I am now working on a web project where the authentication mechanism chosen is windows authentication(intranet application). Once the project goes live, after a gap of two months or so, an STS will be set up. Then the web project should start using it with out much change to the code. How to do it?
I plan to use claims based authentication using WIF 4.5 with my own STS ( a WCF project/web application) and take it to live. once the STS is setup in intranet(ADFS)/cloud(WAAD). I simply change the local STS URL to new 'original' STS.
1) Will it work? 2) Can the local STS be a dll?
STS is not required for Windows authentication, with .NET 4.5 Claims are included in framework, in fact no extra setup/configuration is required to support Claims. Moreover STS is required only if you are trying to federate.
See How-To
It is not a good idea to deploy a custom developed STS to production environment, you should be using ADFS or Thinktecture.IdentityServer.v2 or any other similar product for federation.