[JDEV] proxy

[chetan s ithal]

hi all ,
             We are developing an Instant Messaging client using Jabber
Server . In the Chat application , we are sending the messages through
the jabber server itself but in real life , it may increase the load on
the jabber server so we want to establish direct client to client
connection through jabber . It will significantly reduce the load on the
jabber but what will happen if the user is behind the proxy ? How the
user will be able to get the IP address of the machine which is behind
the proxy ? Has anyone implemented such kind of application ?
          One more thing . Can anybody tell me where the off-line
messages are stored by the jabber(in which file) ?

thanks ,
chetan s ithal