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Re: re-opening the DESCRIBE issue

From: Dan Connolly <connolly@w3.org>
Date: Mon, 03 Apr 2006 10:24:19 -0500
To: Bijan Parsia <bparsia@isr.umd.edu>
Cc: Eric Prud'hommeaux <eric@w3.org>, RDF Data Access Working Group <public-rdf-dawg@w3.org>
Message-Id: <1144077859.14764.289.camel@dirk.w3.org>

On Mon, 2006-04-03 at 11:11 -0400, Bijan Parsia wrote:
> On Apr 3, 2006, at 10:56 AM, Eric Prud'hommeaux wrote:
> [snip]
> > I propose the following text:
> > [[ http://www.w3.org/2001/sw/DataAccess/rq23/#describe
> > 10.4 Descriptions of Resources
> >
> > Current conventions for DESCRIBE constrain it to return an RDF
> > graph.
> 
> You mean the specification? Isn't there reason to leave that a bit 
> open, e.g.,
> 	DESCRIBE according to CBF as HTML
> 
> I.e., why put in *this* constraint (convention?)?

Part of the reason is that EricP is getting sorta conflicting
advice and trying to work a bit rapidly.

If you have words that you'd prefer, I'd very much like to see them.

If you don't, I can understand.

> >  Future SPARQL specifications may further constrain the results
> > of DESCRIBE, rendering some currently valid DESCRIBE responses
> > invalid.
> >
> > [ Non-normative: The DESCRIBE form returns a single result RDF graph
> > containing RDF data about resources. This data is not prescribed by a
> > SPARQL query, where the query client would need to know the structure
> > of the RDF in the data source, but, instead, is determined by the
> > SPARQL query processor. The query pattern is used to create a result
> > set. The DESCRIBE form takes each of the resources identified in a
> > solution, together with any resources directly named by IRI, and
> > assembles a single RDF graph by taking a "description" from the target
> > knowledge base. The description is determined by the query service. ]
> >
> > An empty graph is a valid response to any DESCRIBE query.
> > ]]
> 
> I don't like the non-determinism this introduces. That is, there should 
> be a difference between not having any valid answers and just not 
> handling DESCRIBE.
> 
> Cheers,
> Bijan.
-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Monday, 3 April 2006 15:24:25 GMT

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