Publish and Subscribe
In a publish and subscribe message system, producers address messages to a topic. In this model, the producer is known as a publisher and the consumer is known as a subscriber.
Many publishers can publish to the same topic, and a message from a single publisher can be received by many subscribers. Subscribers subscribe to topics, and all messages published to the topic are received by all subscribers to the topic. This type of message protocol is also known as broadcast messaging because messages are sent over the network and received by all interested subscribers, similar to how radio or television signals are broadcast and received.
The following image illustrates publish and subscribe messaging. Each message consumer subscribes to a topic. When a message is published to that topic, all subscribed consumers receive the message.
