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From David Jencks <>
Subject Re: Daytrader EJB3 development
Date Thu, 08 Mar 2007 15:34:11 GMT

On Mar 8, 2007, at 9:48 AM, Christopher Blythe wrote:

> All...
> Thanks to the efforts of David Jencks, Daytrader 2.0 (trunk)  
> already contains a JPA-based implementation of the Trade services  
> wrapped in an EJB 2.1 stateless session bean. As additional EJB3  
> and EE5 features are delivered in Geronimo (and other appservers),  
> Daytrader should follow suit by exploiting the entire EJB3 and EE5  
> programming model. This would primarily involve conversion of the  
> stateless session beans and MDBs to EJB3. I have already begun some  
> of this work using another development platform that already  
> supports EE5.
> For the time being, I think a direct port of the code from J2EE 1.4  
> to EE5 standards is essential, without changing any of the  
> fundamental business logic. From a performance standpoint, this  
> would provide the best measure of how well an EE5 application  
> stacks up against it's 1.4 counterpart.
> In this EE5 version I foresee 3 modes of operation...
> - Direct (JDBC)
> - Session Direct (EJB3 Session to JDBC)
> - Full EJB (EJB3 Session to EJB3 Entities)
> Nevertheless, I was wondering if an additional JPA mode would be of  
> interest? Based on my understanding of the relationship between JPA  
> and EJB3, the separating factor between the two is the scope of the  
> EntityManager (either application-based or container-based).  
> Consequently, would some form of JPA mode (using an application- 
> based EntityManager) provide a useful comparison?

I can think of 3 more JPA modes:

1. App managed JPA from ejb3
2. container managed JPA from web (using UserTransaction for  
transaction demarcation)
3. App managed JPA from web.

I'd be mostly interested in (2) but that doesn't mean it's most  
important or interesting for anyone else.

thanks for working on this!

david jencks

> Looking a little farther down the road, here are a few other things  
> I see on the horizon...
> - Java6 and JDBC 4.0 (How will this impact direct mode?)
> - At some point, some wholesale changes to the business objects and  
> model should be made to place more demand on the application server  
> and not the database. These changes should also reflect the latest  
> trends in Web 2.0 application development practices. The AJAX/Dojo- 
> based interface that was recently added is a start; however, I feel  
> that more effort is needed here.
> I guess that's all for now... Let's see where this leads us...  
> Questions, thoughts, comments or snide remarks?
> Chris
> -- 
> "I say never be complete, I say stop being perfect, I say let...  
> lets evolve, let the chips fall where they may." - Tyler Durden

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