EJB specifications

Hi,
I know all the concepts of EJB. But I haven't read EJB specs yet. What I want to know from you is:
1. Are the app deployment specifications the same for every app server.
That is, in Weblogic, I have to use WEB-INF dir which has web.xml folder, and the app root directory has a .war file(for web apps)
If I want to deploy my bean in Websphere, is the directory structure same?
This takes me back to my original question, are there specs by sun as to how to name the directories and deployment descriptors.
2. How easy/tough is it to move my app from one server to another server(in terms ofthe knowledge that I would require. I know that EJBs can be moved from one server to another server without making any changes in the code).
Thanks,
Chandana

The structure of an .ear is always the same, as is the structure of a .war. However, this does not mean that the applications are portable as such.
First of all, each application server vendor has the option of using a vendor-specific deployment descriptor for a J2EE module, which obviously isn't portable.
Second, there are some differences in how the application interacts with the container. For example, some application servers have some constraints on how a JNDI name should look like. You should take a look at TSS' clustering experiences to see examples of real-life portability issues.

One of the other major pains in migrating between Application Servers is the difference in class loading.

Chris is back.

Originally posted by Pradeep Bhat:
Chris is back.

Yes, after an extended sabbatical I have returned! Unlike Lasse, I have made a resolution to spend more time on the Ranch over the next year. Just don't tell my wife or kids!

Thanks for noticing Pradeep... now where is that emoticon for the smiley with a tear in its eye when you need it?

Chris, I am still waiting for your JMX article?