[news.eclipse.rt.eclipselink] Re: Eclipselink with OSGi

[shaun.smith@xxxxxxxxxx (Shaun Smith)]

Hi Omar,
,
> I have some questions about Eclipselink JPA in OSGi:
> The first one is about the architecture of JPA OSGi, which bundle from JPA 
> read the persistence.xml? 

org.eclipse.persistence.jpa contains the EclipseLink JPA implementation 
and the persistence.xml is read by code in this bundle.

> And which bundle reads the persistence Unit 
> declared in the manifest?

Same bundle.

> how the persistence Unit is handled by JPA? What 
> happens if I have several bundles publishing the same persistence Unit or 
> what happen if I have several bundles using the same data base with 
> different persistence units?

As of the 1.1.2 release you can't have two persistence units with the same 
name.  This will be addressed in a future release. The same database issue 
is no different in OSGi than outside.

> A big picture would be ok to understand how 
> Eclipselink JPA works with OSGi. Does anybody knows where could I find 
> this information or someone knows how it works?

I gave a presentation on this at OSGi DevCon last month. I don't go into 
great detail as most people want to know how to use it rather than how it 
works, but I do point out some of the implementation challenges and 
solutions.  You can find the slides on my blog: 
http://onpersistence.blogspot.com/2009/06/osgi-persistence-slides-from-osgi.html

--Shaun