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> DCRDFTaskforce/DCRDFExecutiveSummary2

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About this note

DCMI is currently considering the assignment of domains and ranges to DCMI metadata terms. Such a step would have important implications for the interpretation of legacy metadata. This note presents a high-level view of the issue and its implications. No such changes will be undertaken by DCMI until their impact has been well understood and discussed in a public comment period. Implementers with an opinion about the issues presented here are invited to participate in discussion on the DCMI Architecture Working Group mailing list ([WWW]http://www.jiscmail.ac.uk/lists/dc-architecture.html).

Summary

DCMI is in the process of updating the existing guidelines for encoding Dublin Core in RDF ([WWW](1), [WWW](2)) in order to align them with the DCMI Abstract Model. As part of that work (a draft of which is available [WWW](3)), changes have been made that are necessary for the integration of Dublin Core metadata into systems that implement the semantics of RDF, such as inference engines and ontology-based solutions.

The existing specifications from the DCMI have not taken these applications into account, which has resulted in an unknown amount of Dublin Core-based RDF data that is inconsistent with the definitions of the Dublin Core properties. The DC-RDF taskforce has judged that the mentioned changes are necessary, albeit painful, to ensure the long-term viability of Dublin Core in RDF.

For example, in order to state that "John Smith is the creator of http://www.example.com", it is no longer valid to use the following RDF: 

<http://www.example.com>   dc:creator  "John Smith".
The reason is in the DCMI definition of the dc:creator property, the value is described as "an entity primarily responsible...", and the string "John Smith" is not such an entity. Had the dc:creator property been defined to accept as values the name of the entity, "John Smith" would have been an acceptable value.

Instead, the value must be a properly typed resource, with "John Smith" available only as a value string attached to that resource. This is a dramatic tightening of the constrains of the Dublin Core RDF encoding, which as a consequence makes unknown amounts of Dublin Core metadata that uses the first form invalid. The release notes [WWW](4) contain more information on these changes.

References

  1. [WWW]Expressing Simple Dublin Core in RDF/XML, DCMI Recommendation, 2002-07-31

  2. [WWW]Expressing Qualified Dublin Core in RDF / XML, DCMI Proposed Recommandation, 2002-05-15

  3. [WWW]Expressing Dublin Core Metadata in RDF, Working Draft

  4. [WWW]Release Notes for above draft.