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From "Aaron Mulder" <ammul...@alumni.princeton.edu>
Subject Re: JPA plugin (was Re: Java 1.4 and JEE 5)
Date Tue, 08 Aug 2006 19:02:58 GMT
I forgot to mention -- it seems that every JPA provider has been
compiled against a different version of the JPA spec, which is a
little obnoxious.  :)

Thanks,
     Aaron

On 8/8/06, Aaron Mulder <ammulder@alumni.princeton.edu> wrote:
> On 8/8/06, David Blevins <david.blevins@visi.com> wrote:
> > What approach are you taking to get this done?   I was thinking to do
> > App-managed EntityManagers, the EntityManagerFactories looked up
> > through JNDI, and available to both web apps and ejbs.
>
> First of all, the work I'm doing on this is mostly helping with the
> Geronimo integration... so I'm praying my JPA answers are sensible.
> :)
>
> So far the idea is to put an EntityManagerFactory in JNDI for each
> persistence unit at java:comp/env/jpa/(persistence-unit-name) .  The
> problem is that every component type in Geronimo uses a different
> GBean and attribute to hold the JNDI context.  It turns out that Jetty
> and Tomcat both use the same attribute name on the WebModule
> implementation, which makes that easy.  If you can contribute the
> knowhow for EJBs, that would be great -- we just figured web apps were
> the low hanging fruit for JPA.
>
> > You make a note about working on an OpenJPA provider, which makes me
> > wonder.  The way a JPA provider is plugged in is standard, so you
> > shouldn't need to write support for a particular provider.  Any
> > details on why that would be required in the code you're working on?
>
> Form a user perspective, it's mainly the necessary configuration
> options and documentation.  But on the back end, I expect there's
> going to be one JPA plugin with the core logic, and then separate ones
> for each provider that set up the class path for that provider and
> register with the main JPA plugin.  We haven't yet worked out that
> part, but to give a trivial example, Hibernate dies with some kind of
> XML gripe if we just add it as a dependency of the current JPA plugin
> and try to use it.  So there's going to be some amount of work to get
> each provider fully integrated as far as I can tell.
>
> > Regardless, I'm glad I'm not the only one working on this :)
>
> I'll get our code onto SourceForge soon, so this can be a less
> theoretical discussion.  :)  In the mean time, have you had any better
> ideas as to how to read the persistence.xml and write GBeans into the
> web app than to reload and rewrite the serialized Configuration after
> the main web app deployer finishes?
>
> Thanks,
>      Aaron
>

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