W3C home > Mailing lists > Public > public-rdf-dawg-comments@w3.org > June 2010

Re: Standardise method for selecting extensions for DESCRIBE

From: Leigh Dodds <leigh.dodds@talis.com>
Date: Thu, 24 Jun 2010 00:58:06 +0100
Message-ID: <AANLkTik0KqcvW5QNll9hwO2IglJWU-DSJn5pkoSbY8y0@mail.gmail.com>
To: Peter Ansell <ansell.peter@gmail.com>
Cc: public-rdf-dawg-comments@w3.org
Hi Peter,

This was a feature I'd like to have seen in the language too. I
submitted it as a proposed feature during the requirements gathering
process. More detail here:


But as far as I'm aware its not been selected for standardisation as
part of SPARQL 1.1


On 22 June 2010 23:02, Peter Ansell <ansell.peter@gmail.com> wrote:
> Hi,
> It would be nice with the SPARQL review if there could be a minor
> change to the DESCRIBE query syntax to support optional selection of
> the way DESCRIBE should work.
> For example, even if I know that my SPARQL endpoint supports different
> types of DESCRIBE queries, such as Concise Bounded Description [1] and
> Symmetric Concise Bounded Description and basic Subject Predicate
> Object (with or without inferences), there is no standard way of
> telling a DESCRIBE query to use one over the other.
> A syntax may be "DESCRIBE [USING <METHODURI>] <URI>" or any other way
> that is substantially backwards compatible. The METHODURIs for some
> common methods could be suggested, with any new methods being easily
> extensible using URIs that anyone else publishes.
> This wouldn't change the best guess approach that was originally
> standardised for DESCRIBE, but it would give a user some standard way
> of selecting their preferred DESCRIBE method in some cases.
> Virtuoso currently offer this ability using SQL define commands
> attached to the front of a SPARQL query [2].
> Personally I never use SPARQL DESCRIBE because I have no way of
> knowing which method is going to be used, and I don't want to be
> flooded with triples if the method is Symmetric Concise Bounded
> Description for instance, and the URI is in the object position of a
> large number of statements that are not relevant to me right now. It
> would nice to be able to get the ability to discover Blank Nodes in an
> Asymetric way, as you can't iteratively find Blank Nodes using the
> results of past queries that you can do if all subjects and objects
> are URIs.
> Even if this feature doesn't get through, it would be nice to have the
> DESCRIBE query method as a required element the SPARQL Service
> Description so I could at least identify the method that would be used
> by default for an endpoint.
> Sorry if this feature has been brought up before. I couldn't find it
> with my searching.
> Thanks,
> Peter
> [1] http://www.w3.org/Submission/CBD/
> [2] http://docs.openlinksw.com/virtuoso/rdfsparql.html#rdfsqlfromsparqldescribe
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Leigh Dodds
Programme Manager, Talis Platform
Received on Wednesday, 23 June 2010 23:58:40 UTC

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