broker
also: message broker, message queue, pub/sub broker
A broker is a middleware service that receives messages from producers and routes them to consumers, decoupling the sender from the recipient. Common examples include message brokers like RabbitMQ, Apache Kafka, and Redis that handle asynchronous communication in distributed systems.
A broker acts as an intermediary that manages communication between different applications or services. Instead of applications talking directly to each other, they send messages to the broker, which then delivers them to intended recipients based on routing rules.
Message brokers enable asynchronous, decoupled architectures where producers don't need to know about consumers and vice versa. For example, a web server can send a user registration event to a broker, which then routes it to an email service, a logging service, and a database service—all without the web server waiting for responses.
Common Linux-based brokers include RabbitMQ (uses AMQP protocol), Apache Kafka (distributed event streaming), and Redis (lightweight pub/sub). Brokers typically handle message persistence, delivery guarantees, and scaling across multiple nodes.