Amazon Simple Queue Service (SQS) is a distributed message queuing service introduced by Amazon.com as a beta in late 2004 and generally available in mid-2006. It is a fully managed queue service in the AWS cloud that offers queues to support message transactions between software components at any volume, without losing messages or requiring other services to be available. SQS is intended to provide a highly scalable hosted message queue that resolves issues arising from the common producer-consumer problem or connectivity between producer and consumer. SQS enables the web service applications that help to quickly and reliably queue the messages. These messages have one component in their application that generates only when to be consumed by another component. Therefore, the queue is a temporary repository for messages and these messages are awaiting processing. Once these messages are processed, the messages also get deleted from the queue.
SQS provides a simple and reliable way for customers to decouple and connect components (microservices) together using queues. It allows users to decouple individual microservices, distributed systems, and serverless applications from one another and to scale them without requiring the user to establish and maintain their message queues. SQS supports tasks that process asynchronously. This means that rather than a single application needing to invoke another one directly, the app can simply send a message into a queue, where it waits. Other applications can then access the message later.
SQS guarantees at-least-once delivery. Messages are stored on multiple servers for redundancy and to ensure availability. If a message is delivered while a server is not available, it may not be removed from that servers queue and may be resent. As of 2007, Amazon SQS does not guarantee that the recipient will receive the messages in the order they were sent by the sender.
SQS is widely used by companies such as Dropbox, Netflix, and Nextdoor, and is also widely used within Amazon.com.
