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 shouldnt be any more vendor specific DDs in Java EE 5). But for compatibility reasons with my EJB2.1 CMP beans I think I wont 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:[EMAIL PROTECTED] 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 EJBs, two thirds of them are CMP/CMRed 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 Im thinking of doing a soft migration, i.e. migrating 1 by 1 of those EBs 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)
