I depends how you use the CMP. There are some issues that are related to the
spec. For example, some EJB servers allow mapping between beans and non-bean
"dependent objects". However the specification is not detailed in this area,
so these mappings are not portable. On the other hand a CMP implementation
where bean == table, and relationships are only bean to bean will probably
perform lousy.
One approach is to use an OR mapping tool that outputs BMP code, such as
Cocobase. This gives you flexible mapping, and portability across
containers. Cocobase for example supports GemStone/J, WebLogic, WebSphere
and some others I think.
Regards,
-Chris.
> -----Original Message-----
> From: Se Hee Lee [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, May 02, 2000 9:44 AM
> To: [EMAIL PROTECTED]
> Subject: Re: CMP vs. BMP (3rd try)
>
> How hard is it to deploy the CMP EJB in multiple application servers? What
> I
> am saying is, is it relatively painful to move from Weblogic or Gemstone,
> and vice versa with all the finder methods, etc? If this is not true, then
> I
> think it's more coding for BMP, but it's less headache for deployment
> which
> in turn pushes the development in that direction...
>
> Se Hee
>
> -->-----Original Message-----
> -->From: A mailing list for Enterprise JavaBeans development
> -->[mailto:[EMAIL PROTECTED]]On Behalf Of Karl Avedal
> -->Sent: Tuesday, May 02, 2000 5:01 AM
> -->To: [EMAIL PROTECTED]
> -->Subject: Re: CMP vs. BMP (3rd try)
> -->
> -->
> -->Hello Ingo,
> -->
> -->I'd like to even further summarize your comparison, since I
> -->think you do mention a
> -->few issues that should fall under the same category.
> -->
> -->Why use CMP?
> -->
> -->* Simplicity
> -->* Performance
> -->* Database portability
> -->
> -->Why use BMP?
> -->
> -->* Full control
> -->
> -->My conclusion is that BMP should only be used when you
> -->really do need full control,
> -->for any of the reasons you mention. Otherwise, use CMP.
> -->
> -->>
> -->> I have summerized the pros and cons regarding CMP and BMP
> -->from posings on
> -->> this list. Please send your comments, tell me if you have
> -->a different
> -->> opinion in certain points or if I missed something important.
> -->>
> -->> Pro BMP:
> -->> * Ability to express complex relationships among data.
> -->
> -->> Contra CMP:
> -->
> -->> * Difficult to use with complex database schema.
> -->
> -->I have to comment on this issue since I think it's often
> -->described as a bigger deal
> -->than it really is. I agree that CMP might not give you the
> -->control you need at all
> -->times, but in a decent container you can express pretty
> -->complex relationships.
> -->
> --><vendor>
> -->In the Orion Application Server you can have many kind of
> -->relationships between
> -->entities. You can (of course) keep entity bean references
> -->directly in another
> -->entity bean, but you can also keep a Collection of entity
> -->beans (or a List, a Map
> -->or a Set). This does provide pretty strong support for
> -->complex relationships. Of
> -->course, until this is standardized it will be dangerous to
> -->use, but this is a
> -->temporary problem.
> --></vendor>
> -->
> -->>
> -->> 1. Does a container, as a matter of principle, have more
> -->facilities to
> -->> optimize the persistence (e.g. only the container has
> -->knowledge which
> -->> other transactions are currently running -> run-time
> -->optimizations). If
> -->> yes, the consequence would be that sooner or later CMP
> -->_will_ be the
> -->> alternative with the best performance?
> -->>
> -->
> -->Yes, the more abstract the description is, the more the
> -->Container can step in and
> -->optimize things.
> -->
> -->This is of fundamental importance and is why HotSpot can
> -->perform so well and why
> -->it's hard to write assembler-code that is faster than the
> -->code generated by an
> -->optimizing C compiler. It's easier to optimize higher-level
> -->descriptions.
> -->
> -->>
> -->> 2. Are containers really not mature yet (in a sense that
> -->BMP is still much
> -->> faster than CMP)?
> -->>
> -->
> --><vendor>
> -->I can only speak for Orion, but in our tests, CMP is
> -->normally much faster than BMP
> -->today. I'm sure this is the case with some other servers
> -->too, and will be the case
> -->for all once they employ all possible optimizations.
> --></vendor>
> -->
> -->Regards,
> -->Karl Avedal
> -->The Orion team (http://www.orionserver.com)
> -->
> -->=============================================================
> -->==============
> -->To unsubscribe, send email to [EMAIL PROTECTED] and
> -->include in the body
> -->of the message "signoff EJB-INTEREST". For general help,
> -->send email to
> -->[EMAIL PROTECTED] and include in the body of the message "help".
> -->
> -->
>
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