Show all the last messages since the last login, plus some (to help remembering the discussion context). In other words, if I have not logged in since yesterday noon, show me everything since yesterday morning.
As I said, room history does not go by time or last login but rather by amount of messages in history. Anyway, it’d be possible to extend Openfire to support your case.
Before I dive into it, could you please tell me more about the UI when you look at the history. Is that like XChat where you can see the history in the same window as you type your new messages? Or is that split, like with Microsoft Instant Messenger where you explicitly have to call an history window? We would prefer the XChat approach.
XMPP specifies how server and clients should communicate. In the case of MUC, the server will send the history to the client and it’s up to the client to decide how to show it. All of the clients that I know will show the history in the same chat window. You can do a very quick test with your preferred client. Just log in, join a room, send a few messages, leave the room and join again. You will see that you will get the room history in the same window.