A publisher is a user-defined object deployed within a Diffusion™ server which provides one or more topics on which it publishes messages to clients.

There can be one or more publishers deployed with a Diffusion server.

Clients connect to the server and subscribe to topics. Messages relate to topics and when a publisher publishes a message it is broadcast to all clients that are currently subscribed to the message topic. A publisher can also send messages to individual clients and receive messages sent from clients. Clients can request (fetch) topic state, even when not subscribed.

A publisher must be written by the user in Java™ (utilizing the publisher API) and deployed within the server. This is done by extending a supplied publisher class and implementing methods as required. Implement the methods relating to the functionality that you require. For more information, see Writing a publisher.