private ActionResult LogOffAD()
{
WsFederationConfiguration config = FederatedAuthentication.FederationConfiguration.WsFederationConfiguration;
// Redirect to SignOutCallback after signing out.
string callbackUrl = Url.Action("SignOutCallback", "Account", routeValues: null, protocol: Request.Url.Scheme);
SignOutRequestMessage signoutMessage = new SignOutRequestMessage(new Uri(config.Issuer), callbackUrl);
signoutMessage.SetParameter("wtrealm", IdentityConfig.Realm ?? config.Realm);
FederatedAuthentication.SessionAuthenticationModule.SignOut();
return new RedirectResult(signoutMessage.WriteQueryString());
}