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Re: Objective 4.2 : Change "provenance" to "data management"

From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
Date: Mon, 19 Jul 2004 23:53:26 +0100
To: "'RDF Data Access Working Group'" <public-rdf-dawg@w3.org>
Message-ID: <20040719225326.GC13741@login.ecs.soton.ac.uk>

On Mon, Jul 19, 2004 at 05:21:29PM -0500, Dan Connolly wrote:
> Perhaps the objective is fuzzy enough so that the conflict isn't
> clear, but all the concrete designs I have seen
> (e.g. the BRQL SOURCE mechanism) involve the input to the QUERY
> being more than just an RDF graph.

I understand it to be (opionally) a set of RDF grpahs. I would like it if
the intention is that servers that do not need/use source information can
ignore it, eg. treat all triples as having a single source.
 
> The spec doesn't yet explicitly say what the input to a query
> is, but it seems to be more than just a graph:
> 
> "The SOURCE clause added to a triple pattern causes the variable or
> literal to match or bind the RDF graph which the statement came from, if
> the server knows."
>  -- http://www.w3.org/2004/07/08-BRQL/
>  $Revision: 1.14 $ of $Date: 2004/07/19 13:11:51 $
> 
> Does anybody have any test cases for SOURCE? I'm sure those would
> make this crystal clear.

Some trivial ones, BRQLised:

Data

a.rdf:
	:foo  :a  "a"
	:foo  :b  "b"

b.rdf:
	:bar  :a  "a"


SELECT ?s
WHERE (?s ?p ?o) SOURCE <a.rdf>

	+-------+
	| ?s    |
	+-------+
	| :foo  |
	+-------+


SELECT ?s, ?src
WHERE (?s ?p ?o) SOURCE ?src

	+-------+-------+
	| ?s    | ?src  |
	+-------+-------+
	| :foo  | a.rdf |
	| :bar  | b.rdf |
	+-------+-------+


CONSTRUCT * WHERE (?s ?p ?o) SOURCE <a.rdf>

should return an RDF graph equivalent to the orignal asserted a.rdf I
think. I dont have a real test for this, but it seems very useful so I
included it anyway.

	+---------------+
	| *             |
	+---------------+
	| :foo  :a  "a" |
	| :foo  :b  "b" |
	+---------------+

- Steve
Received on Monday, 19 July 2004 18:53:31 GMT

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