Event-Driven Architecture

An event-driven architecture decouples microservices asynchronously using message queues and publish-subscribe patterns. Services emit events to an event bus instead of calling each other directly, enabling independent actions like sending emails or updating analytics without synchronous bottlenecks.

Point-to-Point queues deliver a message to exactly one consumer, while Publish-Subscribe topics broadcast events to multiple independent subscribers. Event-driven systems use queues for task distribution and topics to trigger multiple actions simultaneously from a single event.

Reliable event processing uses at-least-once delivery combined with idempotency to prevent duplicate side effects. Dead-letter queues capture messages that fail consumption, ensuring errors are isolated and can be analyzed without blocking the main message queue.

Kafka, RabbitMQ, and SQS are popular message queue technologies with distinct trade-offs. Kafka excels at high-throughput event streaming, RabbitMQ offers complex routing, and SQS provides managed cloud scaling, allowing you to choose based on your infrastructure needs.

Use event-driven architecture to solve tight coupling and synchronous bottlenecks. It is ideal when a single action, like a user signup, must trigger multiple independent processes such as CRM updates and analytics tracking without forcing the user to wait.