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Date: Sun, 13 Feb 2011 07:07:24 +0000
From: Paolo Castagna <castagna.lists@googlemail.com>
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CC: jena-dev@incubator.apache.org
Subject: Re: [jena-dev] Caching SPARQL results in RDF
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Hi Martynas,
you have already received two answers, I have two questions for you:

  - Why have you been using SDB and not TDB?
  - Why not to cache the entire HTML page?

Just curious.

Finally, the theme of caching SPARQL results or bindings is something I am very interested in. Although, I've done nothing so far.
Is anyone thinking to see if caching BGPs inside ARQ (or in a separate module which would work with ARQ) could possibly work (i.e. boost performances)?
Assuming cache will grow large, it would need to serialize bindings on disk (see: https://issues.apache.org/jira/browse/JENA-45).
Cache invalidation, as result of an update, is also a tricky problem... as always.

Martynas, you should really subscribe to jena-{dev|users}@incubator.apache.org, just send an email to:

  - jena-dev-subscribe@incubator.apache.org
  - jena-users-subscribe@incubator.apache.org

See you there,
Paolo


Martynas Jusevicius wrote:
> Hey list,
> 
> my http://semanticreports.com webapp is based almost exclusively on
> SPARQL results - mostly from remote endpoints, but it also uses SDB to
> store its own RDF (meta)data.
> 
> The issue is, I still want to show the reports/visualizations based on
> a previous result, even if the remote endpoint is currently down.
> Which brings me to caching of SPARQL XML results - and saving them
> with RDF in SDB.
> 
> I imagine it could be saved as XMLLiteral. Does this sound reasonable?
> And which methods should we use? This looks about right:
> http://jena.sourceforge.net/javadoc/com/hp/hpl/jena/rdf/model/Model.html#createLiteral%28java.lang.String,%20boolean%29
> 
> Thanks,
> 
> Martynas
> semantic-web.dk
> 
> 
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