Semantic Web Technologies for UK HE and FE Institutions:

1

Semantic Web Technologies for
UK HE and FE Institutions:

Part 2: RDF and Semantic Web Applications

Dave Beckett

dave.beckett@bristol.ac.uk


1

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

1

Outline

•
Introduce the ideas

•
The technology

•
Some real projects

•
What you can do

•
Open Issues

1

History of the Web

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

•
However in 1989...

the original proposal

1

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

1

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

1

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

1

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

1

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

1

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

1

The element of the Semantic
Web

Called the Resource Description Framework (RDF)

(picture by Tim Berners
-
Lee, 2003
-
01
-
28)

1

Relational Database Tables

1

Tables in RDF

1

Trees in RDF

1

(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

1

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

1

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”

1

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, ...

1

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

1

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

1

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

1

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

1

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

1

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

1

FOAFnaut view of my semantic web

1

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

1

Opportunities

•
Sharing and syndicating descriptions

•
Common vocabularies between services

•
Richer, deeper specialised vocabularies

•
Less yet
-
another
-
XML
-
format

•
Semantics with services

1

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!

1

Questions?


Thank You


dave.beckett@bristol.ac.uk

1

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