How correct work with global variables in Global.asax?

Question

I have a Global.asax file in my project with 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 && 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 });
                }
            }
        }
    }
}

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

Answer 1

Because of stateless of web applications you can't do this through static variable. If I where you, I would save login to Session state in

 protected void Application_AuthenticateRequest(object sender, EventArgs e)
    {
        HttpApplication app = (HttpApplication)sender;
        if (app.Request.IsAuthenticated && 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();
            var userLogin = string.Empty;
            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 });
                Session["UserLogin"] = userLogin;
            }
        }
    }
void Session_End(object sender, EventArgs e)
    {            
        if(Session["UserLogin"]!=null)
        {
            var userLogin = (string)Session["UserLogin"];
            DBUsers.SetUserStatusOnline("0", userLogin); 
        }              
    }