Lenzerini M Franconi E Ligoudistianos S Vassiliadis P Vassiliou Y Concept Based Design of Data Warehouses The DWQ Demonstrators ACM SIGMOD International Conference on Management of Data SIGMOD 2000 Dallas TX May 2000 Jeusfeld M A Quix C Jarke M Design and Analysis of Quality Information for Data Warehouses 17th International Conference on the Entity Relationship Approach ER 98 Sin gapore 1998 Ludwig S A Comparison of a Deductive Database with a Semantic Web reasoning engine Knowledge Based Systems 23 6 2010 pp 634 642 MasterProLog 4 1 Reference Manual IT Masters 1999 Mylopoulos J Borgida A Jarke M Koubarakis M Telos a language for representing knowledge about information systems ACM Trans Information Systems Vol 8 No 4 1990 Mylopoulos J Wong H K T Some features of the TAXIS data model Proc Sixth Interna tional Conference
231. nments Assume that a teacher wants students to exercise a certain modelling task using ConceptBase cc Then he would prepare some Telos files with necessary definitions e g some meta classes and load them into a persistent ConceptBase server After that he can restart the Concept Base server in non persistent mode on the same database created before Student can then work on their extensions while the state of the database can easily be set back to the original state defined by the teacher The module system of ConceptBase cc can be used to support multiple students to work on the same server without interfering with each other see section 5 Recommended options cbserver d MYDB s 2 mu enabled u nonpersistent The second scenario might also be useful in modeling If there are some parts that are regarded as stable the modeller can decide to make them persistent and only add modify those Telos models that are still subject to change In particular for large Telos models this strategy saves time Note that the updates by the users are lost when the non persistent CBserver is stopped This might be useful if you want to re use the same initial database MYDB several times e g for different user groups Scenario 3 Project work Here the students work for several days on a given task Changes shall not be lost The use of the db option will not only store the database in binary form but also store the source code of all modules as text file
232. nor dynamically stratified Note also the example WinNim sml which uses the same query as Win sml but is dynamically stratified Even in the case of stratification violations ConceptBase will display an answer to a query The user can then decide which parts of the answer are usable In principle this decision can also be automated which is subject of future ConceptBase releases 2 7 Datalog queries and rules The definition of queries in ConceptBase is often complicated by the limitations of the expressiveness of the query language or by the limitations of the query optimizer to find the best solution The concept of datalog queries and rules was introduced to overcome these limitations Datalog queries and rules give the experienced user the possibility to define the executable code of query or rule directly including the use of standard PROLOG predicates such as ground 1 to improve the performance of a query or rule Although datalog queries and rules can be used as any other query or rule they can cause an inconsis tent database This is due to the fact that the datalog queries and rules will usually not be evaluated while the semantic integrity of the database is checked 2 7 1 Extended query model Datalog queries are defined in a similar way as standard query classes They must be declared as instance of the class DatalogQueryClass Class DatalogQueryClass isA GenericQueryClass with attribute code String end The attribute
233. ns DownPentagon like Pentagon but rotated 180 degrees Ellipse an ellipse FolderL FolderR folder shapes House a house shape Pentagon Hexagon Sep as the name says tagon Octagon Rect a rectangle RoundRectangle a rectangle with round corners Page a page shape Star a star Triangle TriangleL Trian gleR DownTriangle various triangles Tube a tube shape UpHexagon hexagon with pointed vertex on top bottom StadionCurve variant of a round rectangle resembling a stadion curve UpStadionCurve variant of StadionCurve XCross a cross in the form of an X PolygonShape user definable polygon The user defined polygon curve shape allows you to specify any shape consisting of a set of points The start point must be the same as the end point Assume you want to triangle pointing to the right but the right extreme point being at the same height 0 as the upper left point Then the following graphical type would do the job MyTriangle_GT in JavaGraphicalType with property shape PolygonShape 0 3 0 0 0 0 4 0 implementedBy implBy i5 cb graph cbeditor CBIndividual priority prs 22 end In the shape string the first part PolygonShape indicates that it is a user defined polygon shape the second part 0 3 0 0 are the x coordinates of the polygon points and the third part 0 0 4 0 are its y coordinates Note that the number of x coordinates must be the same as the number of y coordinates
234. nstances of the class However O Telos does not restrict attributes to just values The target of an attribute can be any object Hence the concept of an attribute in O Telos is the generalization of an UML association and an UML attribute A second difference is that an O Telos attribute has essentially several labels tagged to it its own label object label and the labels of its attribute categories class labels The latter are the labels of the attributes declared at the classes of an object the first is the label of the attribution at the level of the object that has the attribute We illustrate this subsequently Attributes at the instance level are instances of attributes at the class level attribute categories An attribute category at the class level can be instantiated several times at the instance level For example consider the frame for Mary mary in Manager with name aliasname 20 hername Mary Smith salary earns 15000 dept advises PR currentdept RD end The object mary has four attributes with object labels hername earns advises and current dept The attribute categories are name aliasname salary and dept The last category is instan tiated twice ConceptBase uses the following predicate facts infix variant of the AL predicate to express the content of the frame mary in Manager mary name hername Mary Smith mary aliasname hername Mary Smith mary salary earns 15000 mary dept advises PR
235. nswer for mat The programming interface is not documented here since this requires extensive knowledge of the ConceptBase server source code For the experienced user we provide an example in the subdirectory Examples AnswerFormat of the ConceptBase installation directory see files externalcall sml and externalcall swi lpi externalcall bim 1pi for BIM Prolog variant Note that one has to create a persistent database load the model externalcall sml into it then terminate the Con ceptBase server and then copy the file externalcall swi lpiorexternalcall bim 1pi into the database directory see also appendix F Thereafter restart ConceptBase and call the query EmpDept 3 2 6 Calling queries in answer formats A query call within an answer format is an example of a so called external procedure The pattern as well as head and tail of an answer format may contain the call to a query possibly the same for which the answer format was defined for This allows to generate arbitrarily complex answers ASKquery Q subst1 subst2 FRAME The argument O is the name of a query The arguments subst 1 subst2 are parameter substitutions see section 2 3 The argument FRAME is the default answer format specified for the query Q It shall be overridden in case that query Q has itself an answer format Instead of FRAME the user can also specify any answer format in the ASKquery call even parameterized answer formats see b
236. nswer shall be returned as a list of Telos frames iff the query does not have a user defined answer format see forQuery attribute below If there is an answer format with a forQuery attribute for the current query it will be selected If there are more than one the first one is selected default This value is leaving the choice to the ConceptBase server For function calls the answer format LABEL is selected for other query calls the format FRAME is selected The main purpose of this format is to provide a more intuitive behavior of CBIva when used for interactively querying ConceptBase answer format name Finally the name of a user defined answer format can be provided like MyFormat This will override any answer format that is assigned via the forQuery attribute for the given query Hence one can maintain several answer formats for the same query Assume we want to execute a query call O abc param1 on the current database and have the answer formatted according as frames we would issue ask Q abc paraml OBJNAMES FRAME Now We assume here that there is no user defined answer format for query Q If there is a user defined answer format like MyFormatA and MyFormat B but the answer formats are not assigned via forQuery to Q we can call ask Q abc param1 OBJNAMES MyFormatA Now and also ask Q abc paraml OBJNAMES MyFormatB Now If we assign MyFormatB to Q via the forQuery attribute the last call is equiv
237. nt triggers will then be put on ql instead of q0 Note that several ECArules can match a given event The switch occurs when the first transactional rule is encountered The second method creates user defined trigger queues via the FOR clause ON Tell x in A FOR x In the above example each event that matches the event clause will also fill the variable x in the FOR clause This will instruct ConceptBase to switch to the new trigger queue labelled x If you use FOR q1 then the method yields the same effect as with the TRANSACTIONAL clause As soon the the trigger queue labelled x is empty ConceptBase will switch back to the newest non empty trigger queue or back to q0 65 The events on q1 are processed before the remaining events of q0 The queue switch leads essentially to a prioritizition of events on q1 over q0 Examples highlighting the differences between the execution modes and the transaction model are pre sented in the CB Forum athttp merkur informatik rwth aachen de pub bscw cgi 2924361 You can use the tracemode high see chapter 6 to debug ECArules The ConceptBase server will then write trace messages about the execution of ECArules on the console terminal 4 1 9 Activate and Deactivate ECA rules The attribute act ive allows the user to deactivate the rule without untelling it Possible values are TRU and FALSE The default value is TRUE i e by default are ECArules active El 4 1 10 Depth The att
238. ny nodes and edges then it is recommended to first click once on the node or edge to be dragged and then to drag it This will switch off the anti aliasing while dragging and thus be faster You may also want to select a group of objects and then move it as a whole To do so either span a selection box with the left mouse button around the object to be selected or press the shift key and 112 select multiple objects individually After a move CBGraph shall redraw dependent edges that might be misplaced Some edges like instantiation links have no label in CBGraph depending on the graphical type associ ated to it see section C In such cases a small square dot is displayed on the edge Click on this square dot to select the edge and to drag it If the edge has a background color see section C different from the edge color then the square dot is drawn in the background color Moving nodes and edges can sometimes lead to quite messy edge curves where the edge middle point is distant from the middle of the straight line between the source and destination of the edge You can clean up such graphs by pressing the shift and control keys together and then click on a node whose edges shall be straightened 8 2 6 Menu bar The menu bar provides access to the most important functions of CBGraph File menu Connect to server Connect to a new server You can have multiple connections to one server or different servers at the sa
239. o called meta formulas are a prominent category of such formulas They have occurrences of predicates with so called meta variables There are two cases First an instantiation predicate x in c x in c orIn_s x c where the class argument c is a variable Second an attribution predicate x m y or x m y where the label argument mis a variable In such cases the concerned class cannot be determined directly even though the formula as such is meaningful ConceptBase relies on predicate typing for the sake of efficiency and static stratification The concerned class is internally used as predicate name This increases the selectivity and reduces the chance on non stratified deduction rules Fortunately all meta formulas can be re written to formulas fulfilling the predicate typing condition The re writing replaces the meta variables by all possible value Since all variables are bound to finite classes the re writing yields a finite set of formulas However if a meta variable is bound to a class with a large extension the re writing will also yield a large set of generated formulas Meta formulas allow to specify assertions involving objects from different levels and hence significantly improve flexibility of O Telos models An example for the usage of meta formulas can be found in the appendix D 2 where the enforcement of constraints in ER diagrams is solved in an elegant way As instructional example assume we want to define that a certain att
240. o the Master module can now reference these objects Now change the module context to Work and TELL the follow ing frame within module Work Work with imports il Master end Now the objects mentioned above are visible in the context of the Work module Check this by loading the Employee object with the Edit Load Object function of CBIva You can now define the specialization Manager of Employee in the context of the Work module Manager isA Employee end When untelling export s attributes from a module ConceptBase checks for integrity violation in all concerned modules Try untelling the export s attributes from the Master module and you should get an error message saying that referential integrity is violated in the Work module The reason for this violation is natural as the class Employee is no longer exported from Master it is no longer visible inside the Work module and therefore referential integrity is violated for the Manager specialization of Employee If you define integrity constraints in the exporting module Master then these constraints are not checked for objects in the importing module Work For example if the attribute name of Employee is declared to be a necessary attribute via a constraint in Master then you can still declare an object like bill in Employee end in module Work that does not fulfill the constraint The integrity constraint in Master cannnot see the objects declared in Work
