If you’re not aware of Amazon API Gateway Service, I’d suggest you to read What is Amazon API Gateway? before going through the FAQ.
Amazon API Gateway is a fully managed service that makes it easy for developers to publish, maintain, monitor, and secure APIs at any scale. With a few clicks in the AWS Management Console, you can create an API that acts as a “front door” for applications to access data, business logic, or functionality from your back-end services, such as applications running on Amazon Elastic Compute Cloud (Amazon EC2), Amazon Elastic Container Service (Amazon ECS) or AWS Elastic Beanstalk, code running on AWS Lambda, or any web application.
- Why use:
- Operations Monitoring
- Lifecycle Management
- Designed for Developers
- Real-Time Two-Way Communication
In Amazon API Gateway, stages are similar to tags. They define the path through which the deployment is accessible. For example, you can define a development stage and deploy your API to it.
Lambda authorizers are AWS Lambda functions. With custom request authorizers, you will be able to authorize access to APIs using a bearer token auth strategy such as OAuth. When an API is called, API Gateway checks if a Lambda authorizer is configured, API Gateway then calls the Lambda function with the incoming authorization token. You can use Lambda to implement various authorization strategies (e.g. JWT verification, OAuth provider callout) that return IAM policies which are used to authorize the request. If the policy returned by the authorizer is valid, API Gateway will cache the policy associated with the incoming token for up to 1 hour.
Amazon API Gateway provides throttling at multiple levels including global and by service call. Throttling limits can be set for standard rates and bursts. For example, API owners can set a rate limit of 1,000 requests per second for a specific method in their REST APIs, and also configure Amazon API Gateway to handle a burst of 2,000 requests per second for a few seconds. Amazon API Gateway tracks the number of requests per second. Any requests over the limit will receive a 429 HTTP response.
Throttling ensures that API traffic is controlled to help your backend services maintain performance and availability.
API Gateway checks against your AWS account limit. If the traffic is below the set account limit, API Gateway checks the limit you have set on a stage or method. If the traffic is below the stage limit, then API Gateway applies the usage plans limits you set on a per-API key basis.
If caching is not enabled and throttling limits have not been applied, then all requests will pass through to your backend service until the account level throttling limits are reached.
Amazon API Gateway acts as a proxy to the backend operations that you have configured. Amazon API Gateway will automatically scale to handle the amount of traffic your API receives.
- When a new client is connected to the WebSocket API, a unique URL, called the callback URL, is created for that client. You can use this callback URL to send messages to the client from the backend service.
Reference: Amazon API Gateway FAQs