1. UKOLN, University of Bath
RDF and Metadata
Andy Powell
UKOLN, University of Bath
UKOLN is funded by the Library and Information Commission, the Joint
Information Systems Committee of the Higher Education Funding Councils, as
well as by project funding from the JISC and the European Union. UKOLN also
receives support from the University of Bath where it is based.

2. Metadata applications
resource discovery
site-maps
content rating
e-commerce, rights management
collaboration
privacy
Web-site management
W3C’s Resource Description Framework (RDF) provides a generic metadata architecture
NDISD’99 - May 1999

3. Presentation outline... what is RDF? model syntax metadata schemas
what is the Dublin Core?
Dublin Core in RDF
some examples
current status of RDF
conclusions
NDISD’99 - May 1999

4. What is metadata? data about data? information about resources?
structured information about ‘stuff’
‘stuff’ includes Web resources, books, museum artifacts, CDs, abstract ‘works’, pieces of music…
machine readable
supports variety of usage scenarios
NDISD’99 - May 1999

5. What is RDF? Resource Description Framework
Input from various communities
Platform for Internet Content Selection (PICS)
Web Collections (Site maps, MCF)
Libraries, museums, archives (DC)
Privacy (P3P)
W3C Metadata Activity
Model and Syntax WG
Schema WG
Interoperability of metadata
semantics, structure, syntax
NDISD’99 - May 1999

6. RDF - the model simple triple-based model arc-node diagrams
resource
property
value
statement
simple triple-based model
arc-node diagrams
resources represented by nodes with URI
property is some attribute of the resource
value can be literal or further statement(s)
a collection of statements about a resource forms a ‘description’
NDISD’99 - May 1999

7. RDF - simple example or, in plain English…
author
Andy Powell
or, in plain English…
“Andy Powell is the author of the resource identified by
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8. RDF - structured example
author
name
Address
Andy Powell
provide structured metadata by replacing simple text value by another node.
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9. RDF - reification possible to make statements about statements
cost
£0.05
validUntil
possible to make statements about statements
process known as reification
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10. RDF - serialisation syntax
title
The UKOLN
Metadata Home
Page
<rdf:RDF>
<rdf:Description
about=”
<title>The UKOLN Metadata Home Page</title>
</rdf:Description>
</rdf:RDF>
2 XML serialisation syntaxes
allows us to write down the RDF model in a way that can be processed by machines
NDISD’99 - May 1999

11. RDF - serialisation syntax
title
The UKOLN
Metadata Home
Page
<rdf:RDF>
<rdf:Description
about=”
<title>The UKOLN Metadata Home Page</title>
</rdf:Description>
</rdf:RDF>
NDISD’99 - May 1999

12. RDF - serialisation syntax
title
The UKOLN
Metadata Home
Page
<rdf:RDF>
<rdf:Description
about=”
<title>The UKOLN Metadata Home Page</title>
</rdf:Description>
</rdf:RDF>
NDISD’99 - May 1999

13. RDF - serialisation syntax
title
The UKOLN
Metadata Home
Page
<rdf:RDF>
<rdf:Description
about=”
<title>The UKOLN Metadata Home Page</title>
</rdf:Description>
</rdf:RDF>
NDISD’99 - May 1999

14. RDF - multiple properties
Here is an example of a description with multiple properties:
<rdf:RDF>
<rdf:Description
about=”
<title>The UKOLN Metadata Home Page</title>
<keywords>Dublin Core, MARC, TEI, IAFA, … </keywords>
<description>
Start of several Web pages about metadata
</description>
</rdf:Description>
</rdf:RDF>
NDISD’99 - May 1999

15. RDF - review
So, we’ve looked at simple arc-node diagrams and serialisation in XML…
but...
what does ‘title’ mean?
is your ‘title’ the same as my ‘title’?
NDISD’99 - May 1999

16. RDF - namespaces XML namespaces are used to uniquely
identify each RDF property
namespaces prefix the property
separated by ‘:’, e.g.
<ukoln:title>some title</ukoln:title>
each namespace has URI associated with it to ensure uniqueness
NDISD’99 - May 1999

17. RDF - schemas RDF Schemas define:
available properties within a particular metadata system
structure
allowable values
semantics
relationships between different schemas
an RDF Schema Specification is currently being finalised by the W3C
namespace URIs may point to schema definitions
NDISD’99 - May 1999

18. What is the Dublin Core? 15 element metadata set
primarily resource discovery
primarily Web-based document-like objects
emphasis on semantics
widespread consensus
several syntaxes currently
early example of an RDF schema
NDISD’99 - May 1999

19. DC history... workshop series - DC-1 to DC-5 email discussion list
DC Policy Advisory Committee
DC Technical Advisory Committee
series of RFCs in preparation
submission to NISO (…ISO)
NDISD’99 - May 1999

