In conformation of the previous postings, I have seen JMS being used while rmi
was a much
better alternative, and TCP/IP ( socket programming ) would have been a perfect
alternative.

For anybody interested in learning J2EE I would suggest learn and develop a very
deep
understanding of computer network programming in Java first before starting
J2EE.

Once you have a clear understanding of computer network programming in Java, you
will
find J2EE very easy to learn and understand.

I would suggest start with TCP/IP ( socket programming ), then learn rmi, JDBC,
IDL,
JNDI, JMS, etc.

I found following one of the best to learn from.

http://java.sun.com/docs/books/tutorial/