Semantic Web and Knowledge Management Ching-Long Yeh 葉慶隆 Department of Computer Science and Engineering Tatung University Taipei, Taiwan Email: [email protected]

Semantic Web and Semantic Web and Knowledge ManagementKnowledge Management

Ching-Long Yeh 葉慶隆Department of Computer Science and Engineering

Tatung UniversityTaipei, Taiwan

Email: [email protected]://www.cse.ttu.edu.tw/chingyeh

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ContentContent

• Web technology evolution• Semantic Web • Ontology and Languages• Semantic Web Service• Semantic Web Applications• Summary

Web Technology EvolutionWeb Technology Evolution

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Web TechnologyWeb Technology

• HTML, HTTP• XML• Electronic Business• Semantic Web

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InformationPool

WWWWWW

HTTP (Hyper Text Transport Protocol)HTML (Hyper Text Markup Language)URL (Uniform Resource Locator)

Web server

ApplicationClient

HTTP

URL

HTML Document

• Human-to-machine interaction• Information explosion

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InformationPool

Interaction Using XML

XML (eXtensible Markup Language)SOAP (Simple Object Access Protocol)

SOAP server

Application

HTTP

XML Document

• Machine-to-machine interaction • Service automation

SOAP server

Application

InformationPool

XML Document

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Web Service Architecture

Serviceregistry

Servicerequester

Serviceprovider

FindWSDL, UDDI

PublishWSDL, UDDI

Bind

Servicedescriptions

Servicedescriptions

Services

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Electronic Business

Transport, routing, packaging

Business processes,business documents

Company ACompany B

Transport, routing, packaging

Business processes,business documents

ERPERP

• Application-to-Application• Business Process Automation• RosettaNet• ebXML

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Semantic WebSemantic Web

• The Semantic Web is a vision:

• See “W3C Semantic Web Activity,” by Marja-Riitta Koivunen, for more descriptions.

the idea of having data on the web defined and linked in a way that it can be used by machines not just for display purposes, but for automation, integration and reuse of data across various applications

http://www.w3.org/Talks/2001/1102-semweb-fin/Overview.html

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Semantic WebSemantic Web

• The Semantic Web is the new generation of the World Wide Web, based on the semantic network knowledge representation formalism, which enables packaging information in the form of object-attribute-value statements, so called triplets.

• By assuming that terms used in these statements are based on the formally specified meaning (for the community of interest), i.e. ontologies, these triplets can be semantically processed by machine agents.

From: http://www2002.org/CDROM/poster/130.pdf

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The Semantic Web Layered ArchitectureThe Semantic Web Layered Architecture

(http://www.w3.org/2001/Talks/0228-tbl/slide5-0.html)

Tim Berners-Lee:“Axioms, Architecture and Aspirations”W3C all-working group plenary Meeting28 February 2001

URI Unicode

XML Namespaces

XML Schema

Sig

RDF M&S

RDF Schema

Ontology

Rules

Logic

Proof

Trust

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The Big Picture of SW

(http://semanticweb.org/about.html#bigpicture)

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查詢瀏覽語意入口網站服務

後設資料層

全球網資源

The metadata layer of the Semantic Web

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What Is in an Ontology?What Is in an Ontology?

• One widely cited definition of an ontology is Gruber’s [Gruber 1993] “A specification of a conceptualization”.

• An ontology is a formal explicit description of – concepts in a domain of discourse (classes (sometimes called

concepts)),

– properties of each concept describing various features and attributes of the concept (slots (sometimes called roles or properties)), and

– restrictions on slots (facets (sometimes called role restrictions)).

• An ontology together with a set of individual instances of classes constitutes a knowledge base.

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Ontology SpectrumOntology Spectrum

What is an Ontology?What is an Ontology?

Catalog/ID

GeneralLogical

constraints

Terms/glossary

Thesauri“narrower

term”relation

Formalis-a

Frames(properties)

Informalis-a

Formalinstance

Value Restrs.

Disjointness, Inverse, part-

of…

(From: http://www.ksl.stanford.edu/people/dlm/papers/ontologies-come-of-age-mit-press-(with-citation).htm)

Semantic Web LanguagesSemantic Web Languages

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What is XML?What is XML?

• Extensible Markup Language• A Syntax for Documents • A Meta-Markup Language• A Structural and Semantic Language, not a Formatting

Language• Not just for Web pages

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XML StandardsXML Standards

• DTD• Namespace• Schema• DOM• CSS, XSL-T, XSL-FO• XLink• XPointer

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XML Protocol: SOAPXML Protocol: SOAP

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RDF M&SRDF M&S• RDF (Resource Description Framework)

– Beyond Machine readable to Machine understandable

• RDF consists of two parts– RDF Model (a set of triples)– RDF Syntax (different XML serialization syntaxes)

• RDF Schema for definition of Vocabularies (simple Ontologies) for RDF (and in RDF)

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RDF Data ModelRDF Data Model• Resources

– A resource is a thing you talk about (can reference)– Resources have URI’s– RDF definitions are themselves Resources (linkage, see

requirement 1)

