If you send things to a group of 30 people, or receive them from a group of 50, and you change who those groups are from hour to hour or message to message, where is that filtering going to be enforced? The UI can work on your Blackberry or iPhone, but will the logic work there too? I don’t think so; you have to go to a server. Could that server be your personal choice of “parent” server for your clients? I guess so. I also must confess that there’s an inevitable element of distribution once enterprises start messaging behind their firewalls, yet wanting to connect to the outside world, and I haven’t really thought that aspect through.

But I still think the idea of writing messages to disk before sending them onward is just braindead. Send them first, THEN persist them quickly, but without allowing that persistence to be a bottleneck. XMPP doesn’t obviate the need for CEP, any more than CEP would replace XMPP.

CAM

This is related to the questions about how to make it scale technically, of course.

My suggestion is that if you want those features, try Wordpress. Twitter is something else. Applications can’t be everything to everyone. Ask Microsoft.

I think scaling discussions have to start with functionality and data query infrastructure.

I don’t think those problems are apt to be solved by any kind of global message bus in which every message whizzes by and you only pick out the ones you want. Rather, I think there has to be a central server (suitably replicated, etc., but logically central) that only sends you the messages you actually asked for, or at most a SMALL superset of those.

CAM