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From Chris Rauschuber <crauschu...@yahoo.com>
Subject Re: [persistence] Some thoughts regarding CMP and JDO
Date Fri, 08 Aug 2003 03:09:21 GMT
Hello Dain and Geronimo,

If there is a need for persistence to LDAP, please take a look at
http://jellyfish.sourceforge.net, a JDO-like persistence mechanism for
LDAP.  We'd be happy to coordinate with you if you're interested.

Regards,
Chris Rauschuber

> > Dain Sundstrom wrote:
> >
> >> Hello Thomas (and the rest of the OJB team),
> >>
> >> Jeremy Boynes and I (and a few others) wrote the CMP 2.0 
> >> implementation in JBoss, and we have been working on the
> persistence 
> >> code in the initial Geronimo code base.
> >>
> >> There is some code right now (a compiler and sql generator) and a 
> >> fairly extensive design, but it looks like we have similar
> designs.  
> >> The design is fairly simple from the high level.  We will support 
> >> several front end layers simultaneously at runtime (CMP, JDO,
> maybe 
> >> Hibernate, heck maybe SQL).   The job of the front end layer is to
> 
> >> handle the life-cycle and callbacks required by the related 
> >> specification, but all real work will be delegated to a
> centralized 
> >> persistence service.  This persistence service handles caching, 
> >> locking, versioning, clustering and so on.  When persistence
> service 
> >> actually needs to manipulate data it delegates to a store manager 
> >> service.  The target initial store managers include SQL 92, SQL
> 99, 
> >> Oracle (which is not really SQL), file based (XML maybe), and we
> have 
> >> plans to add LDAP, clustered database layer and some legacy
> systems.  
> >> The following ASCI picture sums this up (if it comes through):
> >>
> >>                 ---------------
> >> CMP ----------> |             | ------> SQL
> >> JDP ----------> | persistence | ------> Oracle
> >> Hibernate ----> | manager     | ------> LDAP
> >>                 |             | ------> CICS (whatever)
> >>                 ---------------
> >>
> >> Now the persistence manager has a huge job, so it is broken down
> into 
> >> plugins for caching, locking and so on, which effectively  makes
> the 
> >> persistence manager just a coordinator of the plugins.
> >>
> >> Anyway, this is getting a little too technical for right now, 
> >> considering the initial code doesn't even have Entity beans.  From
> 
> >> what I have seen, we have a similar vision, and I think we should 
> >> talk about merging our efforts into a common persistence engine 
> >> (maybe we can even get Gavin and the Hibernate team to sync up
> with 
> >> us).  I think it would be really positive for Java to at least
> have 
> >> all of us at least talking so our systems can play well together,
> but 
> >> if we joined forces....  :D
> >>
> >> -dain
> >>
> >>


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