Extensible Messaging Presence Protocol

XMPP PROTOCOL :

protocol for streaming XML elements over a network in order to exchange messages and present information in close to real-time.

X :

• Means eXtensible.

• an open-source project which can be changed or extended according to the need.
  M :

• Designed for sending messages in real time.

• It has very efficient push mechanism compared to other protocols.
  P :

• It determines whether you are online/offline/busy.

• It indicates the state.
  P :

• A protocol

• A set of standards that allow systems to communicate with each other.

DECENTRALISED :

1. It's based on client-server architecture.It is decentralised means there is no centralised XMPP server just like email, anyone can run their own XMPP server.
2. Each XMPP client is identified by JID (Jabber ID).

XMPP IMPLEMENTATION :

1. The original protocol for XMPP is Transmission Control Protocol using open ended XML streams over long lived TCP connections.
2. There are restricted firewalls, XMPP(port 5222) is blocked.
3. So it can't be used for web applications and users behind restricted firewalls.
4. To overcome this, XMPP community also developed a HTTP transport.