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Foundations III: Languages, Tools and Services
Deborah McGuinness and Peter Fox
CSCI-6962-01
Week 5, Oct. 5, 2009
Key Points Regarding Flu Epidemics
• Wash your hands often, especially after shaking hands with others (use hand disinfectants if there is no
access to soap and water).
• Avoid close contact with people who are sick
• Cover your mouth and nose with a tissue when coughing or sneezing. If you don't have a tissue, use the
inside of your elbow.
• Do not touch your eyes, nose, or mouth, especially after contact with shared keyboards, microscopes,
instruments, or other people.
• STAY HOME-If you have flu-like symptoms (i.e., fever (100 degrees F [37.8 decrees C] or higher, cough,
sore throat, runny or stuffy nose, body aches, headache, chills, fatigue).
• For more information http://www.rpi.edu/about/flu/ .
Review of reading Assignment• Ontology Tool Summary, Pellet, OWL-S,
SAWSDL, Wine Agent
• Assignment 2 clarifications?
• Any comments, questions?
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Contents• Review of reading, comments, questions?
• Languages
• Tools
• Services
• Summary and assignments
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Semantic Web Methodology and Technology Development Process
• Establish and improve a well-defined methodology vision for Semantic Technology based application development
• Leverage controlled vocabularies, et c.
Use Case
Small Team, mixed skills
Analysis
Adopt Technology Approach
Leverage Technology
Infrastructure
Rapid Prototype
Open World: Evolve, Iterate,
Redesign, Redeploy
Use Tools
Science/Expert Review & Iteration
Develop model/
ontology
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Semantic Web Layers
http://www.w3.org/2003/Talks/1023-iswc-tbl/slide26-0.html, http://flickr.com/photos/pshab/291147522/
Languages• RDFS – Resource Description Framework
Schema
• OWL – Web Ontology Language OWL
• SKOS – Simple Knowledge Organization System
• RIF – Rule Interchange Framework
• SPARQL- SPARQL Protocol and RDF Query Language
• OWL-S – OWL for Services 7
RDFS• Note: XMLS not an ontology language
– Changes format of DTDs (document schemas) to be XML
– Adds an extensible type hierarchy• Integers, Strings, etc.• Can define sub-types, e.g., positive integers
• RDFS is recognisable as an ontology language– Classes and properties– Sub/super-classes (and properties)– Range and domain (of properties) 8
However• RDFS too weak to describe resources in sufficient
detail– No localized range and domain constraints
• Can’t say that the range of hasChild is person when applied to persons and elephant when applied to elephants
– No existence/cardinality constraints• Can’t say that all instances of person have a mother that is also a
person, or that persons have exactly 2 parents
– No transitive, inverse or symmetrical properties• Can’t say that isPartOf is a transitive property, that hasPart is the
inverse of isPartOf or that touches is symmetrical
– …
• Difficult to provide reasoning support– No “native” reasoners for non-standard semantics
– May be possible to reason via First Order axiomatisation9
OWL requirementsDesirable features identified for Web Ontology
Language:
• Extends existing Web standards – Such as XML, RDF, RDFS
• Easy to understand and use– Should be based on familiar KR idioms
• Formally specified
• Of “adequate” expressive power
• Possible to provide automated reasoning support10
The OWL language:• Three species of OWL
– OWL full is union of OWL syntax and RDF– OWL DL restricted to FOL fragment (¼ DAML+OIL)– OWL Lite is “easier to implement” subset of OWL DL
• Semantic layering– OWL DL ¼ OWL full within DL fragment– DL semantics officially definitive
• OWL DL based on SHIQ Description Logic– In fact it is equivalent to SHOIN(Dn) DL
• OWL DL Benefits from many years of DL research– Well defined semantics– Formal properties well understood (complexity, decidability)– Known reasoning algorithms– Implemented systems (highly optimized)
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OWL Class Constructors
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OWL axioms
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14See http://www.w3.org/TR/owl-features/ section 2 for features and relation to RDF or OWL species
OWL 2• http://www.w3.org/2007/OWL/wiki/OWL_Wor
king_Group
• Now a proposed recommendation (as of September 22, 2009)
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W3C OWL 2 User Documents• Document Overview –
• http://www.w3.org/TR/owl2-overview/ • The place to start – light introduction to OWL 2 and its relationship to OWL
New Features and Rationale• More details of the new features in OWL 2 along with their motivations
• http://www.w3.org/TR/owl2-new-features/ Primer• An introduction to OWL using a running example
• http://www.w3.org/TR/owl2-primer/ • Next generation of the OWL 1 Guide
Quick Reference • A brief synopsis of the features of OWL along with links into relevant documents (both
to user and specification documents)
• http://www.w3.org/TR/owl2-quick-reference/• Next generation of a portion of the OWL 1 Overview combined with UMBC’s quick
reference card
– Meetings: ISWC, OWLED, ESWC, Web Science, DL, Protégé, …
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Why Some Users May Care about OWL 2
• Datatype support: Many applications need more datatype support including things such as numerical comparisons (e.g., VSTO, SWEET, etc.)
