问如何在浏览器的进度栏中显示FTPWebRequest文件上载的进度？

EN

    public class Handler1 : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            try
            {
                context.Response.ContentType = "text/plain"; //"application/json";

                HttpContext postedContext = HttpContext.Current;


                var r = new System.Collections.Generic.List<ViewDataUploadFilesResult>();

                var js = new JavaScriptSerializer();

                foreach (string file in context.Request.Files)
                {
                    var hpf = context.Request.Files[file] as HttpPostedFile;

uplaodFiles(hpf,pid, id);

   private UploadState uplaodFiles(HttpPostedFile file,Guid pid, string id)
        {


                FtpWebRequest request = (FtpWebRequest)WebRequest.Create(url);

                request.Method = WebRequestMethods.Ftp.UploadFile;

                request.Timeout = 3600000;

                request.Credentials = new NetworkCredential(ftpuser, ftpassword);

                byte[] fileData = null;

                using (Stream input = file.InputStream)
                {
                    using (Stream output = request.GetRequestStream())
                    {
                        input.CopyTo(output);
                    }
                }