UKOLN, University of Bath RDF and Metadata Andy Powell UKOLN, University of Bath a.powell@ukoln.ac.uk http://www.ukoln.ac.uk/ 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.

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

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

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

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

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

RDF - simple example or, in plain English… http://www.ukoln.ac.uk/metadata/ author Andy Powell or, in plain English… “Andy Powell is the author of the resource identified by http://www.ukoln.ac.uk/metadata/” NDISD’99 - May 1999

RDF - structured example http://www.ukoln.ac.uk/metadata/ author name emailAddress Andy Powell a.powell@ukoln.ac.uk provide structured metadata by replacing simple text value by another node. NDISD’99 - May 1999

RDF - reification possible to make statements about statements http://somewhere.com/page.html cost £0.05 validUntil 1999-09 possible to make statements about statements process known as reification NDISD’99 - May 1999

RDF - serialisation syntax http://www.ukoln.ac.uk/metadata/ title The UKOLN Metadata Home Page <rdf:RDF> <rdf:Description about=”http://www.ukoln.ac.uk/metadata/”> <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

RDF - serialisation syntax http://www.ukoln.ac.uk/metadata/ title The UKOLN Metadata Home Page <rdf:RDF> <rdf:Description about=”http://www.ukoln.ac.uk/metadata/”> <title>The UKOLN Metadata Home Page</title> </rdf:Description> </rdf:RDF> NDISD’99 - May 1999

RDF - serialisation syntax http://www.ukoln.ac.uk/metadata/ title The UKOLN Metadata Home Page <rdf:RDF> <rdf:Description about=”http://www.ukoln.ac.uk/metadata/”> <title>The UKOLN Metadata Home Page</title> </rdf:Description> </rdf:RDF> NDISD’99 - May 1999

RDF - serialisation syntax http://www.ukoln.ac.uk/metadata/ title The UKOLN Metadata Home Page <rdf:RDF> <rdf:Description about=”http://www.ukoln.ac.uk/metadata/”> <title>The UKOLN Metadata Home Page</title> </rdf:Description> </rdf:RDF> NDISD’99 - May 1999

RDF - multiple properties Here is an example of a description with multiple properties: <rdf:RDF> <rdf:Description about=”http://www.ukoln.ac.uk/metadata/”> <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

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

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

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

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

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

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

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

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

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

DC in RDF dc:title The UKOLN Metadata Home Page <rdf:RDF http://www.ukoln.ac.uk/metadata/ dc:title The UKOLN Metadata Home Page <rdf:RDF <rdf:Description about=”http://www.ukoln.ac.uk/metadata/”> <dc:title>The UKOLN Metadata Home Page</dc:title> </rdf:Description> </rdf:RDF> NDISD’99 - May 1999

DC in RDF dc:title The UKOLN Metadata Home Page <rdf:RDF http://www.ukoln.ac.uk/metadata/ dc:title The UKOLN Metadata Home Page <rdf:RDF xmlns:dc="http://purl.org/dc/elements/1.0/"> <rdf:Description about=”http://www.ukoln.ac.uk/metadata/”> <dc:title>The UKOLN Metadata Home Page</dc:title> </rdf:Description> </rdf:RDF> NDISD’99 - May 1999

DC in RDF dc:title The UKOLN Metadata Home Page <rdf:RDF http://www.ukoln.ac.uk/metadata/ dc:title The UKOLN Metadata Home Page <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.0/"> <rdf:Description about=”http://www.ukoln.ac.uk/metadata/”> <dc:title>The UKOLN Metadata Home Page</dc:title> </rdf:Description> </rdf:RDF> NDISD’99 - May 1999

DC in RDF dc:title The UKOLN Metadata Home Page http://www.ukoln.ac.uk/metadata/ dc:title The UKOLN Metadata Home Page <?xml version="1.0"?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.0/"> <rdf:Description about=”http://www.ukoln.ac.uk/metadata/”> <dc:title>The UKOLN Metadata Home Page</dc:title> </rdf:Description> </rdf:RDF> NDISD’99 - May 1999

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

DC in RDF - abbreviated dc:title The UKOLN Metadata Home Page http://www.ukoln.ac.uk/metadata/ dc:title The UKOLN Metadata Home Page <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.0/"> <rdf:Description about="http://www.ukoln.ac.uk/metadata/" dc:title="The UKOLN Metadata Home Page" /> </rdf:RDF> NDISD’99 - May 1999

RDF - current status RDF Specification - W3C Recommendation RDF Schema Spec - Proposed Recommendation Some support for RDF in Mozilla RDF toolkits/parsers under development http://www.w3.org/RDF/Implementations/SiRPAC/ Several RDF editors available, e.g. DC-dot, UKOLN Reggie, DSTC http://www.ukoln.ac.uk/metadata/dcdot/ http://metadata.net/dstc/ Various other RDF-based services NDISD’99 - May 1999

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 NDISD’99 - May 1999

Further information Resource Description Framework (RDF) Model and Syntax Specification http://www.w3.org/TR/REC-rdf-syntax/ Resource Description Framework (RDF) Schema Specification http://www.w3.org/TR/PR-rdf-schema/ Dublin Core http://purl.org/dc/ DC-Datamodel home http://www.mailbase.ac.uk/lists/dc-datamodel/ INDECS http://www.indecs.org/ DC-dot http://www.ukoln.ac.uk/metadata/dc-dot/ Reggie http://metadata.net SiRPAC http://www.w3.org/RDF/Implementations/SiRPAC/ http://www.ukoln.ac.uk/metadata/resources/rdf/parser/ Representing vCard v3.0 in RDF http://www.dstc.edu.au/RDU/RDF/draft-iannella-vcard-rdf-00.txt NDISD’99 - May 1999