Skip navigation.

CometD Documentation

CometD Project Overview

The primary purpose of CometD project is to implement responsive user interactions for web clients using AJAX and WebSocket by means of WebSocket and server-push techniques called Comet.

The CometD project provides the Bayeux specification, that defines the protocol used to exchange information between client and server, and provides (eventually) standardized APIs for servers and clients.
Currently the API bindings for JavaScript (on the client) and Java (for both client and server) have reached a stable status.


The CometD distributions are at


Reference Manual

Older documentation

CometD 2.4.0 Reference Manual
CometD 2.3.x documentation.
CometD 1.x documentation.

Other Implementations

The CometD project includes implementations of Bayeux specification in several languages, toolkits and servers. Third party implementations of the Bayeux specification also exist, and are not strictly part of the CometD project, however for completeness the third party implementations are linked off this document where appropriate. Other implementations and integrations include: