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DC Architecture WG meeting

DC Architecture WG meeting. Wednesday 13.30 - 15.30 Seminar Room: 5205 (2nd Floor). Agenda. Review of the Abstract Model and moving forward http://www.ukoln.ac.uk/metadata/dcmi/abstract-model/ RDF resource vs. literal issue http://www.ukoln.ac.uk/metadata/dcmi/rdf-values/

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DC Architecture WG meeting

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  1. DC Architecture WG meeting Wednesday 13.30 - 15.30Seminar Room: 5205 (2nd Floor)

  2. Agenda • Review of the Abstract Model and moving forwardhttp://www.ukoln.ac.uk/metadata/dcmi/abstract-model/ • RDF resource vs. literal issuehttp://www.ukoln.ac.uk/metadata/dcmi/rdf-values/ • XML schema issueshttp://www.ukoln.ac.uk/metadata/dcmi/xmls-issues/ • Identifiers for historical versions of metadata termshttp://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0410&L=dc-architecture&T=0&O=D&P=3366

  3. Review of the year (Sleepy Since Seattle)

  4. …but not that sleepy! • Abstract Model document moved forward (slowly) • “Expressing Dublin Core in HTML/XHTML meta and link elements” issued as a DCMI Recommendation • discussion paper about assigning URIs for metadata terms • something like 200 messages posted to the dc-architecture mailing list

  5. Abstract Model

  6. Major changes • changed 'URI' to 'URI reference' at appropriate points throughout • added 'description set' to the description model to separate out the conceptual grouping of related descriptions (a 'description set') from its instantiation in a particular syntax (a 'record')

  7. Major changes (2) • introduction of 'property/value pair' into the resource model to separate abstract notion of a property from the specific usage of a property to describe a particular resource • modified the definition of 'sub-property' in the resource model

  8. Major changes (3) • added of a note about needing to indicate how 'resource URIs' and 'value URIs' are handled in encoding syntax specifications • explicit indication that 'resource URIs' and 'value URIs' are not supported by the current XML encoding guidelines • explicit indication that 'resource URIs' are not supported by the XHTML encoding syntax

  9. Model summary record (encoded as XHTML, XML or RDF/XML) description set description (about a resource (URI)) vocabulary encoding scheme (URI) statement property (URI) value (URI) representation syntax encodingscheme (URI) value string OR rich value OR related description language(e.g. en-GB)

  10. Remaining issues • possible need for further clarification of how URIs are handled by the AM – in short, dcterms:URI is almost never used and certainly not to indicate a ‘value URI’ • it would be better if we modelled ‘syntax encoding scheme URI’ and ‘vocabulary encoding scheme URI’ as separate entities in the model

  11. Remaining issues (2) • the AM currently restricts the number of ‘parent’ properties that a sub-property can have to a maximum of one - this is an error and will be made unlimited. • does the model get the definitions of ‘simple DC’ and ‘qualified DC’ right? • should the model support ordered lists of values?

  12. RDF resource vs. literal issue

  13. The problem In DC/RDF, these two graphs mean the same thing (in terms of the abstract model) but in RDF they mean different things…

  14. Possible solutions • Status quo • Align behaviour of consuming systems • Align behaviour of consuming and generating systems • Attempt to influence the behaviour of the wider Semantic Web community • Replicate existing DC property semantics in new properties

  15. XML schema issues

  16. Identifiers for historical versions of metadata terms

  17. DC Architecture WG report • agenda: • Abstract Model • encoding DC element values in RDF • XML schema issues • identifiers for DCMI term descriptions • 21 attendees

  18. Wot we did last year… • moved Abstract Model forward slowly • issued XHTML encoding guidelines as a Recommendation • developed issues papers on identifiers • about 200 postings to thedc-architecture mailing list

  19. Abstract Model • discussion around the meanings of ‘simple DC’ and ‘qualified DC’ • no consensus • agreed to remove definitions of these terms from the Abstract Model • discussed possibility of adding support for ‘ordered lists of values’ to the abstract model – little support for this in the room

  20. DC values in RDF • problem: some confusion in RDF implementer community currently • solution (short-term): work item to develop a short clarification document for RDF implementers • solution (long-term): work item to develop a view of possible ‘encoding’ changes to remove confusion and carry out impact analysis • undertaken by small ‘task force’

  21. XML schemas • agreed to provide a persistent URI to the latest version of our XML schemes • agreed to provide two ‘container’ elements for DC descriptions, probably called <dcxml:description> and <dcxml:descriptionSet> • work item: revise DC in XML Guidelines to include explicit mechanism for value URIs

  22. Namespace policy • work item: minimal update to the namespace policy to align some of the terminology with current usage • consider ways of documenting how we assign URIs to DCMI term descriptions

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