Problem: ClickOnce Deployment via Internet May Not Always Upgrade an Application

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;
using System.IO;

namespace CustomHttpHandlers
{
    public class ClickOnceApplicationHandler : IHttpHandler
    {
        public ClickOnceApplicationHandler()
        {
        }

        #region IHttpHandler Members

        bool IHttpHandler.IsReusable
        {
            get { return true; }
        }

        void IHttpHandler.ProcessRequest(HttpContext context)
        {
            Logger.Log("IHttpHandler.ProcessRequest started for " + context.Request.Path);

            context.Response.Cache.SetExpires(DateTime.Now);
            context.Response.Cache.SetValidUntilExpires(true);
            context.Response.Cache.SetCacheability(HttpCacheability.NoCache);

            string path = context.Server.MapPath(context.Request.Path).ToLower();
            if (File.Exists(path))
            {
                //Ensure browser handles application files correctly
                if (path.EndsWith(".application"))
                    context.Response.ContentType = "application/x-ms-application";

                byte[] outputBinaryArray;
                FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);
                BinaryReader r = new BinaryReader(fs);
                outputBinaryArray = r.ReadBytes(Convert.ToInt32(fs.Length));
                r.Close();
                fs.Close();
                context.Response.BinaryWrite(outputBinaryArray);
            }
            else
            {
                throw new HttpException(404, "File not found");
            }
        }

        #endregion

    }
}