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Re: [dotNetRDF-Support] Timeout with serveral SPAQRL-queries
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From: Frank S. <fs...@in...> - 2014-03-18 15:13:13
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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 *
>> * 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
>> _______________________________________________
>> dotNetRDF-Support mailing list
>> dot...@li...
>> https://lists.sourceforge.net/lists/listinfo/dotnetrdf-support
>
>
>
>
>
> ------------------------------------------------------------------------------
> 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
> dot...@li...
> 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! *
************************************************
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