DC Architecture WG meeting

Wednesday 13.30 - 15.30Seminar Room: 5205 (2nd

Floor)

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

Review of the year

(Sleepy Since Seattle)

…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

Abstract Model

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')

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

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

Model summaryrecord (encoded as XHTML, XML or RDF/XML)

description set

description (about a resource (URI))

statement

property (URI) value (URI)

representation

value string

OR rich value

OR related description

vocabulary encoding scheme (URI)

syntax encodingscheme (URI)

language(e.g. en-GB)

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

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?

RDF resource vs. literal issue

The problem

In DC/RDF,these two graphsmean the same thing(in terms of the abstract model)but in RDF they mean different things…

Possible solutions

1. Status quo2. Align behaviour of consuming

systems3. Align behaviour of consuming and

generating systems4. Attempt to influence the behaviour of

the wider Semantic Web community5. Replicate existing DC property

semantics in new properties

XML schema issues

Identifiers for historical versions of metadata

terms

DC Architecture WG report

agenda:– Abstract Model– encoding DC element values in RDF– XML schema issues– identifiers for DCMI term descriptions

21 attendees

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

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

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’

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

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