[redland-dev] SPARQL DESCRIBE unimplemented/broken?

Dave Beckett dave at dajobe.org
Wed Nov 22 04:56:58 UTC 2006


On Tue, 2006-11-21 at 10:54 -0500, Dutton, Jeff wrote:
> Is the SPARQL DESCRIBE verb unimplemented or broken?  I cannot get a
> single result with a DESCRIBE, no matter how trivial my request.

It's not implemented.  What do you think it should do by default
when there is no application logic present?

> I have tried it with my own database, using Redland 1.0.4, Raptor
> 1.4.13, and Rasqal 0.9.13.  I tried using "roqet" from the same build.
> 
> Finally, I tried doing a query using the http://librdf.org/query
> website.  Using http://planetrdf.com/bloggers.rdf as a source (which one
> of Dave's presentations references), I can't get a DESCRIBE to work,
> whether I specify an explicit URI or a bound variable.
> 
> Query:
>   PREFIX dc: <http://purl.org/dc/elements/1.1/>
>   SELECT ?title
>   WHERE { <http://www.nzlinux.org.nz/blogs/> dc:title ?title }
> 
> Query Results: "Visions of Aestia by John Barstow"
> 
> Query:
>   DESCRIBE <http://www.nzlinux.org.nz/blogs/>
> 
> Query Results:  NOTHING
> 
> 
> In the likely event I am missing something, can someone craft a simple
> DESCRIBE query that *will* work against http://librdf.org/query?


I was wondering about making it default to returning triples query like:
  CONSTRUCT { <uri> ?p ?o }
  WHERE  { <uri> ?p ?o }

assuming that you had done a DESCRIBE <uri>

Other possibilities include returning the bnode-closure, but that's
writing a lot more code.

Dave




More information about the redland-dev mailing list