deep integration of python with semantic web technologies

Deep integration of Python with Semantic Web

technologiesMarian Babik Ladislav Hluchy

Intelligent and Knowledge Technologies Group

Institute of Informatics SAS

5thJuly 2006 EuroPython CERN Geneve

Goals of the presentationBrief introduction of Semantic Web technologiesIntroduce deep integration ideasShow initial implementation of the Python integrated with OWLDiscuss architecture


Semantic WebExtension of the current Web providing infrastructure for the integration of data on the Web

Data should be available for further processingIt should be possible to combine and merge data on a Web scaleMetadata reasoning

Making data machine processableNames for resourcesCommon data model RDFAccess to the data SPARQL OWL-QLDefine vocabularies RDFS OWL SKOSReasoning OWL Rules


Resource Description Framework (RDF)

Based on triples (subject predicate object)Labelled connection btw two resources (subject object)Subject predicate are URI-s Object is URI (eg Subject) or Literal ( httpwwwmarianbabikorg httpmyCalendar httpcalendar )

(subject predicate object) can be seen as a labeled edge in a graphSerialization XML Turtle N3 etc


RDF example

httpwwwtukeskfei-citbabik

Marian Babik

httpwwwsemanticscriphellipPaper1pdf

shasName

shasWritten

ltrdfDescriptionrdfabout=httpwwwtukeskfei-citbabikgt

ltshasNamegtMarian BabikltshasNamegtltshasWritten

rdfresource=httpwwwsemanticscriptingorgSFSW2006Paper1pdfgtltrdfDescriptiongt

Turtl

e (N

3)

X

ML

RD

F

lthttpwwwtukeskfei-citbabikgtshasName ldquoMarian BabikrdquoshasWritten lthttpwwwsemanticscriptingorgSFSW2006Paper1pdfgt


RDF Vocabulary Description Language (RDFS)

RDF lacks vocabulary with semantic meaningRDFS defines resources and classes and relationships among classesresource

rdftype rdfsClass rdfssubClassOfrdfssubPropertyOf Resource may belong to several classes (range domain)

Special kind of type system


RDFS example

John Man

Person

rdftype

rdftyperdfssubClassOf

Person rdfssubClassOf Man

John rdftype Man

ltrdfDescription rdfID=ldquoJohnrdquogt

ltrdftype rdfresource=ldquoManrdquogt

ltrdfDescriptiongt

ltrdfDescription rdfID=ldquoManrdquogt

ltrdfssubClassOfrdfresource=ldquoPersonrdquogt

ltrdfDescriptiongt


RDFS example (2)Person rdfssubClassOf Man John rdftype Man isProgrammerrdftype rdfPropertyrdfdomain Personrdfrange rdfsLiteral


Web Ontology Language (OWL)RDFS doesnrsquot solve all the issues

Reasoning about termsBehavior of properties (symmetric transitive etc)Cardinality constraintsEquivalence of classesEnumeration (oneOf) union of classes Datatype properties

Compromise btwRich semantics Feasibility implementability

Three layersOWL-Lite OWL-DL (based on Description Logic ndash SHOIN(D))OWL-Full (might be undecidable)


OWL-DLClass definition axioms

Complex class definitions based on the class descriptions

Property definition axiomsRDF Schema constructs (rdfssubPropertyOf rdfsdomain and rdfsrange)relations to other properties owlequivalentProperty and owlinverseOf)global cardinality constraints owlFunctionalProperty and owlInverseFunctionalPropertylogical property characteristics owlSymmetricProperty and owlTransitiveProperty

Individualsfacts about class membership and property values of individuals


OWL-DL exampleprefix people lthttpsampleorgpeoplegt

peoplePerson a owlClass peopleMan a owlClass rdfssubClassOf peoplePersonpeoplehasChild a owlProperty peoplehasSon a owlPropery rdfssubPropertyOf peoplehasChild

PersonWithSingleSon a owlClass rdfssubClassOf[ a owlRestriction owlcardinality 1^^

owlonProperty hasSon ] rdfssubClassOf

[ a owlRestriction owlcardinality 1^^ owlonProperty hasChild ]

PeopleJohn a peoplePerson PeopleBob a peoplePersonWithSingleSon


SW for developersClasses are types for instances Classes are sets of individualsEach instance has one class (as its type) Classes donrsquot share instances

Each individual can belong to multiple classes

List of classes is known at compile time Classes can be created and changed at runtime

Compilers are used Reasoners are used for classification and consistency

Properties are defined locally to a class Properties are standalone entities (can exist without classes)

Instances have values for attached properties Values must be correctly typed Range constraints are used for type checking

Instance can have arbitrary values for any property Range and domain constraints can be used for type checking and type inference

Closed world assumption Open world assumptionClass behavior through functions and methods

Classes make their meaning explicit in terms of OWL statements

Source wwww3orgTRsw-oosd-primer


Deep integration ideasImport OWL classes alongside classes defined normally (native API)Support for intensional definition of classesproperties (OWL statements)Separation of concerns among declarative and procedural aspectsSimilar to what SQLObject does for databases


BenefitsDefinition of data and domain using Semantic Web tools (Proteacutegeacute SWOOP)Native OWL APIOWL Inference and Web sharing of conceptsNew programming paradigm for PythonNative interface for ontologies developers can work directly with OWL classes and their instancesExisting Python Web frameworks and access to large set of libraries

Ont

olog

ies

Pyt

hon


OWL APIsJena OWL API

Different notion of polymorphism means APIs have to introduce sophisticated design patterns

Resource r = myModelgetResource( myNS + DigitalCamera ) OntClass cls = (OntClass) ras( OntClassclass ) Restriction rest = (Restriction) clsas( Restrictionclass )


RDFOWL APIsPython

RDFLib ndash statement-centric (Daniel Krech)CWM ndash model centricPychinko ndash model statement-centric rule basedMetaLog ndash statement resource-centric based on prologSparta Tramp ndash resource centric

OthersActive RDF (Ruby) ndash native mapping RDF integrated with RailsRDFHomepage (PHP) ndash native mapping


OWL-DL and Python Ontology corresponds to Python moduleOWL Class corresponds to Python ClassInstance of OWL Class corresponds to Python ObjectOWL Property corresponds to Python Class or Python method


Classes

OWL Class corresponds to Python ClassInstances of OWL Class correspond to Python ObjectsClass definition

Each python class has two attributesURI (owlClass URI)definedBy (intensional definition)

gtgtgt from seth import Thing Property gtgtgt Person = Thingnew(lsquo Person a owlClass ) gtgtgt print Personltclass sethMetaPersongt

gtgtgt Man = Thingnew( Man a owlClass rdfssubClassOf Person )


Classes (2)gtgtgt PersonWithSingleSon = Thingnew(PersonWithSingleSon

a owlClass rdfssubClassOf[ a owlRestriction owlcardinality 1^^

owlonProperty hasSon ] rdfssubClassOf[ a owlRestriction owlcardinality 1^^

owlonProperty hasChild ] )

gtgtgt model = OntModel()gtgtgt modelbind(ldquopeoplerdquordquohttpsomewherenetpeoplerdquo)gtgtgt ThingsetOntModel(model)gtgtgt Person = Thingnew(ldquo peoplePerson a owlClass rdquo)


Properties

owlProperty corresponds to special kind of python object

Similar to Class definitionBut such classes donrsquot have instances

owlProperty corresponds to python object attribute (method)

gtgtgt hasChild = Propertynew(hasChild a owlObjectProperty )gtgtgt print hasChildltclass sethMetahasChildgtgtgtgt hasSon = Propertynew(hasSon a owlObjectProperty rdfssubPropertyOf hasChild )

gtgtgt JohnhasChild(Bob)


