Ray,

This is an important question, which I discuss in Chapter 2.

Swapping app servers as you describe happens fairly often, for such
political reasons. It's not disastrous, but I don't recommend it. You
probably won't need to change much of your code (possibly none at all if
your proof of concept is simple), but you will need to understand the
development and deployment issues on both servers, which may be complex. So
you will end up duplicating some effort. For example, each server uses its
own proprietary deployment descriptor format. You'll need to understand this
for each or use tools provided by the server.

Hence I recommend choosing an app server as early as possible in the project
lifecycle. But yes, J2EE applications are portable and it is possible to
swap later.

JBoss or Orion would be a good choice if you want an easy-to-use app server
to start your project on.

If your application doesn't use EJB (and deciding whether to use EJB is
another important question discussed in the book) it will be much easier to
swap between app servers.  Your database access strategy (JDBC, entity
beans, JDO etc.) will also have an impact: the more reliant you are on EJB
container services such as entity bean CMP, the harder migration between
servers will be.

Regards,
Rod

----- Original Message -----
From: "Ray Murphy" <raymurphy@g...>
To: "ExpertJ2EE with RodJohnson" <expertj2ee_with_rodjohnson@p...>
Sent: Saturday, October 19, 2002 11:49 PM
Subject: [expertj2ee_with_rodjohnson] Application Servers in J2EE
Applications


> Having just read the sample chapter for the book, it seems sufficently
> detailed to suggest the book itself may be worth buying.
>
> I'm just becoming involved in a J2EE project, but our objectives so far
> will be limited to producing a proof-of-concept .... For political reasons
> (stemming from implementation of another Java project), the client is
> committed to using Websphere as the application server. Not having looked
> at Websphere yet, this in itself is not a concern, but I do have one
> question about the significance of the choice of application server in a
> J2EE application - having chosen one specific application server for your
> application (be it Websphere, WebLogic or whatever ..) how easy would it
> be to change to another application server later on during your
> development ?
>
> Thanks.
>
> Ray
>