Publish–Subscribe messaging model

Fire-and-forget:

• No storage.
• No replay.

Good for:

• Real-time notifications
• Chat messages
• Cache invalidation
• Live dashboards
• WebSocket triggers

Publisher → Channel → Subscribers

How Redis Pub/Sub works

1. Service A publishes message
2. Service B, C, D (even in different instances) receive instantly
3. Messages are not persisted, if subscriber is offline, message is lost