[jdev] Architecture of a Jabber Server

[Lv Hongliang]

Hello list, 
   I am a newer to Jabber. But I must develop a new IM Server (using XMPP
protocols) for our project, and I do not know very clearly of the
architecture of a IM Server. At present, I just need to implement the
functions as follows:
     Register, authentication, add and remove contact, two users chatting
with each other. In one word, I just need to implement the most fundamental
function (two users can chat with each other).
   Can anyone tell me the architecture? Please tell me which modules this
Server is composed of and the general function of each module.(Just in high
level) If  you can give me a  picture ,it would be better. Thank you in
advance!
    Thanks!
    Lv Hongliang
    April 14, 2006