System Design: The Distributed Messaging Queue

What is a messaging queue?

A messaging queue is an intermediate component between the interacting entities known as producers and consumers. The producer produces messages and places them in the queue, while the consumer retrieves the messages from the queue and processes them. There might be multiple producers and consumers interacting with the queue at the same time.

Here is an illustration of two applications interacting via a single messaging queue:

Motivation

A messaging queue has several advantages and use cases.

• Improved performance: A messaging queue enables asynchronous communication between the two interacting entities, producers and consumers, and eliminates their relative speed difference. A producer puts messages in the queue without waiting for the consumers. Similarly, a consumer processes the messages when they become available. Moreover, queues are often used to separate out slower operations from the critical path and, therefore, help reduce client-perceived latency. For example, instead of waiting for a specific task that’s taking a long time to complete, the producer process sends a message, which is kept in a queue if there are multiple requests, for the required task and continues its operations. The consumer can notify us about ...