title: Using ACS as a service with custom identity provider
body: <p>We are working in an iOS application and we use back-end in azure. We have 2 types of login, one is Facebook login (using Fb as identity provider) and the other will be login directly to our system.
   We decided to use ACS but we had a bunch of technical problems. My question is is it possible to create custom identity provider, which will be a service (for example WCF or WEB API) to generate a token that we pass the ACS to get the claim token. Does ACS support that kind of service interface? If so what what is the practice of generating tokens in our custom identity provider?</p>
  
  <p>Thanks in advance,
  Deuce</p>