What are the best resources for learning the Java Portlet Specification (JSR-168)?

Question

I've been looking online for the last day or so but haven't managed to see anything that clearly explains the spec. The application I'm trying to learn is based on BEA Weblogic Portal Server. I'm primarily looking for links but a good book would also be helpful.

Answer 1

I posted a developers' summary of portlets yesterday, maybe it will be helpful to you too:

http://www.ibm.com/developerworks/ibm/library/i-portletintro/

Answer 2

There is a very good free pdf e-book (Portlets and Apache Portals - 500 pages) available from manning by Stefan Hepper (co-leader of the Java Portlet Specification JSR 168) at http://www.manning.com/hepper/. You will need to sign up for an account at manning publishing though.(free also)