Decoupling Workflows

Question 1

Possible options for frequent SQS message duplication?

Answer 1

• Check for a misconfigured visibility timeout

- Check if the developer is failing to make the delete API call

Question 2

What’s the maximum persistence time for a message in SQS?

Answer 2

14 days

Question 3

How to ensure ordering in SQS?

Answer 3

SQS FIFO

Question 4

How to send proactive notifications?

Answer 4

SNS

Question 5

How to get notifications from CloudWatch alarms?

Answer 5

SNS

Question 6

API Gateway

Answer 6

Secure front door to external communication coming into your environment

Question 7

What’s the maximum size of an SQS message?

Answer 7

256Kb

Question 8

How much time does a message can be kept in a queue in SQS?

Answer 8

From 1 minute to 14 days (4 days by default)

Question 9

What’s the visibility timeout in SQS?

Answer 9

Visibility timeout is the amount of time that the message is invisible in the SQS queue after a reader picks up that message. If the job is not processed within that time, the message will become visible again and another reader will process it. This could result in the same message being delivered twice.

Question 10

What does the WaitTimeSeconds attribute mean in SQS?

Answer 10

WaitTimeSeconds = 0 => Short polling

When the consumer instance polls for new work, the SQS service will allow waiting a certain time for one or more messages to be available before closing the connection.

By default, Amazon SQS uses short polling. Short polling occurs when the WaitTimeSeconds parameter of a ReceiveMessage request is set to 0.

Question 11

What is the maximum “VisibiltyTimeout” of an SQS message in a FIFO queue?

Answer 11

12 hours (do not confuse it with how the message can remain in the queue, which is 14 days)