Creating an abstract AJAX user control

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Security.Permissions;

[assembly: WebResource("AbstractAjaxControl.Resources.AjaxBase.js", "text/javascript")]
namespace AjaxControls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level=AspNetHostingPermissionLevel.Minimal)]
    public abstract class AjaxControl : WebControl
    {
        private string _scope = null;

        public AjaxControl()
        {
            AjaxRequest += new AjaxRequestEventHandler(HandleAjaxRequest);
        }

        public string Scope
        {
            get { return _scope; }
            set { _scope = value; }
        }

        protected override void OnInit(EventArgs e)
        {
            if (!Page.IsPostBack && Page.Request.Form["scope"] == _scope)
            {
                OnAjaxRequest();
            }

            base.OnInit(e);


            Page.ClientScript.RegisterClientScriptResource(typeof(AjaxControl), "AbstractAjaxControl.Resources.AjaxBase.js");
        }

        protected abstract void HandleAjaxRequest(object sender, AjaxRequestEventArgs e);
        protected abstract override void RenderContents(HtmlTextWriter output);

        private delegate void AjaxRequestEventHandler(object sender, AjaxRequestEventArgs e);
        private event AjaxRequestEventHandler AjaxRequest;
        private void OnAjaxRequest()
        {
            if (AjaxRequest != null)
                AjaxRequest(this, new AjaxRequestEventArgs(Page.Request.Form));
        }
    }
}