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From jcd <...@downinthedesert.com>
Subject Re: [persistence] Some thoughts regarding CMP and JDO
Date Fri, 08 Aug 2003 03:20:03 GMT
Aren't we, in some respects, getting a bit overzealous about the 
Persistence Tier?  Let's focus on getting the EJB life-cycle management 
and transaction hierarchies dialed and designed.  Why not gear efforts 
to the production of a solid BMP implementation with Connection, 
Datasource, and Transaction management - get that dialed and define a 
pluggable OPTIONALthird-party persistence interface.

What is the consensus out there regarding the use of BMP?  Is there any 
desire to have the ability to 'unplug' any/all container persistence 
services in exchange for a smaller footprint, lighter weight 
implementation?  Concentrating efforts on the basic EJB container 
services might well prove to be a quicker track to a stable, performing 
implementation that can be extended to accommodate the various 
persistence approaches at a later time.  It is my feeling that this 
approach could postpone much of the inevitable analysis paralysis that 
often accompanies 'The Persistence Debate."  Meanwhile, back at the 
ranch, Geronimo is beating his drums to early release victory.

Best,

John C. Dale
Professional Services
Compuware

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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