Resource Description Framework Presentation by Ray James For Semantic Web UT Austin, Spring 2006 Out of chaos, order March 20, 2006

RDF overview What RDF is What RDF can do How to use RDF Current RDF applications RDF’s future Summary & Sources March 20, 2006

RDF basics Metadata is constructed information Metadata is developed by people for a purpose or function Metadata can be a surrogate From Karen Coyle March 20, 2006

What RDF is Key Definitions: Resource Description Framework: An XML expression used to make simple assertions about relationships between things. RDF Schema: A language used to describe the relationship between classes of things, or relationships between concepts in a particular domain. March 20, 2006

In other words RDF defines a convention essential for the Semantic Web RDF is machine and human readable but primarily for the machine RDF is an infrastructure that enables the encoding, exchange, and reuse of structured metadata.* * Eric Miller March 20, 2006

What RDF is History dates just over a decade Creation process began in 1990s; outgrowth of PICS First RDF working draft October 1997 Semantic Web Activity & first RDF Interest Group meeting, February 2001 Collaborative design process March 20, 2006

What RDF is Breaking down RDF Anything can be a resource: Web page, PDA, document, etc. (identified with URI) Description means how a resource is related to any other resource or object Framework means ontological construct Source: www.w3.org March 20, 2006

Describing RDF RDF promotes semantic interoperability; XML promotes syntactic interoperability. Diagram from Dr. Miles Efron lecture notes. March 20, 2006

Describing RDF RDF is all about the “triples” Resource, Property, Value Or Subject, Predicate, Object March 20, 2006

RDF triples graphically March 20, 2006

More on RDF triples An Object can become Subject of new triple ‘Nesting’ of properties without limit Triples concept maintained in RDF Schema RDFS creates vocabularies RDFS triples are: classes, class properties and (atomic) values March 20, 2006

RDF graphically From: Explorer’s Guide to the Semantic Web March 20, 2006

RDF in words There is a person who is named William Sparks who has a telephone number 435-555-6789 and who has an address which is composed of an address (number and street) and a city and a state and who has an e-mail account which was opened on Aug. 1, 2001 and uses the address wsparks@malto.com. Subject Predicate Object Nested-subject Object March 20, 2006

Reification Reification describes the act of making a data model for a previously abstract concept. Reification allows a computer to process an abstraction as if it were any other data From Wikipedia March 20, 2006

An RDF document <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://dublincore.org/2003/03/24/dces"> <rdf:Description rdf:about="http://www.ukoln.ac.uk/metadata/resources/dc/datamodel/WD-dc-rdf/"> <dc:title> Guidance on expressing the Dublin Core within the Resource Description Framework (RDF) </dc:title><dc:creator> Eric Miller </dc:creator><dc:subject> Dublin Core; Resource Description Framework; RDF; eXtensible Markup Language; XML </dc:subject><dc:publisher> Dublin Core Metadata Initiative </dc:publisher><dc:contributor> Dublin Core Data Model Working Group </dc:contributor><dc:date> 1999-07-01 </dc:date><dc:format> text/html </dc:format><dc:language> en </dc:language></rdf:Description> </rdf:RDF> Adapted from http://www.ukoln.ac.uk/metadata/resources/dc/datamodel/WD-dc-rdf Subject Predicate Object March 20, 2006

In words There is a document declared in Dublin Core Schema found at the Dublin Core namespace (& RDF etc) http://www.ukoln.ac.uk/metadata/resources/dc/datamodel/WD-dc-rdf/ which has the title Guidance on expressing the Dublin Core within the Resource Description Framework (RDF) created by Eric Miller whose subject keywords are Dublin Core; Resource Description Framework; RDF; eXtensible Markup Language; XML published by Dublin Core Metadata Initiative contributed by Dublin Core Data Model Working Group on the date 1999-07-01 written in the format text/html and in the language en (English). Subject Predicate Object March 20, 2006

How RDF works All essential information is at: http://www.w3.org/RDF Find RDF validator at the website: http://www.w3.org/RDF/Validator/ March 20, 2006

RDF applications March 20, 2006

RDF document <!-- /Creative Commons License --> <!-- <rdf:RDF xmlns="http://web.resource.org/cc/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <Work rdf:about=""> <dc:title>Metadata: Data with a Purpose</dc:title> <dc:date>2004</dc:date> <dc:description>A general discussion of document/resource metadata and some related uses.</dc:description> <dc:creator><Agent> <dc:title>Karen Coyle</dc:title> </Agent></dc:creator> <dc:rights><Agent> <dc:title>Karen Coyle</dc:title> </Agent></dc:rights> <dc:type rdf:resource="http://purl.org/dc/dcmitype/Text" /> <dc:source rdf:resource="http://www.kcoyle.net/meta_purpose.html"/> <license rdf:resource="http://creativecommons.org/licenses/by-nc-nd/2.0/" /> </Work> <License rdf:about="http://creativecommons.org/licenses/by-nc-nd/2.0/"> <permits rdf:resource="http://web.resource.org/cc/Reproduction" /> <permits rdf:resource="http://web.resource.org/cc/Distribution" /> <requires rdf:resource="http://web.resource.org/cc/Notice" /> <requires rdf:resource="http://web.resource.org/cc/Attribution" /> <prohibits rdf:resource="http://web.resource.org/cc/CommercialUse" /> </License> </rdf:RDF> March 20, 2006

RDF applications Mozilla: describes e-mail, news RSS: describes blogs Annotea: describes Web pages Dublin Core: describes meta data Webscripter: defines and fuses March 20, 2006

RDF(S) creation applications March 20, 2006

More on Altova site March 20, 2006

RDF’s Future Growing acceptance by Web site producers and users of metadata Programs like SemanticWorks are positive signs that standard is healthy Acceptance means use; use means continuing acceptance Continued support (likely) from W3C March 20, 2006

RDF Summary RDF … …is about relationships. …brings interoperability. …is all about triples. …can be found at http://www.w3.org/RDF March 20, 2006

Sources http://www.w3.org/RDF http://www.altova.com http://www.mozilla.org/rdf/doc/ http://www-db.research.bell-labs.com/user/pfps/publications/oil-ieee.pdf OIL: An Ontology Infrastructure (Fensel and others) www.dlib.org/dlib/may98/miller/05miller.html An Introduction to the Resource Development Framework (Miller) Explorer’s Guide to the Semantic Web (Passin) http://www.kcoyle.net/jal2_Metadata.html Understanding Metadata and Its Purpose (Coyle) March 20, 2006

Questions? March 20, 2006