Dublin Core and its implementation in RDF/XML

1
Dublin Core and its implementation in RDF/XML

• Paul Miller
• Interoperability Focus
• UK Office for Library Information Networking
  (UKOLN)
• P.Miller_at_ukoln.ac.uk http//www.ukoln.ac.uk/

UKOLN is funded by the Library and Information
Commission, the Joint Information Systems
Committee (JISC) 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 Universities of Bath
and Hull where staff are based.
2
Introducing the Dublin Core

• An attempt to improve resource discovery on the
  Web
• now adopted more broadly
• Building an interdisciplinary consensus about a
  core element set for resource discovery
• simple and intuitive
• crossdisciplinary not just libraries!!
• international
• open and consensual
• flexible.

See http//purl.org/dc/
3
Introducing the Dublin Core

• 15 elements of descriptive metadata
• All elements optional
• All elements repeatable
• The whole is extensible
• offers a starting point for semantically richer
  descriptions
• Interdisciplinary
• libraries, government, museums, archives
• International
• available in more than 20 languages, with more on
  the way...

4
Introducing the Dublin Core

• Title
• Creator
• Subject
• Description
• Publisher
• Contributor
• Date
• Type

• Format
• Identifier
• Source
• Language
• Relation
• Coverage
• Rights

http//purl.org/dc/
5
Introducing XML

• eXtensible Markup Language
• World Wide Web Consortium recommendation
• Simplified subset of SGML for use on Web
• Addresses HTMLs lack of evolvability
• Easily extended
• Supported by major vendors
• Increasingly used as a transfer syntax, but
  capable of far more.

See http//www.w3.org/XML/
6
Introducing RDF

• Resource Description Framework
• W3C Recommendation
• Improves upon XML, HTML, PICS
• Machine understandable metadata!
• XML as syntax
• Locally defined semantics
• Supports structure
• Increasing interest.

See http//www.w3.org/RDF/
See http//www.ukoln.ac.uk/metadata/resources/ dc/
datamodel/WDdcrdf/
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Extending DC (semantic)

• Improve descriptive precision by adding
  substructure (subelements and schemes)
• Greater precision lesser interoperability
• Should dumb down gracefully

Element qualifier
Value qualifier
Affiliation
Contact Info
Based on a slide by Stu Weibel
8
Extending DC (modularity)

• Modular extensibility
• Additional elements to support local needs
• Complementary packages of metadata
• but only if we get the building blocks right!

Based on a slide by Stu Weibel
9
Data Integration

• The author of this document is Paul
• Paul is the author of this document
• This document is authored by Paul
• The author of this document is Paul
• At least 3 Representation(s) in XML

ltdocument href http//doc_url author
Paul /gt
ltdocumentgt ltauthorgt ltnamegt Paul
lt/namegt lt/authorgt lturlgt http//doc_url
lt/urlgt lt/documentgt
ltauthorgt lturlgt http//doc_url lt/urlgt
ltnamegt Paul lt/namegt lt/authorgt
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Data Integration

• Querying XML documents is hard
• N ways of mapping XML to logical structure
• Requires the normalization of all possible
  representations for effective query
• Mean the same thing to a person
• Mean very different things to a machine
• RDF much less flexible
• less flexible more interoperable!
• consistent way of representing statements.

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RDF Data Model basics
Resource
Property
Value
12
A simple example
Resource
Author
Paul
13
DC in RDF

• Draft proposal of Dublin Core communitys Data
  Model working group
• Guidance on expressing the Dublin Core within the
  Resource Description Framework (RDF)
• http//www.ukoln.ac.uk/metadata/resources/
  dc/datamodel/WD-dc-rdf/

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Dublin Core Data Model
Based on a slide by Stu Weibel
15
A simple example
Based on a slide by Stu Weibel
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A simple example