• Selected additional expressive power: Different applications may need or benefit from features such as qualified cardinality.
• More support for annotations (e.g., for more support for knowledge provenance )
• Definition and support for profiles
McGuinness – SemTech June 16, 2009
OWL 2• Extends OWL with a small set of features
– That are motivated from application usage– For which semantics and reasoning techniques are well understood– That tool builders are willing and able to support
• Is fully backwards compatible with OWL: – Every OWL ontology is a valid OWL 2 ontology– Every OWL 2 ontology not using new features is a valid OWL
ontology
– OWL Lite & OWL DL are both sublanguages of OWL 2, along with the new profiles (EL, QL, RL)
• Already supported by popular OWL tools & infrastructure:– Protégé, Pellet, FaCT++, OWL API
New Features: Expressiveness– qualified cardinality restrictions, e.g.:
ObjectMinCardinality(2 friendOf hacker)– property chains, e.g.:
SubObjectPropertyOf(SubObjectPropertyChain(parent brother) uncle)– local reflexivity restrictions, e.g.:
ObjectExistsSelf(likes) [for narcissists]– reflexive, irreflexive, symmetric, and antisymmetric properties,
e.g.:ReflexiveObjectProperty(knows); IrreflexiveObjectProperty(husbandOf)
flowsInto rdf:type owl:IrreflexiveProperty. Nothing can flow into itself.
– disjoint properties, e.g.:DisjointObjectProperties(childOf spouseOf)
– keys, e.g.:HasKey( US-Citizen () ( a:hasSSN ) )
New features: MetaModelling– Restricted form of metamodelling via “punning”, e.g.
subClassOf(SnowLeopard BigCat)
ClassAssertion(SnowLeopard EndangeredSpecies)
– Annotations of axioms as well as entities, e.g.:ClassAssertion(Comment(“source: WWF”) SnowLeopard EndangeredSpecies)
– Including annotations of annotations
• Punning allowed in OWL 2 but OWL 2 DL still imposes:– Name cannot be used for both class and datatype– Name can only be used for one type of property
Annotations•Annotation Assertion
– Construct for annotation of ontology entities and anonymous individuals
• Annotation– Construct for annotation of axioms and ontologies(even annotations themselves)
• Annotations about annotation properties– SubAnnotationPropertyOf
• Syntax example: :narrow_synonymrdfs:subPropertyOf:synonym. (UC#5)
– The annotation property :narrow synonym is a subproperty of :synonym. – AnnotationPropertyDomain
• Syntax example: FMA:UWDAIDrdfs:domainFMA:AnatomicalEntity. (UC#2) – Only FMA: AnatomicalEntitycan have an FMA:UWDAID (that is, an FMA ID) – AnnotationPropertyRange
Syntax example: FMA:UWDAIDrdfs:rangexsd:positiveInteger.
New Features: Syntactic Sugar
– Disjoint unions• Shorthand for combination of disjointWith and unionOf
statements• BrainHemisphereowl:disjointUnionOf( :LeftHemisphere:Rig
htHemisphere) . • BrainHemisphereis exclusively either a :LeftHemisphere or
:RightHemisphere and cannot be both of them. • DisjointUnion(Element Earth Wind Fire Water)
– Negative assertions• States that a property does not hold for a particular
individual• NegativeObjectPropertyAssertion(Deborah hasChild Mary)• NegativeDataPropertyAssertion (Peter hasAge 21)
Profiles• OWL defines only one fragment (OWL Lite)• OWL 2 defines three different fragments with useful
computational properties– EL: polynomial time reasoning for schema and data
• Useful for ontologies with large conceptual part
– QL: fast (logspace) query answering using RDBMs via SQL
• Useful for large datasets already stored in RDBs
– RL: fast (polynomial) query answering using rule-extended DBs
• Useful for large datasets stored as RDF triples
EL (Profiles Document Source)• Supported class restrictions
–existential quantification to a class expression (ObjectSomeValuesFrom) or a data range (DataSomeValuesFrom) –existential quantification to an individual (ObjectHasValue) or a literal (DataHasValue) –self-restriction (ObjectHasSelf) –enumerations involving a singleindividual (ObjectOneOf) or a singleliteral (DataOneOf) –intersection of classes (ObjectIntersectionOf) and data ranges (DataIntersectionOf)
• Supported axioms, restricted to class restrictions–class inclusion (SubClassOf) –class equivalence (EquivalentClasses) –class disjointness(DisjointClasses) –object property inclusion (SubObjectPropertyOf) with or without property chains, and data property inclusion (SubDataPropertyOf) –property equivalence (EquivalentObjectPropertiesand EquivalentDataProperties), –transitive object properties (TransitiveObjectProperty) –reflexive object properties (ReflexiveObjectProperty) –domain restrictions (ObjectPropertyDomainand DataPropertyDomain) –range restrictions (ObjectPropertyRangeand DataPropertyRange) –assertions (SameIndividual, DifferentIndividuals, ClassAssertion, ObjectPropertyAssertion, DataPropertyAssertion, NegativeObjectPropertyAssertion, and NegativeDataPropertyAssertion) –functional data properties (FunctionalDataProperty) –keys (HasKey)
