# API Gateway

## Essentials

* Fully managed service to create and manage your own APIs for your apps
* API Gateways act as a "front door" for your applications, allowing access to data/logic/functionality from your back-end services

### Main Features

* Build RESTful APIs with:
  * Resources
  * Methods (i.e. GET, POST, PUT)
  * Settings
* Deploy APIs to a "Stage" (different envs: i.e. dev, beta, production)
  * Each stage can have it's own throttling, caching, metereing, and logging
* Create a new API version by cloning an existing one.
  * You can create and work on multiple versions of an API (API version control)
* Roll back to previous API deployments
  * History of API deployments are kept
* Custom domain names
  * Custom domain names can point to an API or Stage
* Create and manage API keys for access AND meter usage of the API keys through Amazon CloudWatch Logs
* Set throttling rules based on the number of requests per second (for each HTTP method)
  * Request over the limit throttled (HTTP 429 response)
* Security using Signature v.4 to sign and authorize API calls
  * Temporary credentials generated through Amazon Cognito and Security Token Service (STS)
  * Workflows related to controlling billing through AWS!

### Benefits

* Ability to cache API responses
* DDoS protection via CloudFront
* SDK generation for iOS, Android, and JavaScript
* Supports Swagger (popular framework of API dev tools)
* Request/response data transformation (i.e. JSON IN to XML OUT)


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