DCMI Abstract Model and RDF
Library blogs were buzzing last week about a recent announcement of a collaboration around RDA and DC [summary here]. For those not familiar with the acronyms, this basically means an effort to bring a very high-level next-generation approach to library cataloguing together with more grounded ways of encoding metadata in the DC world. It also represents an effort to bring this library expertise to the semantic web.
In general, the commentary is positive. However, Jenn Riley brings up an interesting critique.
This seems to be to be entirely backwards – trying to harmonize DC principles with RDA after the fact. Didn’t the DC community learn its lesson about the pitfalls of this approach when developing the Abstract Model, only realizing long after developing a metadata element set that it would benefit from an underlying model.
She goes on to explain:
This general approach failed miserably with the DC Libraries Application Profile. There, the application profile developers wanted to use some elements from MODS, but weren’t able to because MODS doesn’t conform to the DCMI Abstract Model. So basically what the DC community said here was that application profiles are great, they form the fundamental basis of DC extensibility, but, oh yeah, you can’t actually use elements from any other standards unless they conform to the Abstract Model, even though are no approved encodings for even DC itself more than two years after the Abstract Model was released. OK then. Way to foster collaboration between metadata communities.
Ah, here’s this problem again: the DC group absolutely rightly argues that a model is essential for any real extensibility and interoperability. But the message for the value proposition of the DCMI Abstract Model per se is lost.
If I had a recommendation for the DCMI, it would be to drop the Abstract Model and use RDF. It would save a lot of technical and evangelism work. I’ve said this before, but the Abstract Model offers completely unconvincing value to me. It has a model that is essentially equivalent to RDF, and yet the claimed advantage that it has a non-RDF XML syntax. But the problem is that this syntax is even uglier and more complicated than RDF/XML!
Turning the focus to RDF does not solve Jenn’s issue, of course. The whole point is you agree on a model so that you can go your own way on all the details that really matter: what you call a book title, how you represent related items, and so forth. But with RDF, you get a rich infrastructure of technology and tools that goes way beyond the DCMI Abstract Model. That infrastructure includes OWL, RDF Schema … and GRDDL.
MODS has no model, and so cannot really be harmonized properly with anything. The solution there is to create an RDF version that can. But with GRDDL, you can just write an XSLT to map it your XML to RDF, and so get something like the best of both worlds: the flexibility to use your own XML, and to merge it with other kinds of metadata descriptions via a common model. It seems to me RDF + GRDDL is a better, more practical, solution to interoperability than the DCMI Abstract Model.
Ultimately the RDA/DC announcement will allow just this since it will include an RDF vocabulary, but the message is indeed a little confusing.
