I don’'t work for Jive but I can try to answer your questions:
I read about your smack lib and would like to add the
IM stuff to our Jive based site. Every site user
should get a message center for exchange messages
with other site users and friendly IM users.
Is the lib designed for this kind of stuff? Can it
handle 50 connections to the jabber server
permanently and manage all incomming and outgoing
traffic without any problems?
The Smack API is only designed for doing client-side Jabber work. Most Jabber servers can easily handle 50 users/connections, go to http://www.jabber.org/admin/serverlist.php to see a list of commercial and free Jabber server software that is currently available.
And is there a message queue build into the lib, for
storing messages while the jabber server is not
Storing messages for later delivery is always handled by the server. I suppose you could create a client that stores messages and delivers them when the Jabber server becomes available, but the problem that you’‘re going to have is that typically roster information is stored on the server, so the client wouldn’'t know who it can send messages to once contact with the server is made.