Amazon SQS™ is a distributed message queue system that provides a means for web service applications to quickly and reliably queue messages generated by one component to be consumed by another component. Using Amazon SQS, developers can decouple components of an application so that they run independently, with Amazon SQS easing messaging management between components. Any component of a distributed application can store any type of data in a fail-safe queue on Amazon.com. Any other component can then later retrieve the data programmatically using the SQS API in SOAP, REST, or HTTP Query.
The queue acts as a buffer between the component producing and saving data, and the component retrieving the data for processing. Thus, the queue resolves issues that would otherwise arise if the producer were producing work faster than the consumer can process the work, or if the producer or consumer were only intermittently connected to the network.
SQS ensures "at least once" delivery of messages, and supports multiple readers and multiple writers interacting with the same queue. A single queue can be used simultaneously by many distributed application components, with no need for those components to coordinate with each other to share the queue.
The intended audience for the Amazon SQS is software developers who build distributed web-enabled applications. An application could typically use SQS as a buffer to manage the flow of data from one application component to another component at a different network location.
Amazon SQS is engineered to always be available and deliver messages. One of the tradeoffs that comes from this is that SQS does not guarantee in-order delivery of messages. For many distributed applications, each message can stand on its own. So, as long as all messages are delivered, the order is not important. If order does need to be preserved, sequencing information can be placed in each message, so they can be reordered upon receipt.
Amazon SQS will often be referred to within this guide as simply "SQS"; all copyrights and legal protections still apply.
Amazon SQS includes these features:
At least once delivery of messages via a redundant infrastructure.
Multiple writers and readers of the same queue.
Highly concurrent access to messages.
High availability for sending/retrieving messages.
Message size of 1 byte to 256K using SOAP and REST and 1 byte to 8K using Query.
Guaranteed message availability for 15 days after the message is sent.
Settings configurable on a per queue basis.