Threading to allow cancelling a web request

I'm writing a web app that allows users to download large files over http web request. I need to give them the option to cancel the request, so I create a thread for the request. But, while the download is happening, I still can't get the cancel event to fire. What am I doing wrong? Thanks for any input!

public class downloadThread  { 
           publi开发者_JAVA百科c int isResume;
           public void downloadImage()
            { }
        }
            protected void btnDownload_Click(object sender, EventArgs e)
            {       var x = new downloadThread();
                    x.isResume = 0;

                    tRequest = new Thread(new ThreadStart(x.downloadImage));
                    tRequest.Start();
                    while (tRequest.IsAlive)
                    {
                      DownloadImage(); //this is where the rest request happens 
                    } }
            protected void btnCancelRequest_Click(object sender, EventArgs e)
            {
                if (tRequest != null && tRequest.IsAlive)
                {

                    tRequest.Abort();

                }
            }

Aborting a thread with thread.Abort is maybe not the way you want to do this.

How about an asynchronous web request in your DownloadImage method instead? (See http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.begingetresponse.aspx ). That way you can call the web request's .Abort method rather than aborting the thread.