EL does NOT support• universal quantification to a class expression (ObjectAllValuesFrom) or a
data range (DataAllValuesFrom) • –cardinality restrictions (ObjectMaxCardinality, ObjectMinCardinality,
ObjectExactCardinality, DataMaxCardinality, DataMinCardinality, and DataExactCardinality)
• –disjunction (ObjectUnionOf, DisjointUnion, and DataUnionOf) • –class negation (ObjectComplementOf) • –enumerations involving more than one individual (ObjectOneOfand
DataOneOf) • –disjoint properties (DisjointObjectPropertiesand DisjointDataProperties) • –irreflexiveobject properties (IrreflexiveObjectProperty) • –inverse object properties (InverseObjectProperties) • –functional and inverse-functional object properties
(FunctionalObjectPropertyand InverseFunctionalObjectProperty) • –symmetric object properties (SymmetricObjectProperty) • –asymmetric object properties (AsymmetricObjectProperty)
QL• Supported class restrictions
–Subclass Expressions a classexistential quantification (ObjectSomeValuesFrom) where the class is limited to owl:Thingexistential quantification to a data range (DataSomeValuesFrom)
–SuperclassExpressionsa classintersection (ObjectIntersectionOf)negation (ObjectComplementOf)existential quantification to a class (ObjectSomeValuesFrom)existential quantification to a data range (DataSomeValuesFrom)
• Supported axioms, compliant with class restriction expressions–subclass axioms (SubClassOf) –class expression equivalence (EquivalentClasses) –class expression disjointness(DisjointClasses) –inverse object properties (InverseObjectProperties) –property inclusion (SubObjectPropertyOfnot involving property chains and SubDataPropertyOf) –property equivalence (EquivalentObjectPropertiesand EquivalentDataProperties) –property domain (ObjectPropertyDomainand DataPropertyDomain) –property range (ObjectPropertyRangeand DataPropertyRange) –disjoint properties (DisjointObjectPropertiesand DisjointDataProperties) –symmetric properties (SymmetricObjectProperty) –reflexive properties (ReflexiveObjectProperty) –irreflexiveproperties (IrreflexiveObjectProperty) –asymmetric properties (AsymmetricObjectProperty) –assertions other than individual equality assertions and negative
QL does not support–existential quantification to a class expression or a data range
(ObjectSomeValuesFromand DataSomeValuesFrom) in the subclass position
–self-restriction (ObjectHasSelf) –existential quantification to an individual or a literal (ObjectHasValue,
DataHasValue) –enumeration of individuals and literals (ObjectOneOf, DataOneOf) –universal quantification to a class expression or a data range
(ObjectAllValuesFrom, DataAllValuesFrom) –cardinality restrictions (ObjectMaxCardinality, ObjectMinCardinality,
ObjectExactCardinality, DataMaxCardinality, DataMinCardinality, DataExactCardinality)
–disjunction (ObjectUnionOf, DisjointUnion, and DataUnionOf) –property inclusions (SubObjectPropertyOf) involving property chains –functional and inverse-functional properties (FunctionalObjectProperty,
InverseFunctionalObjectProperty, and FunctionalDataProperty) –transitive properties (TransitiveObjectProperty) –keys (HasKey) –individual equality assertions and negative property assertions
RL–Subclass expressions
•a class other than owl:Thing•an enumeration of individuals (ObjectOneOf)•intersection of class expressions (ObjectIntersectionOf)•union of class expressions (ObjectUnionOf)•existential quantification to a class expression (ObjectSomeValuesFrom)•existential quantification to a data range (DataSomeValuesFrom)•existential quantification to an individual (ObjectHasValue)•existential quantification to a literal (DataHasValue)
–Superclassexpressions•a class other than owl:Thing•intersection of classes (ObjectIntersectionOf)•negation (ObjectComplementOf)•universal quantification to a class expression (ObjectAllValuesFrom)•existential quantification to an individual (ObjectHasValue)•at-most 0/1 cardinality restriction to a class expression (ObjectMaxCardinality0/1)•universal quantification to a data range (DataAllValuesFrom)•existential quantification to a literal (DataHasValue)•at-most 0/1 cardinality restriction to a data range (DataMaxCardinality0/1)
RL does not supportOWL 2 RL supports all axioms of OWL 2 apart
from disjoint unions of classes (DisjointUnion) and reflexive object property axioms (ReflexiveObjectProperty)
OWL 2 Documentation Roadmap
SKOS propertieswww.w3.org/2004/02/skos/ Simple Knowledge Organization SystemW3C Recommendation Status on August 18, 2009
• skos:notee.g. ‘Anything goes.’
• skos:definitione.g. ‘A long curved fruit with a yellow skin and soft, sweet white flesh inside.’
• skos:examplee.g. ‘A bunch of bananas.’
• skos:scopeNotee.g. ‘Historically members of a sheriff's retinue armed with pikes who escorted judges at assizes.’
• skos:historyNotee.g. ‘Deleted 1986. See now Detention, Institutionalization (Persons), or Hospitalization.’
• skos:editorialNotee.g. ‘Confer with Mr. X. re deletion.’
