private void HTTPListener()
    {
        // Create a listener.
        try {
            HttpListener listener = new HttpListener();
            // Add the prefixes from UI.
            listener.Prefixes.Add(URL_field);
		    while (true) {
                listener.Start();
                // Note: The GetContext method blocks while waiting for a request.
                HttpListenerContext context = listener.GetContext();
                HttpListenerRequest request = context.Request;
                using (var bodyStream = request.InputStream)
                {
                    using (System.IO.StreamReader reader = new System.IO.StreamReader(bodyStream, request.ContentEncoding))
                    {
                        AssignText(reader.ReadToEnd());

                    }
                }
            }
        }
        catch (Exception e) {
            string err_msg = "On client connect exception " + e;
			ans = err_msg.ToString();
		}