Introduction to RDF Ken Varnum 9 October 2007

Definition of RDF The Resource Description Framework (RDF) is a general-purpose language for representing information in the Web. RDF Vocabulary Description Language 1.0: RDF Schema Significant Part of “Semantic Web” XML-based tool for describing resources

The Resource Description Framework (RDF) is a general-purpose language for representing information in the Web.

RDF Vocabulary Description Language 1.0: RDF Schema

Significant Part of “Semantic Web”

XML-based tool for describing resources

What’s It Good For? “… [D] oes not specify a vocabulary of descriptive properties such as "author". Instead it specifies mechanisms that may be used to name and describe properties and the classes of resource they describe.” Used to describe Source of ontology What is being described Description Not an Ontology

“… [D] oes not specify a vocabulary of descriptive properties such as "author". Instead it specifies mechanisms that may be used to name and describe properties and the classes of resource they describe.”

Used to describe

Source of ontology

What is being described

Description

Not an Ontology

Concept of “Triples” Subject - Predicate - Object Something Has the Property Characteristic Properties are defined -- in human- or machine-readable format -- at a given URI.

Subject - Predicate - Object

Something

Has the Property

Characteristic

Properties are defined -- in human- or machine-readable format -- at a given URI.

Example Michigan has the postal abbreviation MI MI has the postal abbreviation Michigan Object Predicate Subject

Michigan has the postal abbreviation MI

Convert to RDF -- Step 1 First do the XML thing -- declare name spaces <rdf:RDF xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns# xmlns:terms=&quot;http://purl.org/dc/terms/&quot;> </rdf:RDF> Two name spaces rdf (defined by W3C) terms (defined by Dublin Core)

First do the XML thing -- declare name spaces

<rdf:RDF xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns# xmlns:terms=&quot;http://purl.org/dc/terms/&quot;>

</rdf:RDF>

Two name spaces

rdf (defined by W3C)

terms (defined by Dublin Core)

Convert to RDF -- Step 2 Add Subject <rdf:RDF xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns# xmlns:terms=&quot;http://purl.org/dc/terms/&quot;> <rdf:Description rdf:about=&quot;urn:x-states:Michigan&quot;> </rdf:Description> </rdf:RDF> Use “Description” from the RDF namespace Definition found at RDF “x-states” site

Add Subject

<rdf:RDF xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns# xmlns:terms=&quot;http://purl.org/dc/terms/&quot;>

<rdf:Description rdf:about=&quot;urn:x-states:Michigan&quot;>

</rdf:Description>

</rdf:RDF>

Use “Description” from the RDF namespace

Definition found at RDF “x-states” site

Convert to RDF -- Step 3 Add Object <rdf:RDF xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns# xmlns:terms=&quot;http://purl.org/dc/terms/&quot;> <rdf:Description rdf:about=&quot;urn:x-states:Michigan&quot;> <terms:alternative>MI</terms:alternative> </rdf:Description> </rdf:RDF> Use “alternative” from the terms namespace Definition found at Dublin Core site DC only defines purpose of “alternative” in a machine-readable way

Add Object

<rdf:RDF xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns# xmlns:terms=&quot;http://purl.org/dc/terms/&quot;>

<rdf:Description rdf:about=&quot;urn:x-states:Michigan&quot;>

<terms:alternative>MI</terms:alternative>

</rdf:Description>

</rdf:RDF>

Use “alternative” from the terms namespace

Definition found at Dublin Core site

DC only defines purpose of “alternative” in a machine-readable way

Where Is It? A “flavor” of RSS RDF RSS Atom Underlies data exchange As a rule, systems generate it, not people

A “flavor” of RSS

RDF

RSS

Atom

Underlies data exchange

As a rule, systems generate it, not people

Foundation of “Semantic Web” “ What is meant by ‘semantic’ in Semantic Web is not that computers are going to understand the meaning of anything, but that the logical pieces of meaning can be mechanically manipulated by a machine to useful human ends.” “ What Is RDF” by Joshua Tauberer

“ What is meant by ‘semantic’ in Semantic Web is not that computers are going to understand the meaning of anything, but that the logical pieces of meaning can be mechanically manipulated by a machine to useful human ends.”

“ What Is RDF” by Joshua Tauberer

Sources / Further Reading Wikipedia entry on RDF (overview) http://en.wikipedia.org/wiki/Resource_Description_Framework RDF Specification (technical) http://www.w3.org/RDF/ What Is RDF (overview) http://www.xml.com/lpt/a/1665

Wikipedia entry on RDF (overview) http://en.wikipedia.org/wiki/Resource_Description_Framework

RDF Specification (technical) http://www.w3.org/RDF/

What Is RDF (overview) http://www.xml.com/lpt/a/1665