Session

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

namespace AppName.App_Data
{
    public class CheckLogin :System.Web.UI.Page
    {
        public CheckLogin()
        {
            object IsLogined = System.Web.HttpContext.Current.Session["IsLogined"];
            if (IsLogined != null)
            {
                if (IsLogined.ToString()!="1")
                {
                    HttpContext.Current.Response.Write("Error!");
                    HttpContext.Current.Response.End();
                }
                else
                {
                    HttpContext.Current.Response.Write("OK");
                }
            }
            else {
                HttpContext.Current.Response.Write("Error!");
                HttpContext.Current.Response.End();
            }

        }
    }
}