Re: [Clerezza] manually registering a JenaSparqlEngine in TcManager

[Reto Bachmann-Gmuer <re...@trialox.org>]

Hi Alessandro

I am sorry for addressing you so directly, but I'm not sure where it is more
> appropriate to post such questions (couldn't find a mailing list for users
> on the Clerezza homepage) and unfortunately my issue is very urgent.
>

There's only one mailing list, both for users and devleopers, its
clerezza-dev@incubator.apache.org (added in cc)

>
> I am running an Equinox environment (plain, no SCR/Declarative services),
> which includes some Clerezza bundles (mainly the org.apache.clerezza.rdf.*
> ones).
>
> At some point I need to run a SPARQL query via
> TcManager.executeSparqlQuery(), having obtained TcManager via
> TcManager.getInstance() . This throws a NoQueryEngineException.
>
> However the org.apache.clerezza.rdf.jena.sparql bundle and its dependencies
> are active and started before the bundle that does the query.
>
> Since org.apache.clerezza.rdf.jena.sparql contains a QueryEngine service
> specification in its META-INF/services , shouldn't the Jena query engine be
> registered automatically?

META-INF services is used only outside an OSGi environment.


> Or this doesn't hold in OSGi? Is there a way to register it myself
> programmatically?
>

The problem is that the bindQueryEngine-method is protected so it cannot be
called unless you subclass TcManager or if you use declarative service (or
do the same magic otherwise).

What I'm wondering is how the TcProviders are registered? The getInstance
static method is designed for non-osgi use and locates the TcProvider (such
as the one provided by the org.apache.clerezza.rdf.jena.tdb.storage) using
META-INF/services.

I think you should use declarative service, if not I think the easiest is
subclass TcManager and inject the weightedTcProvider and queryEngine using
the bind-methods (which you don't see when looking at the TcManager source,
nevertheless they are in the compiled class file because they are added by
the maven-scr-plugin).

Cheers,
Reto


> Thank You,
> Alessandro
>
> --
> Alessandro Adamou
> Semantic Technology Laboratory (STLab)
> Institute for Cognitive Science and Technology (ISTC)
> National Research Council (CNR)
> Via Nomentana 56, Rome - Italy
>
>

Re: [Clerezza] manually registering a JenaSparqlEngine in TcManager

[Reto Bachmann-Gmuer <re...@trialox.org>]

On Wed, Jan 5, 2011 at 9:13 PM, Alessandro Adamou <
alessandro.adamou@istc.cnr.it> wrote:

>  Thank you Reto!
>
> Unfortunately I've had no luck having Declarative Services work in Equinox
> so far. Thought it was the org.eclipse.equinox.ds bundle but it didn't work
> for me.
>
I have a wage remembrance of the felix and the equinox implementation having
a bit a different reading of the specification of the service-xml files (one
needed namespaces and the other not) if you find out more it would be great
to know how to have the clerezza-bundles working with both-impls.
Alternatively I think the felix-scr bundles work also on equinox.


>
> I guess I'll try specializing the TcManager then.
>
> I used to bind a TcProvider like this: TcManager.addWeightedTcProvider(new
> SimpleTcProvider()) , but as you hinted perhaps this is not the right
> approach?
>
addWeightedTcProvider is the inherited public version of
bindWeightedTcProvider


> Are there any other protected bind methods that I should call and don't
> appear in the sources?
>
The bind-method are generated for @Reference annotation on the fields, the
only one I see here is for the queryEngine.

>
> Thanks again. I have forwarded this suggestion to my mates.
>
> All the best,
>
To you too!

Reto

>
> Alessandro
>
>
>
> On 1/5/11 8:52 PM, Reto Bachmann-Gmuer wrote:
>
> Hi Alessandro
>
>  I am sorry for addressing you so directly, but I'm not sure where it is
>> more appropriate to post such questions (couldn't find a mailing list for
>> users on the Clerezza homepage) and unfortunately my issue is very urgent.
>>
>
> There's only one mailing list, both for users and devleopers, its
> clerezza-dev@incubator.apache.org (added in cc)
>
>>
>> I am running an Equinox environment (plain, no SCR/Declarative services),
>> which includes some Clerezza bundles (mainly the org.apache.clerezza.rdf.*
>> ones).
>>
>> At some point I need to run a SPARQL query via
>> TcManager.executeSparqlQuery(), having obtained TcManager via
>> TcManager.getInstance() . This throws a NoQueryEngineException.
>>
>> However the org.apache.clerezza.rdf.jena.sparql bundle and its
>> dependencies are active and started before the bundle that does the query.
>>
>> Since org.apache.clerezza.rdf.jena.sparql contains a QueryEngine service
>> specification in its META-INF/services , shouldn't the Jena query engine be
>> registered automatically?
>
> META-INF services is used only outside an OSGi environment.
>
>
>> Or this doesn't hold in OSGi? Is there a way to register it myself
>> programmatically?
>>
>
> The problem is that the bindQueryEngine-method is protected so it cannot be
> called unless you subclass TcManager or if you use declarative service (or
> do the same magic otherwise).
>
> What I'm wondering is how the TcProviders are registered? The getInstance
> static method is designed for non-osgi use and locates the TcProvider (such
> as the one provided by the org.apache.clerezza.rdf.jena.tdb.storage) using
> META-INF/services.
>
> I think you should use declarative service, if not I think the easiest is
> subclass TcManager and inject the weightedTcProvider and queryEngine using
> the bind-methods (which you don't see when looking at the TcManager source,
> nevertheless they are in the compiled class file because they are added by
> the maven-scr-plugin).
>
> Cheers,
> Reto
>
>
>> Thank You,
>> Alessandro
>>
>> --
>> Alessandro Adamou
>> Semantic Technology Laboratory (STLab)
>> Institute for Cognitive Science and Technology (ISTC)
>> National Research Council (CNR)
>> Via Nomentana 56, Rome - Italy
>>
>>
>
>
> --
> Alessandro Adamou
> Semantic Technology Laboratory (STLab)
> Institute for Cognitive Science and Technology (ISTC)
> National Research Council (CNR)
> Via Nomentana 56, Rome - Italy
>
>