technical background user management engine

Hello,

My name is Marco Helmich and i'm student of computer sience. In my modeling course, we are about to discuss the user management engine of SAP Netweaver AS. You have great tutorials on your website, but they all describe a user sight on the UME and not how it works. For that reason i have some questions.

I'm interested in what exactly happens if the UME recieves a request for authorization from the J2EE-engine. Do the UME have components inside? And how do they interact if the UME recieve a request? It acts like a "black box". What are the differences between J2EE secutity roles and the UME roles? Is there a mapping between them? Where does the UME take place in my system landscape? Is it a part of my J2EE server or is it seperated from all servers?

I hope you can give me answers for my quetsions or show me where to find these informations.

Thank you.