• lt?xml version"1.0"?gt
• ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/22-r
  df-syntax-ns" xmlnsdc"http//purl.org/dc/e
  lements/1.0/"gt
• ltrdfDescription rdfabout"http//www.ukoln.ac.uk
  /metadata/resources/dc/datamodel/WD-dc-rdf/"gt
• ltdctitlegt Guidance on expressing the Dublin Core
  within the Resource Description Framework (RDF)
  lt/dctitlegt
• ltdccreatorgt Eric Miller lt/dccreatorgt
• ltdccreatorgt Paul Miller lt/dccreatorgt
• ltdccreatorgt Dan Brickley lt/dccreatorgt
• ltdcsubjectgt Dublin Core Resource Description
  Framework RDF eXtensible Markup Language XML
  lt/dcsubjectgt
• ltdcpublishergt Dublin Core Metadata Initiative
  lt/dcpublishergt
• ltdccontributorgt Dublin Core Data Model Working
  Group lt/dccontributorgt
• ltdcdategt 1999-07-01 lt/dcdategt
• ltdcformatgt text/html lt/dcformatgt
• ltdclanguagegt en lt/dclanguagegt
• lt/rdfDescriptiongt
• lt/rdfRDFgt

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A scary example part 1

• lt?xml version"1.0" encoding"ISO-8859-1"?gt
• ltrdfRDF xmlnsrdf"http//www.w3.org/1999/02/22-r
  df-syntax-ns" xmlnsdc"http//purl.org/dc/eleme
  nts/1.0/" xmlnsdcq"http//purl.org/dc/qualifier
  s/1.0/"gt
• ltrdfDescription rdfabout"http//www.ukoln.ac.uk
  /metadata/resources/dc/datamodel/ WD-dc-rdf/"gt
• ltdctitlegt
• ltrdfAltgt
• ltrdfli xmllang"en"gtGuidance on expressing
  the Dublin Core within the Resource
  Description Framework (RDF)lt/rdfligt
• ltrdfli xmllang"no"gtVeiledning å uttrykke
  Dublin Core innenfor rammen av Resource
  Description Framework (RDF)lt/rdfligt
• ltrdfli xmllang"de"gtDublin Core in RDF
  Eine Anleitunglt/rdfligt
• lt/rdfAltgt
• lt/dctitlegt

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A scary example part 2!

• ltdccreatorgt
• ltrdfBaggt
• ltrdfligtEric Millerlt/rdfligt
• ltrdfligtPaul Millerlt/rdfligt
• ltrdfligtDan Brickleylt/rdfligt
• lt/rdfBaggt
• lt/dccreatorgt
• ltdcdescriptiongt
• ltrdfAltgt
• ltrdfli xmllang"en"gtThis document describes
  work carried out by the Data Model Working Group
  of the Dublin Core Metadata Initiativelt/rdfligt
• ltrdfli xmllang"no"gtDette dokumentet
  beskriver arbeide utført av arbeidsgruppen for
  datamodellering knyttet til Dublin
  Core- initiativet. Spesifikt diskuterer
  dokumentet hvordan de femten elementene i Dublin
  Core lt/rdfligt
• lt/rdfAltgt
• lt/dcdescriptiongt

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A scary example part 3!!

• ltdcsubjectgt Dublin Core Resource Description
  Framework RDF eXtensible Markup Language XML
  lt/dcsubjectgt
• ltdcpublishergt Dublin Core Metadata Initiative
  lt/dcpublishergt
• ltdccontributorgt Dublin Core Data Model Working
  Group lt/dccontributorgt
• ltdcdategt
• ltrdfDescriptiongt
• ltdcqdateSchemegt WTN8601 lt/dcqdateSchemegt
• ltrdfvaluegt 1999-07-01 lt/rdfvaluegt
• lt/rdfDescriptiongt
• lt/dcdategt
• ltdcformatgt
• ltrdfDescriptiongt
• ltdcqformatSchemegt IMT lt/dcqformatSchemegt
• ltrdfvaluegt text/html lt/rdfvaluegt
• lt/rdfDescriptiongt
• lt/dcformatgt

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A scary example part 4!!!

• ltdclanguagegt
• ltrdfDescriptiongt
• ltdcqlanguageSchemegt RFC1766
  lt/dcqlanguageSchemegt
• ltrdfvaluegt en lt/rdfvaluegt
• lt/rdfDescriptiongt
• lt/dclanguagegt
• lt/rdfDescriptiongt
• lt/rdfRDFgt

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Useful Links

• Dublin Core
• http//purl.org/dc/
• RDF
• http//www.w3.org/RDF/
• XML
• http//www.w3.org/XML/
• DCDot
• http//www.ukoln.ac.uk/metadata/dcdot/
• SiRPAC
• http//www.w3.org/RDF/Implementations/SiRPAC/
• DC Datamodel Document
• http//www.ukoln.ac.uk/metadata/resources/
  dc/datamodel/WD-dc-rdf/