Hi Jarek,
I completely agree that this is something we want the Aries JPA container to
cover, but there are a number of issues when considering WABs as persistence
bundles. WABs are simply a special type of WAR file, and WAR files already have
well defined behaviour when interacting with a JPA container. This behaviour
includes injection of JPA resources into servlets, and scanning of particular
locations for persistence descriptors. These behaviours are not described in an
OSGi environment, and do not directly map to the JPA service specification. For
example should a WAB have to specify a Meta-Persitence header to be scanned or
should it follow a Java EE style extension policy?
I wanted to leave these decisions until after the OSGi Enterprise Specification
release (which was last week) so these issues could be discussed on the list. I
will be intermittently available until April 21st, so I propose postponing
further implementation discussion until then.
To further clarify, I absolutely agree with the Geronimo use case, and it has
always been my intention for that to be a first-class mechanism for using
managed JPA in OSGi. I simply thought that it would be better to get the
"simple" situations into the first release without tying our hands for the more
difficult Java EE cases.
Regards,
Tim
> Date: Mon, 29 Mar 2010 23:56:03 -0400
> Subject: Re: JPA & WAB question
> From: [email protected]
> To: [email protected]
>
> Valentin, Tim,
>
> So because there is no integration for web container, the JPA extender
> is ignoring the WABs? If so, that seems weird. Just because there is
> no integration, JPA shouldn't ignore the bundles. We might provide
> that integration in Geronimo but we need the JPA extender to process
> the persistence.xml resources. Unless of course I'm still missing or
> misunderstanding something.
>
> Jarek
>
> On Mon, Mar 29, 2010 at 10:09 AM, Timothy Ward <[email protected]>
> wrote:
> >
> > Hi Jarek,
> >
> > The JPA service specification does not cover any form of managed JPA. The
> > Aries JPA code is not an implementation of the JPA service specification,
> > but attempts to use concepts defined by that specification to provide
> > managed JPA in an OSGi environment. This should hopefully feed back into
> > future versions of the OSGi service specification.
> >
> > Currently, as Valentin points out, there is no integration mechanism that
> > we can use to plug the Aries JPA container into a web container to provide
> > injection into servlets. We felt it safer to temporarily disable WAB
> > persistence units in the Aries container until such support was available.
> > We also need to consider the case where the web container already has JEE
> > style support for WAR persistence units.
> >
> > I hope to be able to write a plugin for the Pax webcontainer to demonstrate
> > how integration can be supported through the existing injection plugin
> > (used by the blueprint integration layer). This should not be a difficult
> > task, and I would hope that porting the code to other web containers is
> > trivial. Once this support is present I would have no issue with removing
> > the restriction in the Aries JPA container.
> >
> > I too would like to hear your use case, as it should be useful in driving
> > further implementation of the JPA web container integration.
> >
> > Regards,
> >
> > Tim
> >
> > ----------------------------------------
> >> From: [email protected]
> >> To: [email protected]
> >> Subject: Re: JPA & WAB question
> >> Date: Fri, 26 Mar 2010 07:05:34 +0000
> >>
> >> Hi Jarek,
> >>
> >> that is correct, the OSGi JPA spec is agnostic of web bundles
> >> altogether.
> >>
> >> Now, in a servlet 2.5 webcontainer there are certain assumptions a
> >> developer can make about how JPA works, including say injecting
> >> persistence contexts. These we cannot satisfy from the Aries JPA
> >> container. Instead this kind of support needs to be provided chiefly
> >> by the webcontainer. Hence, as an initial starting point Tim and I
> >> have decided to explicitly exclude WABs from being handled by our JPA
> >> container. (Maybe the message should read "JPA support for WABs is not
> >> covered by the OSGi JPA specification" to be clearer?)
> >>
> >> The plan is then hopefully to reuse bits of our JPA container
> >> implementation to facilitate adding JPA functionality to any given
> >> OSGi webcontainer. Have you got a use case in mind for Geronimo?
> >>
> >> Regards,
> >>
> >> Valentin
> >>
> >> On 26 Mar 2010, at 04:50, Jarek Gawor wrote:
> >>
> >>> Hi,
> >>>
> >>> The Aries OSGi JPA implementation claims that "WABs that use JPA are
> >>> not supported as part of the OSGi JPA specification". I can't find any
> >>> such text in the OSGi JPA spec. Does anybody know where that's
> >>> described or why that is?
> >>>
> >>> Thanks,
> >>> Jarek
> >>
> >
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