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From: =?iso-8859-1?Q?Emmanuel_L=E9charny?= <emmanuel.lecharny@wanadoo.com>
To: "Alex Blewitt" <Alex.Blewitt@ioshq.com>
Cc: <geronimo-dev@incubator.apache.org>
Subject: RE: Which EJB container? Which Web container?
Date: Thu, 7 Aug 2003 15:44:18 +0200
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> What I wanted to bring up was that it should be possible to run both in
> the same VM, rather than just going for the separate VM
> but-we-can-run-both-VMs-on-the-same-machine approach.

YES !!! If it was your point, I just perfectly agree with you.

> Yes, but older versions of WebSphere used to run them in separate
> processes.

WebSphere 3.5 and 3.0 had a JVM option to allow both containers to run on
the same JVM. I don't remember if it was possible on Websphre 2.0.

> -----Message d'origine-----
> De: Alex Blewitt [mailto:Alex.Blewitt@ioshq.com]
> Date: jeudi 7 ao�t 2003 15:06
> �: Emmanuel L�charny
> Cc: geronimo-dev@incubator.apache.org
> Objet: Re: Which EJB container? Which Web container?
>
>
> > IHMO, having a Web container running on the same JVM process than EJB
> > container should be an option. It can boost performances, but stucks
> > you in
> > an architecture that is not very easy to manage.
>
> I'm not sure that I agree with that by default. Yes, it may be
> desirable to have several Web applications talk to the same EJB
> components, but they can do that by JNDI anyway.
>
> In situations I've been in where that approach was chosen, they ran
> into problems with versioning of the EJB components. So yes, in theory,
> it's nice, but in practice having the EJB components and Web components
> in part of the same application guarantees that the versions between
> them are compatible. Administrators may shudder with the idea of
> updating an EJB component (even with a small change) that many web
> applications are depending on it may break with the 'newer' version and
> be a lot harder to fix (especially if they'd not saved the older
> version :-)
>
> > I like the idea to have a EJB server on a specific machine, and other
> > machines around the (internal) net talking to this EJB server. What if
> > you
> > change an EJB? You'll have to change all the Web Container (and you
> > can have
> > many Web container talking to a single EJB container). That means
> > possible
> > mistakes, that could be avoided by isolating this EJB Container from
> > Web
> > containers.
>
> You'd have to rebuild and/or redeploy the applications, yes. But I
> propose that this situation (where you have multiple Web apps using the
> same EJB apps) happens much less often than having a single Web app
> using a single EJB set.)
>
> Plus, the change of a single EJB may still break other Web apps that
> depend on it ... but that is obviously a management issue.
>
> > Of course, they are different situation where having a Web contaienr
> > and an
> > EJB container sharing the same JVM process could be the best solution.
>
> I'd propose that it would certainly be the best/default way (IMHO :-)
> for running an EAR that contains both WAR and EJB-JAR files.
>
> > So : make it optional.
>
> It could certainly come in useful if you want to architect the system
> you describe above, though with the obvious management
> advantages/disadvantages/caveat.
>
> > BTW, IBM allows you to do whatever you want : WEB container on a JVM
> > and EJB
> > container on another, or both containers on the same JVM, it's just a
> > parameter to set.
>
> Yes, but older versions of WebSphere used to run them in separate
> processes. Now they do allow running the EJBs and Wars in one process,
> and in fact the current best practices suggest to use them in one
> process rather than splitting them.
>
> So, when an EAR contains both WARs and EJB-Jars, deploy them in the
> same VM. But allow for a WAR to be run in a separate VM and EJB-Jar in
> a separate VM when deployed separately.
>
> What I wanted to bring up was that it should be possible to run both in
> the same VM, rather than just going for the separate VM
> but-we-can-run-both-VMs-on-the-same-machine approach.
>
> Alex.
>
>