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From Dain Sundstrom <d...@coredevelopers.net>
Subject Re: [persistence] Some thoughts regarding CMP and JDO
Date Fri, 08 Aug 2003 03:51:02 GMT
Cool.  I'll take a look at it.

-dain

On Thursday, August 7, 2003, at 10:09 PM, Chris Rauschuber wrote:

> 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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/*************************
  * Dain Sundstrom
  * Partner
  * Core Developers Network
  *************************/


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