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Fwd: Standardise method for selecting extensions for DESCRIBE

From: Axel Polleres <axel.polleres@deri.org>
Date: Thu, 24 Jun 2010 10:59:13 +0100
To: SPARQL Working Group <public-rdf-dawg@w3.org>, Gregory Williams <greg@evilfunhouse.com>
Message-Id: <7FF65EE3-833C-45BF-B4A5-F8A4E20A3E6A@deri.org>
Before we send an official reply...some question to Greg, to the group: 

While we have not put elaborating more on DESCRIBE on our features list, I think the suggestion is valuable... however, in my feeling it only makes sense if there was at least one concrete proposal out there for defining such an algorithm, with a URI.
Is there such thing at the moment? I think it is out of scope to define it for us.

Opinions?

Axel



Begin forwarded message:

> Resent-From: public-rdf-dawg-comments@w3.org
> From: "Peter Ansell" <ansell.peter@gmail.com>
> Date: 24 June 2010 01:36:07 GMT+01:00
> To: "Leigh Dodds" <leigh.dodds@talis.com>
> Cc: <public-rdf-dawg-comments@w3.org>
> Subject: Re: Standardise method for selecting extensions for DESCRIBE
> archived-at: <http://www.w3.org/mid/AANLkTimp1hAu1OCUd_xKP3SUq9GRE53-7zaAx-bTMJ2-@mail.gmail.com>
> 
> Thanks,
> 
> I would add to that page that it would be useful to define in Service
> Descriptions a list of URIs for Describe algorithms that an endpoint
> supports. I think it is a very powerful addition to the language when
> it is combined with Service Descriptions.
> 
> Hopefully it isn't being ignored just because it isn't graph
> matching/triple based, as there were (are?) objections in the core
> group about Describe even being in the language at all. [3] With this
> extension there is no guessing as to which algorithm is being used so
> queries are always going to execute the same way on the same dataset
> regardless of the implementation, as long as the implementations
> support the type of query as specified in their Service Description.
> The current randomness may be the cause of the current lack of
> interest in developing it because people misunderstand it.
> 
> Cheers,
> 
> Peter
> 
> [3] http://www.w3.org/2001/sw/DataAccess/issues#DESCRIBE
> 
> On 24 June 2010 09:58, Leigh Dodds <leigh.dodds@talis.com> wrote:
> > 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:
> >
> > http://www.w3.org/2009/sparql/wiki/Feature:ControlOfDescribeQueries
> >
> > But as far as I'm aware its not been selected for standardisation as
> > part of SPARQL 1.1
> >
> > L.
> >
> > 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
> > Talis
> > leigh.dodds@talis.com
> > http://www.talis.com
> >
> 
> 
Received on Thursday, 24 June 2010 09:59:44 GMT

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