Glossary
Pub/Sub (Publish/Subscribe)
A messaging pattern where senders publish messages to named topics and receivers subscribe to them, so the two sides never need to know about each other.
General definition
Publish and subscribe, usually shortened to Pub/Sub, is a messaging pattern that decouples the sender of a message from its receivers. Publishers send messages to a named topic or channel, and any number of subscribers to that topic receive them. A broker or message bus in the middle handles the routing.
This decoupling is the point. Publishers do not know who, if anyone, is listening, and subscribers do not know who is sending. That makes pub/sub well suited to systems that need to scale, fan a single event out to many consumers, or add and remove components without rewiring everything:
- Real-time chat and presence fan-out
- Live feeds, notifications and dashboards
- Event-driven microservices and streaming pipelines
- IoT telemetry, often over MQTT
Pub/Sub vs request and response
In the classic request and response model a client asks one server for one answer. Pub/sub is one-to-many and push-based: a single published event can reach thousands of subscribers instantly. Real-time messaging systems lean on pub/sub so that a message sent to a room is delivered to every participant at once.
Pub/Sub in the Ethora ecosystem
Real-time delivery in Ethora relies on publish and subscribe semantics: a message or presence update published to a chat room is fanned out to every subscribed member. The XMPP-based Ethora Chat Protocol provides this at the messaging layer, and developers get it through the Chat SDK without operating a message broker themselves.
