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Possible Service Description change

From: Gregory Williams <greg@evilfunhouse.com>
Date: Mon, 18 Jun 2012 21:50:32 -0400
Message-Id: <A4DE0D5C-53E4-4C5B-B8A5-303A38E73BA8@evilfunhouse.com>
To: W3C SPARQL Working Group <public-rdf-dawg@w3.org>
I ran across an issue I was hoping for some input on. As a result of working on the protocol tests, and reading David Booth's recent comment on how datasets get constructed[1], I looked over the documentation for sd:DereferencesURIs[2] which can provide some metadata that may help David's issue (and for which I've got an action to respond to his comment).

The motivation for sd:DereferencesURIs was that some implementations (including mine) were already doing dereferencing to construct a dataset for query, and I just extended that in the spec to cover update, too. But now that I think more closely about it, I'm not sure it makes much sense. The current SD text reads:

"""
sd:DereferencesURIs, when used as the object of the sd:feature property, indicates that a SPARQL service willdereference [AWWW] URIs used in FROM/FROM NAMED and USING/USING NAMED clauses and use the resulting RDF in the dataset during query evaluation.
"""

I'm worried that the "USING/USING NAMED" part of that doesn't make any sense. That is, if an implementation constructed a dataset on the fly based on a USING clause, what use is there in performing an update operation? Presumably next time an update is submitted with a USING clause, the updated content in some underlying graphstore may again be masked by the dereferencing feature.

Does anybody have any thoughts on what the best way forward on this is? I can imagine this could get through REC without anyone noticing, but I'm not sure I'd be happy with that. Do you think it's worth the effort to make the change before moving to CR? I'm not aware of any implementations that do dereferencing for update (though there may be some), but I suspect a change like this would require another LC(?). Since we're already doing another LC round for Query, would this be a big deal?

Interested in any thoughts you might have.

thanks,
.greg


[1] http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2012Jun/0002.html
[2] http://www.w3.org/TR/sparql11-service-description/#sd-dereferencesuris
Received on Tuesday, 19 June 2012 01:50:59 GMT

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