I have a coworker who has come to me asking for resources on understanding the J2EE architecture as a whole. That is, he has a basic understanding of what servlets and JSP's and EJB's are, but is having trouble finding info on how (and why) all the various technologies work together within the entire architecture. Given that most of my knowledge of j2ee has come in trial-by-fire situations, I wasn't able to fire anything off the top of my head to help him out.
I've started with a basic list: Sun's J2EE tutorial, the Head First line of books, etc. Are there any other resources (preferably online, but he is willing to buy a book or three if necessary) that give a solid overview of J2EE as a whole, rather than focusing on the individual components without describing how they interact?