Torque and EJBs

["Gonzalo A. Diethelm" <go...@aditiva.com>]

Disclaimer: I know EJBs are generally disliked in this
forum (I dislike them myself). My question is more from
a tool capabilities point of view.

I just started (believe it or not) to look into what the
EJB architecture is all about, and I think I have now a
basic understanding of what Enterprise Beans are, their
types, how to program them, etc. Several questions popped
into my head while doing this study:

* Many people seem to agree on the inefficiency of entity
  beans, specially for massive operations. It looks as if
  CMP beans (i.e., those where the OR mapping is automatically
  handled) are specially non-performant. Now, say you decide
  to only use Entity beans when necessary, and then, only
  BMP beans (where you manually write the OR mapping). Could
  torque generated classes be used for this part of a BMP bean?
  Even more, could Torque generate the whole Bean class?

* There are several interfaces and/or classes (at least 3) to
  be more or less hand-written when creating an EJB. Some of
  the methods for these classes could be automatically generated
  from a higher level bean description (I guess this is what
  some of those fancy IDEs do). Has anybody thought about using
  Torque (Texen?) to generate these classes? The nice thing
  about such a tool is that you might be able to define a more
  sophisticated set of classes implementing an EJB (say, because
  you create a factory, and use a base class for BMP and CMP,
  or whatever); the tool could adjust to your needs simply
  by providing it with different Velocity templates, right?

Just thinking aloud,


-- 
Gonzalo A. Diethelm
gonzalo.diethelm@aditiva.com


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Re: Torque and EJBs

[James Taylor <jt...@4lane.com>]

> * Many people seem to agree on the inefficiency of entity
>   beans, specially for massive operations. It looks as if
>   CMP beans (i.e., those where the OR mapping is automatically
>   handled) are specially non-performant. Now, say you decide

It really depends on the vendor. They don't have to be slower than any
other O/R mapping solution, other than the overhead imposed by being
cluster safe and such. Most of the claims about the performance of
entity beans are comparing them to hand tuned SQL for data manipulation,
where any solution that abstracts the SQL is going to be slower. At
least in the case of EJB you can scale to more machines, which is not an
option for many O/R mappers (Torque falls into this category right now,
OJB is the only free offering I know of that offers clustering).

With 2.0 EJB may not be as slow as you think. If performance were the
only concern I'd probably be using it myself! However in my current
project we have actually abandoned EJB because of the complexity in
development, deployment, and maintenance. We decided (after dealing with
EJB on our last project) that it took too long to develop for too little
benefit. The fact that it is vastly faster (JCS helps a lot here) is
only a bonus.

But this wasn't really meant to be about EJB... =] 

>   to only use Entity beans when necessary, and then, only
>   BMP beans (where you manually write the OR mapping). Could
>   torque generated classes be used for this part of a BMP bean?
>   Even more, could Torque generate the whole Bean class?

Sure, a lot of people use an O/R mapper when implementing BMP, there is
no reason why torque couldn't be adapted to this situation, or even be
made to generate BMP classes.

In practice I expect you would find this not to be faster than CMP. EJB
has come a long way and there are now CMP 2.0 solutions which are quite
fast since the are optimized for the EJB use case.

> * There are several interfaces and/or classes (at least 3) to
>   be more or less hand-written when creating an EJB. Some of
>   the methods for these classes could be automatically generated
>   from a higher level bean description (I guess this is what
>   some of those fancy IDEs do). Has anybody thought about using
>   Torque (Texen?) to generate these classes? The nice thing
>   about such a tool is that you might be able to define a more
>   sophisticated set of classes implementing an EJB (say, because
>   you create a factory, and use a base class for BMP and CMP,
>   or whatever); the tool could adjust to your needs simply
>   by providing it with different Velocity templates, right?

Sure, but there are already some good solutions for this problem.
Particularly on the doclet front -- XDoclet / EJBDoclet are really nice
offerings which allow you to write all types of EJBs with one class per
bean. 

That said, you could certainly get more flexibility using a velocity +
code generation approach if there were a need, but I suspect that the
doclet solution is flexible enough for most people's needs.

YMMV of course, I'm by no means an EJB or O/R mapping expert. That and I
neither use Torque nor pay close attention to it. 

-- jt


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