DC Architecture WG meeting Monday Sept 12 Slot 1: Slot 2: Location: Seminar Room 4.1.E01.

Agenda review of the year revised "DCMI Namespace Policy" recommendation revising "Guidelines for encoding DC in XML recommendation summary of relevant W3C activities (GRDDL and RDF in XHTML) (*) workplan for next year

Review of the year

Progress during 2005 DCMI Abstract Model document issued as a Recommendation agreed persistent URIs for the latest version of our XML schemas developed draft revised "DCMI Namespace Policy proposed changes to XML guidelines set up task force to look at DC/RDF issues

Revised DCMI namespace policy

Revised Namespace Policy new draft policy is available at: mi/namespace-policy/ mi/namespace-policy/

New terminology partly to remove confusion with XML namespaces –DCMI namespace - A collection of DCMI term URIs where each term is assigned a URI that starts with the same 'base URI'. The 'base URI' is known as the DCMI namespace URI. (Note that a DCMI namespace is not the same as an 'XML namespace') –DCMI namespace URI - The URI that identifies a DCMI namespace –vocabulary - A collection of terms (often as used in the context of an 'application profile')

Namespaces vs. vocabularies note that the grouping of term URIs into a DCMI namespace is orthogonal to the grouping of terms into a vocabulary term URIs are grouped into DCMI namespaces in order to ease the assignment of URIs to terms and to streamline their use in particular encoding syntaxes terms are grouped into vocabularies in order to meet a functional need

However… …we quite clearly haven't done this in the case of the DC and DCTERMS namespaces we have kept two namespaces simply for historical reasons therefore suggest replicating all the current terms in the DC namespace into the DCTERMS namespace, using RDFS/OWL to explicitly declare equivalences as necessary

XML encoding guidelines

Summary of relevant W3C activities

Summary of DC RDF Taskforce activities

DC RDF Taskforce Clarification of the recommendations for encoding 'value strings' in DC RDF/XML Guidelines for encoding DC metadata using the RDF Model DC Property Domains and Ranges Proposed changes to DCMI property definitions DCMI Term Decision Tree

DC RDF Taskforce Clarification of the recommendations for encoding 'value strings' in DC RDF/XML Guidelines for encoding DC metadata using the RDF Model DC Property Domains and Ranges Proposed changes to DCMI property definitions DCMI Term Decision Tree

Encoding DC using RDF Model leading towards new DCMI Recommendation replacing the current Simple DC in RDF Recommendation and Qualified DC in RDF Proposed Recommendation mapping from DCMI Abstract Model to RDF Model –therefore can use current and future RDF syntaxs (XML, N3, etc.)

DCMI abstract model a description is made up of –one or more statements (about one, and only one, resource) and –optionally, the URI of the resource being described (resource URI ) each statement is made up of –a property URI (that identifies a property) –a value URI (that identifies a value) and/or one or more representations of the value (value representations)

Value strings each value representation may take the form of a value string, a rich value or a related description each value string is a simple, human- readable string that represents the resource that is the value of the property each value string may have an associated value string language that is an ISO language tag (e.g. en-GB)

Encoding schemes values and value strings can be qualified by using encoding schemes a vocabulary encoding scheme is used to indicate the class of the value –e.g. the value is taken from LCSH a syntax encoding scheme is used to indicate how the value string is structured –e.g. the value string is a date structured according to the W3CDTF rules ( )

Description sets real-world metadata applications tend to be based on loosely grouped sets of descriptions (where the described resources are typically related in some way) known in the abstract model as description sets for example, a description set might comprise descriptions of both a painting and the artist

Records description sets are instantiated, for the purposes of exchange between software applications, in the form of metadata records each record conforms to one of the DCMI encoding guidelines (XHTML meta tags, XML, RDF/XML, etc.) a document andy powell record

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

resourceURI propertyURI valueURI rdfs:label value string propertyURI valueURI rdfs:label value string propertyURI valueURI Description rdf:type vocabularyEncodingSchemeURI

Statement statement resourceURI propertyURI valueURI rdfs:label value string propertyURI valueURI rdfs:label value string propertyURI valueURI rdf:type vocabularyEncodingSchemeURI statement

resourceURI propertyURI valueURI rdfs:label value string Vocabulary encoding scheme URI rdf:type vocabularyEncodingSchemeURI

resourceURI propertyURI valueURI rdfs:label value string Value string

Value string – where property domain is rdfs:Literal resourceURI propertyURI value string

resourceURI propertyURI valueURI rdfs:label value string ^^rdfDatatypeURI Rich representation

resourceURI propertyURI valueURI rdfs:label value string ^^syntaxEncodingSchemeURI Syntax encoding scheme URI

resourceURI propertyURI valueURI rdfs:label value Value string languages

resourceURI propertyURI valueURI rdfs:label value string Related description propertyURI rdfs:label value string propertyURI rdfs:label value string related description

DC RDF Taskforce Clarification of the recommendations for encoding 'value strings' in DC RDF/XML Guidelines for encoding DC metadata using the RDF Model DC Property Domains and Ranges Proposed changes to DCMI property definitions DCMI Term Decision Tree

Domains and ranges domain – the class of resources that a property can be used to describe range – the class of resources that are allowed as values of a property example: what are the domain and range of dc:creator –domain = NonAgentResource –range = Agent making explicit what has been implicit until now

DC RDF Taskforce Clarification of the recommendations for encoding 'value strings' in DC RDF/XML Guidelines for encoding DC metadata using the RDF Model DC Property Domains and Ranges Proposed changes to DCMI property definitions DCMI Term Decision Tree

Revising DC definitions revising the language of the definitions to align them with the DCMI Abstract Model for example dc:relation –was: A reference to a related resource –change to: A related resource –domain: Resource –range: Resource also note issue with use of content of the resource in definitions

DC RDF Taskforce Clarification of the recommendations for encoding 'value strings' in DC RDF/XML Guidelines for encoding DC metadata using the RDF Model DC Property Domains and Ranges Proposed changes to DCMI property definitions DCMI Term Decision Tree

Term decision tree how do you know if something is usable in DC metadata descriptions or not? –has it been explicitly declared as an element, element refinement or encoding scheme? –has it been assigned a unique URI? –is the declaration available at that URI? if the answers are all yes, then the thing can be used in DC metadata

Workplan for 2006

Workplan - taskforce develop short document for RDF implementers, clarifying the resource vs. literal string value issue and providing advice on best practice consider possible RDF encoding changes (in light of above issue), carry out impact analysis and make recommendations

Workplan – tidying up finalise provision of a persistent URI for the latest version of our XML schemes finalise revisions to the Guidelines for implementing Dublin Core in XML document finalise revisions to the Namespace Policy for the Dublin Core Metadata Initiative (DCMI)

Workplan – new stuff evaluate use of GRDDL as mechanism for transforming arbitrary DC/XML documents into RDF (DCMI AM) monitor W3C developments for RDF in XHTML and revise current DC/XHTML guidelines as necessary develop model of application profiles representing Box/Period/Point in DCAM/RDF