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From "Hans J. Prueller" <hans.pruel...@gmx.net>
Subject AW: other appserver/ejb2.1 to geronimo 2.0 migration strategy?
Date Thu, 25 Jan 2007 09:47:02 GMT
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.

 

>> 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 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…?

 

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/> http://hanzz.zapto.org (personal)
 <http://www.cse.dmu.ac.uk/~hansp> http://www.cse.dmu.ac.uk/~hansp
(research)

 

 

 





 


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