241. on 8 3 84 U untellmode controls the way how UNTELL is executed by the server The allowed values are verba tim and cleanup default In verbatim mode the UNTELL operation will only untell the facts directly described by the O Telos frame being submitted as argument In cleanup mode UNTELL will also try to remove the instantiation to the O Telos system classes Individual Attribute InstanceOf and IsA By doing so UNTELL behaves inverse to the TELL operation More details are explained in subsection 6 8 port portnr sets the TCP IP socket portnumber for client connections to the CBserver The value portnr must be between 2000 and 65535 If there is already a process using the portnumber the CBserver will abort The default value for the portnumber is 4001 p portnr is the same as port portnr Deprecated since it conflicts with a predefined command line parameter of SWI Prolog version display version info and exit help display list of CBserver options and exit license display license and exit t tracemode sets the tracemode of the CBserver It is one of silent no minimal low high veryhigh The tracemode determines the amount of text displayed by the server during its execu tion The tracemode does not influence the function but is used for debugging The default tracemode is set to Low display CBserver interface calls plus their answer The tracemode minimal will con figure the CBserver to only trace the CBse
242. onnection 113 If the graph was loaded from a GEL file and it was edited in the session CBGraph shall ask the user whether to save the edited graph to the file when the user terminates CBGraph Edit menu The operations in this menu have an effect on the selected objects You can select an object by clicking on it with the left mouse button Multiple selection is possible dragging a rectangular area while holding down the left mouse button or by holding the Shift key and clicking on objects Erase Selected This option will remove the currently selected nodes and edges from the view This operation has no effect on the database Selection With this submenu you can either select all objects all nodes or all edges in the current frame Furthermore you can clear your current selection Options menu The options will be stored in a configuration file see section 8 5 when you exit CBGraph Language The text for menu items and buttons is available in two languages German and English With this option you can switch between the languages This option is currently without function All menu labels are set to English Background Color Here you can change the background color of the graph to your favorite color Component View With this option you can configure the view of an object if the component view is activated by a double click or by the popup menu By default a tree like representation of the object with its classes instan
243. oposition partof SubView end Attributes of the category inherited_attribute are similar to retrieved attributes of query classes but they are not necessary for answer objects of the views i e an object is not required to have a filler for the inherited attribute for being in the answer set of the view The partof attribute allows the definition of complex nested views i e attribute values are not only simple object names they can also represent complex objects with attributes The following view retrieves all employees with their departments and attaches the head attribute to the departments View EmpDept isA Employee with retrieved_attribute partof dept Department with retrieved_attribute head Manager end end As the example shows the definition of a complex view is straightforward for the inner frame the same syntax is used as for the outer frames The answers of this view are represented in the same way e g John in EmpDept with dept JohnsDept Production with head ProdHead Phil end end Max in EmpDept with dept MaxsDept Research with head ResHead Mary end end To make the definition of views easier we allow some shortcuts in the view definition for the classes of attributes For example if you want all employees who work in the same departments as John you can use the term John dept instead of Department In general the term object attrcat refers to the set of attribute
244. ored asstribute with category m1 and label n that has to be deleted before the new fact is told It is well possible that an attribute is updated untell tell several times by action parts of ECArules during a single ConceptBase transaction Only the state of the attribute after all ECArule firings will be visible after a successful commit There are a few special procedures which may be called within the DO or ELSE part of an ECArule 2Retell is currently restricted to attribution predicates A x ml y and AL x ml n y respectively their infix ver sions x ml y and x ml n y It will replace the old value of attribute ml of x by y ConceptBase realizes the Retell A x ml y by a combination of Untel1 A x ml1 z removing the first stored attribution fact A x ml z and a subsequent Tell A x ml y If there are several facts such as A x ml z1 and A x ml z2 then only the first one is removed by the Unte11 3Note that an object can have more than one attribute value in one attribute category but the attributes must have different labels 62 CreateIndividual Prefix ID A new individual object with the given prefix and a system generated suffix is created The object identifier of the created object is returned in the second argument which must be therefore a free variable The prefix must be an existing object name e g the class name otherwise the ECArule compiler will report an error CreateNew ClassName ID A new instanc
245. ormula exists c d n VAR x in c and y in d and c m n d and x n y The predicates In2 and A2 are also called macro predicates since they are standing for sub formulas They are fully supported in constraints of query classes The predicate A2 is not yet supported for deductive rules and integrity constraints due to limitations of the formula compiler You can use the AL predicate instead Examples on using macro predicates are available from the CB Forum http merkur informatik rwth aachen de pub bscw cgi 877047 19 The relation of the above predicates and the P facts of the object base is defined by the O Telos axioms appendix B For example axiom 7 states Yo x n y p c m d P o x n y A P p c m d A In o p gt AL x m n y So if an attribute object o of an object x is an instance of an attribute object p of the object c then AL x m 1 y also written as x m n y can be derived This axiom provides those solutions to the AL predicate that are directly based on P facts Further solution can be derived via user defined deductive rules The other predicates are based on P facts as well The Ai predicate is for historical reasons not included in the list of axioms It is defined as Vo x n y p c m d P o x n y AP p c m d A In o p gt Ai x m o There are a few variants for the predicates for instantiation specialization and attribution to check whether a fact is actually stored or deduced l In_s x c The object x is
246. out This is a Telos string end If many such frames need to be told the escaping of Telos strings is cumbersome You can use the single quote as argument delimiter in such cases making the escaping the double quotes for the Telos string obsolete tell Peter with comment about This is a Telos string end r 7 4 Interactive use of CBShell The CBShell can be used to run a script file or in can be used in interactive mode In the interactive mode the CBShell shall directly display the response to a command typically the answer of the ConceptBase server Some of the shortcuts like why and cd are specifically defined to make the interactive mode more effective Another feature of the interactive mode is that queries that are represented as a single word can also be asked without the keyword ask in front of it CBShell will then ask the query using default as answer format i e the ConceptBase server will decide in which answer format to use Below is a sample session of CBShell in interactive mode cbshell This is CBShell the command line interface to ConceptBase cc offline gt cbserver t no Starting ConceptBase Server please wait gt CBserver ready on host EG0090 serving port number 4001 Successfully started and connected to server localhost 4001 gt mkdir M1 yes localhost 4001 gt cd M1 97 M1 localhost 4001 gt tell Employee in Class no localhost 4001
247. ow see figure 8 2 If the current operation is an ASK then a single click on the copy button will copy the query to the Telos Editor and a double click will copy the result of the query The size of the history window can be reduced by using the slider bar between the Telos editor and the history window 8 1 6 Display instances This dialog displays the instances of a class The class is entered in the text field When you hit return or press the OK button the instances of this class will displayed in the listbox If you double click on an item in the listbox the instances of this item will be displayed The frame of a selected item can be loaded into the Telos editor by clicking the Telos Editor button A history of already displayed classes is stored in the upper right selection list box The Cancel button closes the dialog 105 Number and type of operation f a AA O Go to previous Copy Text to Redo Go to next operation Telos Editor operation operation Figure 8 2 Buttons of the History Window 8 1 7 Frame browser The Frame Browser see figure 8 3 shows all information relevant to one object in one window The window contains several subwindows with list boxes that show super and subclasses the classes the instances attributes and objects refering this object In the center of the window a small window with the object itself is shown To view the attributes of the object you must first select the at
248. p conceptbase sourceforge net CBICONS You can add your own icons to the local directory CBICONS in your ConceptBase installation directory Below is an example of a relative image location image images AgentIcon png Further examples on using image icons are provided in the CB Forum at http merkur informatik rwth aachen de pub bscw cgi 3506150 153 Appendix D Examples D 1 Example model the employee model The Employee model can be found in the directory CB_HOME examples QUERIES It consists out of the following files Employee_Classes sml The class definition Employee_Instances sml Some instances for this model Employee_Queries sml Queries for this model Note that the files must be loaded in this order into the server D 2 A Telos modeling example ER diagrams D 2 1 The basic model This example gives a first introduction into some features introduced in ConceptBase version 4 0 It demonstrates the use of meta formulas and graphical types while building a Telos model describing Entity Relationship Diagrams The following model forms the basis KKK KKK KKK KKK KKK KK KK KKK KK x x File ERModelClasses x x x ERR REE RERA ERR EER EAE ER ERS Class Domain end Class EntityType with attribute eAttr Domain keyeAttr Domain end Class RelationshipType with attribute role EntityType end 154 Class MinMax end 1 in MinMax with end 1 1
249. phical type of an anonymous edge has bgcolor defined then the square dot is adjusted to the edgewidth and displayed in bgcolor If you set an explicit bgcolor for an edge then the bounding box around the edge label shall be 147 painted in that color If you choose as bgcolor the same value as for the bgcolor of the palette then edge labels appear more readable Do not forget to include the new graphical type into the graphical palette It is not necessary to define a new graphical palette you can extend the default palette Furthermore you have to define the grapht ype attribute of some object in such a way that it refers to the new graphical type Make sure that the new graphical type has a higher priority than other graphical type which might apply 10 is the highest priority of the default graphical types An example of user defined graphical types can be found in D 2 see also the CB Forum at http merkur informatik rwth aachen de pub bscw cgi 188651 for a complete specification of ER diagrams including graphical types C 3 2 Click actions A click action is a property of a graphical type and contains the name of a query class as a string A simple example is clickaction fireTransition If an object has a graph type with a click action then the corresponding query class is called using the object name as single parameters For example if t 1 is the object name then a click on the object in CBGraph will result in calling th
250. ple shows that parameters can also be retrieved and computed attributes Note that variable for the parameter in the constraint is prefixed here with you may also omit the prefix in the constraint as explained above What_SI_Manager in GenericQueryClass isA Manager UnionMember with retrieved_attribute parameter salary HighSalary union Union computed_attribute parameter head_of Department constraint well_off_rule head_of head this end There are two kinds of specializing generic query classes 1 Specialization of a parameter a C Example What_SI_Manager salary TopSalary In this case TopSalary must be a subclass of HighSalary The solutions are those managers in What_SI_Manager that not only have a high but a top salary 2 Instantiation of a parameter v a Example What __SI_Manager Research head_of The variable head_of is the replaced by the constant Research which must be an instance of Department One may also combine several specializations e g What_SI_Manager salary TopSalary Research head_of The specialized queries can occur in other queries in any place where ordinary classes can occur e g 110000 in Integer end QueryClass FavoriteDepartment isA Department with retrieved_attribute head What_SI_Manager 110000 salary end Parameters that don t occur as computed or retrieved attributes are interpreted as existential quantifica tions if they are not instantiated Note that parameter
251. position with parameter class Proposition end The first clause is the Prolog code The predicate must start with the prefix compute followed by the name of the function The first argument is for the result of the function Subsequently each input parameter is represented by two arguments one for the input parameter itself and a second as a placeholder of the type of the input parameter The second clause tells the new function as ConceptBase object so that it can be used like any other ConceptBase function For technical reasons the tell clause may not span over more than 5 lines Use long lines if the object to be defined is large If you just want to invoke the procedure defined in an LPI plugin via the CALL clause of an active tule you do not need to include a tell clause Consider for example the SENDMAIL plugin from http merkur informatik rwth aachen de pub bscw cgi 2269675 You need to be very careful with testing your code Only use this feature for functions that cannot be realized by a regular query class or by active rules LPI code has the full expressiveness of a programming language Program errors may lead to crashes of the CBserver or to infinite loops or to harmful behavior such as deletion of files Query classes deductive rules and integrity constraints can never loop infinitely and can to the best of our knowledge only produce answer not changes to your file system or interact with the operating system A
252. positions P oid x m y tt and x has an attribute with label m with value y believed tt O Telos imposes some structural axioms on knowledge bases e g referential integrity correct instan tiation and inheritance Jeus92 The complete list of axioms is contained in appendix B The axioms are linked to predefined objects that are part of each O Telos object base e Individual contains all individuals as instances Intuitively individuals are objects that are dis played as nodes in a graph e InstanceOf contains all explicit instantiation objects as instances In the graphical representation an instantiation object is a link between some object x and its class c e IsA contains all explicit specialization objects as instances A specialization object is graphically displayed as a link between a subclass c and its superclass d e Attribute contains all explicit attribute objects as instances An attribute object can be displayed by a link between an object x and the object y The label of the attribute object is the name of the attribute link starting from x The object y is also called the value of the attribute In O Telos the class Attribute subsumes relations between objects since values are just objects in O Telos e Proposition contains all propositions as instances i e the union of the instances of Indivi dual InstanceOf IsA and Attribute The term proposition is used as a synonym to object in O Telos Hence all explic
