Using OAuth2 scopes
At its core, Keycloak is an OAuth2 authorization server. In pure OAuth2, there are two main types of applications: clients and resource servers.
As you learned from previous chapters about OAuth2, access tokens are issued to clients so that they can act on behalf of a user, where these tokens are limited to a set of scopes based on the user consent.
On the other hand, resource servers are the consumers of access tokens, which they need to introspect to decide whether the client can access a protected resource on the resource server accordingly to the scopes granted by the user.
As you can see, authorization using OAuth2 scopes is solely based on user consent. It is the best strategy when you want third parties integrating with your APIs so that you delegate to your users the decision on whether a third-party application can access their resources. In this strategy, the main point is to protect user information rather than regular resources at the resource...