Semantic Web by wuyunqing


									Semantic Web

             Meeyoung Park,
   Semantic Web Services
    – By Sheila A. McIlraith, Tran Cao Son, and
      Honglei Zeng, IEEE Intelligent Systems,, March/April 2001,
      Pages 46-53.”

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   Introduction
    –Semantic Web
       • Languages
   Semantic Web Services
   Research Challenges and Perspective
   Future Directions
   References

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  Web : Information Management

[Fig.1] Tim Berners-Lee, CERN, March 1989, May 1990,
        ( )
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  Web : Current Web

[Fig.2] Current Web
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Semantic Web
   The Semantic Web is
    – an extension of the current web in which information is
       given well-defined meaning, better enabling computers
       and people to work in cooperation."
    ( Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web,
       Scientific American, May 2001)

    – a collaborative effort led by W3C with participation from
       a large number of researchers and industrial partners.
    – based on the Resource Description Framework (RDF),
       which integrates a variety of applications using XML for
       syntax and URIs for naming.

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  Semantic Web

[Fig.3] Semantic Web
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The Semantic Web
   Why Semantic Web ?
    – provides a common framework that allows
      data to be shared and reused across
      application, enterprise, and community
    – expresses web data in a machine-readable
    – reduces language dependency and increase

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   Semantic Web Architectural

[Fig.4] Semantic Web “layer cake” tresented by Tim Berners-
        Lee at the XML 2000 Conference
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Languages for Semantic Web
   XML ( eXtensible Markup Language)
    – a simple, very flexible text format derived
      from SGML.
    – the first language to separate the markup of
      Web content from Web presentation.
    – lacks semantics.
         • <salary> Vs. <Wage>

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Resource Description Framework
   RDF is
    – A standard for metadata
    – a language for representing information about resources
       in the World Wide Web

   Why use RDF?
    – Goal
         • to add a formal semantics to the Web, defined on top of XML
         • to provide a data model and syntax convention for
             representing the semantics of data in a standardized
             interoperable manner
    – provides a means of describing the relationships among
       resources in terms of named properties and values.
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RDF data model

    [Fig.5] An RDF Graph Describing Eric Miller
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   RDF Example
<?xml version="1.0"?>

<rdf:RDF xmlns:rdf=""



      <contact:fullName>Eric Miller</contact:fullName>

      <contact:mailbox rdf:resource=""/>
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DARPA Agent Markup Language
   What is DAML ?
    – initiative to fund research in languages, tools,
       infrastructure, and applications
    – to make Web content more accessible and

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 Why use DAML?
    RDF lacks
     – Expressive power
    DAML provides
     – a basic infrastructure that allows a machine to
       make the same sorts of simple inferences that
       human beings do.
     – can allow you to conclude another DAML
(motherOf subProperty parentOf)
                                    (Mary parentOf Bill)
(Mary motherOf Bill)
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Ontology Inference Layer
   What is Ontology?
    – A set of knowledge terms, including the
      vocabulary, the semantic interconnections, and
      some simple rules of inference and logic for
      some particular topic
   OIL (Ontology Inference Layer)
    – a proposal for a web-based representation and
      inference layer for ontologies.
    – designed to be an expressive description logic
      integrated with modern Web technology.

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   DAML+OIL is
    – a semantic markup language for Web resources.
    – a vocabulary of properties and classes added to RDF and RDF
   Why use DAML+OIL?
    – overcomes expressiveness inadequacies plaguing RDF and
    – has a well-defined model-theoretic semantics.
    – is unambiguously computer-interpretable, thus making it
      amenable to agent interoperability and automated-reasoning
    – can manage large Web sites and document and image
      collections, integrating disparate databases.

