Active and Passive Federation in WIF

Question

I am trying to understand the difference between Active and Passive federation in WIF. It appears that one would use an Active Federation if the Relying Party (RP) is a WCF Service instead of an ASP.NET application and a Passive Federation if the RP is an ASP.NET application. Is this accurate?

So, in a scenario in which an ASP.NET application uses a WCF in the backend, the MS articles suggest using a 'bootstrap' security token that is obtained by the ASP.NET app using an ActAs STS and this token is used to authenticate with the WCF. In this scenario, it appears that we are doing a combination of Active (user -> STS -> ASP.NET RP) and Passive (ASP.NET -> ActAs STS -> WCF) Federation?

Answer 1

Active Federation is about authenticating user using WSTrust protocols and your Relying Party is who owns login window and asks for security token to STS. Passive Federation is when Relying Party has no login logic and you are redirected to the login page located on STS. Active Federation is more complex to configure, in my opinion (I'm working with silverlight, so it needs some tricks). I'm planing to post about this subject on my blog, because there is little information about it on internet.