Chache Example Global.asax

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.SessionState;

namespace WebApplication2
{
    public class Global : System.Web.HttpApplication
    {
        public int CatIDToSelect = 2;
        protected void Application_Start(object sender, EventArgs e)
        {

        }

        protected void Session_Start(object sender, EventArgs e)
        {

        }

        protected void Application_BeginRequest(object sender, EventArgs e)
        {

        }

        protected void Application_AuthenticateRequest(object sender, EventArgs e)
        {

        }

        protected void Application_Error(object sender, EventArgs e)
        {

        }

        protected void Session_End(object sender, EventArgs e)
        {

        }

        protected void Application_End(object sender, EventArgs e)
        {

        }
        public override string GetVaryByCustomString(HttpContext context, string custom)
        {
            if (custom == "SelectedCatID")
            {
                return CatIDToSelect.ToString();
            }
            return String.Empty;
        }
    }
}