WSFederationAuthenticationModule v/s SessionAuthenticationModule

Question

According to documentation, both module will used to create instance of IClaimsPrincipal. I am not understanding why WIF bother to use 2 HttpModules instead of one? Sorry, I am new in WIF

Answer 1

The big difference is that the WSFederationAuthenticationModule intercepts requests and will redirect the user to be authenticated by the STS while the SessionAuthenticationModule uses the WIF-token cookie to authorize the user on subsequent requests.

The SessionAuthenticationModule fires first in the pipeline so if you already have a session cookie (i.e., you've already been authenticated), the session module will grant you access.

The MSDN documentation does a decent job of describing this.