• skos:changeNotee.g. ‘Promoted “love” to preferred label, demoted “affection” to alternative label, Joe Bloggs,
2005-08-09.’31
Vocabulary elements• skos:mappingRelation
• skos:closeMatch
• skos:exactMatch
• skos:broadMatch
• skos:narrowMatch
• skos:relatedMatch
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Class and Property relations• S38 skos:mappingRelation, skos:closeMatch, skos:exactMatch,
skos:broadMatch, skos:narrowMatch and skos:relatedMatch are each instances of owl:ObjectProperty.
• S39 skos:mappingRelation is a sub-property of skos:semanticRelation.
• S40 skos:closeMatch, skos:broadMatch, skos:narrowMatch and skos:relatedMatch are each sub-properties of skos:mappingRelation.
• S41 skos:broadMatch is a sub-property of skos:broader, skos:narrowMatch is a sub-property of skos:narrower, and skos:relatedMatch is a sub-property of skos:related.
• S42 skos:exactMatch is a sub-property of skos:closeMatch.• S43 skos:narrowMatch is owl:inverseOf the property
skos:broadMatch.• S44 skos:relatedMatch, skos:closeMatch and skos:exactMatch are
each instances of owl:SymmetricProperty.• S45 skos:exactMatch is an instance of owl:TransitiveProperty. 33
Integrity constraints• skos:exactMatch is disjoint with each of the
properties skos:broadMatch and skos:relatedMatch.
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SKOS example• <?xml version="1.0" encoding="UTF-8"?>
• <rdf:RDF xmlns:dc="http://purl.org/dc/elements/1.1/"
• xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
• xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
• xmlns:skos="http://www.w3.org/2004/02/skos/core#">
• <rdf:Description rdf:about="http://zepheira.com/examples/soa-skos#">
• <rdf:type rdf:resource="http://www.w3.org/2004/02/skos/core#ConceptScheme"/>
• <dc:title>SKOS-based service taxonomy for DevX Article</dc:title>
• <skos:hasTopConcept rdf:resource="http://zepheira.com/examples/soa-skos#Service"/>
• </rdf:Description>
• <rdf:Description rdf:about="http://zepheira.com/examples/soa-skos#Service">
• <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
• <rdfs:comment>An rdfs:Class of services.</rdfs:comment>
• </rdf:Description>
• <rdf:Description rdf:about="http://zepheira.com/examples/soa-skos#PrintingService">
• <rdf:type rdf:resource="http://zepheira.com/examples/soa-skos#Service"/>
• <skos:narrower rdf:resource="http://zepheira.com/examples/soa-skos#LaserPrintingService"/>
• <skos:narrower rdf:resource="http://zepheira.com/examples/soa-skos#PlotterPrintingService"/>
• <skos:prefLabel>Printing Service</skos:prefLabel>
• </rdf:Description>35
SKOS example• <rdf:Description rdf:about="http://zepheira.com/examples/soa-skos#LaserPrintingService">
• <rdf:type rdf:resource="http://zepheira.com/examples/soa-skos#Service"/>
• <skos:narrower rdf:resource="http://zepheira.com/examples/soa-skos#ColorLaserPrintingService"/>
• <skos:narrower rdf:resource="http://zepheira.com/examples/soa-skos#BWLaserPrintingService"/>
• <skos:prefLabel>Laser Printing Service</skos:prefLabel>
• </rdf:Description>
• <rdf:Description rdf:about="http://zepheira.com/examples/soa-skos#PlotterPrintingService">
• <rdf:type rdf:resource="http://zepheira.com/examples/soa-skos#Service"/>
• <skos:prefLabel>Plotter Printing Service</skos:prefLabel>
• </rdf:Description>
• <rdf:Description rdf:about="http://zepheira.com/examples/soa-skos#ColorLaserPrintingService">
• <rdf:type rdf:resource="http://zepheira.com/examples/soa-skos#Service"/>
• <skos:prefLabel>Color Laser Printing Service</skos:prefLabel>
• </rdf:Description>
• <rdf:Description rdf:about="http://zepheira.com/examples/soa-skos#BWLaserPrintingService">
• <rdf:type rdf:resource="http://zepheira.com/examples/soa-skos#Service"/>
• <skos:prefLabel>Black and White Laser Printing Service</skos:prefLabel>
• </rdf:Description>
• </rdf:RDF> 36
SKOS core and RDFS/OWL• Disjoint?
– Should skos:Concept be disjoint with …• rdf:Property ?• rdfs:Class ?• owl:Class ?• www.w3.org/TR/2009/REC-skos-reference-20090818/#L1045
• DL/Full - SKOS is an OWL ontology
• http://skosapi.sourceforge.net/
• Editors– ThManager– http://ftp.informatik.rwth-aachen.de/Publications/CEUR-WS/Vol-401/iswc2008pd_submi
ssion_88.pdf
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Editors• Protégé (http://protégé.stanford.edu)• SWOOP (http://mindswap.org/2004/SWOOP; see
also http://www.mindswap.org/downloads/)• Altova SemanticWorks (
http://www.altova.com/download/semanticworks/semantic_web_rdf_owl_editor.html)
• SWeDE (http://owl-eclipse.projects.semwebcentral.org/InstallSwede.html), goes with Eclipse
• NeON toolkit• ThManager• TopBraid Composer and other commercial tools
Protégé Demo
•http://protege.stanford.edu/•http://protegewiki.stanford.edu/index.php/Protege-OWL•Please check version compatibility when choosing.
