AWS Certified Solutions Architect – Professional (SAP-C02) — Question 217

A company hosts a blog post application on AWS using Amazon API Gateway, Amazon DynamoDB, and AWS Lambda. The application currently does not use API keys to authorize requests. The API model is as follows:

GET /posts/{postId}: to get post details
GET /users/{userId}: to get user details
GET /comments/{commentId}: to get comments details

The company has noticed users are actively discussing topics in the comments section, and the company wants to increase user engagement by making the comments appear in real time.

Which design should be used to reduce comment latency and improve user experience?

Answer options

• A. Use edge-optimized API with Amazon CloudFront to cache API responses.
• B. Modify the blog application code to request GET/comments/{commentId} every 10 seconds.
• C. Use AWS AppSync and leverage WebSockets to deliver comments.
• D. Change the concurrency limit of the Lambda functions to lower the API response time.

Correct answer: C

Explanation

The use of AWS AppSync with WebSockets allows for real-time updates, making it the most effective solution for delivering comments instantly to users, which directly addresses the goal of increasing engagement. The other options either do not provide real-time capabilities (A and B) or are not focused on reducing latency effectively (D).