• Properties – slots, define relationships to other resources or atomic values

• Statements– “Resource has Property with Value”– (Values can be resources or atomic XML data)

• Similar to Frame Systems

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A Simple ExampleA Simple Example• Statement

– “Ora Lassila is the creator of the resource http://www.w3.org/Home/Lassila”

• Structure– Resource (subject) http://www.w3.org/Home/Lassila– Property (predicate) http://www.schema.org/#Creator– Value (object) "Ora Lassila”

• Directed graph

http://www.w3.org/Home/Lassilas:Creator

Ora Lassila

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OWLOWLW3C Web Ontology LanguageW3C Web Ontology Language

• OWL provides three increasingly expressive sublanguages: OWL Lite, OWL DL, and OWL Full.

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OWLOWLW3C Web Ontology LanguageW3C Web Ontology Language

OWL Lite language constructs

RDF Schema Features: Class rdf:Property rdfs:subClassOf rdfs:subPropertyOf rdfs:domain rdfs:range Individual

(In)Equality: equivalentClass equivalentProperty sameAs differentFrom allDifferent

Property Characteristics: inverseOf TransitiveProperty SymmetricProperty FunctionalProperty InverseFunctionalProperty

Property Type Restrictions: allValuesFrom someValuesFrom

Restricted Cardinality: minCardinality (only 0 or 1) maxCardinality (only 0 or 1) cardinality (only 0 or 1)

Header Information: ontology imports

Semantic Web ServicesSemantic Web Services

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Some Motivating TasksSome Motivating Tasks

• The kinds of task we expect OWL-S to enable:– Automatic Web service discovery – Automatic Web service invocation – Automatic Web service composition and interoperation – Automatic Web service execution monitoring

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High-level View of the Service OntologyHigh-level View of the Service Ontology

ServiceProfile

ServiceModel

ServiceGrounding

ServiceResourceprovides

presents

describedBy

supports

What the service does

How it works

How toAccess it

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Top Level of the Process OntologyTop Level of the Process Ontology

Process Profile

AtomicProcess Composite

ProcessSimpleProcess

ControlConstruct

SequenceRepeatUntil

ProcessComponent=Process U ControConstruct



hasProcesshasProfile

computedInputcomputedOutputcomputedEffect

computedPreconditioninvocab

compsedBy

expandcollapserealizes

realizedBy

hasGrounding

InputPrecondition

Outputeffect

Condition

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Grounding a Service to a Concrete Realization Grounding a Service to a Concrete Realization

Process Model

Atomic Process

Operation

DL-Based Types

Inputs/Outputs

Message

Binding to SOAP, HTTP, etc.

WSDL

OWL-S

Semantic Web Services ArchitectureSemantic Web Services Architecture

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IntroductionIntroduction

• Develop architectural and protocol abstractions forming a reference architecture to support Semantic Web Service technologies

• The support functions the architecture will cover– Dynamic Service Discovery– Service Process Enactment and Management– Negotiation and Contracting– Semantic Web Community Support Services– Semantic Web Service Lifecycle and Resource

Management Services– Cross-cutting Issues

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IntroductionIntroduction

• Semantic Web Services are viewed as a way to extend the capabilities of web services in the direction of dynamic interoperability.– Commercial web services, in both B2B and B2C applications– Grid computing– Ubiquitous computing– Information Services

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Functional AreasFunctional Areas

Dynamic Service Discovery B2B B2C Ubiq Grid Info

Advertising of Service Descriptions

Candidate Service Query Formulation

Candidate Service Matchmaking

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Service Process Enactment and Management B2B B2C Ubiq Grid Info

Candidate Service Selection

Service request formation and response interpretation

Request and Response Translation

Choreography interpretation and execution

Process mediation and delegation

Dynamic Service Composition

Process status monitoring and event notification

Service failure handling and compensation

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Negotiation and Contracting B2B B2C Ubiq Grid Info

Service contract negotiation

Dispute Resolution and Compliance

Non-Repudiation/Audit Tracking/Explanation

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Semantic Web Community Support Services B2B B2C Ubiq Grid Info

Ontology Management and Mapping Services

Service catalog and Information brokering Services

Membership and Authority Services

Security (identification/authentication, authorization, delegation)

Privacy Services

Reputation Services

Policy and Protocol Management Services

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Service Lifecycle Support B2B B2C Ubiq Grid Info

Executable process management services

Resource Allocation and Provisioning services

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SummarySummary

• Abstractions of services on emerging technological architectures

• The Semantic Web Service Architecture is probably an integration of the abstractions of services for various functional areas.

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An Architecture of An Architecture of Semantic Community Web Portals

(From: http://www9.org/w9cdrom/134/134.html)

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Development of Web PortalsDevelopment of Web Portals

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A KM Framework over SWA KM Framework over SW

(From: http://www2002.org/CDROM/poster/130.pdf)

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What is Sesame ?What is Sesame ?

