AWS Certified DevOps Engineer – Professional — Question 113
A space exploration company receives telemetry data from multiple satellites. Small packets of data are received through Amazon API Gateway and are placed directly into an Amazon Simple Queue Service (Amazon SOS) standard queue. A custom application is subscribed to the queue and transforms the data into a standard format.
Because of inconsistencies in the data that the satellites produce, the application is occasionally unable to transform the data. In these cases, the messages remain in the SQS queue. A DevOps engineer must develop a solution that retains the failed messages and makes them available to scientists for review and future processing.
Which solution will meet these requirements?
Answer options
- A. Configure AWS Lambda to poll the SOS queue and invoke a Lambda function to check whether the queue messages are valid. If validation fails, send a copy of the data that is not valid to an Amazon S3 bucket so that the scientists can review and correct the data. When the data is corrected, amend the message in the SOS queue by using a replay Lambda function with the corrected data
- B. Convert the SQS standard queue to an SQS FIFO queue. Configure AWS Lambda to poll the SQS queue every 10 minutes by using an Amazon EventBridge schedule. Invoke the Lambda function to identify any messages with a SentTimestamp value that is older than 5 minutes, push the data to the same location as the application's output location, and remove the messages from the queue.
- C. Create an SOS dead-letter queue. Modify the existing queue by including a redrive policy that sets the Maximum Receives setting to 1 and sets the dead-letter queue ARN to the ARN of the newly created queue. Instruct the scientists to use the dead-letter queue to review the data that is not valid. Reprocess this data at a later time.
- D. Configure API Gateway to send messages to different SOS virtual queues that are named for each of the satellites. Update the application to use a new virtual queue for any data that it cannot transform, and send the message to the new virtual queue. Instruct the scientists to use the virtual queue to review the data that is not valid. Reprocess this data at a later time.
Correct answer: C
Explanation
The correct answer is C because creating a dead-letter queue allows for messages that cannot be processed successfully to be isolated and reviewed without being lost. This approach also enables scientists to reprocess the invalid data at a later time. Options A and D do not provide a systematic way to retain and review failed messages, while option B focuses on removing older messages instead of retaining failed ones.