Suggestion: Extended DESCRIBEs

Hi,

Acknowledging that I've missed the original deadline for the call for
suggestions, and so it might not get
considerd, I wanted to raise this additional suggestion with the working
group (it'll at least get recorded
somewhere).

Feature:

  Extended DESCRIBE

Feature Description:

 Currently it is left undefined as to how a SPARQL processor should generate
the results of a
 DESCRIBE query. There are several possible algorithms that might be
applied, and these are useful in
 different contexts.  It would be useful to be able to specify an algorithm
in the SPARQL query, so that
 the client has additional control over the form of the results.

 Algorithms would be referred to be URI. The specification may define zero
or more of these, and implementations
 might converge on a standard set.

Example

 I'd envisage something like:

 DESCRIBE ?x WHERE {
   ?x a foaf:Person.
 }
 USING <http://www.example.org/closure/concise-bounded-desc>

...where USING refers to a standard URI for the algorithm used to describe
the results.

Existing Implementations

 I believe Virtuso has a similar feature using query pragmas.

Use Cases

 Provide more control over form of DESCRIBE query results on the client. It
is not always possible to achieve the
 same effect with a CONSTRUCT query due to other limitations in the language
(e.g. in graph traversal, container
 construction, etc). Even if those issues were resolved there are advantages
in the coarse grain style of query that
 this feature provides.

Cheers,

L.

-- 
Leigh Dodds
Programme Manager, Talis Platform
Talis
leigh.dodds@talis.com
http://www.talis.com