Amazon Simple Queue Service (SQS) is a fully managed distributed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications.
Asynchronous workflows have always been the primary use case for SQS. Using queues ensures one component can keep running smoothly without losing data when another component is unavailable or slow.
Amazon SQS works on the concept like any other messaging queue with minor enhancements. Producer creates a message and puts it into a queue. We can have multiple producers and add multiple messages to the queue at the same time – you don’t have to worry about the traffic or peaks, SQS handles that for you.
Amazon SQS does not support subscription feature for consumer. Consumer is requesting new messages periodically from the queue. You can have multiple consumers, but you must remember that each message can be processed only once. It means that you can have multiple instances of the same consumer, but you can’t read the same message from one queue in two different components.
After a consumer processes the message, it must be deleted from the queue. Deleting is important because SQS assumes that processing can fail. To prevent that, after the consumer receives a message, it is hidden from the queue for a defined period and after that, if it is not deleted, the message shows up in the queue again.
SQS offers two types of message queues. Standard queues offer maximum throughput, best-effort ordering, and at-least-once delivery. SQS FIFO queues are designed to guarantee that messages are processed exactly once, in the exact order that they are sent.
