Sessions are objects that exist within a
Java Virtual machine. Any time you're load balancing, you're going to be dealing with 2 different Java Virtual Machines, and what's in the memory of JVM 1 is totally invisible to JVM 2 and
vice versa.
When you use a clustering system like WebLogic provides, the sessions are serialized out to a common resource where whichever machine needs the session can go and serialize the session into its JVM. However, there's no standard mechanism or format for exporting/importing sessions, so when you mix vendors like iPlanet and WebLogic, you are almost certainly not going to be able to
exchange them.
Even when you're dealing with a single vendor, you will have to configure the server to share sessions, since that's an expensive operation that's normally turned off for performance reasons.
Also pay attention to the requirement that anything in a session that you want to be clusterable MUST be serializable! The compiler won't warn you if you include non-serializable objects, and usually neither will the server. You'll only discover it when the serialized session is imported and the non-serializable items are missing.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.