IndividualsIndividual is python object (class instance)

gtgtgt Bob = PersonWithSingleSon(lsquoBobrsquo)gtgtgt John = Person(Johnlsquo)gtgtgt print John ltsethMetaPerson object at 0xb7a29e4cgtgtgtgt hasChild(Bob John)


OntologiesowlOntology corresponds to Pythonrsquos module

gtgtgt ModuleFactory(ldquopeoplerdquo ldquohttpsomewherenetpeopleowlrdquo)gtgtgt import peoplegtgtgt print peoplePersonltsethpeoplePersonMan a owlClass rdfssubClassOf Person gtgtgt print peopleJohnltsethpeoplePerson object at 0xb7a29e4cgtserializationgtgtgt peopleserialize(ldquotmptestowlrdquo ldquoRDFXML-ABBREVrdquo)


QueriesTriple like queriesgtgtgt for individual in PersonfindInstances() print individual individualnameltsethMetaMan object at 0xb7d0b64cgt PeterltsethMetaPerson object at 0xb7d0b50cgt JohnltsethMetaPerson object at 0xb7d0b6ecgt Janegtgtgt for who in hasSonq(Bob) whonameJohngtgtgt print hasSonquery(Bob John)1

OWL-QL SPARQLNative queries


ArchitectureInteraction with Java-based libraries (reasoners)

FileURIRDFXML OntModel

ClassProperty Generators

Knowledge Base Interface

Interactive

Query EngineQuery language


Python and JavaJython - Python implemented for the Java Virtual Machine JPE(Java-Python Extension) - uses JNI to provide a bridging mechanism between Java and a Python interpreter JPype - interfacing at the native level in both Virtual Machines SPIRO - uses ORB (Object-Request Broker) technology GCJ


IssuesPerformance (conversion between JVMs)CacheDatatype propertiesOpen world semanticsDebuggingRules


SummarySETH Homepagehttpseth-scriptingsourceforgenetAvailable through CVS under MIT licenseDiscussion support mailing listsethuisavbask

ContactMarianBabikgmailcom


ReferencesIntroduction to Semantic Web

httpwwww3org2006Talks0524-Edinburgh-IHOverviewpdf

Deep IntegrationhttpwwwsemanticscriptingorgSFSW2005papersVrandecic-Deep_Integrationpdf httpgigatonthoughtworksnet~ofernand1DeepIntegrationpdf

httpwwwsemanticscriptingorgSFSW2006Paper1pdf


Goals of the presentationBrief introduction of Semantic Web technologiesIntroduce deep integration ideasShow initial implementation of the Python integrated with OWLDiscuss architecture










RDF example


Marian Babik


shasName

shasWritten




Turtl

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3)

X

ML

RD

F








RDFS example

John Man

Person

rdftype



John rdftype Man



ltrdfDescriptiongt



ltrdfDescriptiongt



































Ont

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Pyt

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RDFOWL APIsPython






Classes












Properties




















Interactive























RDF example


Marian Babik


shasName

shasWritten




Turtl

e (N

3)

X

ML

RD

F








RDFS example

John Man

Person

rdftype



John rdftype Man



ltrdfDescriptiongt



ltrdfDescriptiongt



































Ont

olog

ies

Pyt

hon






RDFOWL APIsPython






Classes












Properties




















Interactive




















RDFS example

John Man

Person

rdftype



John rdftype Man



ltrdfDescriptiongt



ltrdfDescriptiongt



































Ont

olog

ies

Pyt

hon






RDFOWL APIsPython






Classes












Properties




















Interactive
















































Ont

olog

ies

Pyt

hon






RDFOWL APIsPython






Classes












Properties




















Interactive



















RDFOWL APIsPython






Classes












Properties




















Interactive

















Classes












Properties




















Interactive





















Properties




















Interactive




























Interactive














deep integration of python with semantic web technologies

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