253. r X11 we have extended the graphical type model for the CBGraph Editor First the class GraphicalType has been specialized by a class Java GraphicalType Class JavaGraphicalType isA GraphicalType with attribute implementedBy String property String priority Integer attribute rule rPriority forall jgt JavaGraphicalType not exists i Integer A_e jgt priority i gt A jgt priority 0 end Individual DefaultIndividualGT in JavaGraphicalType with attribute property bgcolor 210 210 210 textcolor 0 0 0 linecolor 0 0 0 shape i5 cb graph shapes Rect attribute implementedBy implBy i5 cb graph cbeditor CBIndividual end The object Default IndividualGT is an example for the instantiation of a graphical type The attribute implementedBy specifies the full name of the Java class that provides the implementation for this graphical type This class has to be a sub class of i5 cb graph cbeditor CBUserObject The property attribute specifies name value pairs which will be used by the Java implementation to set certain properties e g color shape font The priority value is used to resolve ambiguity if multiple graphical types apply to one object The graphical type with the highest priority will be used The rule specifies a default value of O for the priority The graphical palette has also been extended There are now defaults for different types of objects and graphical types for implicit links can
254. rchy Example The concerned class of e boss b inthe SalaryBound constraint in subsection 2 2 8 is the Employee boss The class of variable e is Employee This is the most special superclass of itself and indeed defines the attribute Employee boss The purpose of the predicate typing condition is to allow ConceptBase to compile attribution predicates x m y to an internal form Adot cc x y that replaces the attribute label m by the object identifier cc of the concerned class This enourmously speeds up the computation of predicate extensions A similar effect is applicable to instantiation predicates Here the concerned class of x in c is c Another effect of the predicate typing condition is that certain semantically meaningless predicate occurrences are detected at compile time For example x m y can only have a non empty extension if some class of x defines an attribute with label m If the argument x in a predicate x m y is a variable then the initial class of x is determined by the the variable range in the formula The variable this of query class constraints can have multiple initial classes being the set of superclasses of the corresponding query class All superclasses of c are also regarded as classes of x If x is a constant then the classes of x are determined by a query to the object base A formula violating the first clause of the predicate typing condition would make a statement about something that is not part of the obj
255. redicates x y UNIFIES x y and IDENTICAL x y defined in earlier releases of ConceptBase are deprecated It is recommended to use x y instead 2 2 6 Typed variables The exact syntax of CBL is given in appendix A The types of variables i e quantified identifiers are interpreted as instantiations e forall x C F gt forall x x in C gt F e exists x C F gt exists x x in C and E The class C attached to variable x is called the variable range The anonymous variable range VAR is treated as follows e forall x VAR F gt forall x F e exists x VAR F gt exists x F Anonymous variable ranges are only permitted in meta formulas see section 2 2 9 2 2 7 Semantic restrictions on formulas We demand that each variable is quantified exactly once inside a formula This is no real restriction in case of double quantification rename one of the variables More important is a restriction similar to static type checking in programming languages that demands a strong relationship between formulas and the knowledge base Predicate typing condition 1 Each constant arguments that are not variables in a formula F must be the name of an existing object in the O Telos object base or it is a constant of the builtin classes Integer Real or String 2 For each attribution predicate x m y or Ai x m o resp occuring in a formula there must be a unique attribute labelled m of some class c of x in the knowledge ba
256. rently set to 50000 If necessary the cache emptying takes place before a transaction The keep mode is on average consuming more main memory than the transient mode but speeds up response time enormously in case of re use of query results c transient The tabling cache is emptied before each transaction ask tell untell retell A subsequent query is always evaluated starting with an empty cache This mode is somewhat safer than the keep mode since it starts each query with an empty cache state While the answer to a query is in principal independent from the cache mode the cache mode has a certain influence on the persistence of objects created within a transaction Specifically results of arithmetic expressions computed during one transaction shall be removed after the transaction when the cache mode is transient In cache mode keep these objects continue to exist and are visible to future transactions ConceptBase will only call tabled evaluation for deductive predicates Other predicates are evaluated by the regular SLDNF engine of the underlying Prolog engine By default the tabling cache mode is activated in mode keep Some statistics on cache usage are written to the terminal window of the ConceptBase server when the tracemode has been set to veryhigh Acknowledgements The techniques for the tabled query evaluator of ConceptBase cc are inspired by the tabled evaluation SSW94 CW96 We do however not delay th
257. ribute category M is transitive ie if x M y and y M z then x M z shall hold Many attribute categories are supposed to be transitive for example the ancestor relation of persons or the connection relation between cities in a railway network The following meta formula defines transitivity once and forever Proposition in Class with attribute Use multi sets as discussed in http merkur informatik rwth aachen de pub bscw cgi 2330042 if you want to constrain the sum of salaries 27 transitive Proposition rule trans_R forall x y z M VAR AC Proposition transitive C Proposition P AC C M C and x in C and y in C and z in C and x M y and y M z gt x Mz end The rule is a meta formula because C and M are meta variables In this case one can re write the formula by replacing all possible fillers for AC i e by the instances of Proposition transitive A filler for AC will determine fillers for C and M since the first argument of a proposition P AC C M C is identifying the proposition As a consequence one can define the ancestor relation to be transitive by simply telling Person in Proposition with transitive ancestor Person end ConceptBase will match the attribute Person ancestor with the variable AC in the above meta formula This yields P Person ancestor Person ancestor Person which binds the meta variable C to Person and M to ancestor The resulting generated formula is forall
258. ribute depth specifies the maximum nesting depth of ECArules ECArules may be fired by events which are produced by actions of the same or other ECArules Because this often results in an endless loop the execution of the ECArule is aborted if the current nesting depth is higher than the specified value The default of this attribute is 0 no limitation 4 1 11 User definable Error Messages If the ECArule rejects the transaction in some cases it is useful to specify an error message The value of the attribute rejectMsg is returned to the user 4 1 12 Constraints The constraints of the class ECArule ensure that the attributes mode active and depth have only single values and that the attribute ecarule has exactly one value 4 2 Examples The Telos source files of the following examples can also be found in your ConceptBase installation directory at CB_HOME examples ECArules Further examples are in the CB Forum at http merkur informatik rwth aachen de pub bscw cgi 1747992 4 2 1 Materialization of views by active rules Materialization of views means that deduced information is stored in the object base We provide here an example how to materialize and maintain simple views Class Employee with attribute salary Integer end View EmployeeWithHighSalary isA Employee with constraint c exists i Integer this salary i and i gt 100000 end Class EmployeeWithHighSalary_Materialized end The view
259. ributes Now you can select the attributes you want to have in the result For selection of more than one attribute you must press the CTRL key and select the attribute with a mouse click at the same time All attributes can be deselected by the popup menu In the right listbox you can add computed attributes The right mouse button brings up a popup menu which lets you add or delete an attribute In the text area below the two list boxes you can add a constraint in the usual CBQL syntax The constraint must be enclosed in signs The text area below shows the Telos definition of the query and is updated after every change you have made If your query is finished you can press the Ask query to test the query i e it is told temporarely and the results are shown in separate window If you are satisfied with the result you can press the Tell button to store the query in the object base 107 Query Editor Latest operation status Operation successful Query Name HighSalary Specialization of Employee Retrieved Attributes Computed Attributes dept Department j csal Integer salary Integer i Constraint Add Computed Attribute this salary csal and csal gt 50000 Telos Definition QueryClass HighSalary isA Employee with computed_attribute csal Integer constraint c this salary csal and csal gt 50000 end Figure 8 5 Query Editor 8 1 11 Tree browser The Tree browser see figure
260. ributes are multi valued For the answer object A this cat1 evaluates to v11 v12 and this cat2 evaluates to v21 For the complex object B a path expression like this cat2 cat21 is allowed and yields v21 Note that all such expressions are set valued this ATTRIBUTE_LABEL denotes the value of the attribute ATTRIBUTE_LABEL of the current answer object this The attribute_label is at the level of the answer object i e not at the class level but at the instance level Therefore this expression is rarely used because the instance level attribute labels are usually unknown at query definition time Example A and B this labe112 evaluates to v12 this ATTRIBUTE_CAT denotes all attribute labels of the answer object this that are grouped under the category ATTRIBUTE_CAT defined in the query class Example this cat1 evaluates to label11 label12 The derivation of pattern is performed for each answer object that is in the result set of a query The answer object A induces the following substition rules this A this catl gt vl11 v12 this cat2 gt v21 this labell1l vil this label12 v12 this label21 v21 this catl gt labell label2 this cat2 gt label21 Extended examples for these simple expressions are given in simple_answerformats1 sml and simple_answerformats2 sml in the directory CB_HOME examples AnswerFormat Note t
261. ribution and use in source and binary forms with or without modification are permitted provided that the following conditions are met 1 Redistributions of source code must retain the above copyright notice this list of conditions and the following disclaimer 2 Redistributions in binary form must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution THIS SOFTWARE IS PROVIDED BY THE CONCEPTBASE TEAM AS IS AND ANY EXPRESS OR IMPLIED WARRANTIES INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED IN NO EVENT SHALL THE CONCEPTBASE TEAM OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT INDIRECT INCIDENTAL SPECIAL EXEMPLARY OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES LOSS OF USE DATA OR PROFITS OR BUSINESS INTERRUPTION HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY WHETHER IN CONTRACT STRICT LIABILITY OR TORT INCLUDING NEGLIGENCE OR OTHERWISE ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE The views and conclusions contained in the software and documentation are those of the authors and should not be interpreted as representing official policies either expressed or implied of the ConceptBase Team This license makes ConceptBase cc free
262. rizes the mechanism for assigning graphical types to objects and adapting the graphical browsing tool for specific application needs Appendix D contains the full Telos notation of an example model D 1 and a case study on the modeling of entity relationship diagrams with Telos D 2 Plenty of further examples for particular application domains and add ons for meta modeling can be retrieved from the ConceptBase cc Forum 1 5 Differences to earlier versions ConceptBase cc 7 8 should be largely source compatible to its direct predecessor The binary database files and the graph files have a new format and are not compatible with their counterparts created by earlier releases The CBserver has now the ability to maintain module sources and query results formatted in external formats in the file system The module sources allow to co develop models both via the ConceptBase cc user interface and by external text editors Exporting query results in external formats is useful when they are post processed by external tools For example one can generate program source code from a ConceptBase cc model and have that code processed by a compiler The active rule component now supports constructs to enforce a transactional execution of delayed triggers Triggers can be passed to different queues that are processed with different priorities This feature allows to delay certain triggers until the consequences of the current trigger are all processed The graph ed
263. rthermore all attributes have to be strings even if they are just numbers e g use 1 instead of 1 as attribute value bgcolor Background color of the shape default transparent textcolor Foreground color of the shape i e text color default black 0 0 0 linecolor Color of the border of the shape default transparent linewidth Width of the border of the shape default 1 edgecolor Color of the edge default black 0 0 0 edgewidth Width of the edge default 1 edgestyle possible values are continuous dashed dotted dashdotted Idashed dashed with longer intervals Idotted default continuous shape The name of the class representing the shape and implementing the interface i5 cb graph shape IGraphShape default no shape The package i5 cb graph shape defines some useful default shapes see below for details The shape will be drawn in the background of the small component In the default implementation the small component is a transparent JLabel thus the shape is completely visible Note that this might not be the case if you are going to change the implementation of a graphical type see subsection C 3 4 below image The location URL of an image icon file that shall be used to display a node CBIndividual The image tag is a replacement for the shape attribute but can also be combined with a shape The image icon can be in PNG GIF or JPG form
