Front and Back Channels
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This course deals with how to deploy, configure, and manage some keys aspects of Azure API management (APIM). In particular, we focus on the authentication mechanism and go into depth about how to set up OAuth 2.0, including creating the Azure AD required application registrations. To help with understanding and troubleshooting the OAuth flow, we utilize Postman to check and validate our configuration.

Next, we take a look at how we can alter API requests at various scopes using API policies. Finally, we look at how to view effective API policies that span multiple scopes and also how to trace API policies during runtime.

Learning Objectives

  • Deploy Azure API Management and import an existing API
  • Gain an understanding of how the configure authentication against APIM using OAuth 2.0
  • Implement API policies against the imported API to alter the API request
  • Use Postman to make API requests against APIM and request and use OAuth authorization tokens
  • Secure the imported API by requiring a valid Azure AD token

Intended Audience



You might be wondering the reason we create two applications. Let's look at the OAuth diagram again. When talking about OAuth, there is the concept of front channel and back channel. The front channel could be a browser on a user's computer. A browser is very good at interacting with users. For example, presenting the user with a login screen and asking for user approvals. However, we don't control the browser, and we can't trust it with sensitive information. The back channel is considered servers or code we control or, more importantly, we can trust with sensitive information. 

This is why we get an access token in two phases. First, we get an authorization token through the browser or front channel. We can then exchange this authorization token over the back channel using the client ID and secret we have already configured. OAuth utilizes the best things about the front channel and the best things about the back channel in order to obtain the access token or bearer token securely.

About the Author

Matthew Quickenden is a motivated Infrastructure Consultant with over 20 years of industry experience supporting Microsoft systems and other Microsoft products and solutions. He works as a technical delivery lead managing resources, understanding and translating customer requirements and expectations into architecture, and building technical solutions. In recent years, Matthew has been focused on helping businesses consume and utilize cloud technologies with a focus on leveraging automation to rapidly deploy and manage cloud resources at scale.