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From Askild Aaberg Olsen <ask...@xangeli.com>
Subject Re: using jena
Date Thu, 03 May 2007 11:36:42 GMT
Al Brown wrote:
> Askild Aaberg Olsen wrote:
>> I've been using Jena with Cocoon without problems, so it's definitely 
>> possible. If i remember correctly, Jena is included with the 
>> Deli-block. You probably should make sure that this block is excluded 
>> from the build.
>>
>> You should also check that the error you get is actually a result of 
>> you replacing jena.jar. If not, this is another issue that should be 
>> resolved before you continue.
>>
>> Askild
>> -
> Thanks, its good to know that I'm not alone.
>
> I have part of my code working. I can open a prebuilt  repoistory and 
> create a model.
> When I go to run a query it fails. I have checked the version number, 
> at runtime, and I'm using the jena that came with cocoon.
> It seems to not use my java classpath at all.
> I have look in the jena-2.1.jar and it is a lot different than the one 
> that came with jena-2.5.2
>
> I will try to reconfirm that I have a problem switching jena. I assume 
> that you are using what came with cocoon. Are you doing any sparql 
> querries?
>
> Al
We replaced jena-2.1.jar with 2.3 or 2.4 i think, and also did 
SPARQL-queries. This was from Flow and in XSLT (calling Java from Saxon, 
which is actually a very nice feature...).
I haven't tried it with XSP.

There should not be any problems using Jena with Cocoon. I guess that if 
you sort out your classpath-problems, then you'r up and running.

One issue I can think of is finding a way to keep the model in memory 
between requests. We did not get as far as solving this, since that part 
of the project are "resting", but I guess you could create your own 
class with a static field to hold your models, like when keeping 
Hibernate SessionFactories as in 
http://www.hibernate.org/hib_docs/v3/reference/en/html_single/#tutorial-firstapp-helpers

And there's also the Issue of what to do with your results in Cocoon. I 
guess that your planning to output your SPARQL-results into a pipeline. 
Going from a graph-based model to XML (not RDF/XML) is not trivial, but 
we were inspired by the following paper:
http://www.idealliance.org/papers/extreme/proceedings/html/2006/Souzis01/EML2006Souzis01.html

This resulted in a working prototype on an XQuery-engine towards the 
Jena API.

I'm interested in hearing your results on these issues :-)

Askild
-

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