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DAML+OIL Example
<!-- $Revision: 1.7 $ of $Date: 2001/06/06 01:38:21 $. -->
    xmlns:rdf =""
    xmlns ="" >

<daml:Class rdf:ID="Animal"> <rdfs:label>Animal</rdfs:label>
         This class of animals is illustrative of a number of
           ontological idioms.
<daml:Class rdf:ID="Male">
   <rdfs:subClassOf rdf:resource="#Animal"/>
<daml:Class rdf:ID="Female">
   <rdfs:subClassOf rdf:resource="#Animal"/> <daml:disjointWith
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Agents and the Semantic Web

    [Fig.6] Agents and the Semantic Web
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Semantic Web services

    [Fig.7] A framework for Semantic Web services
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Semantic Web services enables..

   Automatic Web service discovery
    – Involves automatically locating Web services.
    ? “Find a service that sells airline tickets between
      San Francisco and Toronto and that accepts
      payment by Diner’s Club credit card.”
     With Semantic markup of services, semantic
       search engine can automatically locate
       appropriate services.

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Semantic Web services enables..

   Automatic Web service execution
    – Involves a computer program or agent
      automatically executing an identified Web
    ? “Buy me an airline ticket from on UAL flight 1234 from
       San Francisco to Toronto on March.3 ”
     The markup tells the agent what input is
       necessary, what information will be returned,
       and how to execute the service automatically.

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Semantic Web services enables..

   Automatic Web Service composition and
    – Involves the automatic selection, composition,
      and interoperation of appropriate Web services.
    ? “Make the travel arrangements for my
       IJCAI2001 conference trip.”
     The information necessary to select, compose,
       and respond to services is encoded at the
       service web sites.

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DAML-enabled agent technology

   ConGolog
    – A high-level logic programming language
      developed as the University of Toronto.
    – For robot programming and to support high-
      level robot task programming.
    – Built on top of situation calculus.

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   Agent technology
    – Online ConGolog interpreter in Quintus Prolog
    – Open Agent Architecture agent brokering
   Web services
    – Communicate through DAML.
    – Markup : DAML+OIL.
    – Information extraction program : World Wide
      Wrapper Factory(http:/

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   You want to travel from Kansas City to
    Chicago on conference with the university
    – Constraints
         • you wish to drive rather than fly.
         • You must use an American carrier for business

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Research Challenges and Perspective

    The Semantic Web will enable
      – Computers will be able to “understand” data in
        ways they cannot today.
      – A more open market for information processing and
        computer services.
    Applications
      – Applications for organization
         • Ontology-based market place development for
           B2B e-commerce.
         • Bioinformatics.
      – Application for the masses
         • Intelligent personal assistant that gathers

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Semantic Web Services Example

   The Semantic Web Site
    – Semaview's Sherpa
    – Dublin Core Metadata Initiative
    – Searching - TAP

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Future Directions
   Facilitate Semantic Web infrastructure

    – stimulate the network effect of data.
   Development of ontology registries for Open
    vocabularies to help bootstrap application deployment
    in interoperable manners.

   Investigate additional enabling standards that help
    build the Semantic Web.

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   “The semantic web and its languages, Dieter Fensel, IEEE
    Intelligent Systems, November/December 2000, Pages: 67-73.”
   “Agents and the Semantic Web, Hendler, J., Intelligent
    Systems, IEEE, Volume: 16 , Issue: 2 , March-April 2001,
    Pages: 30 – 37”
   “DAML+OIL An Ontology Language for the Semantic Web,
    Mcguinness, D.L, Fikes, R., Hendler, J., Stein, L.A., Intelligent
    Systems, IEEE , Volume: 17 , Issue: 5 , Sept.-Oct. 2002 ,
    Pages: 72 – 80”
   “Research Challenges and Perspectives of the Semantic
    Web, Euzenat, J., Intelligent Systems, IEEE, Volume:
    17 , Issue: 5 , Sept.-Oct. 2002
    Pages:86 – 88”

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Useful Sites
   SemanticWeb.Org
   World Wide Web Consortium (W3C)
   Resource Description Framework (RDF)
   Web-Ontology (WebOnt) Working Group
   Extensible Markup Language (XML)
   DARPA Agent Markup Language (DAML)
   Ontology.Org

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             Thank you!
              Any Questions ?

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