RDF

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Definition

• The Resource Description Framework (RDF) is a language for representing information about resources in the World Wide Web.

• Originally RDF was primarily intented to represent metadata about Web resources, such as the title, author, and modification date of a Web page, copyright and licensing information about a Web document, or the availability schedule for some shared resource. However, by generalizing the concept of a "Web resource", RDF can also be used to represent information about things that can be identified on the Web, i.e. the semantic web.

Major RDF vocabularies

Metadata

• Learning Object Metadata Standard
• Dublin Core

Content syndication and social software

• RSS 1.0 which is not very popular, most RSS formats are not RDF since bloggers don't understand issues related to the semantic web :)
• FOAF Friends-of-a-friend vocabulary for person networks

Semantic Web

• OWL
• SparQL (Query language)

RDF basics

At its core, RDF has a simple relational data model: Subject - Verb - Object or expressed differently Predicate (Subject, Object)

• Sujet = The resource
• Objet = Value
• Verb = Predicate = propriety = relation of the subjet with the object

Here is a typical RDF fragment

<?xml version="1.0"?>
 <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
          xmlns:mon_schema="http://tecfa.unige.ch/lib/mon_schema" >
 <rdf:Description rdf:about="http://tecfa.unige.ch/perso/staf/lattion/">
  <mon_schema:Creator>Stéphane Lattion</mon_schema:Creator>
 </rdf:Description>
</rdf:RDF>

It expresses a relation like this:

A simple ressource-author relationship

RDF and the semantic web

The RDF Software stack

The RDF software stack

The RDF bus

Software clients of the RDF bus

Links

Standards

• Resource Description Framework (RDF) Overview
• Resource Description Framework (RDF): Concepts and Abstract Syntax, W3C Recommendation 10 February 2004
• Resource Description Framework (RDF) Model and Syntax.
• RDF Semantics, W3C Recommendation 10 February 2004 (rather difficult reading).
• RDF/XML Syntax Specification, W3C Recommendation 10 February 2004.
• RDF Vocabulary Description Language 1.0: RDF Schema, W3C Recommendation 10 February 2004

OWL

• OWL Web Ontology Language Overview, W3C Recommendation 10 February 2004.
• OWL Web Ontology Language Guide, W3C Recommendation 10 February 2004
• OWL Web Ontology Language Semantics and Abstract Syntax, W3C Recommendation 10 February 2004
• Dean M., Schreiber G (Editors); van Harmelen F., Hendler J., Horrocks I., McGuinness D.L., Patel-Schneider P.F., Stein L.A. (Authors), OWL Web Ontology Language Reference, W3C Recommendation, 10 February 2004. HTML

Other RDF Applications

• SPARQL Query Language for RDF (last checkedwas: W3C Working Draft 17 February 2005)
• PICS (Platform for Internet Content Selection)

Overviews

• Mozilla's RDF pointers
• Oasis Resource Description Framework (RDF)
• W3C Data Formats A older (1997) note on the planned XML-centered framework
• Chris Waterson, RDF in Fifty Words or Less, Mozilla Magazine.

On-line validation

• W3C RDF validation service

RDF-related web sites

• http://www.semanticplanet.com/
• W3C Semantic Web page.

Various to sort out

• Supercharging WSDL with RDF Managing structured Web service metadata article by Uche Obbuji
• Rudolf: RDFViz Exploring tools for RDF Graph Visualisation by Dan Brickely, project page.

References

• Eric Miller An Introductionto the Resource Description Framework (1998), D-Lib Magazine May 1998, ISSN 1082-9873, HTML

• Manola Frank and Eric Miller (2004). RDF Primer, W3C Recommendation 10 February 2004, W3C.