JENA–ASEMANTICWEBTOOL

byRanjaniSankaran

&krishnaPriyankaChebrolu

RDF

•  ResourceDescriptorFramework•  W3CStandardfordescribingresourcesontheweb.

•  IsdesignedtoprovidecommonwaytodescribeinformaNonsoitcanbereadandunderstoodbycomputerapplicaNon.

•  WhatisJena•  CapabiliNesofJena•  RDFImplementaNonusingJena

WhatisJena

•  JenaisaJavaframeworkforthecreaNonofapplicaNonsfortheSemanNcWeb.

•  ProvidesinterfacesandclassesforthecreaNonandmanipulaNonofRDFrepositories.

•  Alsoprovidesclasses/interfacesforthemanagementofOWL‐basedontologies

CapabiliNesofJena

•  RDFAPI•  ReadingandwriNnginRDF/XML,N‐Triples

•  OWLAPI

•  In‐memoryandpersistentstorage

•  SPARQLqueryengine

RDFImplementaNonusingJena

RDFAPI‐Example•  HelloWorldExample:importcom.hp.hpl.jena.rdf.model.Model;importcom.hp.hpl.jena.datatypes.xsd.XSDDatatype;importcom.hp.hpl.jena.rdf.model.ModelFactory;importcom.hp.hpl.jena.rdf.model.Property;importcom.hp.hpl.jena.rdf.model.Resource;publicclassHelloRDFWorld{

publicstaNcvoidmain(String[]args){ Modelm=ModelFactory.createDefaultModel(); StringNS="h`p://example.com/test/"; Resourcer=m.createResource(NS+"r"); Propertyp=m.createProperty(NS+"p"); r.addProperty(p,"helloworld",XSDDatatype.XSDstring); m.write(System.out,"Turtle"); }

}

RDFAPI–Examplecond..

•  //NamespacedeclaraNonssta$cfinalStringfamilyUri="h-p://1nman.cs.gsu.edu#";•  //CreateanemptyModelmodel=ModelFactory.createDefaultModel();model.setNsPrefix("student","h`p://Nnman.cs.gsu.edu#");•  //CreateanemptyModelmodel=ModelFactory.createDefaultModel();model.setNsPrefix("student","h`p://Nnman.cs.gsu.edu#");•  //CreateresourcesrepresenNngthepeopleinourmodelResourceranjani=model.createResource(familyUri

+"Ranjani");

• 

RDFAPI‐ExampleCont..•  //AddproperNestodescribingtherelaNonshipsbetweenthemranjani.addProperty(fullname,"RanjaniSankaran");•  //Statementscanalsobedirectlycreated...Statementstatement1=

model.createStatement(ranjani,college,"gsu");•  //...thenaddedtothemodel:model.add(statement1);•  //ArraysofStatementscanalsobeaddedtoaModel:Statementstatements[]=newStatement[5];statements[0]=model.createStatement(ranjani,major,"csc");model.add(statements);

RDFAPI‐Contd..

•  //AListofStatementscanalsobeaddedListlist=newArrayList();list.add(model.createStatement(ranjani,course,"DBandtheWeb"));

•  model.add(list);

model.write(newPrintWriter(System.out));

RDFRepresentaNonofVcard

• AnalternaNveRDFmappingfortheformatdefinedbyvCard

QueryingRDFusingJENA//ListstudentswhohavetakenacourseResIteratorstudents_course=model.listSubjectsWithProperty(course);

//BecausesubjectsofstatementsareResources,themethodreturnedaResIterator

while(students_course.hasNext()){

//ResIteratorhasatypednextResource()methodResourceperson=students_course.nextResource();

//PrinttheURIoftheresourceSystem.out.println("Thelistofstudentswhohavetaken

coures"+person.getURI());}

QueryingRDFusingJENAcontd..

//Tofindallthecoursestakenbyastudent,themodelitselfcanbequeried

NodeIteratormoreStudents1=model.listObjectsOfProperty(priyanka,course);

System.out.println("****LISTOFCOURSESTAKENBYPRIYANKA***");

while(moreStudents1.hasNext()){

System.out.println(moreStudents1.nextNode().toString());}

RDFValidator•  ValidatestheformatofRDFdocumentscreatedusingJENApublicstaNcvoidmain(Stringargs[]){ Modeldata=FileManager.get().loadModel("student.rdf");InfModelinfmodel=ModelFactory.createRDFSModel(data);ValidityReportvalidity=infmodel.validate();if(validity.isValid()){System.out.println("OK");}else{System.out.println("Conflicts");for(Iteratori=validity.getReports();i.hasNext();){System.out.println("‐"+i.next());

JENAONTOLOGYMODEL

•  AnontologymodelisanextensionoftheJenaRDFmodelthatprovidesextracapabiliNesforhandlingontologies.OntologymodelsarecreatedthroughtheJenaModelFactory.Thesimplestwaytocreateanontologymodelisasfollows:

•  OntModelm=ModelFactory.createOntologyModel();Thiswillcreateanontologymodelwiththedefaultsenngs,whicharesetformaximumcompaNbilitywiththepreviousversionofJena.

