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Introducing InterProlog

Introducing InterProlog. Architecture Functionality and examples From Prolog side From Java side A Java-Prolog-Java event roundtrip Term displayers etc. Under the hood. A Prolog application. A Java application. InterProlog predicates. InterProlog classes. Prolog executable.

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Introducing InterProlog

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  1. Introducing InterProlog • Architecture • Functionality and examples • From Prolog side • From Java side • A Java-Prolog-Java event roundtrip • Term displayers etc. • Under the hood

  2. A Prolog application A Java application InterProlog predicates InterProlog classes Prolog executable Java VM sockets, console redirection 1st InterProlog architecture - sockets Terms Objects

  3. InterProlog architecture (cont.) • Java/Prolog connection • Sockets (SubprocessEngine) • Java program linked to Prolog through I/O and object sockets, launches “PrologEngines” • currently XSB, SWI, YAP • JNI (NativeEngine) • native methods and built-in predicate for callbacks were added to XSB Prolog 2.5 and later • Dynamic Prolog->Java calls using Reflection • Serialized objects are parsed/generated by a Definite Clause Grammar :-)

  4. Yet another use for DCGs :-)

  5. Programming on the Prolog side • I think I’m under a console process • The listener window and the first “Hello, World” ?- writeln('Hello, world!'). • javaMessage(Target,Message(Args)) javaMessage( ‘java.lang.System’-out, println(string(‘hello, world’)) ) • Cynical’s perspective: yet another RPC • Wide open API, as far as Java security allows • Variations handle exceptions, return value, cf. docs • Full version: javaMessage( Target, Result, Exception, MessageName, ArgList, NewArgList ) • Needed: a generic approach to specifying objects and basic type values, stay tuned…

  6. Object specifications in Prolog • string(Atom) and 'null' • ipObjectSpec('InvisibleObject',X,[ID],_) • Object X should be the object already existing and registered as (int) ID on the Java side  • ipObjectSpec('IPClassObject',X,[C],_) •  X is the class object for class with name C  • ipObjectSpec('IPClassVariable',X,[C,V],_) •  X is the class variable V of class C  • ipObjectSpec(boolean,X,[B],_) •  X is a boolean basic type for B (which should be 1 or 0); similar ipObjectSpec facts are available for the remaining basic types: byte, small, int, long, float, double, char  •  ipObjectSpec(C,X,Variables,_) • (Generic case) New object X of class C; C must be the fully qualified class name • How to add mine? to be seen in Sudoku example

  7. Hello world, in a window javaMessage('javax.swing.JFrame',W,'JFrame'(string(myTitle))),javaMessage(W,C,getContentPane), javaMessage('javax.swing.JLabel',L, 'JLabel'(string('Hello Prolog, greetings from Swing:-)')) ),javaMessage(C,add(string('Center'),L)),javaMessage(W,pack), javaMessage(W,show). • Note concerning previous slide: • javaMessage/3 calls ipObjectSpecification/4 before calling javaMessage/6. A first look at interprolog.P

  8. Programming on the Java side - basics • 1 PrologEngine <-> 1 XSB (or SWI or YAP) engine • Implementation restrictions • Object[] deterministicGoal( String G, String Ovars, Object[] objectsP, String RVars ) • object specification subgoals must be included in G to accept objectsP (in Ovars list) and to generate the result (in RVars list) • Simpler variantes are available, e.g. not requiring input objects or not returning bindings, cf. Javadoc • int registerJavaObject(Object x) • Allow Prolog to refer x by an integer key reference • interrupt(), shutdown()

  9. Programming on the Java side PrologEngine engine = new SWISubprocessEngine();engine.consultFromJar("test.pl"); /* or consultRelative (to the class location), or consultAbsolute(File),…*/Object[] bindings = engine.deterministicGoal( "descendent_of(X,someAncestor)", "[string(X)]" );if(bindings!=null){// succeeded String X = (String)bindings[0]; System.out.println( "X = " + X); }

