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CommentResponse:PA-2
From SPARQL Working Group
> 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.
Peter,
The ability to choose a DESCRIBE algorithm was one of the features proposed[1] for inclusion in SPARQL 1.1. However, compared to several other features which will be in SPARQL 1.1, there was little support within the working group for standardizing a means of choosing a DESCRIBE algorithm.
> 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.
The SPARQL 1.1 Service Description document currently describes a sd:feature property meant for use in describing arbitrary features of a SPARQL endpoint. Provided a URI for a DESCRIBE algorithm, a service description could describe its implementation with:
[] a sd:Service ; sd:feature <http://www.example.org/closure/concise-bounded-desc> ; ...
Does this use of sd:feature fit your needs?
thanks, Gregory Williams (on behalf of the SPARQL Working Group)
[1] http://www.w3.org/2009/sparql/wiki/Feature:ControlOfDescribeQueries [2] http://www.w3.org/TR/sparql11-service-description/