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RDF: The Resource Description Framework

RDF: The Resource Description Framework. Machine Understandable Metadata for the Web. Ralph R. Swick swick@w3.org W3C/MIT 2-November-1998. Introducing: RDF. Improve on PICS, HTML, and XML Machine understandable metadata Support structured values Support metadata bureaus

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RDF: The Resource Description Framework

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  1. RDF:The Resource Description Framework Machine Understandable Metadata for the Web Ralph R. Swickswick@w3.orgW3C/MIT2-November-1998

  2. Introducing: RDF • Improve on PICS, HTML, and XML • Machine understandable metadata • Support structured values • Support metadata bureaus • Encourage authenticated metadata • Base for a variety of descriptions: • cataloging, privacy, accessibility, IPR, ...

  3. RDF Components • Formal data model • Syntax for interchange of data • Schema Type system (schema model) • Syntax for machine-understandable schemas • Query and profile protocols

  4. RDF Data Model • Imposes structural constraints on the expression of application data models • for consistent encoding, exchange and processing of metadata • Enables resource description communities to define their own semantics • Provides for structural interoperability

  5. RDF Data Model • Directed labeled graphs • Model elements • Resource • Property • Property value • Statement

  6. Property Statement RDF Model Primitives Resource Value

  7. RDF Model Example John Smith Creator page.html Title John’s Home Page

  8. Name Email John Smith js@corp.com Structured Value page.html Creator Title John’s Home Page

  9. RDF Syntax • Uses eXtensible Markup Language (XML) • Highly formalized • graph serialization • Property Names and Values are always unambiguous

  10. Basic Example John Smith DC:Creator page.html DC:Title John’s Home Page

  11. Basic RDF Example <?xml version=“1.0”?> <rdf:RDFxmlns:rdf=“http://www.w3.org/TR/WD-rdf-syntax#”xmlns:dc=“http://purl.org/metadata/dublin_core#”> <rdf:Description about=“page.html”> <dc:Creator>John Smith</dc:Creator> <dc:Title>John’s Home Page</dc:Title> </rdf:Description> </rdf:RDF>

  12. Structured Value Example page.html dc:Creator dc:Title Name Email John’s Home Page John Smith js@corp.com

  13. Structured Value Example - 1 <?xml version=“1.0”?> <RDFxmlns=“http://www.w3.org/TR/WD-rdf-syntax#”xmlns:dc=“http://purl.org/metadata/dublin_core#”xmlns:corp=“http://mycorp.com/corpSchema/”> . . .

  14. Structured Value Example - 2 . . .<Description about=“page.html”> <dc:Creator> <Description> <corp:Name>John Smith</corp:Name> <corp:Email>js@corp.com</corp:Email> </Description> </dc:Creator> <dc:Title>John’s Home Page</dc:Title></Description> </RDF>

  15. Abbreviations: 1 <rdf:RDF><rdf:Description about=“page.html”> <dc:Creator> <rdf:Description corp:Name=“John Smith” corp:Email=“js@corp.com” /> </dc:Creator> <dc:Title>John’s Home Page</dc:Title></rdf:Description> </rdf:RDF>

  16. Abbreviations: 2 <rdf:RDF><rdf:Description about=“page.html”> <dc:Creator corp:Name=“John Smith” corp:Email=“js@corp.com” /> <dc:Title>John’s Home Page</dc:Title></rdf:Description> </rdf:RDF>

  17. ValidUntil 18-Apr-1999 Meta-description page.html $0.15 Cost

  18. Subject Object ValidUntil type Predicate Statement 18-Apr-1999 Cost Property Reification page.html $0.15 Cost

  19. Meta-description Example - 1 <?xml version=“1.0”?> <RDFxmlns:rdf =“http://www.w3.org/TR/WD-rdf-syntax#”xmlns:corp =“http://mycorp.com/schema/”> . . .

  20. Meta-description Example - 2 . . .<rdf:Description about=“page.html” bagID=“D_001”> <corp:Cost>$0.15</corp:Cost></rdf:Description><rdf:Description aboutEach=“#D_001”> <corp:ValidUntil>18-Apr-1999</corp:ValidUntil></rdf:Description> </rdf:RDF>

  21. Meta-description Example - 3 <rdf:RDF><rdf:Description about=“page.html” bagID=“D_001” corp:Cost=“$0.15”/><rdf:Description aboutEach=“#D_001” corp:ValidUntil=“18-Apr-1999”/> </rdf:RDF>

  22. Summary • RDF is a general-purpose framework • RDF provides structured, machine-understandable metadata for the Web • Metadata vocabularies can be developed without central coordination • RDF Schemas describe the meaning of each property name • Signed RDF is the basis for trust

  23. For More Information... The RDF Model and Syntax specification: http://www.w3.org/TR/WD-rdf-syntax RDF Schema Working Draft: http://www.w3.org/TR/WD-rdf-schema General information about RDF: http://www.w3.org/RDF

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