•Do you have plugins you like?
•(Prompt not compatible with version 4.0)
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Query• Querying knowledge representations in OWL and/or
RDF• OWL-QL (for OWL)
http://projects.semwebcentral.org/projects/owl-ql/ • SPARQL for RDF http://www.sparql.org/ and
http://www.w3.org/TR/rdf-sparql-query/ – Now a W3C Recommendation January 15, 2009
• XQUERY (for XML)• SeRQL (for SeSAME)• RDFQuery (RDF)• Few as yet for natural language representations
(ROO – Dolbear, et al., …)
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What is Query?• http://esw.w3.org/topic/SPARQL• Languages
– SPARQL for RDF (http://www.sparql.org/ and http://www.w3.org/TR/rdf-sparql-query/ )
– RDFQuery for RDF– SeRQL for RDF (SeSAME)– OWL-QL for OWL (
http://projects.semwebcentral.org/projects/owl-ql/ )
– XQUERY for XML
• Few as yet for natural language representations (ROO – Dolbear, et al., …)
SPARQL• W3 Recommendation, Jan 2008
• SPARQL has 4 result forms:– SELECT – Return a table of results.– CONSTRUCT – Return an RDF graph, based on
a template in the query.– DESCRIBE – Return an RDF graph, based on
what the query processor is configured to return.– ASK – Ask a boolean query.
• The SELECT form directly returns a table
• DESCRIBE and CONSTRUCT use the outcome of matching to build RDF graphs.
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SPARQL Solution Modifiers• Pattern matching produces a set of solutions.
This set can be modified in various ways:– Projection - keep only selected variables– OFFSET/LIMIT - chop the number solutions (best
used with ORDER BY)– ORDER BY - sorted results– DISTINCT - yield only one row for one
combination of variables and values.
• The solution modifiers OFFSET/LIMIT and ORDER BY always apply to all result forms.
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Query examples
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?url
FROM <bloggers.rdf>
WHERE {
?contributor foaf:name "Jon Foobar" .
?contributor foaf:weblog ?url .
}
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Returns a table in ‘url’ (can use $)
namespace
Triple patterns usingTurtle syntax
What happens• These triples together comprise a graph pattern.• The query attempts to match the triples of the graph pattern to
the model. • Each matching binding of the graph pattern's variables to the
model's nodes becomes a query solution, and the values of the variables named in the SELECT clause become part of the query results.
• In this example, the first triple in the WHERE clause's graph pattern matches a node with a foaf:name property of "Jon Foobar," and binds it to the variable named contributor.
• In the bloggers.rdf model, contributor will match the foaf:Agent blank-node at the top of the figure.
• The graph pattern's second triple matches the object of the contributor's foaf:weblog property.
• This is bound to the url variable, forming a query solution.46
Using SPARQL with Jena• Jena calls RDF graphs "models" and triples
"statements" because that is what they were called at the time the Jena API was first designed
• ARQ's query engine can also parse queries expressed in RDQL or its own internal query language. ARQ is under active development, and is not yet part of the standard Jena distribution.
• http://jena.sourceforge.net/ARQ/Tutorial/data.html• Can also use SPARQL from the command line
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com.hp.hpl.jena.query package// Open the bloggers RDF graph from the filesystem
InputStream in = new FileInputStream(new File("bloggers.rdf"));
// Create an empty in-memory model and populate it from the graph
Model model = ModelFactory.createMemModelMaker().createModel();
model.read(in,null); // null base URI, since model URIs are absolute
in.close();
// Create a new query
String queryString =
"PREFIX foaf: <http://xmlns.com/foaf/0.1/> " +
"SELECT ?url " +
"WHERE {" +
" ?contributor foaf:name \"Jon Foobar\" . " +
" ?contributor foaf:weblog ?url . " +
" }”;
Query query = QueryFactory.create(queryString);
// Execute the query and obtain results
QueryExecution qe = QueryExecutionFactory.create(query, model);
ResultSet results = qe.execSelect();
// Output query results
ResultSetFormatter.out(System.out, results, query);
// Important - free up resources used running the query
qe.close();
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More complex queries@prefix foaf: <http://xmlns.com/foaf/0.1/> .
_:a foaf:name "Jon Foobar" ;
foaf:mbox <mailto:jon@foobar.xx> ;
foaf:depiction <http://foobar.xx/2005/04/jon.jpg> .
_:b foaf:name "A. N. O'Ther" ;
foaf:mbox <mailto:a.n.other@example.net> ;
foaf:depiction <http://example.net/photos/an-2005.jpg> .
_:c foaf:name "Liz Somebody" ;
foaf:mbox_sha1sum "3f01fa9929df769aff173f57dec2fe0c2290aeea"
_:d foaf:name "M Benn" ;
foaf:depiction <http://mbe.nn/pics/me.jpeg> . 49
Querying FOAF data with an optional block
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?name ?depiction
WHERE {
?person foaf:name ?name .
