A starters guide from SQS and some learning along the way

#sqs #aws #serverless

In this guide, we will go through the basics of what SQS is and why it’s important for you to start using it.

What is it?

Is a service from AWS which is queue where messages wait their turn to be processed.

As a fun fact, SQS was the first Serverless Service launched by AWS in 2006

Why is it important?

SQS allows you to improve the resilence and retryability of your system.

Let's imagine that you've the following scenario:

Your API exposes a POST /create-order endpoint, and it’s connected directly to a Lambda function called 'CreateOrder'.

If your system receives a lot of traffic, your CreateOrder Lambda may start throttling, which means some orders could be lost.

In order to avoid this, we can put an SQS in the middle.

Having the SQS in the middle ensures that requests are not lost.

The queu will hold each request until it gets consumed or it has reached the maximum age of the message in the queue, by default is 4 days and the maximum is 14 days.).

When a consumer begins processing a message, SQS hides it temporarily so that no other consumer can process it at the same time.
This is controlled by the visibility timeout, which defines how long a message stays hidden while being processed.

The message is attempted to be consumed up to the amount of times defined by the maxReceiveCount.
This count represents how many attempts the message can go through before being considered “failed.”