Sesame is RDF Schema-based repository

and querying facility that offers:

• A persistent store of RDF data

• Export of repository contents in RDF format

• Data administration functionality

• Query engine (RQL , SeRQL)

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Sesame’s ArchitectureSesame’s Architecture

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Web server

Web server

Web server

Web server

Content providers

User User User User

Ontology Knowledgewarehouse

Portal

Annotator Wrapper

Discovery Use Tailoring Social

Inference engine

An Ontology-Based Portal for Digital Library Services

Syntax Transformation of RDFSyntax Transformation of RDF

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What is RDFWhat is RDF• RDF (Resource Description Framework)

– The common language used for the semantic interoperability of the Semantic Web.

– Consisting of • a data model in directed labeled graph and • the corresponding XML serializations

<rdf:RDF> <rdf:Description about="http://www.w3.org/Home/Lassila"> <s:Creator> <rdf:Description about="http://www.w3.org/staffId/85740"> <v:Name>Ora Lassila</v:Name> <v:Email>[email protected]</v:Email> </rdf:Description> </s:Creator> </rdf:Description> </rdf:RDF>

http://www.w3.org/Home/Lassila

Ora Lassila [email protected]

Creator

Name Email <rdf:RDF> <rdf:Description about="http://www.w3.org/Home/Lassila"> <s:Creator rdf:resource="http://www.w3.org/staffId/85740"/> </rdf:Description> <rdf:Description about="http://www.w3.org/staffId/85740"> <v:Name>Ora Lassila</v:Name> <v:Email>[email protected]</v:Email> </rdf:Description></rdf:RDF>

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(RDF in XML)n

(RDF in XML)i

(RDF in XML)2

(RDF in XML)1DOM +

Procedure1

A single RDF data model

MultipleRDF in XML

DOM +Procedure2

DOM +Procedurei

DOM +Proceduren

Transformation ofRDF Using DOM

Transformation of RDF Using DOM

Resulti

Transformation results

ProblemProblem

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MultipleRDF in XML

Transformation ofRDF Using DOM

Resulti

Transformation results

Syntax-directed Transformation of RDF

(RDF in XML)n

(RDF in XML)i

(RDF in XML)2

(RDF in XML)1

Syntax-directedTransformation

GoalGoal

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Two System ArchitecturesTwo System Architectures

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RDF Grammar to Yacc RulesRDF Grammar to Yacc RulesAn RDF Grammar RuleRDF ::= ['<rdf:RDF>'] obj* ['</rdf:RDF>']RevisionRDF ::= xmlDeclaration stgRDF obj* etgRDFxmlDeclaration::= ‘<?xml’ ‘version’ ‘=‘ ‘1.0’ encoding ‘>’encoding::= ‘encoding’ ‘=‘ coding | emptystgRDF::= '<‘ ‘rdf:’ ‘RDF’ namespaceDef xmlBase ‘>‘ | emptyetgRDF::= '<‘ ‘/’ ‘rdf:’ ‘RDF’ ‘>‘ | empty

def p_stgRDF(t): 'stgRDF : LP rdf RDF namespaceRule xmlbaseRule RP'def p_etgRDF(t): 'etgRDF : LP DIV rdf RDF RP'def p_namespaceRule(t): '''namespaceRule : namespace | empty'''def p_xmlbaseRule(t): '''xmlbaseRule : xmlbase1 | empty'''def p_empty(t): 'empty : ' pass

Yacc Rulesdef p_RDF(t): 'RDF_file : xmlDeclaration RDFRule‘ global triplec; triplec=len(triple) storeNamaspace(); storeResource(); storeProperty(); storeObject(); storeTriple(); displayTripleTable()

def p_xmlDeclaration(t): '''xmlDeclaration : declaration | empty'''def p_RDFRule(t): '''RDFRule : stgRDF obj etgRDF | obj'''

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RDF Grammar to DCG RulesRDF Grammar to DCG RulesAn RDF ruledescription::='<rdf:Description' idAboutAttr? bagIdAttr? propAttr* '/>' | '<rdf:Description' idAboutAttr? bagIdAttr? propAttr* '>‘ propertyElt* '</rdf:Description>' | typedNode

The DCG rule:description(_) --> halfSTG('Description',NS),(idAboutAttr(IdAboutAttr);[]), (bagIdAttr(BagIdAttr);[]),propAttrStar(IdAboutAttr), (['/>'];['>'], propertyEltStar(_,IdAboutAttr),fullETG('Description',NS)), {reificationOfStatements(IdAboutAttr,BagIdAttr),!} ;typedNode.

DCG rules for converting RDF to Triples and frames % RDF to Tripleobj(Obj) --> container(Obj);description(_),{getAllTriples(Obj)}.%RDF to KSLobj(Obj) --> container(Obj);description(_),{getKSLDocument(Obj)}.

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ConclusionConclusion

• The Web is evolving toward automation of resource consumption and services– Electronic Business – Semantic Web and Services

• The Semantic Web Service Architecture is probably an integration of the abstractions of services for various functional areas.– Commercial applications, including B2B, and B2C– Grid computing– Ubiquitous computing– Information services