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Semantic Web Technologies for UK HE and FE Institutions:

Part 2: RDF and Semantic Web Applications

Dave Beckett

dave.beckett@bristol.ac.uk

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Dave Beckett – Introduction

• Dublin Core Metadata Initiative• UK JISC Services - mirror.ac.uk• RDN – WSE• W3C Semantic Web Activity• W3C RDF Core WG• EU IST SWAD Europe

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Outline

• Introduce the ideas• The technology• Some real projects• What you can do• Open Issues

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History of the Web

• In 1991 Tim Berners-Lee invents the Web at CERN

• However in 1989...the original proposal

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Information Management, a Proposal, Tim Berners-Lee, March 1989

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Searching the Web

• Same issues in 2003• Current searches:– Which documents contain these words and

phrases?

• Does not give you the information– Descriptions for humans– Must be made usable for software also

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My Data

• Maintain data where it naturally is• PC revolution – PC on all desktops• Web revolution - everyone has web• Centralising is unsustainable• Distribution is more appropriate

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Web Architecture

• Universal, scalable, evolvable• Mostly for people to interpret• URIs for identification, linking

“the web works best when any [thing] of value and identity has a first class object” - Tim Berners-Lee

• Can link to anything

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HTML – The Web of Markup

• Documents for people to read• URIs linking to other documents• Can point to anything• ... even if it doesn't exist the web

doesn't break• To software, very little information

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XML – The Generic File Format

• Unicode• A tree (mostly)• XML Schemas– Good for databases– Hard for humans

• No linking in core XML (but Xlink)• Not webby

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The element of the Semantic Web

Called the Resource Description Framework (RDF)(picture by Tim Berners-Lee, 2003-01-28)

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Relational Database Tables

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Tables in RDF

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Trees in RDF

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(Semantic) Web Fundamentals

• Everything has a URI– Resources, properties, classes

• Unbounded set of terms, 404s OK• Layering is expected• A graph (web) structure• Semantic links not <a href=”..”>text</a>• Terms can have schemas

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RDF Vocabularies (RDF Schema)

• URIs for relationships and classes• Good if you re-use existing ones• You can make your own• Better if you re-use and share them• Connect them to other terms• Formalise in a vocabulary or

ontology

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CORES declaration

• November 2002• GILS, ONIX, LoC/MARC, CERIF, DOI,

IEEE/LOM, DC, W3C• “... agree– To assign URIs to our elements– To articulate and publish policies regarding

the stability, persistence and maintenance of the URIs assigned to the elements”

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RDF Family

• RDF itself• RDF Schema – vocabulary

description• OWL Web Ontology Language• Lots of vocabularies– Dublin Core– FOAF – Friend of a Friend– RSS 1.0, Creative Commons, AKT, Geo, ...

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OWL – Web Ontology Language

• Web-like linking of ontologies• Strong formal semantics• Compatibility with XML, RDF, XSD• Based on mature DAML+OIL work• Flavours – OWL, OWL DL, OWL Lite

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Case Study – Sun SwoRDFish

• Sun Knowledge Services group– Create and share knowledge to solve service

issues– Many sources of data inside organisation– Many internal and external users– Business rules and access control

• Want to– Enable sharing business practice, model– Add technology support for knowledge

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Case Study – Sun SwoRDFish

• Open standards based– RDF, SOAP/XML, DAML+OIL

• SunSolve improved– Enables more precise search– Standardises product names– Improves user experience (consistency)– Eliminates manual maintained links

• Vocabulary – DC + Sun element set

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Sun SwoRDFish – Outcomes

• Organisational-lead approach • Integrates enterprise knowledge• Data can remain distributed• Capable of flexible layering• Future opportunities for– Better RDF-aware searching and navigation– Richer ontology-aware, mining, inference tools

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hyphen.info – AKT

• Information on UK researchers• RAE data (HERO) – converted

– People, Publications, Groups

• An ontology in RDF, OWL– akt:Award, akt:Degree, akt:Academic-Degree

• CS in the UK – extracted from HTML– People, Publications, Projects

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Friend of a Friend (FOAF)

• People - who they know, what they do• Tracking provenance – who said what• FOAFNaut (SVG) – visualising• FOAF Explorer (web) – browsing• FOAFbot (IRC) – conversational• ... plus can be used with anything else

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FOAFnaut view of my semantic web

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Where are the services? Portals?

• Data-centric description so-far• Processing of these involves

– Discovery of data, schemas, vocabularies– Query, Rules, Inference– Transferring RDF – HTTP, SOAP payloads– Web Services – however web built in REST model– Web Service Choreography – DAML-S, planning– Semantic Grid

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Opportunities

• Sharing and syndicating descriptions• Common vocabularies between services• Richer, deeper specialised vocabularies• Less yet-another-XML-format• Semantics with services

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Action!

• Webize your data processing tools• Adapt to an unbounded web world• Semantic web ideas and standards• Model your world, not your documents• Use RDF to transfer description• NOT: convert all your data to RDF

– Although convert it if you like!

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Questions?

Thank You

dave.beckett@bristol.ac.uk

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References

• Architecture of the World Wide Web, W3C Working Draft, W3C TAG

• Nodes and Arcs 1989-1999: WWW history and RDF, Dan Brickley

• SwoRDFish presentation, Kathy MacDougal, Sun at W3C Tech Plenary, March 2003

• Why the RDF model is different from the XML model, Tim Berners-Lee