Semantic Web and Knowledge Management

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Semantic Web and Knowledge Management

• Ching-Long Yeh ???
• Department of Computer Science and Engineering
• Tatung University
• Taipei, Taiwan
• Email chingyeh_at_cse.ttu.edu.tw
• http//www.cse.ttu.edu.tw/chingyeh

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Content

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

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Web Technology Evolution
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Web Technology

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

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WWW
Information Pool
Application
Client
Web server
URL
HTML Document
HTTP

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

• Human-to-machine interaction
• Information explosion

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Interaction Using XML
Information Pool
Information Pool
Application
Application
SOAP server
SOAP server
XML Document
XML Document
HTTP

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

• Machine-to-machine interaction
• Service automation

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Web Service Architecture
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Electronic Business

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

Company B
Company A
ERP
ERP
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Semantic Web

• The Semantic Web is a vision

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

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

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Semantic 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 Architecture
Trust
Sig
Proof
Tim Berners-Lee Axioms, Architecture and
Aspirations W3C all-working group plenary
Meeting 28 February 2001
Logic
Rules
Ontology
RDF Schema
(http//www.w3.org/2001/Talks/0228-tbl/slide5-0.ht
ml)
RDF MS
XML Schema
XML
Namespaces
URI
Unicode
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The Big Picture of SW
(http//semanticweb.org/about.htmlbigpicture)
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The metadata layer of the Semantic Web
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What Is in an Ontology?

• One widely cited definition of an ontology is
  Grubers 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 Spectrum
(From http//www.ksl.stanford.edu/people/dlm/pape
rs/ontologies-come-of-age-mit-press-(with-citation
).htm)
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Semantic Web Languages
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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 Standards

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

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XML Protocol SOAP
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RDF MS

• 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 Model

• Resources
• A resource is a thing you talk about (can
  reference)
• Resources have URIs
• 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 Example

• Statement
• Ora Lassila is the creator of the resource
  http//www.w3.org/Home/Lassila
• Structure
• Resource (subject) http//www.w3.org/Home/Las
  sila
• Property (predicate) http//www.schema.org/Cre
  ator
• Value (object) "Ora Lassila
• Directed graph

sCreator
http//www.w3.org/Home/Lassila
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OWLW3C Web Ontology Language

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

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OWLW3C Web Ontology Language
OWL Lite language constructs
RDF Schema Features Class rdfProperty
rdfssubClassOf rdfssubPropertyOf rdfsdomain
rdfsrange 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
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Semantic Web Services
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Some 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 Ontology
Service
Resource
provides
presents
supports
describedBy
ServiceProfile
ServiceGrounding
What the service does
How to Access it
ServiceModel
How it works
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Top Level of the Process Ontology
Input Precondition Output effect
hasProcess hasProfile
Process
Profile
Condition
Atomic Process
has Grounding
computedInput computedOutput computedEffect comput
edPrecondition invocab
Composite Process
expand collapse
realizes realizedBy
Simple Process
compsedBy
Control Construct
Sequence
Repeat Until
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Grounding a Service to a Concrete Realization
OWL-S
DL-Based Types
Process Model
Inputs/Outputs
Atomic Process
Message
Operation
Binding to SOAP, HTTP, etc.
WSDL
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Semantic Web Services Architecture
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Introduction

• 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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Introduction

• 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 Areas
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Functional Areas
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Functional Areas
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Functional Areas
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Functional Areas
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Summary

• 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 Semantic Community Web Portals
(From http//www9.org/w9cdrom/134/134.html)
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Development of Web Portals
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A KM Framework over SW
(From http//www2002.org/CDROM/poster/130.pdf)
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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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Sesames Architecture
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An Ontology-Based Portal for Digital Library
Services
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Syntax Transformation of RDF
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What 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

ltrdfRDFgt ltrdfDescription about"http//www.w3
.org/Home/Lassila"gt ltsCreatorgt
ltrdfDescription about"http//www.w3.org/staffId/
85740"gt ltvNamegtOra Lassilalt/vNamegt
ltvEmailgtlassila_at_w3.orglt/vEmailgt
lt/rdfDescriptiongt lt/sCreatorgt
lt/rdfDescriptiongt lt/rdfRDFgt
http//www.w3.org/Home/Lassila
Creator
ltrdfRDFgt ltrdfDescription about"http//www.w3
.org/Home/Lassila"gt ltsCreator
rdfresource"http//www.w3.org/staffId/85740"/gt
lt/rdfDescriptiongt ltrdfDescription
about"http//www.w3.org/staffId/85740"gt
ltvNamegtOra Lassilalt/vNamegt
ltvEmailgtlassila_at_w3.orglt/vEmailgt
lt/rdfDescriptiongt lt/rdfRDFgt
Name
Email
Ora Lassila
lassila_at_w3.org
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Problem
Transformation of RDF Using DOM
(RDF in XML)n
DOM Proceduren
(RDF in XML)i
DOM Procedurei
Resulti
(RDF in XML)2
DOM Procedure2
(RDF in XML)1
DOM Procedure1
Transformation results
A single RDF data model
Multiple RDF in XML
Transformation of RDF Using DOM
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Goal
Syntax-directed Transformation of RDF
(RDF in XML)n
(RDF in XML)i
Syntax-directed Transformation
Resulti
(RDF in XML)2
(RDF in XML)1
Transformation results
A single RDF data model
Multiple RDF in XML
Transformation of RDF Using DOM
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Two System Architectures
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RDF Grammar to Yacc Rules
An RDF Grammar Rule RDF 'ltrdfRDFgt' obj
'lt/rdfRDFgt' Revision RDF xmlDeclaration
stgRDF obj etgRDF xmlDeclaration lt?xml
version 1.0 encoding gt encoding
encoding coding empty stgRDF 'lt
rdf RDF namespaceDef xmlBase gt
empty etgRDF 'lt / rdf RDF gt empty
Yacc Rules def p_RDF(t) 'RDF_file
xmlDeclaration RDFRule global triplec
tripleclen(triple) storeNamaspace()
storeResource() storeProperty()
storeObject() storeTriple()
displayTripleTable() def p_xmlDeclaration(t)
'''xmlDeclaration declaration
empty''' def p_RDFRule(t) '''RDFRule
stgRDF obj etgRDF obj'''
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
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RDF Grammar to DCG Rules
An RDF rule description'ltrdfDescription'
idAboutAttr? bagIdAttr? propAttr '/gt'
'ltrdfDescription' idAboutAttr? bagIdAttr?
propAttr 'gt propertyElt
'lt/rdfDescriptiongt'
typedNode The DCG rule description(_) --gt
halfSTG('Description',NS),(idAboutAttr(IdAboutAttr
)), (bagIdAttr(BagIdAttr)),propAttrStar(I
dAboutAttr), ('/gt''gt',
propertyEltStar(_,IdAboutAttr),fullETG('Descriptio
n',NS)), reificationOfStatements(IdAboutAt
tr,BagIdAttr),! typedNode.
DCG rules for converting RDF to Triples and
frames RDF to Triple obj(Obj) --gt
container(Obj)description(_),getAllTriples(Obj)
. RDF to KSL obj(Obj) --gt
container(Obj)description(_),getKSLDocument(Obj)
.
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Conclusion

• 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