An acronym for eXtensible Messaging and Presence Protocol This is the generalized XML streaming protocol that underlies Jabber (and the newly hyped 'Google Wave').
See RFC 3920 [L1 ], RFC 3921 [L2 ] and http://www.xmpp.org/
RLH 2009-06-01: Does Tcl have anything library wise that talks xmpp?
PT 2009-06-03: The coccinella jabber application has provided its underlying jabber library jabberlib as an independent module for a number of years. This is also used by tkchat. The tkabber developers have produced a client access library called tclxmpp which can be obtained from [L3 ]. Earlier versions of tkabber used a forked version of jabberlib but since about 0.11 it has switched library to tclxmpp. New projects should probably use this library.
DKF: XMPP can also be used as a transport protocol for SOAP, which is helpful for when you have long-lived webservice communications between two parties (especially when one party doesn't want to open incoming ports in their firewall).