A company runs a web application on Amazon EC2 instances that accepts user uploads. The uploads need to be processed by a backend service that performs virus scanning and thumbnail generation. The backend processing can take up to 30 seconds per upload. Users should not experience delays when submitting their files. The company wants to decouple the web tier from the processing tier so that the web application can immediately return a response to the user while the processing happens asynchronously. The solution must be fully managed, durable, and scale automatically with demand. Which AWS service should the company use?

Amazon Simple Notification Service (Amazon SNS)

Amazon SNS is a publish/subscribe messaging service that pushes messages to subscribers (e.g., email, SMS, or HTTP endpoints). It does not provide a message queue where a consumer can poll and process at its own pace. If the backend is unavailable when a message is sent, the message could be lost or require complex retry logic. SNS is not designed for decoupling asynchronous work queues.

Amazon Kinesis Data Streams

Amazon Kinesis Data Streams is designed for real-time streaming of data at scale, where multiple consumers can process data in near real-time for analytics. It is more complex than needed for simple asynchronous processing and is not intended for long-lived queuing of individual tasks. It also requires managing shards and throughput, whereas SQS provides a simpler queue abstraction.

Amazon MQ

Amazon MQ is a managed message broker service that supports standard messaging protocols (e.g., AMQP, MQTT). While it can be used for queueing, it is typically chosen when migrating existing applications that rely on those protocols. For new cloud-native applications, Amazon SQS is simpler, fully serverless, and more cost-effective because it does not require provisioning or managing broker instances.

What does this CLF-C02 question test?

Read the scenario before looking for a memorised answer.

What is the correct answer to this question?

The correct answer is: Amazon Simple Queue Service (Amazon SQS) — This scenario requires decoupling the web application from the backend processing to handle asynchronous tasks without blocking the user. Amazon Simple Queue Service (Amazon SQS) is a fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications. SQS acts as a buffer between the web tier and the processing tier. The web application sends a message to an SQS queue immediately after receiving an upload, and the backend service polls the queue and processes messages as capacity allows. This ensures the user gets an immediate response, and the processing happens reliably. SQS is durable (messages are stored redundantly across multiple Availability Zones) and scales automatically to handle any volume of messages. The other services do not fit this use case: SNS is a pub/sub messaging service for push notifications, not for queue-based decoupling; Kinesis Data Streams is designed for real-time streaming data ingestion and analytics, not for simple asynchronous processing; Amazon MQ is a managed message broker for existing applications that use standard protocols like AMQP, but it requires provisioning and managing instances, making it less suitable than the simpler, serverless SQS.

What should I do if I get this CLF-C02 question wrong?

Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.