Re: Comment on LDF spec

+1 for making the paragraph:

Only results of CONSTRUCT
        (and thus not SELECT, DESCRIBE or ASK) SPARQL queries
        are considered Linked Data Fragments.
        This is because only the execution of CONSTRUCT queries
        guarantees responding in data triples.
        However, other query formats can be embedded in a CONSTRUCT query using subqueries (http://www.w3.org/TR/sparql11-query/#subqueries).


DESCRIBE is an informative part of the SPARQL 1.1 spec and is therefore quite unpredictable. It's doesn't even specify what will be returned, could even be an image describing the resource. From the spec (http://www.w3.org/TR/sparql11-query/#describe):

The DESCRIBE form takes each of the resources identified in a solution, together with any resources directly named by IRI, and assembles a single RDF graph by taking a "description" which can come from any information available including the target RDF Dataset. The description is determined by the query service.

Best,

Miel

On 11 Jun 2015, at 19:27, John Walker <john.walker@semaku.com> wrote:

> For me no need to add an example. I just found it strange that CONTRUCT, SELECT and ASK are mentioned, but not DESCRIBE. Made me ask if it is an mistake or if it was left out on purpose for some unspecified reason (hence this post).
> 
> So for me omitting it is more confusing.
> 
> Regards,
> John
> 
> On 11 Jun 2015, at 18:10, Tom Johnson <tom@dp.la> wrote:
> 
>> +1 on including DESCRIBE queries as examples of SPARQL fragments.
>> 
>> On Thu, Jun 11, 2015 at 8:51 AM, Ruben Verborgh <ruben.verborgh@ugent.be> wrote:
>> Hi John,
>> 
>> > In section 4.3 SPARQL query results [1] it talks about CONSTRUCT, but shouldn't also DESCRIBE be mentioned here too?
>> 
>> Thanks for mentioning this!
>> 
>> I would personally say that DESCRIBE queries are implementation-specific CONSTRUCT queries,
>> and they are quite hard to capture because of this.
>> Furthermore, the section is non-normative, so it serves more as an example here.
>> 
>> However, I'm open to include DESCRIBE here if it's an added value,
>> i.e., adds more than it confuses people :-)
>> 
>> So I'll bounce the question back to you and to the community:
>> what do you think, is adding DESCRIBE an added value?
>> 
>> Best,
>> 
>> Ruben
>>