OPTIONAL {
?person foaf:depiction ?depiction .
} .
}
| name | depiction |
| "A. N. O'Ther" | <http://example.net/photos/an-2005.jpg> |
| "Jon Foobar" | <http://foobar.xx/2005/04/jon.jpg> |
| "Liz Somebody" | |
| "M Benn" | <http://mbe.nn/pics/me.jpeg>
50
Query with alternative matches, and its results
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?name ?mbox
WHERE {
?person foaf:name ?name .
{
{ ?person foaf:mbox ?mbox } UNION { ?person foaf:mbox_sha1sum ?mbox }
}
}
| name | mbox |
| "Jon Foobar" | <mailto:jon@foobar.xx> |
| "A. N. O'Ther" | <mailto:a.n.other@example.net> |
| "Liz Somebody" | "3f01fa9929df769aff173f57dec2fe0c2290aeea" |51
Filter to retrieve RSS feed items published in April 2005
PREFIX rss: <http://purl.org/rss/1.0/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
SELECT ?item_title ?pub_date
WHERE {
?item rss:title ?item_title .
?item dc:date ?pub_date .
FILTER xsd:dateTime(?pub_date) >= "2005-04-01T00:00:00Z"^^xsd:dateTime &&
xsd:dateTime(?pub_date) < "2005-05-01T00:00:00Z"^^xsd:dateTime
}52
Find people described in two named FOAF graphs
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?name
FROM NAMED <jon-foaf.rdf>
FROM NAMED <liz-foaf.rdf>
WHERE {
GRAPH <jon-foaf.rdf> {
?x rdf:type foaf:Person .
?x foaf:name ?name .
} .
GRAPH <liz-foaf.rdf> {
?y rdf:type foaf:Person .
?y foaf:name ?name .
} .
} 53
Which graph describes different people
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?name ?graph_uri
FROM NAMED <jon-foaf.rdf>
FROM NAMED <liz-foaf.rdf>
WHERE {
GRAPH ?graph_uri {
?x rdf:type foaf:Person .
?x foaf:name ?name .
}
}
| name | graph_uri |
| "Liz Somebody" | <file://.../jon-foaf.rdf> |
| "A. N. O'Ther" | <file://.../jon-foaf.rdf> |
| "Jon Foobar" | <file://.../liz-foaf.rdf> |
| "A. N. O'Ther" | <file://.../liz-foaf.rdf> | 54
Personalized feed by query filterPREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX rss: <http://purl.org/rss/1.0/>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
SELECT ?title ?known_name ?link
FROM <http://planetrdf.com/index.rdf>
FROM NAMED <phil-foaf.rdf>
WHERE {
GRAPH <phil-foaf.rdf> {
?me foaf:name "Phil McCarthy" .
?me foaf:knows ?known_person .
?known_person foaf:name ?known_name .
} .
?item dc:creator ?known_name .
?item rss:title ?title .
?item rss:link ?link .
?item dc:date ?date.
}
ORDER BY DESC[?date] LIMIT 10
55
Returning as XML• SPARQL allows query results to be returned as
XML, in a simple format known as the SPARQL Variable Binding Results XML Format.
• This schema-defined format acts as a bridge between RDF queries and XML tools and libraries.
• There are a number of potential uses for this capability. You could transform the results of a SPARQL query into a Web page or RSS feed via XSLT, access the results via XPath, or return the result document to a SOAP or AJAX client.
• To output query results as XML, use the ResultSetFormatter.outputAsXML() method, or specify --results rs/xml on the command line.
56
Final examplePREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX rss: <http://purl.org/rss/1.0/>
SELECT ?link ?title
FROM <http://rss.slashdot.org/Slashdot/slashdotScience>
FROM <http://www.nature.com/nprot/current_issue/rss/index.html>
WHERE {
?i rss:link?link .
?i dc:date?date . FILTER (?date > "2008-08-31")
?i rss:description?desc. FILTER regex(?desc,"biolog|mathematic","i")
?i rss:title?title
} 57
2-page reference guide• http://www.dajobe.org/2005/04-sparql/
SPARQLreference-1.8-us.pdf
58
59
Using Protégé• SPARQL plug-in to run queries on your
ontology
60
Semantic Web with Rules• Metalog• RuleML• SWRL• WRL• Cwm• N3 - http://hydrogen.informatik.tu-
cottbus.de/wiki/index.php/N3_Notation • Jess• Jena• RIF
61
Rules - expressing logic• Notation - e.g. Horn rules
– (P1 ∧ P2 ∧ ...) → C– parent(?x,?y) ∧ brother(?y,?z) ⇒ uncle(?x,?z)
– for any X, Y and Z: if Y is a parent of X, and Z is a brother of Y then Z is the uncle of X
62
Examples from http://www.w3.org/Submission/SWRL/
• A simple use of these rules would be to assert that the combination of the hasParent and hasBrother properties implies the hasUncle property. Informally, this rule could be written as:– hasParent(?x1,?x2) ∧ hasBrother(?x2,?x3) ⇒ hasUncle(?x1,?x3)
• In the abstract syntax the rule would be written like:– Implies(Antecedent(hasParent(I-variable(x1) I-variable(x2)) hasBrother(I-variable(x2) I-variable(x3)))Consequent(hasUncle(I-variable(x1) I-variable(x3))))
• From this rule, if John has Mary as a parent and Mary has Bill as a brother then John has Bill as an uncle.
