Apache Vysper
Apache Vysper aims to be a modular, full featured XMPP (Jabber) server. It has highly modular design. The core of XMPP is defined in the standards RFC3920 and RFC3921....
Jabberd project has been rewritten from the ground up to be scalable, architecturally sound and to support the latest X.M.P.P Extension Protocols coming out of the X.S.F...
jabberd :
jabberd 2.x project is the next generation of the jabberd project. it has been rewritten from the ground up to be scalable, architecturally sound and to support the latest xmpp extension protocols coming out of the xsf.please note : jabberd 2.x is not a newer version of jabberd 1.x but a completely different project.
why xmpp ?
extensible messaging and presence protocol is an ietf accepted open internet standard for xml based communications technology. it has been formalized under rfc 3920 and rfc 3921.xmpp was designed for realtime communication, which powers a wide range of applications including instant messaging, presence, media negotiation, whiteboarding, collaboration, lightweight middleware, content syndication, edi, rpc and more.
php xmpp c-development xmpp-jabber-server