Hi Moritz,
As a starting point are you able to get the sample walkthrough SPASQL
application we have at:
http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtSPASQLWinFormApp
working ?
The booleans being mapped to integers is a known issue that is scheduled to be
fixed in a future/next release ...
Best Regards
Hugh Williams
Professional Services
OpenLink Software
Web: http://www.openlinksw.com
Support: http://support.openlinksw.com
Forums: http://boards.openlinksw.com/support
Twitter: http://twitter.com/OpenLink
On 26 Jan 2011, at 13:12, Moritz Eberl wrote:
> Hello Rob,
>
> currently i do not use any API. I first wanted to be able to get the RDF data
> with basic SPARQL queries.
> While trying to figure out what i was doing wrong, i also used your API. The
> results where pretty much the same. All typed literals were returned as
> strings.
>
> You are right about the boolean datatype in Virtuoso. I just tried to store a
> xsd:boolean, which resulted in a xsd:integer using the RDF/XML
> representation.
>
> Cheers,
> Moritz
>
> Am 26.01.2011 13:03, schrieb Rob Vesse:
>>
>> Hi Moritz
>>
>> What API are you using to manipulate the RDF within your application or have
>> you rolled your own?
>>
>> My API dotNetRDF (http://www.dotnetrdf.org) has Virtuoso integration built
>> in and might be helpful to you as it handles all the data type retrieval
>> appropriately. I've had isolated reports that on some machines things don't
>> come back correctly and I know that it was an issue with older 6.x releases
>> of Virtuoso (though should be fine in the version you're using).
>>
>> One think to note about datatypes is that in my experience Virtuoso doesn't
>> return all datatypes correctly even when you do a SPASQL select like you've
>> done and do all the type handling. If my memory serves me this particularly
>> applies to xsd:boolean typed literals which come back as a 1/0 rather than a
>> true/false though if you do a CONSTRUCT over the same data the type does
>> come back correctly.
>>
>> Regards,
>>
>> Rob Vesse
>>
>> From: "Moritz Eberl" <[email protected]>
>> Sent: 26 January 2011 11:51
>> To: [email protected]
>> Subject: [Virtuoso-users] Missing datatypes using ADO.NET
>>
>> Hello,
>>
>> i am trying to use Virtuoso as RDF store for a C# application with .Net
>> 4, but i have some issues with the ADO.NET library. I have no troubles
>> creating triples with SPARQL using SPASQL, but the retrieval is
>> problematic. In the result set, all typed literals are strings without
>> type information. I get the IRI as SqlExtendedString and the literals
>> with language information as SqlRdfBox, so no problem there. Now i am
>> wondering what i'm doing wrong.
>> This is how i access the data:
>>
>> DataTable results = new DataTable();
>> results.Columns.Add("s", typeof(System.Object));
>> results.Columns.Add("p",typeof(System.Object));
>> results.Columns.Add("o", typeof(System.Object));
>> VirtuosoCommand cmd = Connection.CreateCommand();
>> cmd.CommandText = "SPARQL select * where {?s ?p ?o.}"; //just an example
>> here
>> VirtuosoDataAdapter adapter = new VirtuosoDataAdapter(cmd);
>> adapter.Fill(results);
>>
>> I also tried to use the RDF/XML output, although not optimal
>> performance-wise, it kind of worked. One thing i noticed though, was
>> that ASK statments produce malformed XML.
>> As example, this statment
>> SPARQL define output:format "RDF/XML" ask where {?s ?p ?o.};
>> produced
>>
>> xmlns:rs="http://www.w3.org/2005/sparql-results#";
>> xmlns:xsd="http://www.w3.org/2001/XMLSchema#"; >
>>
>>
>> rdf:datatype="http://www.w3.org/2001/XMLSchema#boolean";>1
>>
>>
>> The prefix of the closing result tag is missing. You can try it in the
>> Interactive SQL form of the conductor.
>>
>> My system specs:
>> OS: Windows 7 64-bit
>> Virtuoso: Open-Source-Edition Version 06.01.3127 - Build Jul 9 2010 32-bit
>> virtado3.dll: Version 6.2.3128.1
>>
>> It would be great if somebody could help me to resolve my issues.
>>
>> Cheers,
>> Moritz
>>
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>
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> Finally, a world-class log management solution at an even better price-free!
> Download using promo code Free_Logger_4_Dev2Dev. Offer expires
> February 28th, so secure your free ArcSight Logger TODAY!
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