Advanced Classloading in J2EE is a pretty good explanation of the various intricacies of Java classloaders. I'm planning on taking knowledge gained from this (and other) articles and incorporating it into forehead, my classloader management project.
Classloading can be one of the nasty issues in a J2EE environment. Questions come to mind like: How to integrate with 3rd party libraries, which have conflicting classes, how to use remote stubs, etc.
This article will describe an especially sophisticated classloading system that combines ease of use with efficiency and compliant behaviour in order to deal with the mentioned questions. This classloading approach also contains a mechanism to separate internally used libraries from user-installable libraries that could potentially conflict with each other.
As an example, such advanced classloading mechanisms are implemented in IONA's Orbix E2A Application Server. It's classloading techniques will be illustrated and their usage demonstrated.