Número de visitas simultáneas

// ...
namespace Developers
{
  public class Global : System.Web.HttpApplication
  {
    public static int nbUsers;
 
    protected void Application_Start(Object sender, EventArgs e)
    {
      nbUsers = 0;
    }
 
    protected void Session_Start(Object sender, EventArgs e)
    {
      nbUsers++ ;
    }
 
    protected void Session_End(Object sender, EventArgs e)
    {
      nbUsers-- ;
    }
    //...
  }
}