I am having a hard time understanding JAAS. It all seems more complicated than it should be (especially the Sun tutorials). I need a simple tutorial or example on how to implement security (authentication + authorization) in java application based on Struts + Spring + Hibernate with custom user repository. Can be implemented using ACEGI.
Here are some of the links I used to help understand JAAS:
http://www.owasp.org/index.php/JAAS_Tomcat_Login_Module
http://www.javaworld.com/jw-09-2002/jw-0913-jaas.html
http://jaasbook.wordpress.com/
Also have a look at the Apache tomcat realms configuration how-to: