DVA-C02 · Question #268
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
The correct answer is D. Create an AWS Lambda function to process the requests. Create an Amazon Simple Queue. An SQS FIFO queue guarantees exactly-once processing and strict ordering, which directly addresses duplicate, lost, and out-of-order shipping requests within the 256 KB message size limit.
Question
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?
Options
- ACreate an Amazon Kinesis Data Firehose delivery stream to process the requests. Create an
- BCreate an AWS Lambda function to process the requests. Create an Amazon Simple Notification
- CCreate an AWS Lambda function to process the requests. Create an Amazon Simple Queue
- DCreate an AWS Lambda function to process the requests. Create an Amazon Simple Queue
How the community answered
(21 responses)- A24% (5)
- B5% (1)
- C14% (3)
- D57% (12)
Why each option
An SQS FIFO queue guarantees exactly-once processing and strict ordering, which directly addresses duplicate, lost, and out-of-order shipping requests within the 256 KB message size limit.
Kinesis Data Firehose is designed for streaming data delivery to destinations like S3 or Redshift, not for task queue processing; it does not provide deduplication or strict per-request ordering semantics suitable for transactional shipping requests.
SNS is a pub/sub fan-out service and does not guarantee ordering or exactly-once delivery; using SNS alone would not resolve the duplicate or out-of-order issues.
A standard SQS queue provides at-least-once delivery and best-effort ordering, meaning duplicates and out-of-order messages can still occur, which does not meet the stated requirements.
SQS FIFO queues use message deduplication IDs to prevent duplicates and message group IDs to enforce strict ordering. Because requests are under 256 KB and take 5-10 minutes to process, a Lambda function consuming from a FIFO queue with appropriate visibility timeout provides reliable, ordered, exactly-once delivery.
Concept tested: SQS FIFO queue for ordered exactly-once message processing
Source: https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/FIFO-queues.html
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