OAuth 2.0 - Architecture

In this chapter, we will discuss the architectural style of OAuth 2.0.


Step 1 − First, the user accesses resources using the client application such as Google, Facebook, Twitter, etc.

Step 2 − Next, the client application will be provided with the client id and client password during registering the redirect URI (Uniform Resource Identifier).

Step 3 − The user logs in using the authenticating application. The client ID and client password is unique to the client application on the authorization server.

Step 4 − The authenticating server redirects the user to a redirect Uniform Resource Identifier (URI) using authorization code.

Step 5 − The user accesses the page located at redirect URI in the client application.

Step 6 − The client application will be provided with the authentication code, client id and client password, and send them to the authorization server.

Step 7 − The authenticating application returns an access token to the client application.

Step 8 − Once the client application gets an access token, the user starts accessing the resources of the resource owner using the client application.

OAuth 2.0 has various concepts, which are briefly explained in the following table.

Sr.No. Concept & Description
1 Terminology

OAuth provides some additional terms to understand the concepts of authorization.

2 Web Server

Web server delivers the web pages and uses HTTP to serve the files that forms the web pages to the users.

3 User-Agent

The user agent application is used by client applications in the user's device, which acts as the scripting language instance.

4 Native Application

Native application can be used as an instance of desktop or mobile phone application, which uses the resource owner password credentials.