The debate around Push versus Pull architecture has been resurrected, sparked by a posting from Jive Software's CTO Matt Tucker declaring that the push based approach of XMPP is the future for cloud services:
There's a new firestorm brewing in web services architectures. Cloud services are being talked up as a fundamental shift in web architecture that promises to move us from interconnected silos to a collaborative network of services whose sum is greater than its parts. The problem is that the protocols powering current cloud services; SOAP and a few other assorted HTTP-based protocols are all one way information exchanges. Therefore cloud services aren't real-time, won't scale, and often can't clear the firewall. So, it's time we blow up those barriers and come to Jesus about the protocol that will fuel the SaaS models of tomorrow--that solution is XMPP (also called Jabber) . Never heard of it? In just a couple of years Google, Apple, AOL, IBM, Livejournal and Jive have all jumped on board.