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From "Christopher Blythe" <>
Subject Daytrader EJB3 development
Date Thu, 08 Mar 2007 14:48:23 GMT

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?

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
2.0application 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?


"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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