264. rver interface calls without answers and the tracemode no virtually disables tracing The tracemode silent is even surpressing the message CBserver ready when starting up the CBserver The tracemode high and veryhigh are useful for debug ging the system In these two modes an unlikely fatal signal like division by zero will not directly abort the CBserver process but start a debug dialog Enter h for options to diagnose the problem in collaboration with the ConceptBase developers c cachemode turns on the query cache to allow recursive query evaluation The value cachemode is one of off transient and keep default In transient mode the cache is emptied before each transaction In keep mode the cache is emptied when the maximum number of entries in the cache is exceeded or an update has invalidated the cache Further details are explained in section 6 6 0 optmode controls the optimizer for rules constraints and queries The value optmode is one of 0 no optimization 1 structural optimization by exploiting builtin O Telos axioms 2 optimizing join order 3 combines 1 and 2 or 4 combines 1 and 2 with trigger pruning Default and recom mended is 4 r secs automatically restarts the CBserver after a crash or when it was started with option sm slave and the last client exits The value secs specifies how many seconds to wait before restart You may want to use this option in a multi user setting where the CBserver runs
265. ry newsalary Optionally one can specify an ELSE part which consists of actions that are executed when the IF part is not satisfiable for any binding of the free variables The Ask action is only useful for ECArules that have an ELSE part In this case the Ask will retrieve information from the database that cannot be retrieved within the IF part The special action reject will abort the complete transaction that directly or indirectly triggered the ECArule The effect of ECArules is subject to the regular integrity checking of ConceptBase If an integrity violation is detected then the whole transaction including all updates by ECArules is rolled back The integrity test is started after all enabled ECArules have fired 4 1 Definition of ECArules In ConceptBase active rules are defined similar to query classes The user has to create an instance of the builtin class ECArule The following frame shows the Telos definition of the class ECArule Class ECArule with attribute ecarule ECAassertion priority_after ECArule priority_before ECArule mode ECAmode active Boolean depth Integer rejectMsg String constraint 60 end A correct ECArule must specify at least the attribute ecarule the other attributes are optional The language for ECAassertions is a extension of the assertion language it is specified as text between signs in the same way as rules and constraints 4 1 1 ECAassertion
266. rying object bases using the Telos syntax We provide support for Java and to a very limited degree for C C Descriptions of the interfaces and the correspond ing libraries that are delivered with ConceptBase cc can be found in the ConceptBase cc Programmers Manual available via the CB Forum at http merkur informatik rwth aachen de pub bscw cgi 885553 We like to note that the C C interfaces were not maintained since we switched the user interface to Java Besides the Java C API the CBShell client see section 7 can be used to interact with a CBserver via the command line or in shell scripts CBShell is indeed a Java client of the CBserver The CBShell can also serve as an example client for programming own application specific client tools There is also a tool that creates an HTTP interface to a CBserver see section BrokerReproxy in the CB Forum http merkur informatik rwth aachen de pub bscw cgi 895647 Clients would then interact with ConceptBase via HTTP requests Graph Telos Mail Browser 2 Editor 5 Tool 8 GBROWSE EDIT SEND RECEIVE Communication channel intemet TEL f NOTIFY ASK i SQL SQL CB rel rel z3 E Server 23 DBMS 1 DBMS 2 EE E a EE Y Representation of ervirorment within CB s object base Figure 1 1 The client server architecture of ConceptBase cc ConceptBase cc comes with a standard usage environment impl
267. s whole enterprises or even trans national networks In these applications which are crucial for the huge integration tasks to be tackled in the 1990s the possibility not only to execute systems but also to reason formally about their structure and capabilities can be considered a competitive advantage over the other approaches ConceptBase has provided some validity to this claim by extensive usage experiments in several of the above areas A performance comparison Lud2010 of ConceptBase cc with Proteg Racer found that Concept Base cc is orders of magnitude faster for queries It lacks however the reasoning capabilities of Pro teg Racer 1 1 1 Telos and O Telos The language underlying ConceptBase Telos has been one of the earliest attempts to integrate deductive and object oriented data models Stan86 MBJK90 The O Telos Jeus92 dialect supported in Concept Base cc takes a conservative integration approach with the main design goals of semantic simplicity sym metry of deductive and object views flexibility and extensibility This emphasis technically supported by a careful mapping of Telos to Datalog with negation has paid off both in user acceptance and ease of im plementation In essence ConceptBase cc is based on deductive database technology woth object oriented abstraction principles like object identity class membership specialization and attribution being coded as pre defined deductive rules and integrity constraints
268. s and constraints The semantics of an O Telos database including such rules and constraints is the perfect model of the deductive database with the P o x l y as the only extensional predicate and all axioms and user defined rules constraints as deductive rules Note that integrity constraints can be rewritten to deductive rules deriving the predicate inconsistent This list of axioms is excerpted from M A Jeusfeld Anderungskontrolle in deduktiven Objektbanken Dissertation Universit t Passau Germany 1992 Available as Volume DISKI 19 from INFIX Verlag St Augustin Germany or via http merkur informatik rwth aachen de pub bscw cgi d340216 diski19 paf in German Axioms 19 21 have been corrected after Christoph Radig found an example that led to the undesired instantiation of an individual object to Inst or Spec respectively 142 Appendix C Graphical Types The concept of a graphical type enables the specification of an external graphical presentation for Concept Base objects The graphical type is declared using a special pre defined attribute category An application program then uses this information to determine the graphical presentation of an object The next subsection introduces the basic concepts behind graphical types while section C 2 presents the standard graphical type definitions for the ConceptBase Graph Editor Section C 3 describes the definition of application specific types C 1 The graphical type model A
269. s are represented like in the subsequent example P mary mary mary mary tt millisecond 1992 1 11 17 5 42 102 infinity The object mary is believed since 17 05 42 on January 11 1992 The label infinity denotes that the end time of the object lies in the future and is not yet known In any case the current time Now is regarded to be smaller than infinity Right open belief times indicate objects that are part of the current knowledge base Closed intervals denoted by binary tt terms indicate historical objects i e objects that have been untold Example P E1 mary instanceof M tt millisecond 1992 1 11 17 5 42 0 millisecond 1995 12 31 23 59 59 999 The object E1 i e the instantiation of mary to the class Manager is believed from 17 05 42 on January 11 1992 until the end of the last millisecond of the year 1995 We call the first component of the belief time also the start time object and the second component the end time Start and end time of an object can be retrieved by the predicates Known and Terminated see section 2 2 2 2 Rules and constraints The ConceptBase predicative language CBL JK90 is used to express integrity constraints deductive rules and queries The variables inside the formulas have to be quantified and assigned to a type that limits the range of possible instantiations to the set of instances of a class ConceptBa
270. s come from the tradition of deductive databases or semantic data models and aim at formal as well as practical support for general database systems and applications Examples in clude the deductive databases EKS LDL CORAL NAIL and the concept logic systems CLASSIC BACK and LOOM A sample of the former two groups of systems is described in TKDE90 whereas several prototypes of the latter are reported in SIGA91 Although a certain confluence can be observed these systems do not only differ in their background theories but also in their intended application domains The first group wants to support non standard applications such as the handling of complex engineering objects The second group aims at an easier programming environment for standard applications addition ally they emphasize the goal of making applications written in different languages interoperable The third group pursues as one of its goals the support for AI applications such as natural language understanding or expert systems However this may remain a fairly limited portion of the software market The reason why we became interested in this group of languages is therefore a slightly different one the important role we expect them to play in meta data management Meta data applications range from the uniform access to heterogeneous data sources to the coordination of design processes to the integration of heterogeneous information services in networked production chain
271. s in directory MYDB Recommended options cbserver db MYDB s 2 mu enabled If ConceptBase cc is used in a multi user setting then one can combine the update mode with the module feature see section 5 In this scenario multiple users access the same CBserver A common super module e g the module oHome carries the common objects of the users Each user can be assigned to her own hown module a sub module of the common super module and create and update objects in this workspace without interfering with other users If several groups of users shall share their definitions then they would be assigned to the same home module The home module may have sub modules for testing and releasing definitions By employing access rights to modules one can also design which user has which read write permissions The builtin query 1istModule allows to save the contents of a module to a Telos source file see section 5 7 6 8 The UNTELL operation ConceptBase cc realizes the concept of a historical database The TELL operation submits O Telos frames to the CBserver The CBserver extracts the novelty of the submitted frames and translates it into a set of P facts to be stored in the object store Any P fact has a so called belief time associated to it see section 2 1 The belief time is an interval t t2 whose left boundary t is the time point when the P fact was inserted to the object store 1 e the time when the transaction was executed that le
272. s module source fails Error messages shall be displayed in the trace log of the CBserver Note that the CBserver can be started with a non empty database The import of source files will be added to the already existing content of the database Examples cbserver d DB1 save home m DB1SRC This command starts up a CBserver that will eventually save the module sources in the specified direc tory Note that the saving takes place either at CBserver shutdown or when a client tool disconnects partial save cbserver u nonpersistent save home m SRC This variant will start a CBserver with a persistent database but the contents will nevertheless stored as Telos sources files cbserver u nonpersistent load SRC1 save SRC2 81 This command starts a the CBserver i e only system objects are defined and then loads module sources from the directory SRC1 Then client tools may modify the contents of the database Finally the module contents are saved in directory SRC2 cbserver d DB1 load home meee DB1SRC save home m DB1SRC The load and save directories may also be the same Note that the save function will eventually over write the files that have been loaded at CBserver startup cbserver u nonpersistent load DB1SRC This command will start a non persistent CBserver and loads the module sources of directory DB1SRC Module sources do not contains the historic states of objects that are maintained with rollback ti
273. s need to be known as objects before using them in query calls 2 3 1 Query definitions versus query calls Telling a frame that declares an instance of QueryClass as well as its sub classes GenericQuery Class and Function constitutes the definition of a query It shall be compiled internally into Datalog code not visible to the user Once defined a query can be called simply by referring to its name Hence if Q is a the name of a defined query class then Q is also an admissable query call It results in the set of all objects that fulfill the membership constraint of O ConceptBase regards these objects as derived instances of the query class Q If a query class has parameters then any of its specialized forms is also an admissable query call For example if Q has two parameters p1 p2 in its defining frame then Q v1 p1 v2 p2 is the name of a class whose instances is the subset of instances of Q where the parameters p1 and p2 are substituted by 35 the values v1 and v2 The substitution yields a simplified membership constraint that precisely defines the extension of Q v1 p1 v2 p2 If a generic query class is called with all parameters substituted by fillers then one can omit the param eter labels Assume that the query Q has just the parameters p1 and p2 Then the expression Q v1 v2 is equivalent to O v1 p1 v2 p2 ConceptBase uses the alphabetic order of parameter labels to convert the shortcut form to the full form 2 3 2 Query
274. s of the root module System They include for example the definitions of the objects Proposition Individual Attribute InstanceOf and IsA Further the objects Class QueryClass Function ECArule Module and many more are defined that are needed to formulate queries and to use the capabilities of the system Whenever a new database is created the files from this System database are copied into the new database directory This allows experienced ConceptBase users to adapt the System database to their needs Just start a ConceptBase server with cbserver d CB_HOME lib SystemDB s 0 Replace CB_HOME by the path to your ConceptBase installation directory Then start a CBIva user interface connect to the CBserver and switch to the module System Assume you want to predefine the class Container and declare a Model as subclass of Container Container with attribute contains Proposition end Model isA Container end You can also add rules and constraints about containers e g that containers may not contain them selves A more significant extension would be to add active rules to the system database For example the active rules in CB Forum at http merkur informatik rwth aachen de pub bscw cgi 3260276 changes the semantics of the UNTELL operation Such definitions are subsequently included in any new database that you create Be careful with deleting system objects The code of the CBserver relies on the existence of certain system
