99. API Gateway

Question 1:
As a Solutions Architect, you are building business applications on a serverless architecture. In this application, the process of acquiring, registering, and changing DynamoDB data is performed by a Lambda function. You need to be able to call this application over HTTP.
How can this requirement be achieved?
Options:
A. Install API Gateway and integrate with Lambda functions
B. Set the IAM role to a Lambda function to allow HTTP access
C. Set HTTP permissions in the Lambda function settings
D. Configure NACLs to allow HTTP access to Lambda function
Answer: A
Explanation
Option 1 is the correct answer. The API gateway provides HTTP access to back-end services via the API. API gateway is a service that can be integrated with Lambda, and by implementing this setting to integrate API gateway with Lambda function, you can access Lambda function with HTTP.
Option 2 is incorrect. The IAM role allows one AWS resources to access another AWS resource. It is not a function that allows HTTP access.
Option 3 is incorrect. There is no function to allow HTTP access in the Lambda function settings.
Option 4 is incorrect. There is no ability to configure the network ACLs to allow HTTP access to Lambda functions.

Question 2:
The product team at a startup has figured out a market need to support both stateful and stateless client-server communications via the APIs developed using its platform. You have been hired by the startup as a solutions architect to build a solution to fulfill this market need using AWS API Gateway.
Which of the following would you identify as correct?
Options:
A. API Gateway creates RESTful APIs that enable stateful client-server communication and API Gateway also creates WebSocket APIs that adhere to the WebSocket protocol, which enables stateful, full-duplex communication between client and server
B. API Gateway creates RESTful APIs that enable stateless client-server communication and API Gateway also creates WebSocket APIs that adhere to the WebSocket protocol, which enables stateless, full-duplex communication between client and server
C. API Gateway creates RESTful APIs that enable stateful client-server communication and API Gateway also creates WebSocket APIs that adhere to the WebSocket protocol, which enables stateless, full-duplex communication between client and server
D. API Gateway creates RESTful APIs that enable stateless client-server communication and API Gateway also creates WebSocket APIs that adhere to the WebSocket protocol, which enables stateful, full-duplex communication between client and server
Answer: D
Explanation
Correct option:
API Gateway creates RESTful APIs that enable stateless client-server communication and API Gateway also creates WebSocket APIs that adhere to the WebSocket protocol, which enables stateful, full-duplex communication between client and server
Amazon API Gateway is a fully managed service that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale. APIs act as the front door for applications to access data, business logic, or functionality from your backend services. Using API Gateway, you can create RESTful APIs and WebSocket APIs that enable real-time two-way communication applications.
API Gateway creates RESTful APIs that:
Are HTTP-based.
Enable stateless client-server communication.
Implement standard HTTP methods such as GET, POST, PUT, PATCH, and DELETE.
API Gateway creates WebSocket APIs that:
Adhere to the WebSocket protocol, which enables stateful, full-duplex communication between client and server. Route incoming messages based on message content.
So API Gateway supports stateless RESTful APIs as well as stateful WebSocket APIs. Therefore this option is correct.
Incorrect options:
API Gateway creates RESTful APIs that enable stateful client-server communication and API Gateway also creates WebSocket APIs that adhere to the WebSocket protocol, which enables stateful, full-duplex communication between client and server
API Gateway creates RESTful APIs that enable stateless client-server communication and API Gateway also creates WebSocket APIs that adhere to the WebSocket protocol, which enables stateless, full-duplex communication between client and server
API Gateway creates RESTful APIs that enable stateful client-server communication and API Gateway also creates WebSocket APIs that adhere to the WebSocket protocol, which enables stateless, full-duplex communication between client and server.
These three options contradict the earlier details provided in the explanation. To summarize, API Gateway supports stateless RESTful APIs and stateful WebSocket APIs. Hence these options are incorrect.

Question 3:
A Big Data analytics company wants to set up an AWS cloud architecture that throttles requests in case of sudden traffic spikes. The company is looking for AWS services that can be used for buffering or throttling to handle such traffic variations.
Which of the following services can be used to support this requirement?
Options:
A. Amazon Gateway Endpoints, Amazon SQS and Amazon Kinesis
B. Amazon API Gateway, Amazon SQS and Amazon Kinesis
C. Elastic Load Balancer, Amazon SQS, AWS Lambda
D. Amazon SQS, Amazon SNS and AWS Lambda
Answer: B
Explanation
Correct option:
Throttling is the process of limiting the number of requests an authorized program can submit to a given operation in a given amount of time.
Amazon API Gateway, Amazon SQS and Amazon Kinesis – To prevent your API from being overwhelmed by too many requests, Amazon API Gateway throttles requests to your API using the token bucket algorithm, where a token counts for a request. Specifically, API Gateway sets a limit on a steady-state rate and a burst of request submissions against all APIs in your account. In the token bucket algorithm, the burst is the maximum bucket size.
Amazon SQS – Amazon Simple Queue Service (SQS) is a fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications. Amazon SQS offers buffer capabilities to smooth out temporary volume spikes without losing messages or increasing latency.
Amazon Kinesis – Amazon Kinesis is a fully managed, scalable service that can ingest, buffer, and process streaming data in real-time.
Incorrect options:
Amazon SQS, Amazon SNS and AWS Lambda – Amazon SQS has the ability to buffer its messages. Amazon Simple Notification Service (SNS) cannot buffer messages and is generally used with SQS to provide the buffering facility. AWS Lambda is a compute service and does not provide any buffering capability. So, this combination of services is incorrect.
Amazon Gateway Endpoints, Amazon SQS and Amazon Kinesis – A Gateway Endpoint is a gateway that you specify as a target for a route in your route table for traffic destined to a supported AWS service. This cannot help in throttling or buffering of requests. Amazon SQS and Kinesis can buffer incoming data. Since Gateway Endpoint is an incorrect service for throttling or buffering, this option is incorrect.
Elastic Load Balancer, Amazon SQS, AWS Lambda – Elastic Load Balancer cannot throttle requests. Amazon SQS can be used to buffer messages. AWS Lambda cannot be used for buffering. So, this combination is also incorrect.