AWS Certified Solutions Architect – Associate (SAA-C03) — Question 927

A company is developing machine learning (ML) models on AWS. The company is developing the ML models as independent microservices. The microservices fetch approximately 1 GB of model data from Amazon S3 at startup and load the data into memory. Users access the ML models through an asynchronous API. Users can send a request or a batch of requests.

The company provides the ML models to hundreds of users. The usage patterns for the models are irregular. Some models are not used for days or weeks. Other models receive batches of thousands of requests at a time.

Which solution will meet these requirements?

Answer options

• A. Direct the requests from the API to a Network Load Balancer (NLB). Deploy the ML models as AWS Lambda functions that the NLB will invoke. Use auto scaling to scale the Lambda functions based on the traffic that the NLB receives.
• B. Direct the requests from the API to an Application Load Balancer (ALB). Deploy the ML models as Amazon Elastic Container Service (Amazon ECS) services that the ALB will invoke. Use auto scaling to scale the ECS cluster instances based on the traffic that the ALB receives.
• C. Direct the requests from the API into an Amazon Simple Queue Service (Amazon SQS) queue. Deploy the ML models as AWS Lambda functions that SQS events will invoke. Use auto scaling to increase the number of vCPUs for the Lambda functions based on the size of the SQS queue.
• D. Direct the requests from the API into an Amazon Simple Queue Service (Amazon SQS) queue. Deploy the ML models as Amazon Elastic Container Service (Amazon ECS) services that read from the queue. Use auto scaling for Amazon ECS to scale both the cluster capacity and number of the services based on the size of the SQS queue.

Correct answer: D

Explanation

Option D is correct because an Amazon SQS queue is the optimal way to handle asynchronous API requests and buffer sudden bursts of traffic. Since the ML microservices must download and load 1 GB of data from Amazon S3 at startup, AWS Lambda (Options A and C) would suffer from severe cold-start latencies and is not suitable for this startup profile. Amazon ECS combined with SQS-based auto scaling allows the system to scale down to zero during idle periods and scale up both tasks and container instances to handle large batches.