Show Table of Contents
3.2.2. The Publish-Subscribe Pattern
With publish-subscribe messaging, many senders can send messages to an entity on the server, often called a topic (it is used this way in the JMS world, for example).
There can be many subscriptions on a topic; a subscription is just another word for a consumer of a topic. Each subscription receives a copy of each message sent to the topic. This differs from the message queue pattern where each message is only consumed by a single consumer.
Subscriptions can optionally be durable, which means they retain a copy of each message sent to the topic until the subscriber consumes them - even if the server crashes or is restarted in between. Non-durable subscriptions only last a maximum of the lifetime of the connection that created them.
An example of publish-subscribe messaging would be a news feed. As news articles are created by different editors around the world they are sent to a news feed topic. There are many subscribers around the world who are interested in receiving news items - each one creates a subscription and the messaging system ensures that a copy of each news message is delivered to each subscription.
Where did the comment section go?
Red Hat's documentation publication system recently went through an upgrade to enable speedier, more mobile-friendly content. We decided to re-evaluate our commenting platform to ensure that it meets your expectations and serves as an optimal feedback mechanism. During this redesign, we invite your input on providing feedback on Red Hat documentation via the discussion platform.