Jena ARQ QueryExecutionFactory.sparqlService() and Choosing the Reasoning Level

[david....@gmail.com]

Good afternoon,

I have just started using StarDog v2 - downloaded, unpacked and running within minutes - kudos to the team on making that so easy!

I am trying to run SPARQL queries using Jena against the StarDog HTTP endpoint. I leveraged the HttpAuthenticator support in Jena 2.11 I am able to successfully execute queries against the StarDog HTTP endpoint with authentication enabled. However, I have not been able to figure out how to set the HTTP header with the SD-Connection-String parameter. It appears that this is the only way to have StarDog run the reasoner in response to a query. Is it possible to make this work using the sparqlService() method versus using StarDog-specific classes for the connection?

The header I'm referring to is mentioned in the documentation (http://docs.stardog.com/owl2/#sd-Using-Reasoning) and specifically shows an example where an HTTP header is added:
curl -u admin:admin -X GET -H "SD-Connection-String: reasoning=QL" \
      "http://localhost:5822/myDB/query?query=..."

Thank you,

Dave Read

[Stephen Nowell]

Hi Dave,

The preferred way of passing in a connection string via HTTP as of
Stardog 2.1 is via the sd-connection-string URL parameter instead of the
header.

curl -u admin:admin -X GET

"http://localhost:5822/myDB/query?sd-connection-string=reasoning%3DQL&query=..."

I will update our documentation to reflect this. Thanks for pointing it out!

-Stephen

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[david....@gmail.com]

Stephen,

Thank you! That works perfectly.

Dave

[Rob Vesse]

Just to close the loop on how you'd do this with Jena

When you call QueryExecutionFactory.sparqlService() you get back a QueryExecution which is of type QueryEngineHTTP, if you cast to this class you can then call the addParam() method to add custom parameters.

Hope this helps,

Rob

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[david....@gmail.com]

Rob,

I appreciate the additional info. That will come in handy for setting other parameters in the request.

Dave