messagebus

MessageBus is a software abstraction that enables components within a software system to communicate by sending messages through a central channel or broker. It provides decoupling between producers and consumers, allowing them to operate asynchronously and without direct references.

A message bus typically presents producers with interfaces to publish messages and consumers with subscriptions or queues to receive them. Implementations may be brokered, with a central broker that routes messages, or brokerless, relying on direct or peer-to-peer delivery. Common features include message formats, routing keys or topics, transformed or enriched messages, and delivery guarantees such as at-least-once, at-most-once, or exactly-once semantics.

Patterns supported include publish-subscribe, point-to-point, and request-reply; routing can be static, topic-based, or content-based; dead-letter queues; retries; and message ordering or idempotency controls.

In practice, message buses are central to event-driven architectures and microservices, enabling scalable, resilient communication and loose coupling, while introducing additional operational complexity and potential latency.

Notable implementations include Apache Kafka, RabbitMQ, NATS, Azure Service Bus, and Google Cloud Pub/Sub.

See also Enterprise Service Bus, event bus, and message queue.