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From Enrico Daga <enricod...@gmail.com>
Subject Re: Do Stanbol have a global SPARQL endpoint?
Date Fri, 18 Mar 2011 12:29:21 GMT
On 18 March 2011 12:21, Olivier Grisel <olivier.grisel@ensta.org> wrote:
> 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.
Actually it looks like named graphs are supported. Thank you for the
analysis, I've seen it in the clerezza dev list.
About the performance issue (I didn't get this because of a very
limited dataset), this is only a problem of the TDB triple store, if I
understood correctly, and should not happen with other storage, such
sesame, right?
Ok to implement this for clerezza/tdb.

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



-- 
Enrico Daga

--
http://www.enridaga.net
skype: enri-pan

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