What Is the Pub/Sub Pattern?

Publish/Subscribe (pub/sub) is a messaging pattern where publishers send messages to a named channel without knowing who (if anyone) is listening, and subscribers receive messages from channels they've chosen to listen to.

Why it exists

• Directly coupling every sender of an event to every possible receiver becomes unmanageable as a system grows
• Pub/sub decouples the two sides entirely — publishers and subscribers never need direct knowledge of each other, only of a shared channel name

How to apply it

• Use pub/sub when multiple, potentially varying, parts of a system need to react to the same event independently
• Common implementations range from simple in-process event emitters to full distributed systems like Redis Pub/Sub or Kafka

FAQ

Is pub/sub the same as a message queue?

They're related but distinct — a queue typically delivers each message to exactly one consumer for processing, while pub/sub typically delivers each message to every current subscriber of that channel.