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Date: Fri, 11 Aug 2006 20:23:46 -0600
From: Jeff Genender <jgenender@apache.org>
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To: dev@geronimo.apache.org
Subject: Re: JPA plugin (was Re: Java 1.4 and JEE 5)
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Aaron Mulder wrote:
> On 8/11/06, Jeff Genender <jgenender@apache.org> wrote:
>> Isn't this the same problem we (and other app servers) have with Spring
>> and Commons Logging?  If you are duplicating the persistence units, then
>> it should be handled the same way its handled for Spring, yes?
> 
> What way is that?

Server --> EAR --> WAR

Based upon the delegation model, the version of Commons Logging or
Spring was utilized at the Server or EAR level if it existed.  The issue
was that the Spring calls would utilize the Server/EAR (since already
loaded) and the WAR calls would get CNFEs since the server/EAR had no
downward view into the WAR.  Thus our reason to play with the filtering
of classes for modules.

With regard to duplicating PUs, in theory, it shouldn't make a
difference if the PU was already loaded in a parent loader.  But unless
the spi jar uses some sort of mechanism using static declarations or
componanents like Spring, then it really shouldn't be an issue.  If it
is, I think its reasonable to claim storage of duplicate PUs in the same
package causing the problem (again, like the Spring Commons Logging
problem).

> 
> Thanks,
>     Aaron
> 
>> Aaron Mulder wrote:
>> > So what happens if an EJB JAR has a persistence.xml and a web app in
>> > the same EAR has a separate persistence.xml?  If we just look in the
>> > class loader, when we go to deploy the web app, we'll see them both
>> > because the EJB JAR is added to the parent classpath of the WAR.  Is
>> > there a good way to distinguish "resource in my ClassLoader" from
>> > "resources in my ClassLoader tree"?
>> >
>> > Thanks,
>> >     Aaron
>>