Publishers
A publisher is an application that makes information about a specified topic available to a pub/sub broker in a publish/subscribe system. The pub/sub broker can be an MQ broker (queue manager) or an MQTT broker.
In a publish/subscribe system, an application, known as the publisher, can send a message to a pub/sub broker. Another application, known as the subscriber, can send a subscription request to the pub/sub broker, which then sends relevant publication messages to the message queue or port of the subscriber.
A published message can be requested by more than one subscriber, and a subscriber can request messages, on the same or different topics, from more than one publisher.