Event Bus

An Event Bus is a pub/sub pattern for loose coupling, where producers emit events and consumers subscribe to topics for async communication.

Implemented with libraries like EventEmitter or Redis Pub/Sub.

Use Event Bus when:

• Decoupling microservices or modules.
• Handling domain events in DDD.
• Scaling async workflows.
• Implementing CQRS patterns.

Note: Use idempotent handlers.

Version events for backward compat.

Monitor with tracing.