Event-Driven Architecture

Tiny Pub/Sub Event Bus

When two parts of your app need to talk without a direct reference (a Zustand store telling the toaster, a service worker pushing to the UI), a tiny pub/sub bus is often cleaner than threading callbacks. This snippet builds a minimal `on/off/emit` bus, adds a `once` shorthand, and shows the typed channels pattern that scales to a real codebase. Drop it in next to your state library.

Event-Driven Architecture & Pub/Sub

Event-driven architecture (EDA) is a style where services communicate by emitting and reacting to immutable events instead of calling each other directly. This lesson covers the publish/subscribe pattern, the difference between event notification and event-carried state transfer, the role of an event bus, and how EDA reshapes coupling, scalability, and consistency. We compare it with request/response, walk through real implementations on Kafka, Kinesis, EventBridge, and SNS, and end with the operational pitfalls (event versioning, ordering, schema drift, observability) that bite teams who adopt EDA without preparation.