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Subject: Re: Cayenne under OSGi
From: Andrus Adamchik <andrus@objectstyle.org>
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Date: Sun, 3 Mar 2013 12:23:11 +0300
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To: dev@cayenne.apache.org

Ok, I think understand the task in general, but some details still do =
not fully connect in my head. I guess I need to dive into OSGi and to =
tie all the loose ends in Cayenne class loading. E.g. it would be nice =
to avoid registering each class manually, and just pass the right =
ClassLoader somehow, preferably via DI instead of a static method. Your =
code and this discussion certainly make it much easier.=20

Also something I haven't explored yet is this separate dependencies =
bundle.=20

As usual, the toughest part is finding time to do this work. And I'll be =
certainly happy if someone with OSGi experience takes it over. Will be =
happy to apply the patches :) But otherwise, I'll put it in my Cayenne =
queue.

Thanks,
Andrus

On Mar 1, 2013, at 11:53 AM, Cristiano Ghersi =
<cristiano.ghersi@abodata.com> wrote:

> Hi Andrus,
>=20
> you perfectly caught the point: the difference is in the class =
loading.
> The class loaders are populated from the application that uses =
Cayenne,
> with the following example snippet:
>=20
> ServerRuntime myRuntime =3D new ServerRuntime("myDomain.xml");
> ...
> ClassRegistry.registerClass(MyPersistentClass1.class);
> ClassRegistry.registerClass(MyPersistentClass2.class);
> //call ClassRegistry.registerClass(Class) for each class created by
> CayenneModeler
>=20
> you can find ClassRegistry class in org.apache.cayenne.di.spi package; =
it
> is the other brick added by ourselves in order to correctly run under =
OSGi
>=20
> Let me know if you need any further information!
>=20
> Thanks
> Cristiano
>=20
> 2013/2/28 Andrus Adamchik <andrus@objectstyle.org>
>=20
>> Hi Cristiano,
>>=20
>> So I guess our goal is to tweak the Cayenne build process (and code =
if
>> needed) so that it builds OSGI-compatible jars.
>>=20
>> Let's start with the code=85 I created a diff to better demonstrate =
the
>> change in DefaultAdhocObjectFactory between Cayenne and your code:
>>=20
>> +import java.util.List;
>> +
>> import org.apache.cayenne.CayenneRuntimeException;
>> import org.apache.cayenne.di.AdhocObjectFactory;
>> import org.apache.cayenne.di.Inject;
>> @@ -102,6 +104,16 @@
>>             return Class.forName(className, true, classLoader);
>>         }
>>         catch (ClassNotFoundException e) {
>> +                       //try with the class loader registry
>> +                       List<ClassLoader> registeredClassLoaders =3D
>> ClassLoaderRegistry.registeredClassLoaders();
>> +                       for (ClassLoader loader : =
registeredClassLoaders) {
>> +                               try {
>> +                                       return =
loader.loadClass(className);
>> +                               }
>> +                               catch (ClassNotFoundException cnfe) {
>> +                               }
>> +                       }
>> +
>>             if (!className.endsWith("[]")) {
>>                 if ("byte".equals(className)) {
>>                     return Byte.TYPE;
>>=20
>>=20
>> I guess this is what you described in the previous message (only =
slightly
>> different naming - ClassLoaderRegistry). I couldn't find who actually
>> populates those extra class loaders inside ClassLoaderRegistry? Could =
you
>> comment on this please?
>>=20
>> So other than that, I guess all we need is changing cayenne-server
>> packaging from "jar" to "bundle" (and configuring the bundle plugin =
in the
>> pom).
>>=20
>> Andrus
>>=20
>>=20
>>=20
>> On Feb 28, 2013, at 12:19 PM, Cristiano Ghersi <
>> cristiano.ghersi@abodata.com> wrote:
>>> Hi Andrus,
>>>=20
>>> I know you have been very busy with the new upcoming release of =
Cayenne.
>>>=20
>>> I'd like to know if and when we can resume the task of Cayenne
>>> OSGi-fication.
>>>=20
>>> I'm at your disposal for every clarification.
>>>=20
>>> Thank you very much
>>> Best
>>> Cristiano
>>=20
>>=20
>>=20