Message -> sqs vs Message -> sns -> sqs

Question

I have a task generator to generate task messages to SQS queue and a bunch of workers to poll the SQS queue to process the task. In this case, is there any benefit to let the task generator to publish messages to a SNS topic first, and then the SQS queue subscribes to the SNS topic? I assume directly publish to SQS queue is enough.

Answer 1

Assuming you're not needing to fan out the messages to different types of workers, and your workers are doing the same job then no you don't.

Each worker can take and process one message.

One item to be aware off is the timeouts before the messages become visable on SQS again. i.e. not configuring the timeouts correctly could cause another worker to process the same message.

https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-visibility-timeout.html

When a consumer receives and processes a message from a queue, the message remains in the queue. Amazon SQS doesn't automatically delete the message. Because Amazon SQS is a distributed system, there's no guarantee that the consumer actually receives the message (for example, due to a connectivity issue, or due to an issue in the consumer application). Thus, the consumer must delete the message from the queue after receiving and processing it. Visibility Timeout

Immediately after a message is received, it remains in the queue. To prevent other consumers from processing the message again, Amazon SQS sets a visibility timeout, a period of time during which Amazon SQS prevents other consumers from receiving and processing the message. The default visibility timeout for a message is 30 seconds. The minimum is 0 seconds. The maximum is 12 hours. For information about configuring visibility timeout for a queue using the console