275. s the deductive rules to be compiled See section 5 7 1 for more details The background image is not stored as a serializable Java object but as a PNG image using the ImagelO class of Java It is always stored as the last element since the input routines shall read it until the end of the file Note that some strings can be just null 8 3 An example session with ConceptBase In this section we demonstrate the usage of the ConceptBase cc User Interface by involving an exam ple model It consists of a few classes including Employee Department Manager The class Employee has the attributes name salary dept and boss In order to create an instance of Employee one may specify the attributes salary name and dept The attribute boss will be computed by the system using the bossrule There is also a constraint which must be satisfied by all instances of the class Employee which specifies that no employee may earn more money than its boss The Telos notation for this model is given in Appendix D 1 8 3 1 Starting ConceptBase To start a ConceptBase session we use two terminal windows one for the ConceptBase cc server and one for the usage environment We start the ConceptBase cc server by typing the command cbserver port 4001 d test in a terminal window of let us say machine alpha The parameter port sets the port number under which the CBserver communicates to clients and the parameter d specifies the name of the dire
276. s which will be used to visualize Telos objects see 110 Appendix C On startup CBGraph retrieves all information about the graphical types from the CBserver If CBIva has no connection with a server CBGraph will be started without a connection and no internal window will be opened within CBGraph The connection to a CBserver can also be established via the File Connect menu The dialog box has two tabs The first is for providing the host and port number number of the CBserver The second is for providing the start object default Class to be displayed the graphical palette pick from a list and the database module default oHome The most comfortable way to start CBGraph is to double click the graph file It is equivalent to starting it via the command cbgraph graph gel To do so you need to configure your desktop according to the instructions at http conceptbase sourceforge net CB Mime html 8 2 3 The cograph command You can also start CBGraph as a stand alone utility The command cbgraph options will start an unconnected graph editor You can interactively connect it to a running CBserver and open new windows to display graphs More interesting is the use with a stored graph file or several graph files resp cbgraph options filename filename The format of the graph file is called Graph Editor Layout GEL It stores not only the layout of nodes and links but all other data necessary to edit
277. se the so called concerned class 3 For each instantiation predicate x in c the argument c must be a constant 24 All instantiation and attribution predicates need to be typed according to the predicate typing condi tion Formally we don t assign types to such predicates but concerned classes Any instantiation predicate and any attribution predicate in a formula must have a unique concerned class It is determined as follows e The concerned class of an instantiation predicate x in c is the class c The argument c may not be a variable e The concerned class of attribution predicates x m y and Ai x m o is principally the most special attribute with label m of all classes of x The O Telos axioms listed in appendix B in par ticular axiom 17 make sure that there may not be more than one candidate attribute if x is the name of an existing object If x is a variable we demand that there is at most one candidate in the variable range of x and its superclasses If no class of x i e also no superclass of any class of x defines such an attribute and the CBserver has been started with the predicate typing mode extended then the concerned class is determined from the subclasses of the classes of x Theoretically one can choose the common superclass of all such attributes of subclasses of the classes of x if existent However ConceptBase currently demands that there must be a single such attribute in the subclass hiera
278. se Team All rights reserved Source Mode off Y gt Distributed under a FreeBSD license See CB FreeBSD License txt for details t Eae A gt M Jeusfeld University of Skovde 54128 Skovde Sweden Update Mode nonpersistent v gt M Jarke C Quix RWTH Aachen Ahornstr 55 52056 Aachen Germany p l gt mp conceptbase cc Untell Mode cleanup v Multi user Mode disabled x gt CBserver ready on host myon serving port number 4001 Predicate Typing strict vw gt gt gt 2014 01 31 13 21 06 CALL ENROLL_ME ON CBlva jeusfeld myon ETS Keep ly gt gt gt 2014 01 31 13 21 06 CBiva s69558723_9 CALL GET_MODULE_CONTEXT ON ECA Mode safe v W B 4 il i gt OK Cancel Stop CBserver Figure 8 13 Start CBserver dialog and CBserver output window 8 3 2 Connecting CBlIva to the CBserver Next we establish a connection between the ConceptBas cc server and the user client CBIva This is done by choosing the option Connect from the File menu of CBIva An interaction window appears see Figure 8 14 querying for the host name and the port number of the server i e the number we have specified within the command cbserver port 4001 d test Connect to CBserver 4001 Host Port Figure 8 14 The connect to server dialog 8 3 3 Loading objects from external files The objects manipulated by ConceptBase cc are persistently stored in a collection of external files which reside in a directory called application or
279. se offers a set of predicates for the predicative language defined on top of an O Telos object base as visible for a given rollback time OBrvi P oid x l y P oid x 1l y tt OB rbt during tt The value of the rollback time depends on the kind of formula to be processed integrity constraints are evaluated on the current object base OBy Now the smallest time interval that contains the current time The rollback time of queries is usually provided together with the query when it is submitted from a user interface to a ConceptBase server By default it is Now as well 7Only objects that have a right open belief time shall be visible OByoy This is due to the fact that the end time of an object can only be changed once namely when the object is untold The UNTELL operation can only have happened in the past when OByow is built 18 2 2 1 Basic predicates The following predicates provide the basic access to an O Telos object base Some have both an infix and a prefix notation As usual we employ the object identifer to refer to an object 1 10 11 12 13 x in c orIn x c The object x is an instance of class c c isA d or Isa c d The object c is a specialization subclass of d x m y orA x m y The object x has an attribution link to the object y and this link has the attribute category m Structural integrity demands that the label m belongs to an attribute of a class of x Ai x m o The objec
280. serted as instance of Class then the event statement is Tell In x Class Furthermore an event may be a query e g if you specify the eventAsk find_instances Class class the ECA rule is executed before the evaluation of the query find_instances with the parameter Class Potential updates to the database caused by the ECA rules will be persistent i e in such cases an Ask van well update the database It is possible to use variables as a placeholders for parameters in the Ask event clause The event detection algorithm takes only extensional events into account Events that can be deduced by arule or a query are not detected However the algorithm is aware of the predefined Telos axioms e g if an object is declared as an instance of a class the object is also an instance of the super classes of this class 4 1 3 Conditions The condition IF part of an ECArule consists of predicates combined by the logical operators and or and not Quantified sub expressions forall exists are not allowed You can however use query classes to encode such sub expressions The arguments of the predicates are either bound by the ON part of the ECA rule or they are free variables When an event occurs that fires an ECArule then the condition is 1 An example for a quantified sub expressions is not exists y D x m y 61 evaluated against the database yielding bindings for the free variables Each such binding will be passed to the a
281. server is restarted whenever the last client logs off Hence the definitions of different users are not permanently stored on the CBserver Configure the Java interface to use the public CBserver via the variable PublicCBserver It can be set by the menu item Options Edit Options Manually of CBIva see section 8 1 1 A value different from none enables the use of the public CBserver by CBGraph You can optionally append a port number like myhost acme com 4002 The default value for the port number is 4001 Don t forget to save the options after changing the variable Since the Windows variant of the CBserver is stuck at version 7 5 the CBGraph tool should use a public CBserver on Windows by default The best way to interact with a public CBserver is to use graph files see section 8 2 3 Assume that a public CBserver is running on host cbserver acme com and that cbserver acme com was configured as the public CBserver to be used Then calling cbgraph graphl gel will connect to the public CBserver instead of localhost The port number for the connection is taken from the graph file Do not forget to save the graph file before exiting CBGraph if the public CBserver was started in non persistent mode If you subsequently open the graph file it will attempt to connect to the same host You can force it to attempt the connection to localhost instead by 89 cbgraph host localhost graphl gel 6 6 The tabling subsystem Since
282. so be modified CBIva via the Options menu e Variables related to CBIva PathForLoadModel Path used by the load model dialog contains the most recent directory se lected in a dialog RecentConnections Comma separated list of recent connections in the format host port applies also to CBGraph PreParseTelosFrames Frames are be parsed on client side before sent to the server true false UseQueryResultWindow Use the query result window to display results of a query true false ConnectionTimeout Number of milliseconds the interface waits for a response of the server LPICall Enable LPI Call internal use only ShowLineNumbers If set to true the Telos editor of CBIva shall display line numbers PublicCBserver Either none disabled or the domain name of a computer that hosts a pub licly accessible ConceptBase server A port number can be appended as well like in my host acme com 4002 Default port number is 4001 The variable PublicCBserver also applies to CBGraph and CBShell See section 6 5 for more details If the value is different from none then CBIva shall attempt to connect to the public CBserver at startup Variables related to CBGraph PathForLayout Path used by the dialog to store and load graphs contains the most recent directory selected in a dialog 131 ComponentView Default view for the detailed representation in CBGraph might be frame or tree SaveLayoutWithGraphTyp
283. software as promoted by the Free Software Foundation The license is upwards compatible to the GNU Public License GPL i e developers can combine GPL ed software with ConceptBase software as long as they include the above FreeBSD style license for the Con ceptBase components It should also be compatible with many other free license models The source code is copyrighted by the the ConceptBase Team consisting of all contributors to the source code at the central code repository of the system You are welcome to contribute the ConceptBase cc project Join the ConceptBase cc Forum at http conceptbase sourceforge net CB Forum html to do so 1 7 Disclaimer and rights All trademarks are owned by their respective owners This report may contain flaws based on human errors We disclaim liability for any such flaws It may also be that the ConceptBase cc does not provide all functionality described in this report or that the functionality is provided by other mechanisms as described in this report Links to external websites are provided for informational academic purposes We disclaim responsibility for the views expressed on these websites You can freely use the ConceptBase cc user manual for private and academic purposes Changes to the user manual may however only be made by members of the ConceptBase cc Team as listed on http conceptbase cc cbteam html If you make changes to your own copy of the source code of ConceptBase cc then you m
284. sses and attributes of this object see figure 8 8 e Super classes sub classes classes instances for each menu item you can select whether you want to see only the explicitly defined super classes or sub classes etc or all super classes including all implicit relationships The query to the CB server to retrieve this information will be done when you select the menu item So the construction of the corresponding submenu might take a few seconds e Incoming and outgoing attributes CBGraph will ask the CBserver for the attribute classes that apply to this object For each attribute class it is possible to display only explicit attributes or all attributes as above The attribute class Attribute applies for every object and all attributes are in this class Therefore all explicit attributes of an object will be visible in this category However there will be no attributes shown in the All submenu as it would take too much time to compute the extension of all implicit attributes e Add Instance Class SuperClass SubClass Attribute Individual These menu items will open the Create Object dialog where you can specify new objects that should be created in the database Note that these modifications are not performed directly on the database The editor will collect all modifications and send them to the CBserver when you click on the Commit button See section 8 2 9 for more details Delete object from database
285. state of the database 8 1 4 Telos editor The Telos Editor is an editable text area where you can edit Telos frames The operations can be executed from the menu bar or the buttons in the tool bar Furthermore the text area has a popup menu on the right mouse button with the following items Display Instances Displays the instances of the currently marked object Load Object Loads the Telos frame of the currently marked object into the Telos editor View Object as Tree Opens the tree browser with the currently marked object as root Display in Graph Editor Shows the object in the current window of CBGraph CBGraph has to be started before menu Browse Change Module Changes the module context to the module path defined by the currently marked text Clear Cut Copy Paste same as in the menu bar If the Telos editor window is empty then you can drag and drop Telos text files file type sml or sml txt into it CBIva will open the file and paste the content into the Telos editor window This function requires that the option Show Line Numbers is enabled see section 8 1 1 You can also drag and drop URLs pointing to publicly accessible Telos text files 8 1 5 History window The history window is part of the main Telos editor It stores all operations and their results so that they can later be used again The buttons scroll the history back or forward copy the text into the Telos editor or redo the operation in the history wind