OWLAPI//CreateanemptyontologymodelOntModelontModel=ModelFactory.createOntologyModel();Stringns=newString(“h`p://www.example.com/onto1#”);StringbaseURI=newString(“h`p://www.example.com/onto1”);Ontologyonto=ontModel.createOntology(baseURI);

//Create‘Person’,‘MalePerson’and‘FemalePerson’classesOntClassperson=ontModel.createClass(ns+"Person");OntClassmalePerson=ontModel.createClass(ns+"MalePerson");OntClassfemalePerson=ontModel.createClass(ns+"FemalePerson");

//FemalePersonandMalePersonaresubclassesofPersonperson.addSubClass(malePerson);person.addSubClass(femalePerson);

//FemalePersonandMalePersonaredisjointmalePerson.addDisjointWith(femalePerson);femalePerson.addDisjointWith(malePerson);

OWLAPI‐ProperNes//Createdatatypeproperty'hasAge'DatatypePropertyhasAge=ontModel.createDatatypeProperty(ns+"hasAge");//'hasAge'takesintegervalues,soitsrangeis'integer'//Basicdatatypesaredefinedinthe‘vocabulary’packagehasAge.setDomain(person);hasAge.setRange(XSD.integer);//com.hp.hpl.jena.vocabulary.XSD

//CreateindividualsIndividualjohn=malePerson.createIndividual(ns+"John");Individualjane=femalePerson.createIndividual(ns+"Jane");Individualbob=malePerson.createIndividual(ns+"Bob");

//Createstatement'JohnhasAge20'Literalage20=ontModel.createTypedLiteral("20",XSDDatatype.XSDint);StatementjohnIs20=ontModel.createStatement(john,hasAge,age20);ontModel.add(johnIs20);

Reasoning

•  Jenaisdesignedsothatinferenceenginescanbe‘plugged’inModelsandreasonwiththem.

•  ThereasoningsubsystemofJenaisfoundinthecom.hp.hpl.jena.reasonerpackage.

•  AllreasonersmustprovideimplementaNonsofthe‘Reasoner’Javainterface

•  OnceaReasonerobjectisobtained,itmustbe‘a`ached’toaModel.ThisisaccomplishedbymodifyingtheModelspecificaNons

Reasoning‐OWLexample

•  Asampleschemaandadatafilearetaken.•  WecancreateaninstanceoftheOWLreasoner,specializedtotheschemaandthenapplythattothedatatoobtainaninferencemodel.

Reasoning‐Example

Modelschema=FileManager.get().loadModel("owlDemoSchema.owl");

Modeldata=FileManager.get().loadModel("owlDemoData.rdf");

Reasonerreasoner=ReasonerRegistry.getOWLReasoner();

reasoner=reasoner.bindSchema(schema);InfModelinfmodel=ModelFactory.createInfModel(reasoner,data);

SPARQLqueryprocessing•  JenausestheARQenginefortheprocessingofSPARQLqueriesThe

ARQAPIclassesarefoundincom.hp.hpl.jena.query•  BasicclassesinARQ:Query:RepresentsasingleSPARQLquery.•  Dataset:Theknowledgebaseonwhichqueriesareexecuted

(EquivalenttoRDFModels)•  QueryFactory:CanbeusedtogenerateQueryobjectsfromSPARQL

strings•  QueryExecuNon:ProvidesmethodsfortheexecuNonofqueries•  ResultSet:Containstheresultsobtainedfromanexecutedquery•  QuerySoluNon:Representsarowofqueryresults.

–  Iftherearemanyanswerstoaquery,aResultSetisreturnedauerthequeryisexecuted.TheResultSetcontainsmanyQuerySoluNons

SPARQLQUERY‐Example//CreateanewqueryStringqueryString="PREFIXrdfs:<h`p://www.w3.org/2000/01/rdf‐schema#>"+"PREFIXrdf:<h`p://www.w3.org/1999/02/22‐rdf‐syntax‐ns#>"+"select?uri"+"where{"+"?urirdfs:subClassOf<h`p://www.opentox.org/api/1.1#Feature>

"+"}\n";com.hp.hpl.jena.query.Queryquery=

QueryFactory.create(queryString);

References

•  IntroducNontoJENA

•  JenaOntologyAPI

h`p://jena.sourceforge.net/ontology/#creaNngModels