AWS Certified Developer – Associate — Question 158

A company has migrated an application to Amazon EC2 instances. Automatic scaling is working well for the application user interface. However, the process to deliver shipping requests to the company's warehouse staff is encountering issues. Duplicate shipping requests are arriving, and some requests are lost or arrive out of order.

The company must avoid duplicate shipping requests and must process the requests in the order that the requests arrive. Requests are never more than 250 KB in size and take 5-10 minutes to process. A developer needs to rearchitect the application to improve the reliability of the delivery and processing of the requests.

What should the developer do to meet these requirements?

Answer options

• A. Create an Amazon Kinesis Data Firehose delivery stream to process the requests. Create an Amazon Kinesis data stream. Modify the application to write the requests to the Kinesis data stream.
• B. Create an AWS Lambda function to process the requests. Create an Amazon Simple Notification Service (Amazon SNS) topic. Subscribe the Lambda function to the SNS topic. Modify the application to write the requests to the SNS topic.
• C. Create an AWS Lambda function to process the requests. Create an Amazon Simple Queue Service (Amazon SQS) standard queue. Set the SQS queue as an event source for the Lambda function. Modify the application to write the requests to the SQS queue.
• D. Create an AWS Lambda function to process the requests. Create an Amazon Simple Queue Service (Amazon SQS) FIFO queue. Set the SQS queue as an event source for the Lambda function. Modify the application to write the requests to the SQS queue.

Correct answer: D

Explanation

The correct answer is D because using an SQS FIFO queue guarantees that messages are processed exactly once and in the order they are sent, which meets the requirements of avoiding duplicates and maintaining order. Option A does not guarantee order, and Kinesis Data Firehose is not suitable for this type of message processing. Option B uses SNS, which does not ensure message order or duplicate avoidance. Option C uses an SQS standard queue, which may lead to duplicates and does not guarantee the order of processing.