Hi Ryan,

>> The effect of which is to make a transparent 
>> layer to store data adhering to a common schema on different 
>> physical databases.  The business logic would be totally 
>> unaware that it's going to different places to get it's data. 
>>  If I write my own ConnectionFactory this would be pretty 
>> easy to do, however I'd really like to be able to use OJB so 
>> that we don't waste weeks of time writing O/R classes by 
>> hand.  From what I can tell, OJB doesn't really support what 
>> I want to do.. 

> OJB *does* allow to work simultaneously with multiple databases!
> It does *not* provide a 2 phase commit mechanism to synchronize 
> the transactions against all these databases. This must be done 
> in user code!

Of course, if you have a managed environment, JTA would provide 2-phase
commit and OJB does work in a managed environment.

Raghu.


-----Original Message-----
From: Mahler Thomas [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, January 14, 2003 7:41 AM
To: 'OJB Users List'
Subject: AW: OJB C/S


Hi Ryan,

> Hello,
> 
> I have been evaluating OJB for use in our next application 
> and have a couple questions that I hope someone can answer.  
> I've already read through the archives (at least those that 
> matched my query) and saw some disappointing news.  However, 
> I want to see if there may be a way around it.
> 
> Basically we have a very large database and run a large 
> number of online transactions against it.  In the next 
> version, we plan to 'roll-our-own' DB clustering for 
> scalability reasons.  We like to be able to partition user 
> records across multiple DB instances based upon a hashing 
> algorithm.  

'Roll-your-own' could be quite a risk in this context!
RDBMS like Oracle or DB2 provide native clustering techniques. 
I would always recommend to use these features!

> The effect of which is to make a transparent 
> layer to store data adhering to a common schema on different 
> physical databases.  The business logic would be totally 
> unaware that it's going to different places to get it's data. 
>  If I write my own ConnectionFactory this would be pretty 
> easy to do, however I'd really like to be able to use OJB so 
> that we don't waste weeks of time writing O/R classes by 
> hand.  From what I can tell, OJB doesn't really support what 
> I want to do.. 

OJB *does* allow to work simultaneously with multiple databases!
It does *not* provide a 2 phase commit mechanism to synchronize the
transactions against all these databases. This must be done in user code!

> worse, it appears (from the list archives) 
> that even the described client/server functionality doesn't 
> work.  

Correct c/s mode is currently out of order. But I don't see any reason why
you should rely on c/s mode in your application scenario?

> Since this is a production system with paying 
> customers, should I abandon OJB and go for another solution?

1. I don't know of any other o/r tool that does this kind of job
2. If you have paying customers, let them buy a database with built in
clustering support!

cheers,
Thomas

> 
> Thanks,
> 
> Ryan Clifton
> Systems Engineering Manager
> 


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