Key Components of Azure APIM

Backend API

This is the API endpoint exposed by the app created and hosted using various other platforms. Eg. Say a web API app built using .NET Core and hosted on an on-premise server.

API Gateway

This acts as an abstraction layer between the consumers of the API and the backend architecture of the API. With the API Gateway, complex details of how the API is developed, the code, the hosting details etc. is hidden. This makes it easier to perform other management and monitoring tasks of the API that do not need such added information. The API Gateway receives both inbound and outbound requests for the Backend API. Azure provides with an Azure managed API gateway that is associated to the API endpoints.

Azure also provides Managed and Self Hosted Gateways.

• Managed API Gateway: Handled and maintained by Azure.
• Self Hosted Gateway: A way to create and manage your own gateway. Here you spin up a container and host the gateway in a setup managed and operated by yourself. This could be an option if you need greater control for security , traffic to the endpoints, or want the API gateway to be in the same region of where your API is hosted.

Whichever is used, it is the gateway that handles the requests and responses along with integrating with Azure monitoring capabilities, it is responsible to relay log and metric information and fulfill policy requirements.

API Management Plane

Provides management capabilities to setup API endpoints, create API service instance, add or remove policies, provide templates to create different endpoints. Basically management plane provides administrative tools for API service management. The management plane also has a REST API endpoint, making it also possible to programmatically maanage and administer API management services via ARM templates, SDKs, PowerShell, Visual Studio etc.

Developer Portal

This is an auto-generated yet customizable website that displays all published APIs and documentation needed to use the APIs. The developer portal also provides a console to test the API endpoints from within it. It is a great management tool that lets developers login, subscribe or even guest users to use the available APIs.

Azure API Management Service is a PaaS (Platform as a Service) offering by Azure. This service provides a secure way to publish and manage the APIs created by on-premise or cloud backend services. Azure APIM service acts as an intermediate layer between the backend applications that hold the code behind the API endpoints and the consumers of the API endpoints.

This platform as a service offering provides easy management of the APIs by way of many built-in policies that control requests and responses, built-in authentication methods, and monitoring capabilities.