Bidirectional-streams Over Synchronous HTTP (BOSH) (XEP-0124)

Overview
BOSH (or HTTP binding) is a technique designed for asynchronous XMPP communication between client and server using HTTP. Unlike Jabber HTTP Polling (XEP-0025), it uses multiple request/response pairs to improve responsiveness and avoid unnecessary polling. Besides client and server, there is a Connection Manager entity in BOSH architecture, that serves as a mediator handling HTTP requests from clients and communicating with server. Client communicates with CM via HTTP-POST requests/HTTP responses defined in mentioned XEP and CM communicates with XMPP server either acting as ordinary XMPP client or using component protocol. For sake of server-initiated XMPP messages there should be always a HTTP request pending in client-CM connection. In practice, CM can be standalone HTTP server or extension of XMPP server (more on the technique)

Possible utilization is in web-based XMPP applications or as an option for users behind restrictive firewalls.

Servers
Servers with built-in Connection Manager.
 * Openfire - XEP-0124 listed in supported XEPs.
 * ejabberd - Release notes for version 2.0.0 mention XEP-0124 support.
 * Tigase Server - BOSH support since 3.0.2

Standalone Connection Managers
Act as a proxy between client and XMMP server.
 * Araneo - Minimal CM written in Python using Twisted.
 * Punjab - Python and Twisted again.
 * rhb - CM in Ruby.
 * JabberHTTPBind- Java servlet implementing XEP-0124.

Clients

 * JWChat - full featured JavaScript client. Needs CM to operate, uses JSJaC library.
 * soashable
 * Minichat
 * Tigase Messenger
 * SparkWeb

Libraries
Connection Manager.
 * gloox (C++) - BOSH support done by MattJ during GSoC 2007. BOSH Connection classes are included in svn trunk and 1.0-beta2 (download page).
 * xmpp4r (Ruby)
 * xmpp4js (JavaScript)
 * JSJaC (JavaScript)
 * emite (Google Web Toolkit, Java) - XMPP library and client GUI for gwt, connecting through BOSH
 * agsXMPP (.NET / c# / Mono)
 * MatriX (Silverlight c#)
 * XMPP4GWT - Java library for Google Web Toolkit framework
 * XIFF (Flex/ActionScript)

Discussion
A small, low-volume discussion list about BOSH technologies is located at bosh@xmpp.org -- join the list by sending email to bosh-subscribe@xmpp.org or by visiting http://mail.jabber.org/mailman/listinfo/bosh.