286. stitutions of a query call available to answer formatting 3 2 3 Iterations over expressions In case of expressions with multiple values the user may want to generate a complex text that uses one value after the other as a parameter This is in particular useful to transform multiple attribute values like this cat1 The Foreach construct has the format Foreach exprl expr2 x1 x2 expr The expression expr1 is evaluated yielding each a list of solutions s11 s12 The same is applied to expr2 yielding a list s21 s22 Then the variables x1 x2 are matched against the first entries of all lists ie x1 s11 x2 s21 This binding is then applied to the expression expr which should contain occurences of x1 x2 This replacement is continued with the second entries in all lists yielding bindings x1 s12 x2 s22 This is continued until all elements of all lists are iterated If some lists are smaller than others the missing entries are replaced by NULL During each iteration the new bindings induce substitution rules for the binding Iteration 1 x1 gt sill X2 gt 521 Iteration 2 x1 gt s12 1x2 522 54 Note that the third argument expr may contain other subexpressions even a nested Foreach An example for iterations is given in CB_HOME examples AnswerFormat iterations sml The Foreach construct contains three arguments separated by commas These two commas are used
287. t although only java awt Component is required as return value AWT Component will probably not work correctly in the Swing based CBGraph Editor If the method returns null then the result of getCom ponent will be used to visualize the object Component getComponent returns the main component for this user object This component is used when the small component is not shown To be compatible with the CBGraph which is implemented in JFC Swing the component should be a subclass of JComponent This method may return null but then getSmallComponent must return a value Shape getShape returns the shape for this component Shape is defined in the package java awt and represents any type of shape e g polygon rectangle ellipse etc As said above the shape is shown in the background of the small component so it may not be visible if the small component is not transparent The default implementation in CBIndividual and CBLink provide a transparent JLabel as small component so that the shape is visible The CBGraph Editor contains several predefined shapes see below boolean doCommit This method is called when the user has clicked on the Commit button Changes that have been made within this component e g within a form can then be added to the list of objects to be removed added from the database If the method returns false then the commit operation will be aborted Furthermore the CBUserObject class provides several methods whi
288. t belong to category dept and have source mary Note that and are only allowed to occur within assertions whereever classes may be interpreted as range restrictions e g in quantifications or at the right hand side of in predicates The full syntax which allows combinations of all basic constructors can be found in the appendix For illustration we just give two examples here The first is an alternative representation for the rule above the second could be a constraint stating that all bosses of Mary earn exactly 50 000 1 forall e Employee m Manager m in e dept head gt e boss m 2 forall b Mary dept head b salary 50000 2 2 11 User definable error messages for integrity constraints ConceptBase provides a couple of errors messages in case of an integrity violation These errors messages refer to the logical definition of the constraint and are sometimes hard to read To provide more readable er ror messages one can attach so called hints to constraint definitions These hints are attached as comments with label hint to the attribute that defines the constraint Consider the salary bound constraint above A hint could look like Employee SalaryBound with comment hint An employee may not earn more than her his manager end It is also possible to attach hints to meta level constraints In this case the hint text can refer to the meta level variables occuring in the meta level constraint These variab
289. t empty the definitions from the sources are added to the current database It may well be that the operation causes an integrity violation or fails because the current user has no write permission on a given module In case of success we say CBGraph loads the module sources from the graph file and writes them to the CBserver rw Enable bidirectional synchronization default rw No synchronization f Enable bidirectional synchronization and also write the module sources to text files in the directory where your started CBGraph useful for debugging 111 host hostport Instruct CBGraph to use the hostname and portnumber from hostport rather than those defined in the graph file when loading the graph file If you provide a filename or several then it must have been previously created by another graph editor e g a graph editor started via CBIva The above command will then display the graph stored in the graph file in an internal window and attempt to connect to the same CBserver that was active when the graph file was created Hence the graph file is a materialized view on the CBserver database that is visualized with cbgraph You edit a graph file with cbgraph like you are editing a drawing with a drawing tool The only difference is that the graph is linked to the database If the CBserver module specified in the graph file is not accessible the graph is still opened and you can edit it You can then however not commit
290. t x has an explicit attribute o This attribute is instance of an attribute category with label m x m n y orAL x m n y The object x has an attribution link labelled n to the object y The attribution has the category m From p Xx The object p has source x To p y The object p has destination y Label p 1 The object p has label 1 If 1 is used as a variable it must be quantified over the class Label ES p x 1 y There is an object P p x 1 y in the object base OB Known p t The object p is known in OB since t i e an object P p x 1 y tt is part of the object base OB and t is the start time of tt The argument t is a string of the format tt millisecond yr mo d h min sec millisec It is regarded as an instance of the class TransactionTime Terminated p t The object p is unknown in OB after t i e an object P p x 1 y tt is part of the object base OB and t is the end time of tt The argument t is represented like with Known An object that has not yet been untold has the end time tt infinity x in mc or In2 x mc The object x is an instance of class c and c is an instance of class mc In other words x in mc is equivalent to exists c VAR x in c and c in mc x m y orA2 x m y The object x and y are linked by an attribute al The attribute a1 is an instance of an attribute a2 which itself is an instance of an attribute a3 with label m The predicate is equivalent to the f
291. tart an implementation of Telos and quickly realized that the original semantics was too complex for an efficient implementation The temporal component of Telos included both valid time when an information is true in the domain and transaction time when the information is regarded to part of the knowledge base The temporal reasoner for the valid time was based on Allen s interval calculus and was co NP hard We implemented both temporal dimensions in ConceptBase cc V3 0 only to see that there were undesired effects with the query evaluator and the uniform representation of information into objects Specifically the specialization of a class into a subclass could have a valid time which could be incomparable to the valid time of an instance of the subclass Any change in the network of valid time intervals could change the set of instances of a class Because of that we dropped the valid time as a built in feature of objects but we kept the transaction time A few other features like the declarative TELL UNTELL and RETELL operations as proposed by Manolis Koubarakis in his master thesis on Telos were only implemented in a rather limited way essentially forbidding direct updates to derived facts On the other hand O Telos extends the universal object representation to any piece of explicit information and reduces the number of essential builtin objects to just five So some of the roots of Telos in artificial intelligence were abandoned in favor of
292. tart the server with an empty database d newfile and then add the objects in these files by using Load Model Note that the sml extension may be omitted During the load operation of external models ConceptBase checks for syntactical and semantical correctness and reports all errors to the history window as it is done when updating the object base interactively using the editor This protocol field collects all operations and errors reported since the beginning of the session 8 3 4 Displaying objects To display all instances of an object e g the class Employee we invoke the Display Instance facility by selecting the item Display Instances from the menu bar In the interaction window we specify Employee as object name The instances of the class Employee are then displayed see Figure 8 15 F Display Instances Employee History Christopher Edward Eleonore Telos Editor Cancel Figure 8 15 Display of Employee instances After selecting a displayed instance we can load the frame representation of an instance to the Telos Editor or display further instances 8 3 5 Browsing objects The Graph Editor is the preferred tool for browsing the objects managed by a CBserver CBGraph is started by using the menu item Graph Editor from the Browse menu of CBIva Select Employee as the initial object to be shown in CBGraph After starting CBGraph it will open an internal frame conn
293. tch between the two representations The two procedures arg2val and val2arg are useful for defining new builtin functions on the basis of Prolog s arithmetic functions Assume for example that the object iden tifier id123 has been created to correspond to the real number 1 5 Then the following relations hold makeName 1d123 1 5 arg2val id123 1 5 Hence makeName returns the label 1 5 whereas arg2val returns the number 1 5 The interface shall be extended in the future to provide more functionality Be sure that you only use this feature if user defined query classes cannot realize your requirements 169 Bibliography BBD 90 BBMR89 BCG 87 BMS84 Chen76 CW96 Eber97 Gal190 HJEK90 Jark93 JeJa91 JeSt92 Jeus92 JGJ 95 Bellosta M J Bessede A Darrieumerlou C Gruber O Pucheral P Thevenin J M Stef fen H GEODE Concepts and Facilities Manual INRIA Roquencourt France 1990 Borgida A Brachman R J McGuiness D L Resnick L A CLASSIC a structural data model for objects Proc ACM SIGMOD Intl Conf Management of Data Portland Or 58 67 1989 Banerjee J Chou H T Garza J F Kim W Woelk D Ballou N Kim H J Data model issues for object oriened applications ACM Trans Office Information Systems 5 1 3 26 1987 Brodie M L Mylopoulos J Schmidt J W ed On Conceptual Modeling Springer Verlag 1984 Chen P P C
294. te 10000 The third method to instantiate an explicit attribute to an attribute category is via a user defined rule We use the employee example again Employee in Class with attribute salary Integer premium Integer country String rule premrule forall e Employee prem Employee premium e country NL and Ai e premium prem gt prem in Employee salary end Now consider the following instances marijke in Employee with salary sal 50000 premium pr 3000 country ctr NL end This makes the following attribution facts true marijke salary sal 50000 marijke salary 50000 A_e marijke salary 50000 arijke premium pr 3000 arijke premium 3000 A_e marijke premium 3000 arijke salary pr 3000 arijke salary 3000 A_e marijke salary 3000 marijke country ctr NL marijke country NL A_e marijke country NL 3 3 3 anaanaanannnanananan 3 Hence any explicit premium attribute of an employee of the Netherlands is regarded as an explicit salary as well Note that the three cases discussed here are for explicit attribution objects You may also define rules that derive x m y or x m n y directly In such cases there is no need for an explicit attribute between x and y The attribution is complelety derived 2 2 4 Reserved words In order to avoid ambiguity neither in and isa nor the logical connectives and and or are allowed as attribute labels Likew
295. te for incremental changes to a model Larger changes should better be made via the Telos Editor or even to an external text file that is loaded via the File Load Model facility of CBIva If the changes were successfully told to the CBserver CBGraph reloads the information of every visible object In particular the graphical types of the objects will be updated As the object Address is declared as instance of Class it will get the graphical type of a class i e a turquoise box The result is shown in figure 8 24 The object Employee is shown in the detailed component view in this case the frame representation of the object is shown As you can see the attribute address is now also visible in the frame representation 8 3 7 Using the query facility Lets assume that we need to ask the server for all Employees working for Angus We open a new Telos Editor see menu item Browse Then we define a new query class AngusEmployees as follows AngusEmployees in QueryClass isA Employee with constraint c this boss Angus end We can tell this query so that it is stored in ConceptBase cc and we can reuse it later or we can just ask the query i e the query will told temporarily and evaluated If we ask the query the answer is displayed in 128 5 localhost4001 E localhost4001 Gs MN LES SR adgfess F Create Object Instantiation Ok Cancel
296. te the ER_GraphBrowserPalette select this graphical palette when you start the Graph Editor or make a new connection in the Graph Editor see section 8 2 Handling inconsistencies The necessary and single conditions on attributes from the previous section could also be expressed as deductive rule The difference is that 1f they are formulated as constraints every transaction violating the constraint would be rejected The definition of rules handling necessary and single enables the user to handle inconsistencies in his model The following example demonstrates this 159 concept in the context of our ER model The example defines rules handling the restriction of roles by the min max constraint This restriction is not implemented using constraints Instead a new Class Inconsistent is defined containing all role links which violate the constraint These inconsistent links get a different graphical type e g a red coloured attribute link than consistent role links to visualize the inconsistency graphically KOK KK KKK KK KK OK KR KK KK KK KK KK RK RK KK KKK S File ERIncons x Definition of a Class Inconsistent x x containing roles violating the 1 x gt x constraint x KK A RK KK OK OK IK RK OK OK OK OK OK kK kk K amp S new attribute category revNec for attributes which are reverse necessary Class with attribute revNec Proposition end x roles with 1 must fu
