CmpE 583- Web Semantics: Theory and Practice INTRODUCTION TO RDF Atilla ELÇİ Computer Engineering Department Eastern Mediterranean University 31.10.04 updated 23.10.07 CmpE 583 Fall 2008

Introduction RDF is basis for the world of the Semantic Web. RDF representation is simplest through Notation 3 (N3). Graphics is another means to work with RDF. Due to ease of processing, we use XML serialization of RDF- called RDF/XML. It is important to grasp the model of interaction mechanics and hierarchy of components in effecting semantic Web systems of which RDF is the basis. 31.10.04 updated 11.11.08 CmpE 583 Fall 2008

Agenda RDF (data-) model Notation 3 RDF Syntax RDF Semantics 31.10.04 updated 23.10.07 CmpE 583 Fall 2008

Semantic Web: Part Played by RDF Principal Semantic Web technologies fit into a set of layered specifications framework: RDF Core Model, RDF Schema language, and, Web Ontology Language. Building on these core components is a standardized query language for RDF enabling the 'joining' of decentralized collections of RDF data. These languages all build on the foundation of URIs, XML, and XML namespaces. The Resource Description Framework (RDF) is a language for representing information about resources in the semantic Web. 31.10.04 updated 10.11.08 CmpE 583 Fall 2008

RDF model: Introduction by N3 Primer: Getting into RDF & Semantic Web using N3 by Tim-Berners Lee. Slides by Tim-Berners Lee. 31.10.04 updated 23.10.07 CmpE 583 Fall 2008

RDF proper by Recommendations RDF Primer by Frank Manola, Eric Miller (eds.): Introductory volume of the six current recommendations. Different serializations: Fig 12 & Example 4; contrast with Example 5. Typed literals: Example 7 & 8 using XML Schema Part 2: Datatypes: 3.2 Primitive datatypes. Typed nodes: contrast Example 12 & 13. Take note of the transitions among graphics, N3 and XML serializations of RDF in the recommendation. 31.10.04 updated 11.11.08 CmpE 583 Fall 2008

RDF Specifications by W3C Obsolete recommendations of 1999: RDF Model and Syntax (1999 Recommendation) RDF Schema (1999 Proposed Recommendation). Current Recommendations set dated 10 February 2004: RDF/XML Syntax Specification (Revised) by Dave Beckett (ed.). RDF Vocabulary Description Language 1.0: RDF Schema by Dan Brickley, R.V. Guha (eds.). RDF Primer by Frank Manola, Eric Miller (eds.). Resource Description Framework (RDF): Concepts and Abstract Syntax by Graham Klyne, Jeremy Carroll (eds.). RDF Semantics by Patrick Hayes (ed.) RDF Test Cases by Jan Grant, Dave Beckett (eds.). 31.10.04 updated 23.10.07 CmpE 583 Fall 2008

Where to Get More Information A full-day Semantic Web Tutorial by TBL et. al. Basic RDF, pp. 15-42 in Tutorial on Semantic Web Technologies by Ivan Herman, dated 27 Oct 2004. Semantic Web: WWW Consortium Semantic Web pages, 2004. END of PRESENTATION 31.10.04 updated 11.11.08 CmpE 583 Fall 2008

RDF proper by XML Basic RDF: pp. 15-42 in [Herman] 31.10.04 updated 23.10.07 CmpE 583 Fall 2008

RDF/XML Read Ch. 3 in the textbook by Yu. May study Ch.s 7 & 8 in Lacy: Simple introductory examples Some N3 to XML serialization Study RDF Model View in UML: Fig. 7-3 . 31.10.04 updated 23.10.07 CmpE 583 Fall 2008

RDF/XML Documents RDF doc: File Header (rdf:RDF) Ex: <rdf:RDF xmlns:rdf=“....ns URI...”> RDF Statements (rdf:Description) Ex: <rdf:Description rdf:ID=“...resource URI...”> 31.10.04 updated 23.10.07 CmpE 583 Fall 2008

RDF Statements (rdf:Description) Creating a new subject resource: <rdf:Description rdf:ID=“Me”/> Qualifiying an existing resource: <rdf:Description rdf:about=“Me”> <profile:shirtSize>XL</profile:shirtSize> </rdf:Description> <property>value</property> 31.10.04 updated 23.10.07 CmpE 583 Fall 2008

RDF Statement Values (ie, inner text) Plain Literal: rdf:parseType=“Literal” Simply insert regular XML text: <rdf:Description rdf:about=“Me”> <profile:bestColors rdf:parseType=“Literal”> <i>Blue & Red</i> </profile:bestColors> </rdf:Description> Rest of the Intro is here. 31.10.04 updated 23.10.07 CmpE 583 Fall 2008