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Re: User defined operations and PREMISES keyword

From: Dan Connolly <connolly@w3.org>
Date: Thu, 12 May 2005 09:21:45 -0500
To: Stephane Fellah <stephanef@imagemattersllc.com>, public-rdf-dawg-comments@w3.org
Message-Id: <1115907705.13402.378.camel@localhost>

Sorry for the delay in responding to your comment of 20 Apr 2005
http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2005Apr/0038.html


> I am currently trying to create user-defined spatial operators for
SPARQL.

Interesting!

[...]

> It seems to me that the  current specification does not provide a way
to
pass the description of p1 in the query
[...]
> To support this query, SPARQL needs a mechanism to pass the user
defined
> triples, so they could be added as premises in the query engine (DQL is
> using such concept) prior to the evaluation on any graph.

Note that the FROM keyword is back in the recent draft...
http://www.w3.org/TR/2005/WD-rdf-sparql-query-20050419/#specifyingDataset

which allows specifying premises by reference.

> The handling of
> the premises would be pretty straightforward to implement by any SPARQL
> query engine. 

One implementation strategy that is consistent with the specification
is for the engine to index its dataset before receiving queries and
not handle on-the-fly additional premises.


> ISSUE 2: OPTIONAL OR NULL PARAMETERS.
> ISSUE 3: DESCRIPTION OF SUPPORTED FUNCTIONS IN SPARQL PROTOCOL.

More on those separately...


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
see you at XTech in Amsterdam 24-27 May?
Received on Thursday, 12 May 2005 14:21:51 GMT

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