public void Init( HttpApplication app )
{
app.AuthenticateRequest += OnAuthenticate;
//app.PostAuthenticateRequest += OnPostAuthenticateRequest;
//app.BeginRequest += BeginRequest;
app.EndRequest += OnEndRequest;
string sImpersonationEnabled = System.Configuration.ConfigurationManager.AppSettings["EnableApplicationImpersonation"];
ImpersonationEnabled = !string.IsNullOrEmpty(sImpersonationEnabled) && (sImpersonationEnabled.ToUpper() == "TRUE" || sImpersonationEnabled.ToUpper() == "YES");
}