Transcript Semantic Web Technologies for UK HE and FE Institutions: Part 2: RDF and Semantic Web Applications Dave Beckett [email protected].

Semantic Web Technologies for
UK HE and FE Institutions:
Part 2: RDF and Semantic Web Applications
Dave Beckett
[email protected]
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Dave Beckett – Introduction
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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
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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
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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
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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)
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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
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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
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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
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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)
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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
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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
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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!
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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
[email protected]
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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
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