20. Dublin Core - elements 15 element core metadata set Title Format
Subject
Description
Creator
Publisher
Contributor
Date
Type
Format
Identifier
Source
Language
Relation
Coverage
Rights
NDISD’99 - May 1999

21. Qualified DC DC semantics are defined very broadly. Possible to:
refine the meaning of elements using ‘type’:
Relation TYPE=IsPartOf
associate value with externally defined ‘scheme’:
Subject SCHEME=LCSH
Date SCHEME=ISO8601
indicate ‘language’ of value
Title LANGUAGE=en
NDISD’99 - May 1999

22. How is DC currently used?
Embedded into HTML Web pages
<META> tag
limited functionality
no structure
HTML version 4.0 support for SCHEME and LANG
syntax for qualified DC in <META> tags not well established
NDISD’99 - May 1999

23. DC in HTML <HTML><HEAD>
<TITLE>UKOLN Home Page</TITLE>
<META NAME="DC.Title” CONTENT="UKOLN: UK Office for Library and Information Networking">
<META NAME="DC.Subject" CONTENT="national centre, network information support, library community, awareness, research, information services, public library networking, bibliographic management, distributed library systems, metadata, resource discovery, conferences, lectures, workshops">
<META NAME="DC.Description" CONTENT="UKOLN is a national centre for support in network information management in the library and information communities. It provides awareness, research and information services">
<META NAME="DC.Creator" CONTENT=”UKOLN Information Services Group">
</HEAD>
...
NDISD’99 - May 1999

24. DC in RDF dc:title The UKOLN Metadata Home Page <rdf:RDF
dc:title
The UKOLN
Metadata Home
Page
<rdf:RDF
<rdf:Description
about=”
<dc:title>The UKOLN Metadata Home Page</dc:title>
</rdf:Description>
</rdf:RDF>
NDISD’99 - May 1999

25. DC in RDF dc:title The UKOLN Metadata Home Page <rdf:RDF
dc:title
The UKOLN
Metadata Home
Page
<rdf:RDF
xmlns:dc="
<rdf:Description
about=”
<dc:title>The UKOLN Metadata Home Page</dc:title>
</rdf:Description>
</rdf:RDF>
NDISD’99 - May 1999

26. DC in RDF dc:title The UKOLN Metadata Home Page <rdf:RDF
dc:title
The UKOLN
Metadata Home
Page
<rdf:RDF
xmlns:rdf="
xmlns:dc="
<rdf:Description
about=”
<dc:title>The UKOLN Metadata Home Page</dc:title>
</rdf:Description>
</rdf:RDF>
NDISD’99 - May 1999

27. DC in RDF dc:title The UKOLN Metadata Home Page
dc:title
The UKOLN
Metadata Home
Page
<?xml version="1.0"?>
<rdf:RDF
xmlns:rdf="
xmlns:dc="
<rdf:Description
about=”
<dc:title>The UKOLN Metadata Home Page</dc:title>
</rdf:Description>
</rdf:RDF>
NDISD’99 - May 1999

28. DC in RDF in HTML !
can’t embed ‘standard’ RDF/XML syntax because content not hidden
embed using ‘abbreviated syntax’
embed at end of HTML <HEAD> section
if this isn’t possible <LINK> to external RDF file, e.g.
<LINK rel="meta" href="mydocMetadata.dc.rdf">
NDISD’99 - May 1999

29. DC in RDF - abbreviated dc:title The UKOLN Metadata Home Page
dc:title
The UKOLN
Metadata Home
Page
<rdf:RDF
xmlns:rdf="
xmlns:dc="
<rdf:Description
about="
dc:title="The UKOLN Metadata Home Page"
/>
</rdf:RDF>
NDISD’99 - May 1999

30. RDF - current status RDF Specification - W3C Recommendation
RDF Schema Spec - Proposed Recommendation
Some support for RDF in Mozilla
RDF toolkits/parsers under development
Several RDF editors available, e.g.
DC-dot, UKOLN
Reggie, DSTC
Various other RDF-based services
NDISD’99 - May 1999

31. Conclusions RDF is a general-purpose framework
RDF provides structured, machine- understandable metadata for the Web
metadata vocabularies can be developed without central coordination
RDF Schemas describe the meaning of each property name
Dublin Core is one of the key RDF Schemas
signed RDF is the basis for trust
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32. Further information
Resource Description Framework (RDF) Model and Syntax Specification
Resource Description Framework (RDF) Schema Specification
Dublin Core
DC-Datamodel home
INDECS
DC-dot
Reggie
SiRPAC
Representing vCard v3.0 in RDF
NDISD’99 - May 1999