JABBER ARCHITECTURE TECHNOLOGY AND PROTOCOL

JABBER ARCHITECTURE TECHNOLOGY AND PROTOCOL

Introduction

The first application of Jabber technology is an instant messaging and presence system that originated in and continues to be developed by the open-source community. The Jabber instant messaging (IM) system is distinguished from existing IM services by the following  key features:

•    XML foundation
•    distributed network
•    open protocol and code
•    modular, extensible architecture

This chapter provides a high-level overview of the architecture of Jabber, focusing especially on the design of the Jabber open-source server, which is now at version 1.4.
Jabber was designed in large measure along the same lines as the most successful messaging system on the Internet: namely, email. Thus Jabber communications are made possible by a distributed network of servers that use a common protocol, to which specialized clients connect to receive messages as well as to send messages to users of the same server or any other Jabber server that is connected to the Internet.
However, whereas email is a store-and-forward system, Jabber delivers messages in close to real time because the Jabber server (and, by extension, other Jabber users) knows when a particular user is online. This knowledge of availability is called presence and is the key enabler of instant messaging. Jabber combines these standard IM characteristics with two additional features that make Jabber unique.
 The first is an open protocol which enables interoperability among messaging systems. The second is a strong foundation in XML, which makes structured, intelligent messaging possible not only between human users but also between software applications.