297. ted graphical types Insertion and deletion of Telos objects is also supported The interface is based entirely on Java so it should be usable on all platforms with a compatible Java runtime environment The Java interface includes a graphical browser and editor Both applications CBIva and CBGraph can be run as a stand alone Java application or as an applet inside a web browser The use of CBlva as applet requires a browser with a Java Plugin If you install a Java Runtime Environment on your machine the plugin is usually also installed and configured for your browsers Linux users might have to install the plugin manually into a dedicated directory of their web browser if they want to create web pages with CBIva or CBGraph as applets 8 1 CBlIva You can start the CBIva workbench by the command cbiva We assume that lt CB_HOME gt is the installation directory of ConceptBase cc and that it is added to the search path of executable programs After a few seconds the CBIva main window should pop up If an error occurs you may have to edit the script batch file so that the correct Java Virtual Machine is found Figure 8 1 shows the main window connected to a server and gives a short description of the buttons in the tool bar The user interface uses the MDI multiple document interface model i e all windows are displayed as subwindows in the main window The main window consists of a menu bar a tool bar with a button panel the area for subwi
298. ters chorra SRE A A Ew SB 3 2 1 Function paterns lt lt o r essre a AA eae ae 3 2 0 Calling queries in answer formats o ss coce corpa ek aaa eS 3 2 7 Expressions in head and tail o oe rer a ee ea 3 2 8 Conditional expressions lt lt 265464 pS SEVERE ERR A RE Oe 3 259 Views and path expressions oes cese ee ee ee ewe SH Parametenized answer TORTAS 2 4 6 2 06 4268 edie Bae ee eee BSS 34 Wile type ot answertormidis oo creec ae ee RE SR ERE ERE SERRE SR ERS ao BWES CAE cc bi epee eee MS Shae Sues Bee Peeks PES S Active Rules 4 Delimbo of BOARS o s o cce a GA DE SR HES BO AS a 41 1 BCAASSSHION e 64 ces awe edie e ee ee e LL BES oo eena a e oa eed Bled Se we SS SAS Se ot 4 COMORAS cae RRO Me ee Ee EEG RE Ewe BS MAA PONE oS cents BH ESS 4 ke EHD E EEO WS GHG 8 SE 4 Pee EN AIS Pees oe os wa ee ee eee oe EE ee bo oe ee eee d 416 Coupling modeof an ECA mile 2 24 064 48 8455 48945429425 4 157 Execution Semantic ce ee GR Se OE Mo ee EE Re Ele ENDE QUAE lt lt eh eS PE Oe es SEA PORES aD a SS 4 1 9 Activate and Deactivate ECA rules oo c ecoa ee RR ee ee 41 00 Depi os 4s oh bee ba ae Gad Se Eee ee a 4 1 11 User definable Error Messages e e 4 12 COUTA cos e i AA a a eS oe ESRDE a AR Blk he oe RG A RA da RG 4 2 1 Materialization of views by active rules o E o eet NAAA Llao IIMESTAMpE e e a E AI RA 420 Slalom OL Peni Neis oc oo ok ede ee a a eS 43 Optimizatio
299. that have been added the right list shows the objects that have been removed By clicking on the button Re Insert Delete object the selected objects will be re inserted in or deleted from the graph 8 Freddy Bill BillsDepartment Freddy gt Employee Bill Bill gt Employee Re Insert Delete Figure 8 12 List of objects which have been added or removed If you are satisfied with the changes you have done you can click on the Commit button Then CBGraph will transform the objects to be added or removed into a list of Telos frames and send them to the server using the TELL UNTELL or RETELL operation If the operation was successful all explicit objects will be checked if they are still valid and if their graphical type has changed as in the Validate and update operation from the Current Connection menu If there is an error the error messages of the server will be displayed in a message box The internal buffer with the objects to add or remove will be not changed in this case 8 2 10 Caching of query results within CBGraph To improve the performance of CBGraph several caches are used On the other hand the use of a cache causes several problems which will be addressed in this section In particular the caches of CBGraph are 8 You can unselect an object by holding down the Control key and clicking on the object 119 not updated automatically if the corresponding data in the serv
300. the file in the URL syntax For example Class AgentGT in JavaGraphicalType with rule gtrule forall a Agent a graphtype AgentGT property textcolor 1 0 0 0 linecolor 0 0 0 image http myserver comp eu images AgentIcon png implementedBy implBy i5 cb graph cbeditor CBIndividual priority pr 20 end associates the graphical type Agent GT to the image icon Agent Icon png You can also point to local files via the file protocol Class AgentGT in JavaGraphicalType with rule gtrule forall a Agent a graphtype AgentGT 152 property textcolor 0 0 0 linecolor 0 0 0 image file home jonny images AgentIcon png implementedBy implBy i5 cb graph cbeditor CBIndividual priority pr 20 end Note that the image icon is looked up by CBGraph Hence the location must be in the file system of the computer on which CBGraph runs If you place the image icon on a web server then CBGraph will be able to fetch it from any computer provided that the access rights are set properly If you specify an image icon for a graphical type then you can also set its textposition for example image file home jonny images AgentIcon png textposition top By default the node s text label is placed at the bottom of the image In this case it shall be placed on top of it Other possible values are center left and right Note that the property textposition is only eva
301. the graph objects In particular it contains connection details of the CBserver module from which the graph was created The are a few options for the cbgraph command synchronizing the data stored in the graph file with the CBserver r With this option CBGraph will be instructed to load the module sources on its current module path from the CBserver and save it to the graph file when the save function is enacted The System module will not be saved since it is typically not changed For example if CBGraph displays objects of module System oHome M 1 then the save function will store the module sources of oHome and M to the graph file We say CBGraph reads the sources from the CBserver and saves them to the graph file This option disables writing the module sources from the graph file to the CBserver when CBGraph is started w This option enables the reverse direction It will instruct CBGraph to extract module sources from the given graph file or any graph file that is loaded via CBGraph and tell them to the CBserver that it is connected to You have to start a CBserver as a separate process using the hostname and port number that is stored in the graph file This option disables by default including the module sources to the graph file when saving the graph file The CBserver can well have an empty database because all required user defined objects are stored as sources in the graph file If the database is no
302. tion it has all objects as instances 3 A user does not need to decide to which meta class level an object belongs Strict conformance to the membership to meta class levels can still be enforced by user definable integrity constraints As a user you don t work directly with propositions but with textual frame and graphical semantic networks views on them Both are not based on the oid s of objects but on their label components To guarantee a unique mapping we need the following naming axiom Naming axiom see also axioms 2 3 4 in appendix B 1 The label name of an individual object must be unique i e if two objects have the same label than they are the same 2 The label of an attribute must be unique within all attributes with a common source object i e no two explicit attributes of the same object can have the same label However two different objects can well have attributes sharing the same label 3 The source and destination of an instantiation object are unique i e between two objects x and y may be at most one explicit instantiation link 4 The source and destination of a specialization object are unique The frame syntax of O Telos groups the labels of propositions with common source o around the label of o The exact syntax is given in appendix A In this section we introduce it by modeling the employee example Employee in Class with attribute name String salary Integer dept Department
303. tive rule evaluator section 4 is currently rather limited We measured around 100 rule firings per second This can be a performance bottleneck when many active rules are being processed 93 Chapter 7 The CBShell Utility The ConceptBase cc Shell CBShell is a command line client for ConceptBase cc It allows to interact with a CBserver via a text based command shell Moreover it can process commands from a script file without further user interaction The utility can be employed to automate certain activities such as batch loading a large number of Telos models into a CBserver or to extract certain answers from a CBserver 7 1 Syntax There are two ways to use the CBShell The first one processes the commands from a script file batch mode The second one prompts the user for commands interactive mode cbshel cbshel options scriptFile params options 1 11 7 2 Options l1 This options instructs CBShell to write errors and some statistic information to the files error log and stat log f scriptFile Execute the commands specified in scriptFile rather that requesting commands from the com mand line interface If the f option is used and a scriptFile is specified the commands of the file will be executed without user interaction and CBShell will exit at the end The prefix f can also be omitted i e cbshell scriptFile is equivalent to cbshell f scriptFile t This option can only be used in com
304. tribute category in the subwindow Attribute Classes E Frame Browser E Super Classes o g i Classes fF Subclasses Function DefaultJavaPalette Function Class QueryClass Figure 8 3 Frame Browser The Frame Browser can be used with and without a connection to a CBserver If it is not connected it retrieves the information out of a local cache which can be loaded from a file by using the Load button The file has to be plain text file with Telos frames All objects in the cache can be saved into a text file as Telos frames with the Save button The contents of the cache can be viewed with the Cache button The result of a query can be added to the cache by using the Add query result button The button Telos Editor inserts the Telos frame of the current object into the Telos Editor 8 1 8 Display queries This dialog displays all visible queries stored in the current object base see figure 8 4 From the list box you can select a query and ask it or load its definition into the Telos editor If you ask a generic query class with parameter another dialog will ask you to specify the parameters For each parameter you can specify whether the value entered should be used as substitute for the SVisible queries are those queries that are not instantiated to the class HiddenObject Functions and certain system queries are excluded from the display
305. tted or its localized variant is available in the module oHome and its submodules It is not available for checking permission to access the System module The reason is that user details are stored in oHome and signature of CB_Permitted requires that the user details are known The protection of the System module is instead configured via the security level of the CBserver option s e Level 0 No access control Read and write operations are allowed to the System module e Level 1 Read and writes are allowed but only if the current module is set to System e Level 2 Read is permitted but write operations to System are disallowed Caution The access control feature of ConceptBase avoids some unwanted interferences in a setting where multiple users work on the same server The system in not save against malicious attacks Neither does it prevent all unwanted interferences 5 7 Listing the module content The contains attribute allows to check which objects belong to a module It can be used by a simple query that lists the module content of all modules that are currently visible ShowModule in QueryClass isA Module with computed_attribute cont Proposition constraint ccont this contains cont end A more sophisticated method is to use the builtin query listModule A call of 1istModule without parameters will list the current module as Telos frames You can also provide the module to be listed as a parameter e g listMod
306. ttributes computed attributes are necessary i e any solution of a query with a computed attribute must assign a value for this attribute There is no limit in the number of retrieved and computed attributes The more of them are defined for a query class the more arguments shall the answer predicate have Recursion can be introduced to queries by using recursive deductive rules or by refering recursively to query classes The example asks for all direct or indirect bosses of bi11 QueryClass BillsMetaBoss isA Manager with constraint billsBosses S bill boss this or exists m Manager m in BillsMetaBoss and m boss this end Further examples can be found in the directory SCB_HOME examples QUERIES Queries are represented as O Telos classes and consequently they can be stored in the knowledge base for future use It is a common case that one knows at design time generic queries that are executed at run time with certain parameters CBQL supports such parameterizable queries GenericQueryClass isA QueryClass with attribute parameter Proposition end 34 Generic queries are queries of their own right they can be evaluated Their speciality is that one can easily derive specialized forms of them by substituting or specializing the parameters An important property is that each solution of a substituted or spezialized form is also a solution of the generic query This is a consequence of the inheritance scheme The exam
307. tus either offline or the hostname and portnumber of the ConceptBase server The content of an internal window is a graphical view on the database module of the ConceptBase server it is connected to It is possible that different internal windows connect to different ConceptBase servers though this is not a typical use of CBGraph If you start CBGraph from CBIva then you can only start a single instance of it However you can start any number of CBGraph instances via the cbgraph command see below The two left internal windows of figure 8 7 are connected to the same server and show the same model 109 CBGraph File Edit Options View Current connection Dob y it Al DefaultjavaPalette oHome localhost4001 Individual QueryClass QueryClass in Class isA Cla a attribute retrieved_attribute Prol computed_attribute Pri constraint MSFOLque Connected with localhost Figure 8 7 CBGraph with three internal windows but in different representations This is caused by the fact that for the upper window the default graphical palette has been chosen and for the lower window a customized graphical palette specifically designed for the ER model has been selected see appendix D 2 and C Furthermore you can notice that the object QueryClass is represented by two different components In the upper view the detailed component view has been activated
308. ule System module will list the content of the module System ConceptBase will check read permission before a module content is listed You can also use a module path as parameter e g listModule System oHome Work module A module path is formed much like a directory path in a file system The root module is System and modules names are separated by the character The implementation of the 1istModule query preserves the order in whoch objects have been created Note that the System module is defining the essential objects that ConceptBase requires to run correctly You can list the System module but you should not change it 5 7 1 Restrictions of 1istModule The query 1istModule extracts all objects of a module into a single Telos source Since a module is typically created by a sequence of TELL UNTELL transactions this Telos source can in rare cases fail to be told by a single transaction An example is the specification of the ERD model in http merkur informatik rwth aachen de pub bscw cgi 188651 The university model and then university data depend on rules defined in the model ERD Semantics specifically the semantics of the ISA type instances of subclasses are also instances of superclasses If you tell the university model and the ERD semantics in the same transaction then the rules for the ISA type are not yet usable for checking the 80 consistency of the university model A way out is to store the university model
