Re: [dotNetRDF-Support] Timeout with serveral SPAQRL-queries

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Frank

Unfortunately that information is not available in most (if not all) cases.

The SPARQL specifications don't require implementations to track how many
triples were inserted/deleted so there is no standard for responding with
this information over HTTP.  You mentioned you are using Virtuoso who are
well known for their non-standard SPARQL extensions so it may be worth
searching their documentation to see if they actually return this
information over HTTP in any way.

Or a quicker way may be to try an update through your browser and use a
browser extension to view the HTTP headers of the response to see if they
include that information in a custom header.

Rob

On 18/03/2014 15:12, "Frank Schumacher" <fs...@in...>
wrote:

>Hey Rob,
>
>this was exactly the problem! Thanks a lot!
>I also considered your recomendation about using the
>SparqlRemoteUpdateEndpoint class - it works fine. Is it possible to get
>any feedback about the success of the action like in sql (from where I
>come), i.e. "5 triples deleted" or "2 triples inserted"?
>
>Thanks again, you saved my day :)
>Frank
>
>Am 18.03.2014 15:17, schrieb Rob Vesse:
>> I'm guessing you do anything with the result of the QueryRaw() call
>>which
>> is a HttpWebResponse?
>>
>> If you don't then you are leaving the connections open and the .Net
>> runtime imposes a limit on the number of open connections to a single
>> server.  I believe this is in fact 2 connections hence why the third
>> request always fails since it is waiting for a connection to be free but
>> they are already used by the previous request.  You should make sure you
>> wrap any usage of QueryRaw() in a using block like so:
>>
>> using (HttpWebResponse response = endpoint.QueryRaw(update)) {
>>    // If you get here then the request succeeded and we close the
>>response
>> explicitly
>>    response.Close();
>> }
>>
>> Then even if the request errors the using block ensures that any
>>response
>> gets disposed of (which internally closes the connection) so you are
>> covered either way.
>>
>> You may want to consider using the complementary
>> SparqlRemoteUpdateEndpoint class for running updates, it has an Update()
>> method which handles submitting SPARQL updates and ensuring connections
>> are appropriately closed.
>>
>> Hope this helps,
>>
>> Rob
>>
>> On 18/03/2014 13:12, "Frank Schumacher" <fs...@in...>
>> wrote:
>>
>>> Hi folks,
>>>
>>> I am using the dotNetRDF-Framework to access a SPARQL-endpoint of our
>>> virtuoso server. At first, let me thank you to provide this framework,
>>> as it is a good tool for a semantic web beginner to get started with!
>>>
>>> I just stumbled upon a mysterious error, which I hope you can shed some
>>> light on. I am trying some examples to see how to insert/delete triples
>>> to the graph. After executing a delete and an insert, the endpoint
>>> doesn't react anymore and I run into a timeout. But let me show you
>>>some
>>> code!
>>>
>>> // define the endpoint
>>> SparqlRemoteEndpoint endpoint = new SparqlRemoteEndpoint(new
>>> Uri("http://www.creativeartefact.org/sparql"),
>>> "http://139.18.2.148/MusicBusinessOntology");
>>> endpoint.Timeout = 100000;
>>>
>>> // get everything in the graph
>>> string everything = "select * where {?s ?p ?o}";
>>>
>>> // insert data
>>> string insert1 = "INSERT DATA { GRAPH
>>> <http://139.18.2.148/MusicBusinessOntology> {
>>> <http://139.18.2.148/MusicBusinessOntology/URIDISILLU>
>>> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
>>> <http://artefakt.org/MusicBusinessVocabulary/MusicArtist>.
>>> <http://139.18.2.148/MusicBusinessOntology/URIDISILLU>
>>> <http://www.w3.org/2000/01/rdf-schema#label> \"Disillusion\" . } }";
>>>
>>> // delete data
>>> string delete1 = "DELETE WHERE { GRAPH
>>> <http://139.18.2.148/MusicBusinessOntology> {
>>> <http://139.18.2.148/MusicBusinessOntology/URIDISILLU> ?p ?o } }";
>>>
>>> 1) endpoint.QueryRaw(delete1);
>>> 2) endpoint.QueryRaw(insert1);
>>> 3) SparqlResultSet results = endpoint.QueryWithResultSet(everything);
>>>
>>> when I execute delete and insert, the next query will run into a
>>>timeout
>>>
>>> 1) endpoint.QueryRaw(delete1);
>>> 3) SparqlResultSet results = endpoint.QueryWithResultSet(everything);
>>> works
>>>
>>> 2) endpoint.QueryRaw(insert1);
>>> 3) SparqlResultSet results = endpoint.QueryWithResultSet(everything);
>>> works as well
>>>
>>> It is always the third request:
>>> 1) endpoint.QueryRaw(delete1);
>>> 2) endpoint.QueryRaw(insert1);
>>> 3) endpoint.QueryRaw(delete1);
>>> 4) endpoint.QueryRaw(insert1);
>>> 5) SparqlResultSet results = endpoint.QueryWithResultSet(everything);
>>>
>>> => the timeout occurs at the third query.
>>>
>>> I even put a breakpoint at the third line. Before executing this line,
>>>I
>>> execute the select statement vie webinterface against the
>>> SPAQRL-endpoint. The webinterface request works fine - but if I let the
>>> program continue, it still runs into a timeout. I even tried a second
>>> SparqlRemoteEndpoint instance - same problem.
>>>
>>> Any idea, what might be the reason for this behaviour and how to fix
>>>it?
>>>
>>> Many thanks,
>>> Frank
>>>
>>> --
>>> ************************************************
>>> * Universität Leipzig, Institut für Informatik *
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>>> ************************************************
>>>
>>> 
>>>------------------------------------------------------------------------
>>>--
>>> ----
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>>> applications. Written by three acclaimed leaders in the field,
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>>
>>
>>
>>
>>
>> 
>>-------------------------------------------------------------------------
>>-----
>> Learn Graph Databases - Download FREE O'Reilly Book
>> "Graph Databases" is the definitive new guide to graph databases and
>>their
>> applications. Written by three acclaimed leaders in the field,
>> this first edition is now available. Download your free book today!
>> http://p.sf.net/sfu/13534_NeoTech
>> _______________________________________________
>> dotNetRDF-Support mailing list
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>> https://lists.sourceforge.net/lists/listinfo/dotnetrdf-support
>>
>
>
>-- 
>************************************************
>* Universität Leipzig, Institut für Informatik *
>*  Abteilung Betriebliche Informationssysteme  *
>*     http://bis.informatik.uni-leipzig.de     *
>*            Tel.: 0341 / 97 32 256            *
>*                                              *
>* ========== Opera Metal: molllust =========== *
>*           http://www.molllust.com            *
>*          M'era Luna Newcomer 2013!           *
>************************************************
>
>--------------------------------------------------------------------------
>----
>Learn Graph Databases - Download FREE O'Reilly Book
>"Graph Databases" is the definitive new guide to graph databases and their
>applications. Written by three acclaimed leaders in the field,
>this first edition is now available. Download your free book today!
>http://p.sf.net/sfu/13534_NeoTech
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