63
Examples• An even simpler rule would be to assert that Students are Persons, as in– Student(?x1) ⇒ Person(?x1).Implies(Antecedent(Student(I-variable(x1)))Consequent(Person(I-variable(x1))))
– However, this kind of use for rules in OWL just duplicates the OWL subclass facility. It is logically equivalent to write instead• Class(Student partial Person) or • SubClassOf(Student Person)
– which would make the information directly available to an OWL reasoner.
64
Rule Interchange Format (RIF)• Leading candidate for W3 Recommendation
• Interlingua (similar to KIF)
• http://www.w3.org/2005/rules/wiki/RIF_Working_Group
• Tools starting (just) to emerge
• http://www.w3.org/2005/rules/wiki/RIF_FAQ
Test an interchanged RIF rule set• testQuery(Literal) test the literal (= rule head or fact)• testNotQuery(Literal) negatively test the literal with
default negation• testNegQuery(Literal) negatively test the literal with
explicit negation• testNumberOfResults(Literal, Number) test number of results
derived for the literal = stated value• testNumberOfResults(Literal, Var, Number) test number of results for
the variable in the literal• testNumberOfResultsMore(Literal,Number) test number of results for
the literal > given value• testNumberOfResultsLess(Literal,Number) test number of results for
the literal < given value• testNumberOfResultsMore(Literal,Var,Number) test number of results for
the variable in the literal > given value• testNumberOfResultsLess(Literal,Var,Number) test number of results for
the variable in the literal < given value 65
More RIF testing• testResult(QueryLiteral,ResultLiteral) test if the second literal is
an answer of the query literal• testResults(Literal,Var,[<BindingList>]) test if the list of binding
results for the variable in the literal can be derived• testResultsOrder(Literal,Var,[<BindingList>]) test if the list of ordered
binding results for the variable in the literal can be derived• testQueryTime(Literal, MaxTime) test if the literal can be
derived in less than the stated time in milliseconds• testNotQueryTime(Literal, MaxTime) test if the literal can be
derived negatively by default in less than the stated time in milliseconds• testNegQueryTime(Literal, MaxTime) test if the literal can be
derived strongly negative in less than the stated time in milliseconds• getQueryTime(Literal, Time) get the query time for the literal• getNotQueryTime(Literal,Time) get the default negated
query time for the literal• getNegQueryTime(Literal,Time) get the explicitly negated
query time for the literal
66
Testing class membershipDocument(
Prefix(fam http://example.org/family#)
Group (
Forall ?X ?Y (
fam:isFatherOf(?Y ?X) :- And (fam:isSonOf(?X ?Y) fam:isMale(?Y) ?X#fam:Child ?Y#fam:Parent )
)
fam:isSonOf(fam:Adrian fam:Uwe)
fam:isMale(fam:Adrian)
fam:isMale(fam:Uwe)
fam:Adrian#fam:Child
fam:Uwe#fam:Parent
)
)
Conclusion: fam:isFather(fam:Uwe fam:Adrian) 67
XML for conclusion<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Document [
<!ENTITY rif "http://www.w3.org/2007/rif#">
<!ENTITY xs "http://www.w3.org/2001/XMLSchema#">
<!ENTITY rdf "http://www.w3.org/1999/02/22-rdf-syntax-ns#">
]>
<Atom xmlns="&rif;">
<op>
<Const type="&rif;iri">http://example.org/family#isFather</Const>
</op>
<args>
<Const type="&rif;iri">http://example.org/family#Uwe</Const>
<Const type="&rif;iri">http://example.org/family#Adrian</Const>
</args>
</Atom>
<!--XML document generated on Tue Dec 30 12:08:16 EST 2008-->68
Language options that you can implement
• JenaRules is based on RDF(S) and uses the triple representation of RDF descriptions (see also N3 Notation and Turtle Syntax).
69
70
Examples<ex:Driver rdf:about="http://example.com/John">
<ex:state>New York</ex:state>
<ex:hasTrainingCertificate rdf:datatype="http://www.w3.org/2001/XMLSchema#boolean">true</ex:hasTrainingCertificate>
</ex:Driver>
@prefix rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns#
@prefix ex: http://example.com/
@prefix xs: http://www.w3.org/2001/XMLSchema#
[eligibleDriver: (?d rdf:type ex:EligibleDriver)
<-
(?d rdf:type ex:Driver)
(?d ex:state "New York")
(?d ex:hasTrainingCertificate "true"^^xs:boolean)]
Any driver living in New York and having training driver certificate is eligible for insurance.
A driver is young if has between 18 and 25 years old.
