DVA-C02 Development with AWS Services Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Set up an Amazon EventBridge rule to capture SQS events and invoke Lambda.

  Why it's wrong here

  Amazon EventBridge is designed to route events from various AWS services, your own applications, and SaaS applications to targets like Lambda. However, EventBridge does not natively capture SQS message events (e.g., a message being sent to or received from a queue) as a direct event source for its rules. While you could use a separate mechanism (like another Lambda) to process SQS messages and then publish custom events to EventBridge, EventBridge itself does not directly poll or listen to SQS queues.

• ✗

  Use Amazon SNS to subscribe to the SQS queue and trigger Lambda.

  Why it's wrong here

  Amazon SNS operates on a publish/subscribe model where publishers send messages to an SNS topic, and subscribers receive those messages. While an SQS queue can be a subscriber to an SNS topic, SNS itself cannot subscribe to an SQS queue. Therefore, SNS cannot read messages from an SQS queue and subsequently trigger a Lambda function based on those SQS messages. The direction of the subscription is inverted for this proposed solution.

• ✗

  Use AWS Step Functions to poll the SQS queue and invoke Lambda.

  Why it's wrong here

  AWS Step Functions is a workflow orchestration service that allows you to define state machines to coordinate multiple AWS services. While Step Functions can interact with SQS (e.g., sending messages or waiting for tasks), it does not offer a built-in, continuous polling mechanism for an SQS queue to automatically trigger a Lambda function upon message arrival. Implementing such continuous polling within a Step Functions workflow would be overly complex and less efficient than Lambda's native SQS integration.

• ✓

  Configure an SQS event source mapping on the Lambda function.

  Why this is correct

  Configuring an SQS event source mapping on a Lambda function is the correct and most efficient approach. This mechanism enables Lambda to automatically poll the specified SQS queue, retrieve batches of messages, and then synchronously invoke the Lambda function with these messages as the event payload. Lambda manages the polling infrastructure, scaling, and ensures messages are processed, deleted upon successful execution, or returned to the queue if the function fails.

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