Jabber Technical Overview

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Jabber Technical Overview
Presenter Ming-Wei Lin
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Introduction

• The term "Jabber" is widely used to refer to a
  set of open protocols for streaming XML elements
  between any two points on a network, and to the
  technologies built using those protocols
• The core protocols provide an XML streaming
  infrastructure that has been used to build a wide
  variety of real-time communications systems.

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A Quick Example

• The architecture of Jabber IM systems is
  extremely similar to that of the most time-tested
  messaging system on the planet email

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Architectural Foundations

• Communications both in email and in Jabber are
  made possible by a distributed network of servers
  that use a common protocol
• Specialized clients connect to servers in order
  to receive messages from other users and send
  messages to users on the same server or any other
  server that is connected to the network
• Jabber servers deliver messages in close to real
  time

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Architectural Foundations (cont.)

• Three additional features
• The first is a set of open, well-documented,
  easy-to-understand protocols
• The second is the fact that the Jabber protocols
  are 100 XML
• The third is that Jabber uses addresses that are
  based on DNS and recognized URI schemes,
  resulting in addresses of the same form as those
  used in email

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Client/Server

• Jabber technologies use a client-server
  architecture
• This connection is "always-on" for the life of
  the client's session on the server, which means
  the client does not have to poll for messages as
  an email client does.

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Open Protocols

• the original Jabber team defined an open protocol
  for streaming XML over the wire.
• This protocol continues to grow in depth and
  breadth
• The depth comes mainly from work completed by the
  XMPP Working Group within the Internet
  Engineering Task Force (IETF)
• The breadth comes mainly from work by the Jabber
  Software Foundation in defining extensions to the
  core protocols for a wide variety of features ,
  including groupchat, file transfer, service
  discovery, avatars, and much more.

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XML Data Format

• XML is an integral part of Jabber technologies
• It makes them fundamentally extensible and able
  to express almost any structured data
• A client connects to a server, it opens a one-way
  XML stream from the client to the server, and the
  server responds with a one-way XML stream from
  the server to the client.

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XML Data Format (cont.)

• Example
• ltmessage from'juliet_at_capulet.com'
  to'romeo_at_montague.net'gt ltbodygtWherefore art
  thou, Romeo?lt/bodygt
• lt/messagegt

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Distributed Network

• Each user connects to a "home" server, which
  receives information for them, and the servers
  transfer data among themselves on behalf of users.

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Modular Servers

• Handling client connections and communicating
  directly with Jabber clients.
• Communicating with other Jabber servers
• Coordinating the various server components
  associated with the server.

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Modular Servers (cont.)

• Jabber servers are designed to be modular, with
  specific internal code packages.
• Jabber servers can be extended with external
  components, which enable server administrators to
  supplement the core server with additional
  services

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Simple Clients

• The only things a Jabber client must do are
• Communicate with the Jabber server over TCP
  sockets.
• Parse and interpret well-formed XML "stanzas"
  over an XML stream.
• Understand the core Jabber data types
• In practice, many of the low-level functions of
  the client (e.g., parsing XML and understanding
  the core Jabber data types) are handled by Jabber
  client libraries, enabling client developers to
  focus on the user interface

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Standards-Based Addressing

• There are many different entities that need to
  communicate with each other. These entities can
  represent servers, gateways, groupchat rooms, a
  single Jabber user, etc. Jabber IDs are used both
  externally and internally to express ownership or
  routing information.

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Standards-Based Addressing (cont.)

• Key characteristics of Jabber IDs include
• They uniquely identify individual objects or
  entities for communicating instant messages and
  presence information.
• They are easy for users to remember and express
  in the real world. Ex name_at_ServerName.com
• They are flexible enough to enable the inclusion
  of other IM and presence schemes

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Conclusion

• Jabber protocols and technologies provide a true
  open alternative to the closed, proprietary
  services offered by legacy IM vendors such as AIM
  and MSN.
• Jabber's IETF pedigree and XML foundation enable
  developers to create robust, near-real-time
  messaging and presence solutions for IM and
  beyond.