FilteringClassLoader

This article on ClassLoaders in WebLogic is extremely interesting:

http://download.oracle.com/docs/cd/E12840_01/wls/docs103/programming/classloading.html

I have taken some notes:

bootstrap classloader
extensions classloader
system classpath classloader

application classloaders
(EAR: root classloader for EJBs, child classloader for each WAR)

in weblogic-application.xml with classloader-structure you can customize the classloaders

APP-INF/lib

manifest Class-Path entry

when 2 modules share the same classloader, call by reference is possible. Otherwise call-by-value is used.

classes in $CLASSPATH are always loaded before than whose in application classpath, unless you specify a FilteringClassLoader.
a FilteringClassLoader allows you to load classes locally to your classloader
add prefer-application-packages descriptor element to the weblogic-application.xml