Exams / CLF-C02 / Messaging and business applications / Question 1
CLF-C02 practice question: Messaging and business applications (1 of 2)
Cloud Technology and Services A free question from our original CLF-C02 practice exam. Try it, then open the answer to see why each option is right or wrong.
When a customer places an order, a company wants one message to be delivered at the same time to an Amazon SQS queue for order fulfilment, another SQS queue for analytics, and an email address for the sales team. Which service should publish the message?
Choose one answer.
- AA. Amazon SQS on its own, with one queue shared by all three consumers
- BB. Amazon Simple Notification Service (Amazon SNS)
- CC. AWS Step Functions
- DD. Amazon Simple Email Service (Amazon SES) on its own
Show the answer and explanation
Answer: B
- A. Wrong: With a single queue each message is normally processed by one consumer, so the three systems would not each get a copy.
- B. Right: Correct. An SNS topic delivers a copy of each published message to every subscriber, including SQS queues and email addresses.
- C. Wrong: Step Functions coordinates the steps of a workflow. It is not the service for publishing one message to many subscribers.
- D. Wrong: SES sends email. It cannot deliver the message to SQS queues.
Explanation
Amazon SNS is a publish/subscribe service. Publishers send a message to a topic, and SNS delivers a copy to every subscriber, such as SQS queues, Lambda functions, HTTP endpoints, email, SMS and mobile push. Pairing SNS with several SQS queues is the 'fan-out' pattern, which lets each system process the same event independently.
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