RE: [Springframework-developer] EJBs vs POJOs

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Dmitriy,
        I haven't had a chance to look at Spring EJB support as yet but =
it sounds
interesting, Will be reading about Spring support this weekend. IDEs =
such as JBuilder
makes EJB development very easy, testing aside, is Spring EJB support =
easier to code
than straight EJBs?=20
=20
Paul=20
=20

=20

-----Original Message-----
From: spr...@li... =
[mailto:spr...@li...]On Behalf =
Of Dmitriy Kopylenko
Sent: Thursday, April 21, 2005 6:25 PM
To: spr...@li...
Subject: Re: [Springframework-developer] EJBs vs POJOs

To put simply - if you absolutely require to physically distribute your =
application, EJB (SLSB facade) would probably be the good choice here. =
Please note that you still would want to use Spring-EJB support as it =
transparently exposes your POJO business interfaces as EJB =
implementations (via proxies) and also frees the application code from =
low level plumbing code related to EJB programming model e.g. JNDI =
lookups, etc. Coupled with IoC container (for DI) you get easy testable =
code with minimal dependence on EJB container.

Regards,
Dmitriy.

Garvey, Paul M (GE Commercial Finance) wrote:=20

James,

      Your response was insightful and you did partially answered my =
question.

Let me try to be a bit clearer, If I had to create an application that =
needed to

be distributed across multiple machines I would normally use EJBs =
(stateless Bean + Entity Beans)

or (stateless beans + DAOs) or (stateless beans + hibernate) etc. Could =
I use Spring

in this senario? Would it make more sense to stick with the EJB =
paradigm? I want to have a clear picture=20

in my mind of when to use Spring on a project and when to use EJBs. In =
other words,=20

when does it make most sense to use EJBs instead of Spring and vice =
versa?

Are there times when Spring is just not the solution to the problem and =
EBJ is?

Paul

-----Original Message-----

From:  spr...@li...

[ mailto:spr...@li...]On Behalf

Of James Cook

Sent: Thursday, April 21, 2005 5:25 PM

To:  spr...@li...

Subject: RE: [Springframework-developer] EJBs vs POJOs

Spring simply provides a convenient fa=E7ade to other persistence

implementations, including EJB!

You may have meant Entity Beans when you stated EJB. If so, another

way of wording your question is, "Are there cases when EJB is

preferred as a persistence mechanism over a POJO persistence

(Hibernate, TopLink, iBatis, JDO, EJB3, and dozens of others)

mechanism?"

Take these with a grain of salt, since I don't have hands-on

experience with all of the POJO persistence mechanisms. A few benefits

don't come easily to the world of POJO persistence.

a) POJO-based approaches (AFAIK) with the exception of EJB3, do not

support distributed security contexts. Even if you were writing an EJB

implementation, you would want to limit the number of network calls

your app has to make. But if you really have part of your application

on one machine, and part on another, you can invoke EJB's on the

various machines and remain within the same security context.

b) Clustered sessions are still the realm of the J2EE container.

Distributed caching of persistent object between machines is difficult

to achieve using POJO persistence.

c) Support for CORBA clients is a standard feature of J2EE.

There may be more. Of course, EJB3 will probably turn this discussion

on its ear.

If I totally missed your point, and you just wanted to know if Spring

provided lightweight (sorry Hani) alternatives for the specification

components that make up Enterprise Java Beans (EJB), namely:

- Stateless Session Bean (yes, via service interfaces, pojos you write)

- Stateful Session Bean (no)

- Entity Bean (yes, via Hibernate, TopLink, iBatis, JDO passthrus)

- Message Driven Bean (No, AFAIK)

- Timer Bean (yes, via quartz)

- Web Service Endpoints (yes, via http invoker, hessian, burlap, axis, =
maybe

others)

 =20

-----Original Message-----

From:  spr...@li...

[ mailto:spr...@li...] On=20

Behalf Of Garvey, Paul M (GE Commercial Finance)

Sent: Thursday, April 21, 2005 3:53 PM

To:  spr...@li...

Subject: [Springframework-developer] EJBs vs POJOs

All,

I fairly new to Spring and I am currently reading some documentation=20

on it. I have bought into the concept of the lightweight feature of=20

Spring. I do have a quick question, Springs seems to handle every=20

scenario that I would

use EJBs, is there a few cases where EJBs are unavoidable to use? In =
other

words

are there any scenarios where Spring is just not the best tool to use =
and

EJBs is

the more suited? Any thoughts?

Paul

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