SAA-C03 · Question #584
SAA-C03 Question #584: Real Exam Question with Answer & Explanation
The correct answer is B: Configure an Amazon API Gateway REST API to invoke an AWS Lambda function that publishes. A company is migrating a monolithic web application to a serverless microservices architecture, requiring an event-driven, loosely coupled system using a publish/subscribe pattern, with the most cost-effective solution.
Question
A company is migrating from a monolithic architecture for a web application that is hosted on Amazon EC2 to a serverless microservices architecture. The company wants to use AWS services that support an event-driven, loosely coupled architecture. The company wants to use the publish/subscribe (pub/sub) pattern. Which solution will meet these requirements MOST cost- effectively?
Options
- AConfigure an Amazon API Gateway REST API to invoke an AWS Lambda function that publishes
- BConfigure an Amazon API Gateway REST API to invoke an AWS Lambda function that publishes
- CConfigure an Amazon API Gateway WebSocket API to write to a data stream in Amazon Kinesis
- DConfigure an Amazon API Gateway HTTP API to invoke an AWS Lambda function that publishes
Explanation
A company is migrating a monolithic web application to a serverless microservices architecture, requiring an event-driven, loosely coupled system using a publish/subscribe pattern, with the most cost-effective solution.
Common mistakes.
- A. This option is very similar to the correct answer but specifies 'multiple Amazon API Gateway REST APIs' for publishing. For a single entry point that initiates a pub/sub flow, using a single API Gateway REST API is typically more cost-effective than managing multiple separate APIs, making option B generally more efficient.
- C. Using an Amazon API Gateway WebSocket API is for persistent, bidirectional communication and is generally more expensive and complex than a standard REST API for a one-way publish/subscribe pattern. Amazon Kinesis Data Streams, while excellent for high-throughput streaming, is also typically more expensive than Amazon SNS for broadcast-style pub/sub for loosely coupled event-driven architectures.
- D. While an Amazon API Gateway HTTP API is a cost-effective API type, publishing to an Amazon SQS queue primarily supports point-to-point messaging or work queues, not the fan-out 'publish/subscribe (pub/sub) pattern' explicitly requested, which is best handled by Amazon SNS for broadcasting to multiple subscribers.
Concept tested. Serverless pub/sub, event-driven architectures, cost optimization
Reference. https://aws.amazon.com/sns/ ; https://aws.amazon.com/lambda/ ; https://aws.amazon.com/api-gateway/
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