protected void btnCallPOSTwebService_Click(object sender, EventArgs e)
    {
        //  The user has clicked on the "Call POST web service" button
        try
        {
            string WebServiceURL = tbWebServiceURL.Text;

            // Convert our JSON in into bytes using ascii encoding
            ASCIIEncoding encoding = new ASCIIEncoding();
            byte[] data = encoding.GetBytes(tbJSONdata.Text);

            //  HttpWebRequest
            HttpWebRequest webrequest = (HttpWebRequest)WebRequest.Create(WebServiceURL);
            webrequest.Method = "POST";
            webrequest.ContentType = "application/x-www-form-urlencoded";
            webrequest.ContentLength = data.Length;

            //  Get stream data out of webrequest object
            Stream newStream = webrequest.GetRequestStream();
            newStream.Write(data, 0, data.Length);
            newStream.Close();

            //  Declare & read the response from service
            HttpWebResponse webresponse = (HttpWebResponse)webrequest.GetResponse();

            // Fetch the response from the POST web service
            Encoding enc = System.Text.Encoding.GetEncoding("utf-8");
            StreamReader loResponseStream = new StreamReader(webresponse.GetResponseStream(), enc);
            string result = loResponseStream.ReadToEnd();
            loResponseStream.Close();

            webresponse.Close();

            txtResult.Text = result;
        }
        catch (Exception ex)
        {
            txtResult.Text = "An exception was thrown: " + ex.Message;
        }
    }