Basic Amazon SQS architecture

This section outlines the parts of a distributed messaging system and explains the lifecycle of an Amazon SQS message.

Distributed queues

There are three main parts in a distributed messaging system: the components of your distributed system, your queue (distributed on Amazon SQS servers), and the messages in the queue.

In the following scenario, your system has several producers (components that send messages to the queue) and consumers (components that receive messages from the queue). The queue (which holds messages A through E) redundantly stores the messages across multiple Amazon SQS servers.

Message lifecycle

The following scenario describes the lifecycle of an Amazon SQS message in a queue, from creation to deletion.

A producer (component 1) sends message A to a queue, and the message is distributed across the Amazon SQS servers redundantly.

When a consumer (component 2) is ready to process messages, it consumes messages from the queue, and message A is returned. While message A is being processed, it remains in the queue and isn't returned to subsequent receive requests for the duration of the visibility timeout.

The consumer (component 2) deletes message A from the queue to prevent the message from being received and processed again when the visibility timeout expires.

Note

Amazon SQS automatically deletes messages that have been in a queue for more than the maximum message retention period. The default message retention period is 4 days. However, you can set the message retention period to a value from 60 seconds to 1,209,600 seconds (14 days) using the SetQueueAttributes action.