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From Olivier Grisel <olivier.gri...@ensta.org>
Subject Re: Do Stanbol have a global SPARQL endpoint?
Date Fri, 18 Mar 2011 11:21:48 GMT
2011/3/17 Enrico Daga <enricodaga@gmail.com>:
>>
>> It seems to me by reading the source code of
>> TcManager#executeSparqlQuery and JenaSparqlEngine#execute and
>> TcDataset#getNamedGraph that the clerezza sparql execution should be
>> able to perform queries accross several graphs. The second argument of
>> TcManager#executeSparqlQuery is just the default named graph used when
>> the sparql query does not have FROM clause.
>>
>> Please try to build a SPARQL query with an explicit FROM clause
>> pointing to a graph id used by kres to check this assertion. If it
>> works, try another query that mixes triples from both graphs
>> (reengineer and enhancer) using the GRAPH keyword in the body of the
>> SPARQL query as in
>> http://www.w3.org/TR/rdf-sparql-query/#restrictByLabel for instance.
>>
>> If it does not work, i think we should ask the question on the
>> clerezza mailing list directly instead.
> Thank you Olivier. Yes, it looks like it should support this.
> So I can assume that the answer to my question is YES, Stanbol has a
> Sparql endpoint which should cover all graphs in the store. So we
> don't need additional components for that, just use the /sparql path
> and maybe improve it, if needed.
> I'll do more test about it.

If your tests don't work as expected, or the performance is too poor,
this might be the consequence of some design limitations of the
current TdbTcProvider / JenaSparqlEngine implementation that is overly
generic. I have discussed this issue with the clerezza developers on
the best way to improve upon this and the results is available in
these two issues:

https://issues.apache.org/jira/browse/CLEREZZA-466
https://issues.apache.org/jira/browse/CLEREZZA-467

I am sure they would appreciate to review patches should you want to
implement those improvements.

-- 
Olivier
http://twitter.com/ogrisel - http://github.com/ogrisel

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