How correct work with global variables in Global.asax?
<p>I have a Global.asax file in my project with code:</p>

<pre><code>using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.SessionState;
using System.Data.SqlClient;
using WrapperObjects;
using System.Security.Principal;

namespace Application
{
    public class Global : System.Web.HttpApplication
    {
        private string userLogin = string.Empty;
        void Application_Start(object sender, EventArgs e)
        {            

        }

        void Application_End(object sender, EventArgs e)
        {

        }

        void Application_Error(object sender, EventArgs e)
        {

        }

        void Session_Start(object sender, EventArgs e)
        {                               

        }

        void Session_End(object sender, EventArgs e)
        {
            DBUsers.SetUserStatusOnline("0", userLogin);   
            Session["curUserRole"] = string.Empty;
            Session["curUserLogin"] = string.Empty;
        }

        protected void Application_AuthenticateRequest(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;
            if (app.Request.IsAuthenticated &amp;&amp; User.Identity is FormsIdentity)
            {
                SqlConnection myConnection = new SqlConnection(DBConnection.GetConnectionString());
                SqlCommand myCommand = new SqlCommand("SELECT * FROM Users WHERE login=@login", myConnection);
                myCommand.Parameters.AddWithValue("login", app.Context.User.Identity.Name);
                myCommand.Connection.Open();
                SqlDataReader Reader = myCommand.ExecuteReader();
                string role = string.Empty;                
                while (Reader.Read())
                {
                    userLogin = Reader["login"].ToString();
                    role = Reader["role"].ToString();
                }
                if (role != string.Empty)
                {
                    FormsIdentity fi = (FormsIdentity)app.User.Identity;
                    app.Context.User = new GenericPrincipal(fi, new string[] { role });
                }
            }
        }
    }
}
</code></pre>

<p>When user login into the project run function <code>protected void Application_AuthenticateRequest(object sender, EventArgs e)</code> and I try to store user login in private string type <code>userLogin</code> variable. But when session end run function <code>void Session_End(object sender, EventArgs e)</code> in this function I try to save in database by user login status "offline" but variable <code>userLogin</code> is empty. Where I can quickly save user login and get it in funtion <code>void Session_End(object sender, EventArgs e)</code>?</p>
