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From "Hans J. Prueller" <hans.pruel...@gmx.net>
Subject AW: AW: other appserver/ejb2.1 to geronimo 2.0 migration strategy?
Date Thu, 25 Jan 2007 19:17:41 GMT
>> entity beans with cmr can you still migrate them one by one or do you 
>> have to migrate the entire tree of objects?

if I want to migrate one by one, I think I'll have to break up the CMR
relations anyway, that’s right.

> I'm not understanding what you are saying here.  Geronimo 1.2 (not
> quite released yet) includes jpa support and runs on jdk 1.5 only but
> is (or will be) a j2ee 1.4 app server.  In particular the jpa
> annotations all work fine (with openjpa).

yes, but if I want to deploy the existing CMP2.X EB's to Geronimo first,
I'll have to write the full blown mapping file, in this case XDoclet
would ease things like Annotations do with Java5 and JPA.

But to point it out:

I found another .ear application which is rather small sized (ca. 5 CMP
EB's, 2 SLSB's). I will try to use this simple project as an "evaluation
run" about migrating to Geronimo. So if I'd like to start migration of
this app what would you suggest: start right with Geronimo 2.0 or start
with 2.1 - will there be major upgrading issues from G1.2 to G2.0???

I think I'll start to migrate the existing Java EE 1.4 .ear 1:1 to Geronimo
and check out what has to be done and how it works..

regards,
Hans

> -----Ursprüngliche Nachricht-----
> Von: David Jencks [mailto:david_jencks@yahoo.com]
> Gesendet: Donnerstag, 25. Jänner 2007 17:46
> An: user@geronimo.apache.org
> Betreff: Re: AW: other appserver/ejb2.1 to geronimo 2.0 migration
> strategy?
> 
> 
> On Jan 25, 2007, at 1:47 AM, Hans J. Prueller wrote:
> 
> > David,
> >
> >
> >
> > thank you for your thoughts. You provided good entry points for me.
> > I mentioned hibernate specifically because
> >
> > we already are using hibernate and CMP in parallel within our
> > project (as CMP2.x sometimes does not fulfill all needs).
> >
> >
> >
> > targeting JPA instead of hibernate specifically is essential –thank
> > you for that.
> >
> >
> >
> > I also would like to do a one-by-one migration because I am afraid
> > if we would migrate the whole project at once,
> >
> > everything could collapse. Doing smaller steps provides more
> > control I think.
> 
> That's easy to understand :-).  However if you have entity beans with
> cmr can you still migrate them one by one or do you have to migrate
> the entire tree of objects?
> >
> >
> > >> However this would mean that you would need to start by
> > generating the cmp2 mapping info.
> >
> >
> >
> > so this is what should to be contained in the Geronimo deployment
> > plan right? are deployment plans required also
> >
> > in Geronimo2 ? (I think there shouldn’t be any more “vendor”
> > specific DDs in Java EE 5). But for compatibility reasons
> >
> > with my EJB2.1 CMP beans I think I won’t come around to provide a
> > mapping file at all ;-)
> I suspect that some plans will still be needed to specify things like
> datasource configuration.
> 
> I was wondering if it would be practical to run your app on geronimo
> while it was being converted: I suspect not because you would need to
> have the cmp2 mapping info in a form geronimo could understand, and
> producing that would probably be harder than migrating to jpa directly.
> 
> > I asked about XDoclet support for Geronimo some months ago, at that
> > point in time there was no usable version around.
> >
> > As Java 2 EE 1.4 requires Java 1.4 I cannot work with annotations
> > unless the whole app is migrated, so XDoclet would
> >
> > be of great help…?
> I'm not understanding what you are saying here.  Geronimo 1.2 (not
> quite released yet) includes jpa support and runs on jdk 1.5 only but
> is (or will be) a j2ee 1.4 app server.  In particular the jpa
> annotations all work fine (with openjpa).
> 
> thanks
> david jencks
> 
> >
> >
> > regards,
> >
> > Hans
> >
> >
> >
> > Von: David Jencks [mailto:david_jencks@yahoo.com]
> > Gesendet: Donnerstag, 25. Jänner 2007 09:24
> > An: user@geronimo.apache.org
> > Betreff: Re: other appserver/ejb2.1 to geronimo 2.0 migration
> > strategy?
> >
> >
> >
> >
> >
> > On Jan 24, 2007, at 10:15 PM, Hans J. Prueller wrote:
> >
> >
> >
> >
> > hi together,
> >
> >
> >
> > I have been working with the JOnAS Java 2 EE application server for
> > about 5 years now, meanwhile
> >
> > I have several projects, one of them is rather big already, it
> > contains about 60-70 EJB’s, two thirds
> >
> > of them are CMP/CMR’ed entity beans, the rest stateless session beans.
> >
> >
> >
> > I am thinking about migrating these projects to Geronimo for some
> > months now, and I decided to
> >
> > wait for the first Java EE 5 release of Geronimo (Geronimo 2) – as
> > it will be released within the
> >
> > near future I would be interested in which migration strategies you
> > could suggest?
> >
> >
> >
> > I think the most problematic part will be to migrate the ca. 50 CMP
> > entity beans, there are a lot
> >
> > of EJB-QL finders and all of those beans are inter-related with CMR.
> >
> >
> >
> > Currently I’m thinking of doing a “soft” migration, i.e. migrating
> > 1 by 1 of those EB’s within the
> >
> > currenty architecture from CMP to hibernate, and after that
> > performing the move to Geronimo (which will
> >
> > mean that then only the session beans will have to be migrated
> > which should be less problematic).
> >
> >
> >
> > First of all I would target JPA rather than Hibernate specifically.
> >
> >
> >
> > Second, IIUC Dain has reimplemented CMP2 in openejb3 so it is
> > backed by openjpa.  This should mean that you could migrate the
> > entity beans one at a time and have coherent caching between the
> > jpa pojos and cmp entity beans.  However this would mean that you
> > would need to start by generating the cmp2 mapping info.
> >
> >
> >
> > I converted daytrader from entity beans to jpa very quickly.  It
> > was fairly easy because there were already data objects that hold
> > (most of) the same data that the entity beans hold.  I just added
> > annotations to the data beans and added the relationships (that had
> > been left out of the data beans for some reason).  If your
> > application already has something like a pojo data model layer it
> > would probably be easiest to simply start annotating the data
> > classes and drop the entity beans.
> >
> >
> >
> > Daytrader is not quite a toy app but it's much smaller than your
> > application so my results may not map directly to your situation.
> >
> >
> >
> > thanks
> >
> > david jencks
> >
> >
> >
> >
> >
> >
> > what do you think about that?
> >
> >
> >
> > Anybody already migrated large CMP/CMR apps to Geronimo?
> >
> >
> >
> > regards,
> >
> > Hans
> >
> >
> >
> > ===========================
> > virtually hanzz...
> >
> >
> >
> > http://hanzz.zapto.org (personal)
> > http://www.cse.dmu.ac.uk/~hansp (research)
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >


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