RESTful Java Web Services - Third Edition

Understanding the grant types in OAuth 2.0

Grant types in the OAuth 2.0 protocol are, in essence, different ways to authorize access to protected resources using different security credentials (for each type). The OAuth 2.0 protocol defines four types of grants, as listed here; each can be used in different scenarios, as appropriate:

• Authorization code: This is obtained from the authentication server instead of directly requesting it from the resource owner. In this case, the client directs the resource owner to the authorization server, which returns the authorization code to the client. This is very similar to OAuth 1.0, except that the cryptographic signing of messages is not required in OAuth 2.0.
• Implicit: This grant is a simplified ...