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From Michael Dick <michael.d.d...@gmail.com>
Subject Re: OpenJPA and GWT Serialization
Date Mon, 11 Apr 2011 14:22:01 GMT
Hi Jason,

Detachment and proxy classes are fairly complicated in OpenJPA. Like Rick
mentioned I've started looking at what it'd take to remove the proxies and
it's turned into a more sizable effort than I'd hoped.

OpenJPA was originally designed with JEE application servers in mind and it
answers that need well. Geronimo, WebSphere, and at least some versions of
WebLogic use OpenJPA as the basis for their persistence framework.

Outside of that area OpenJPA may require some massaging.

There has been some work done with GWT. The OpenTrader example :
http://openjpa.apache.org/opentrader.html uses some parts of GWT, but the
documentation is a little light in places. The source code is available
though, and may be of some help (I have no experience with GWT and can't
really judge).

HTH
-mike

On Sat, Apr 9, 2011 at 6:18 PM, Jason Ferguson <fergusonjason@gmail.com>wrote:

> I'm running with 2.1.0.  I figured if I was going to learn to use JPA
> versus Hibernate, I may as well use the most current version.
>
> So let me see if I'm doing this right. I added the following property
> to persistence.xml:
>
> <property name="openjpa.DetachState" value="loaded(LiteAutoDetach=true)" />
>
> The docs seem to recommend adding a version field, which I haven't
> done yet. I also choose "loaded" versus "fetch-group" because I hadn't
> defined any custom fetch groups.
>
> With no offense intended towards the developers, I'm getting the
> impression that OpenJPA is currently not the right choice for a GWT
> project, until this particular issue is resolved.
>
> Jason
>
>
> On Sat, Apr 9, 2011 at 7:43 AM, Rick Curtis <curtisr7@gmail.com> wrote:
> > Jason -
> >
> >> Sorry if this is a frequently asked question.
> > This isn't a frequent question... yet. It seems that this issue has come
> up
> > a number of times on users/dev. There was a recent post[1] on a similar
> > issue that didn't end with much of a solution. Mike has had this
> > detach/proxy business on his list of things he wanted to do for quite a
> > time... :-)
> >
> > What version of OpenJPA are you running with?
> >
> > If you're running 2.0.0 or later and you're in need of a workaround in
> the
> > short term.... and depending on how your application is structured,
> enabling
> > LiteAutoDetach[2] might get you by this problem. The only reason I'm
> > suggesting this property as I know that it will remove all proxies on
> > EntityManager.close().
> >
> > [1] http://openjpa.markmail.org/thread/sczpivhncne27co4
> > [2]
> >
> http://openjpa.apache.org/builds/latest/docs/manual/manual.html#ref_guide_detach_state---
> > openjpa.DetachState=loaded(LiteAutoDetach=true)
> >
> > Thanks,
> > Rick
> >
> > On Sat, Apr 9, 2011 at 6:55 AM, Jason Ferguson <fergusonjason@gmail.com
> >wrote:
> >
> >> Sorry if this is a frequently asked question.
> >>
> >> I have an entity, Location, which has a bidirectional
> >> OneToMany/ManyToOne relationship with another entity, BorderPoint.
> >> Both entities implement Serializable and IsSerializable.
> >>
> >> The BorderPoint collection within the Location object is an ArrayList.
> >> Unfortunately, OpenJPA uses a proxy class which is not serializable by
> >> GWT. I've tried annotating both entities with
> >> @DetachedState(enabled=true) with no luck.
> >>
> >> Can anyone assist?
> >>
> >> Jason
> >>
> >
>

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