Did you think about integration with XMPP protocol (RFC 3920) ? One application of this protocol is Jabber IM. But this protocol core is REALLY well suited for Automation and M2M. Look at XMPP. It's nice.
In fact, we have been considering using an XMPP implementation to facilitate Mango-to-Mango communication. The idea is for Mango to be able to use another Mango instance as a data source. This approach would also allow anything else that uses XMPP to be a data source as well, but as far as we’re aware there is no equipment that implements anything like it.