Exam AWS Certified Solutions Architect - Professional topic 1 question 554 discussion

Exam question from Amazon's AWS Certified Solutions Architect - Professional

Question #: 554
Topic #: 1

[All AWS Certified Solutions Architect - Professional Questions]

A Solutions Architect is responsible for redesigning a legacy Java application to improve its availability, data durability, and scalability. Currently, the application runs on a single high-memory Amazon EC2 instance. It accepts HTTP requests from upstream clients, adds them to an in-memory queue, and responds with a
200 status. A separate application thread reads items from the queue, processes them, and persists the results to an Amazon RDS MySQL instance. The processing time for each item takes 90 seconds on average, most of which is spent waiting on external service calls, but the application is written to process multiple items in parallel.
Traffic to this service is unpredictable. During periods of high load, items may sit in the internal queue for over an hour while the application processes the backlog.

In addition, the current system has issues with availability and data loss if the single application node fails.
Clients that access this service cannot be modified. They expect to receive a response to each HTTP request they send within 10 seconds before they will time out and retry the request.
Which approach would improve the availability and durability of the system while decreasing the processing latency and minimizing costs?

A. Create an Amazon API Gateway REST API that uses Lambda proxy integration to pass requests to an AWS Lambda function. Migrate the core processing code to a Lambda function and write a wrapper class that provides a handler method that converts the proxy events to the internal application data model and invokes the processing module.
B. Create an Amazon API Gateway REST API that uses a service proxy to put items in an Amazon SQS queue. Extract the core processing code from the existing application and update it to pull items from Amazon SQS instead of an in-memory queue. Deploy the new processing application to smaller EC2 instances within an Auto Scaling group that scales dynamically based on the approximate number of messages in the Amazon SQS queue.
C. Modify the application to use Amazon DynamoDB instead of Amazon RDS. Configure Auto Scaling for the DynamoDB table. Deploy the application within an Auto Scaling group with a scaling policy based on CPU utilization. Back the in-memory queue with a memory-mapped file to an instance store volume and periodically write that file to Amazon S3.
D. Update the application to use a Redis task queue instead of the in-memory queue. Build a Docker container image for the application. Create an Amazon ECS task definition that includes the application container and a separate container to host Redis. Deploy the new task definition as an ECS service using AWS Fargate, and enable Auto Scaling.

Show Suggested Answer

Suggested Answer: B 🗳️

by jay1ram2 at March 17, 2020, 7:43 a.m.

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jay1ram2

Highly Voted 3 years, 11 months ago

Not sure why C is the correct answer. The obvious challenges here are long workloads, scalability based on queue load, and reliability. Almost always the defacto answer to queue related workload is SQS. Since the workloads are very long (90 minutes) Lambdas cannot be used (15 mins max timeout). So, autoscaled smaller EC2 nodes that wait on external services to complete the task makes more sense. If the task fails, the message is returned to the queue and retried. My answer is B

upvoted 27 times

vkbajoria

3 years, 9 months ago

It is not because of Lambda that question A is incorrect. It is because it didn't talk about local queue that was in used in EC2.

upvoted 2 times

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VrushaliD

3 years, 10 months ago

Its 90 seconds not minutes, but still ans is B

upvoted 5 times

LisX

3 years, 9 months ago

What is the issue with A then using Lambda?

upvoted 1 times

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AWSum1

Highly Voted 3 years, 9 months ago

This question is long and causes brain fatigue lol. B , sqs will satisfy the need

upvoted 8 times

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SkyZeroZx

Most Recent 2 years, 1 month ago

Selected Answer: B

B , sqs will satisfy the need

upvoted 1 times

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TechX

3 years, 1 month ago

Selected Answer: B

I'll go with B

upvoted 1 times

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ravisar

3 years, 2 months ago

Will Answer B satisfy the requirement below? "They anticipate receiving a response to each HTTP request they submit within 10 seconds, at which point the request will time out and be retried." Will SQS processing time depends on the subscriber?

upvoted 1 times

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