[OAI-implementers] Qualified Dublin Core

Pete Johnston p.johnston at ukoln.ac.uk
Thu Aug 12 14:19:47 EDT 2004


Apologies for heavy snipping...
> But otherwise, I don't think it's a major leap of faith to 
> take elements represented as being in namespaces known to me 
> at face value. Certainly I'd rather harvest the qualified DC 
> based OLAC, NSDL, and CDP formatted records than settle for 
> their dumbed down simple DC records. I'm confident in those 
> instances that <dcterms:spatial> means <dcterms:spatial> in 
> spite of the fact that their records also may include some 
> additional non-DC semantics.

I think your leap of faith is justified in these cases because (I guess)
you (as service provider) know that those formats are explicitly based
on the conventions suggested in the DC-in-XML guidelines (and so
represent resource-property-value statements).

But I must admit I'd feel slightly nervous about assuming that those
conventions have been applied in any unknown XML format that I came
across even in the OAI-PMH context - and even if I did encounter an XML
element named dcterms:spatial associated with the appropriate XML
namespace name in the first level of the tree structure. OK, given the
context, the chances are it does carry the meaning you expect, but it
seems to me that unless the data provider has said that explicitly,
then, strictly speaking, a service provider is left to guess.

The further we get into service providers trying to make decisions based
on what are really unknown semantics, the more I feel we are on very,
very shakey ground. If that is the direction we are heading, then (it
seems to me) we really need the foundations of a framework like RDF to
be able to do so with any degree of reliability. The DC-in-XML
guidelines do not (IMHO) provide that framework.  
> And also I don't think it unreasonably demanding for my 
> application to inspect XSDs returned in response to 
> ListMetadataFormats verb, even to point of inspecting one or 
> two levels of imported XSDs to discover namespaces being 
> invoked of possible interest to me. Of course that gets back 
> to the balancing act of who should do what between data 
> providers and service providers. Perhaps in this instance I'm 
> being too liberal in trying to minimize effort of data providers.


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