AWS Serverless Asynchronous Event Submission With an SQS Queue
What is AWS SQS
AWS SQS stands for AWS Simple Queue Service.
It exchanges messages between components.
A component is part of the software with its own behavior and data.
How AWS SQS Works
AWS SQS works in steps:
- The message is added in a queue
- The message is picked from the queue
- Message is processed
- The message is deleted from the queue
Read more about AWS SQS:
Read about AWS SQS introduction hereRead about AWS SQS overview here
Read about AWS SQS limits here
AWS SQS Video
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Asynchronous Event Submission With an SQS Queue
Amazon SQS creates an asynchronous connection between Lambda and the API request.
It satisfies the request regardless of how long the Lambda function will run.
SQS queues are backed up with built-in retries, should any queue fail.
The Lambda holds a client connection until data is available.
This process is called long polling.
How Asynchronous Event Submission Works
When the client sends a request, it passes through the API Gateway.
The API Gateway sends the request to Amazon SQS and receives a message ID.
With a message ID, a client can track the message.
The message gets stored in the queue which Lamba polls.
When Lambda finds a new message in a queue, it invokes the Lambda function.
Lambda function then processes the message.
Related reads:
AWS Cloud LambdaUsing AWS Lambda with Amazon SQS
Standard Queues vs. FIFO Queues
Amazon SQS has two types of queues. The Standard queue and the FIFO queue.
FIFO stands for First-In-First-Out.
It means that the data that goes into the queue first should be retrieved first.
The table below shows the difference between the two.
| FIFO | Standard |
|---|---|
| Can deliver 300 messages per second, per API action | Can deliver an almost unlimited number of messages per second |
| Can deliver messages more than once | Can deliver messages more than once |
| The message order is assured based on the group ID | The order of messages isn't guaranteed |