<ex:age rdf:datatype="http://www.w3.org/2001/XMLSchema#integer">21</ex:age><br>
</ex:Driver>
@prefix rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns#
@prefix ex: http://example.com/
@prefix xs: http://www.w3.org/2001/XMLSchema#
[youngDriver: (?d rdf:type ex:YoungDriver)
<-
(?d rdf:type ex:Driver)
(?d ex:age ?a)
greaterThan(?a,18)
lessThan(?a,25)]
71
Negation<ex:Driver rdf:about="http://example.com/John">
<ex:name>Jojn Smith</ex:name>
</ex:Driver>
@prefix rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns#
@prefix ex: http://example.com/
[eligibleDriver: (?d rdf:type ex:TypicalDriver)
<-
(?d rdf:type ex:Driver)
noValue(?d rdf:type ex:YoungDriver)
noValue(?d rdf:type ex:SeniorDriver)]
72
Multiple rules, split disjunction<ex:Driver rdf:about="http://example.com/John">
<ex:state>Vancouver</ex:state>
<ex:accidentsNumber rdf:datatype="http://www.w3.org/2001/XMLSchema#integer">1</ex:accidentsNumber>
</ex:Driver>
@prefix rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns#
@prefix ex: http://example.com/
[eligibleDriver_1: (?d rdf:type ex:EligibleDriver)
<-
(?d rdf:type ex:Driver)
(?d ex:state "New York")
(?d ex:accidentsNumber ?an)
lessThan(?an,2)]
[eligibleDriver_2: (?d rdf:type ex:EligibleDriver)
<-
(?d rdf:type ex:Driver)
(?d ex:state "Vancouver")
(?d ex:accidentsNumber ?an)
lessThan(?an,2)]73
74
Using Protégé• SWRL plugin for editing rules
• Jena (instructions for running the rule engine and using inference: http://hydrogen.informatik.tu-cottbus.de/wiki/index.php/JenaRules)
Inference structure
75
Lastly and briefly• Jess rules (LISP-like)
– Jess rules engine - http://herzberg.ca.sandia.gov/jess/
– http://www.jessrules.com/jess/docs/Jess71p2.pdf
76
Summaries
• Michael Denny’s Table: (a bit out of date)
• http://www.xml.com/2004/07/14/examples/Ontology_Editor_Survey_2004_Table_-_Michael_Denny.pdf
• ESW Wiki: http://esw.w3.org/topic/SemanticWebTools
78
Triple Stores• Jena (http://jena.sourceforge.net/)
• SeSAME/SAIL (http://www.openrdf.org/)
• KOWARI (http://www.kowari.org/) ->
• Mulgara (http://www.mulgara.org/)
• Redland (http://librdf.org/index.html)
• Oracle (!)
• Many others (relational, object-relational)
79
Software development tools• Protégé, 3 or 4, w/ plug-ins - some better
than others• SWOOP (OWL analyzer – species validator,
partitioner)• Jena (http://jena.sourceforge.net/)• Eclipse (full integrated development
environment for Java; http://www.eclipse.org/)• Top Quadrant suite• Sandsoft (Sandpiper Software)• … see Semantic Technologies 2007, 8, 9
80
Reasoners (aka Inference engines)
• Pellet **• Racer (and Racer Pro) **• SHER (IBM)
http://www.alphaworks.ibm.com/tech/sher • Medius KBS• FACT++• fuzzyDL• KAON2• MSPASS• QuOnto• Jess (for Rules)• …
81
Services• Ontologies of services, provides:
– What does the service provide for prospective clients? The answer to this question is given in the "profile," which is used to advertise the service. To capture this perspective, each instance of the class Service presents a ServiceProfile.
– How is it used? The answer to this question is given in the "process model." This perspective is captured by the ServiceModel class. Instances of the class Service use the property describedBy to refer to the service's ServiceModel.
– How does one interact with it? The answer to this question is given in the "grounding." A grounding provides the needed details about transport protocols. Instances of the class Service have a supports property referring to a ServiceGrounding.
82
Services, not standard…• Now 4 submissions to W3C
– OWL-S - http://www.w3.org/Submission/OWL-S (updated journal publication - http://springerlink.com/content/wp8q2133g5725340/ )
– SWSO/F/L - Semantic Web Services Ontology/Framework/Language - http://www.w3.org/Submission/SWSF/
– WSMO/X/L - Web Services Modeling Ontology/Exection/Language - http://www.w3.org/Submission/WSMX/ www.wsmo.org, www.wsmx.org
– SAWSDL - (WSDL-S)
83
Explanation, Proof (path to Trust)
• Proof markup language (PML)– an interlingua representation for justifications of
results produced by Semantic Web services
• Not W3C, but no competition• Implemented in InferenceWeb
(http://iw.stanford.edu)• CWM and N3 and theorem provers - not yet
adapted to OWL-based languages • Recent incubator group
http://www.w3.org/2005/Incubator/prov/charter
Woods Hole Oceanographic• Andy Maffei and Art Gaylord
85
Assignments for Week 5
• Reading: – Ontology Evolution (3 papers)– OWL-S editor tutorial – WSDL references
• Assignment 2 due next Tuesday