DVA-C02 · Question #279
An application that runs on AWS receives messages from an Amazon Simple Queue Service (Amazon SQS) queue and processes the messages in batches. The application sends the data to another SQS queue to…
The correct answer is A. Use an SQS FIFO queue. Configure the visibility timeout value. SQS FIFO queues guarantee strict message ordering and exactly-once processing, and the visibility timeout prevents re-delivery while the legacy system processes each message.
Question
An application that runs on AWS receives messages from an Amazon Simple Queue Service (Amazon SQS) queue and processes the messages in batches. The application sends the data to another SQS queue to be consumed by another legacy application. The legacy system can take up to 5 minutes to process some transaction data. A developer wants to ensure that there are no out-of-order updates in the legacy system. The developer cannot alter the behavior of the legacy system. Which solution will meet these requirements?
Options
- AUse an SQS FIFO queue. Configure the visibility timeout value.
- BUse an SQS standard queue with a SendMessageBatchRequestEntry data type. Configure the
- CUse an SQS standard queue with a SendMessageBatchRequestEntry data type. Configure the
- DUse an SQS FIFO queue. Configure the DelaySeconds value.
How the community answered
(29 responses)- A76% (22)
- B14% (4)
- C3% (1)
- D7% (2)
Why each option
SQS FIFO queues guarantee strict message ordering and exactly-once processing, and the visibility timeout prevents re-delivery while the legacy system processes each message.
An SQS FIFO queue enforces first-in-first-out ordering, eliminating out-of-order updates to the legacy system. Configuring the visibility timeout to exceed the maximum legacy processing time (5 minutes) ensures that a message is not re-delivered before the legacy system finishes processing it, preventing duplicate or concurrent processing without modifying the legacy system.
An SQS standard queue provides best-effort ordering only and can deliver messages out of order; SendMessageBatchRequestEntry does not enforce FIFO semantics.
Same limitation as B - a standard queue cannot guarantee strict ordering regardless of batch configuration, so out-of-order updates remain possible.
DelaySeconds postpones the initial delivery of a message but does not control re-delivery timing after the first consumer receives it, so it does not prevent re-delivery during long processing windows.
Concept tested: SQS FIFO queue ordering and visibility timeout configuration
Source: https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/FIFO-queues.html
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