309. ulting frame in ConceptBase shall be Jet 400 in MyClass end Essentially single quotes of CBShell parameters are converted to double quotes within ConceptBase An simple example is given in http merkur informatik rwth aachen de pub bscw cgi 3372687 A more elaborate example is available in the CB Forum at http merkur informatik rwth aachen de pub bscw cgi 3384265 The main example is in the fileSizeDemo 99 7 8 CBShell in a pipe Assume you have a program generator that analyzes some input data e g from files and produces output in the form of CBShell commands te11 ask etc Then this output can be directly passed to CBShell in a Unix pipe generator cbshell p The generator program must take care of generating all required commands in particular making sure that CBShell is connected to a CBserver Consider as example generator the script file print files 4cbshe11 from the CB Forum at http merkur informatik rwth aachen de pub bscw cgi 3384578 bin sh echo enrollMe localhost 4001 for file in do if f file then fsize stat c s S file frame S file in File with size s S fsize end echo tell S file in File with size s fsize end fi done It first generates a command to enroll to a CBserver on localhost at port 4001 Then it forms a frame for each filename in the current directory to tell the file s size to the CBserver You can run the script in
310. ur firewall prevents external access If you work with an existing database you may want to specify some access rights rules like suggested in section 5 6 We neglect them in this simple example Now start the public CBserver with suitable parameters under Linux Unix cbserver r 2 a jonny g public u nonpersistent d FRESHDB gt log cb txt amp The option g public enables the slave mode implicitely and tells oHome as an instance of Auto HomeModule The combination of the slave mode and the option r instructs CBserver to stop and restart when the last client exits The update mode is nonpersistent As a consequence the restarted CBserver will use the unchanged state of FRESHDB This is useful if you want to provide the service of CBserver to a larger group of anonymous users They can log in with a client operate on the database in nonpersistent mode and eventually leave the CBserver When the last user leaves the CBserver it will freshly start up after 2 seconds Hence user defined objects are only stored at the CBserver while there are still users enrolled to the CBserver The parameter a sets the administrator user of the public CBserver This user is allowed to shutdown the CBserver from a client The auto home feature will assign different users to individual workspaces Unless you introduce access rights and enable them via the CBserver option s 2 the users can also manipulate the modules of other users However the CB
311. ursivley their descendants in a single answer string for that person The nested ASKquery inside an answer format usually results in the unfolding also using an answer format possibly the same as used for the original query This feature allows the user to specify very complex structured answers that might even contain the complete database In particular complex XML representations can be constructed in this way 3 2 7 Expressions in head and tail The features head and tail are similar to pattern The difference is that any expression using this the running variable for answer objects is disallowed This only leaves function patterns such as ASKquery expressions and pre defined patterns such as user Of course the head and tail strings can contain multiple occurences of ASKquery or other function patterns 3 2 8 Conditional expressions Conditional expressions allow to expand a substring based on the evaluation of a condition The syntax is IFTHENELSE predicate thenstring elsestring The predicate can be one of e GREATER exprl1l expr2 e OWER exprl expr2 Oo E QUAL expr1 expr2 e AND exprl expr2 e OR exprl expr2 e ISFIRSTFRAME 0 Example GREATER this salary 10000 Note that the arguments may also contain ex pressions The predicate ISFIRSTFRAME is true when ConceptBase starts with processing answer frames It is
312. ute rela tionships are represented as dotted shaded and labelled directed arcs between their source and destination components O Telos propositions have a temporal component the belief time The belief time of a proposition is not assigned by the user but by the system at the transaction time of an update TELL or UNTELL Con SThe original specification of Telos has two temporal components The valid time and the belief time The valid time is defined as the time interval when the statemment made by a Telos proposition is true in the world The belief time is the time when this statement is part of the knowledge base O Telos skipped the valid time because it is virtually impossible to have a tractable imple mentation when in interplays with deductive rules Earlier versions of ConceptBase until version 3 1 did however implement both time components 17 gt attribute Class mum Proposition d y 4 SimpleClass salary Integer E l 4 Employee name 4 A sE AN dept aly A ma String boss 4 AE A Manager epartment SEA Y PR Token advises R amp D mary currentdept 3 earns 15000 hername gt Mary Smith Figure 2 1 Graph representing the example proposition network ceptBase uses right open and closed predefined time intervals Right open time interval
313. values of object in the attribute category attrcat This path expressions may be extended to any length e g John dept head refers to all managers of departments in which John is working A second shortcut is the explicit enumeration of allowed attribute values The following view retrieves all employees who work in the same department as John and earn 10000 15000 or 20000 Euro View EmpDept2 isA Employee with retrieved_attribute 39 dept John dept salary 10000 15000 20000 end As mentioned before inner frames use the same syntax as normal frames You can also specify constraints in inner frames which refer to the object of an outer frame View EmpDept_likes_head isA Employee with retrieved_attribute partof dept Department with retrieved_attribute partof head Manager with constraint c A this likes this dept head end end end The rule for using the variable this in nested views is that it always refers the object of the main view in this case an employee Objects of the nested views can be referred by this label where label is the corresponding attribute name of the nested view In the example we want to express that the employees must like their bosses Because the inner view for managers is already part of the nested view for departments we must use the double colon twice this dept refers to the departments and this dept head refers to the managers If you relo
314. were started by the same user This option is useful when a CBserver is only needed while still clients are registered A master CBserver must always be stopped explicitly g cmd provides a special command to the CBserver There are currently three such commands The command nolpi instructs the CBserver to ignore any plug in file see section F The command public configures the CBserver as a public CBserver see 6 5 The command exit instructs the CBserver to exit immediately after start up This can be useful to combination with the option views db and save to materialize some excerpts from a stored database a user designates user as administrator of this CBserver For the time being this just gives the right to shutdown the CBserver By default the user who started the CBserver is its administrator This user shall also keep the right to shutdown the server even when another user is the designated adminis trator Ifa CBserver is started without any parameter then the update mode shall be set to nonpersistent the trace mode to no multi user mode is disabled and the server mode to slave The other parameters are set to their defaults Such a CBserver is useful as companion of tools that need it only while they are running For example a graph file that contains the module sources can be processed by cbserver amp cbhgraph mygraph gel CBGraph connects to the slave CBserver and tells its module sources The graph can be edited
315. wo different attributes Employee dept and Guest dept apply as candidates for the predicate x dept PR forall x GuestEmployee x dept PR gt not x in Manager In order to solve this ambiguity we demand that in such cases a common subclass exists that defines an attribute dept which conforms to both definitions e g Shop in Class end GuestEmployee with attribute dept ShopDepartment end ShopDepartment in Class isA Shop Department end The third clause of the predicate typing condition is forbidding instantiation predicates with a variable in the class postion The restriction is a pre condition for an efficient implementation of the incremental formula evaluator of ConceptBase Without a constant in the class position of x in c any update of the instances of any class matches the predicate Hence ConceptBase would need to re evaluate the for mula that contains the predicate Since any update TELL UNTELL RETELL is containing instantiation facts any formula with an unrestricted predicate x in c has to be re evaluated for any update This inefficiency can be avoied by demanding that the class position is a constant A relaxation to this clause and clause 2 is discussed in sub section 2 2 9 When compiling the frames ConceptBase will make sure that the attribute Guest Employee dept is specializing the two dept attributes of Shop and Department As a consequence the attribution predicate x dept PR can be unique
316. x y z VAR x in Person and y in Person and z in Person and x ancestor y and y ancestor zZ gt x ancestor zZ which can be shortened to forall x y z Person x ancestor y and y ancestor z gt x ancestor zZ This formula is fulfilling the predicate typing condition Likewise the connection relation of cities gets transitive via City in Proposition with transitive connection City end The advantage of meta formulas is that they save coding effort by re using them in different modelling contexts If a meta formula is linked to an attribute category like transit ive in the example above then the semantic of several such attribute category can be combined by just specifying that a certain attribute has multiple categories Assume for example that we have defined acyclicy with a similar meta formula Proposition in Class with attribute acyclic Proposition constraint acyclic_IC forall x y M VAR AC Proposition acyclic C Proposition 28 P AC C M C and x in C and y in C and x M y gt not y M x end Then the ancestor attribute can be specified to be both transitive and acyclic by Person in Proposition with transitive acyclic ancestor Person end The more categories like transitive and acyclic are defined with meta formulas the greater is the productivity gain for the modeler Not only does it save coding effort It also reduces coding errors since formula specification is a difficult tas
317. y evaluate the IF part but will just append a trigger de f e r to the trigger queue q When all events in the event list are converted to triggers i e when all frames in a Tell Untell transac tions are transformed and stored or when the Ask call has been processed then ConceptBase will start to process the trigger queue q It is processed in a first in first out FIFO manner Each do and def trigger 64 is processed according to its type If the entry has the form do r actions then ConceptBase will execute the actions in the second parameter possibly leading to new events and triggers A last fired next free Figure 4 1 State of the trigger queue Figure 4 1 shows a snapshot of a trigger queue The triggers tj have the form do r actions or def e r There are two pointers last fired initially 0 and next free initially 1 to manage the queue New triggers are added at the right end incrementing the next free pointer The processing of the queue starts from left to right The last processed item is pointed to by the last fired pointer The queue is empty resp completely processed iff last fired plus 1 equals to next free If the entry has the form def e r then ConceptBase will first determine all combinations of vari ables in the IF part of r Then it will call the actions of the DO or ELSE part for the computed answers Note that the event e typically bin
318. y leads to a binding of variables in the rule s IF and DO parts This binding is stored in the rule s representation within the work set The rules in the working set are sorted to reflect the priority settings of ECArules If two rules have no priority defined between them then the definition order is used to sort them older rules before newer rules Each rule r in the working set will then be processed as follows one after the other The rule processing depends on the coupling mode of the ECArule in the working set If the mode is Immediate then the IF part is evaluated yielding all possible combinations of variables that make the IF part true If the answer set is empty then ConceptBase will call the ELSE actions of the ECArule Otherwise ConceptBase will call the DO part for each variable combination determined in the previous step If the mode is ImmediateDeferred then ConceptBase will evaluate the IF part of the current rule like before Instead of calling the DO or ELSE part it will however put a trigger do r actions on a trigger queue g The parameter r identifies the rule The parameter actions contains all instantiations of the DO part of r by the variable substitutions computed by the evaluation of the IF part of r If there are no such substitutions then actions is set to the ELSE part of r if existent Otherwise no actions would be appended to the wating queue If the mode is Deferred then ConceptBase will not immediatel
319. yClass MetabossDatalogQuery isA Manager with attribute parameter e Employee attribute code 48 ri In e Employee A e boss this r2 vars m In e Employee In m query MetabossDatalogQuery e e A m boss this end Note that the disjunction of the original query is represented by two code attributes The example shows also the use of query expressions and existential variables The second example is the datalog version of the rule for the HighSalary class The infix predicate gt is represented by the predicate GE Class HighSalary2 isA Integer end DatalogInRule HighSalaryRule2 with concernedClass cc HighSalary2 code c In this Integer GE this 60000 end The last example shows the definition of a rule for an attribute It also shows how the performance of a rule can be improved by specifying different variants for different binding patterns The example defines two rules depending on the binding of the variable src The rule defines the transitive closure of the boss attribute Rule r1 is applied if both arguments src and dst are unbound The second rule is used if at least src is bound and the last rule will be applied if we have a binding for dst but not for src DatalogAttrRule MetabossRule with concernedClass cc Employee boss code rl vars m var srce var dst

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