AWS Certified Solutions Architect – Associate (SAA-C03) — Question 3

A company is building an ecommerce web application on AWS. The application sends information about new orders to an Amazon API Gateway REST API to process. The company wants to ensure that orders are processed in the order that they are received.
Which solution will meet these requirements?

Answer options

• A. Use an API Gateway integration to publish a message to an Amazon Simple Notification Service (Amazon SNS) topic when the application receives an order. Subscribe an AWS Lambda function to the topic to perform processing.
• B. Use an API Gateway integration to send a message to an Amazon Simple Queue Service (Amazon SQS) FIFO queue when the application receives an order. Configure the SQS FIFO queue to invoke an AWS Lambda function for processing.
• C. Use an API Gateway authorizer to block any requests while the application processes an order.
• D. Use an API Gateway integration to send a message to an Amazon Simple Queue Service (Amazon SQS) standard queue when the application receives an order. Configure the SQS standard queue to invoke an AWS Lambda function for processing.

Correct answer: B

Explanation

Option B is the correct choice because using an SQS FIFO queue ensures that messages are processed in the exact order they were received. Options A and D use standard queues or SNS, which do not guarantee order. Option C does not address the requirement to process orders in sequence and could lead to delays in processing.