  10. Programming on the Java side Object[] bindings = engine.deterministicGoal( “X=string(helloWorld), ipObjectSpec(‘java.lang.Integer’,Y,[value=13]”, ”[X,Y]” ); String hw = (String)bindings[0]; Integer lucky = (Integer)bindings[1]; • The deterministicGoal variants • More examples • see packages com.declarativa.interprolog.gui, com.declarativa.interprolog.examples, PrologEngineTest class

  11. “Hello World”, with a roundtrip CREATING WINDOW FROM PROLOG: ipPrologEngine(Engine), javaMessage( 'com.declarativa.interprolog.examples.HelloWindow', 'HelloWindow'(Engine))

  12. Control flow in “Hello World”

  13. Prolog Term displayers • browseList([one(X),two(Y),1+1+1,X/Y]). • browseLiteralInstances(foo('First','Last'),[foo('Miguel','Calejo'),foo('Terry','Swift'),foo('David','Warren'),foo('Robert','Pokorny')]). • browseTreeTerm(t(root,[t(child1,[]),t(child2,[]),t(child3,[t(granchild31,[t(grandgrandchild311,[])])])])).

  14. More Prolog support stuff • The TermModel class • A convenient way to have Prolog term copies on the Java side • Building a Java representation of an arbitrary Prolog term… • buildTermModel(Term,TermModel) • …and vice-versa • recoverTermModel(TermModel,Term) • How to write a visual term browser • Hint: TermModel implements TreeModel

  15. Playing with several Prologs callAnotherProlog(Engine,G) :- buildTermModel(G,GM), javaMessage(Engine,SM,deterministicGoal(GM)), recoverTermModel(SM,G). ?- javaMessage( 'com.declarativa.interprolog.SWISubprocessEngine', SWI,'SWISubprocessEngine'), callAnotherProlog(SWI, findall(op(P,T,Name), current_op(P,T,Name), SWIops)), findall(op(XSBP,XSBT,XSBO), ( current_op(XSBP,XSBT,XSBO), not(member(op(XSBP,XSBT,XSBO),SWIops) ), XSBonly).

  16. A larger example: Sudoku puzzle editor and solver • Java side • A Sudoku board in a window (to start, call its constructor) • SudokuWindow class with inner classes • SudokuBoard extends JTable • SudokuModel implements TableModel • A few others • Menus call Prolog goals • Prolog side • Known numbers Ni in predicate facts n(X,Y,Ni) • resolve(PlacedNumbers1,PlacedNumbersN) • Front-end "action" predicates act on current puzzle • newPuzzle, openPuzzle(File,Array), savePuzzle(File) • How is data passed between Java and Prolog?

  17. Getting object specification predicates from object examples • Sudoku example uses two object types for communication: • int[][] matrix for "bulk assigment" of the whole board model in one step • CellValue[] objects, representing a few cells, for "sparse" (a few at a time) assigment • Teaching InterProlog about my classes • teachMoreObjects(ObjectExamplePair[])

  18. “Under the hood”:Java package/file structure • com.declarativa.interprolog • com.declarativa.interprolog.gui • com.declarativa.interprolog.examples • com.declarativa.interprolog.util • xsb,swi,yap,gnu subdirectories with specific Prolog file • com.xsb.interprolog • NativeEngine and two related classes

  19. “Under the hood” • The serialization grammar • About javaMessage • javaMessage/2, javaMessage/3, javaMessage/6 • Returning objects rather than references: getRealJavaObject • A special Java object • ipPrologEngine(E) • The deterministicGoal/javaMessage tandem • Prolog peer classes • Supporting multiple Prolog systems • Walkthrough of ipPrologEngine(E), javaMessage(E,R,getPrologVersion)

  20. Installation • Make sure Java and the Prolog systems work • Download and expand interprolog.zip • Edit windowsVariables • There are other ways to let InterProlog find the Prolog executables • Running • Use script to launch listener window • JUnit test • Use script to launch your app using the interprolog.jar

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