Un cop està preparada tota la configuració necessària per fer la invocació només queda aquesta pròpiament dita. En l'aplicació també hi han els botons de "Load" i "Save" que el que fan és escriure els valors dels controls en un fitxer XML i recuperar els valors, no cal que els expliqui...

private string SendRequest(string SOAP, 
			   string URL, 
			   string SOAPAction, 
			   string ContentType, 
			   clsProxy pProxy, 
			   clsHTTPBasicAuthorization HTTPBasic)
{
    HttpWebRequest req = (HttpWebRequest) WebRequest.Create(URL);
    req.ContentType = ContentType;
    req.Method = "POST";


    if (!string.IsNullOrWhiteSpace(SOAPAction)) req.Headers.Add("SOAPAction", SOAPAction);
    
    if (pProxy != null) req.Proxy = pProxy.GetProxy();
    if (HTTPBasic != null)
    {
	string auth = HTTPBasic.CreateAuthorization();
	req.Headers.Add("Authorization", "Basic " + auth);
    }
    try
    {
	string responseSOAP = "";
	using (Stream stm = req.GetRequestStream())
	{
	    using (StreamWriter stmw = new StreamWriter(stm))
	    {
		stmw.Write(SOAP);
	    }
	}

	WebResponse response = req.GetResponse();
	Stream responseStream = response.GetResponseStream();
	StreamReader reader = new StreamReader(responseStream);

	responseSOAP = reader.ReadToEnd();

	return responseSOAP;
    }
    catch (Exception E)
    {
	return E.Message;
    }
}

private void btnPOST_Click(object sender, EventArgs e)
{
    btnPOST.Enabled = false;
    try
    {
	string SOAPString = txtSOAP.Text;
	string URL = txtURL.Text;
	string SOAPAction = txtSOAPAction.Text;
	clsProxy Pxy = null;
	clsHTTPBasicAuthorization HTTPBasic = null;
	int Iteracions = int.Parse(txtIteracions.Text);

	txtResultats.Text += Environment.NewLine + DateTime.Now.ToShortDateString()
		+ " " + DateTime.Now.ToLongTimeString()
                + " ----------------------" + Environment.NewLine;
	if(chkUseProxy.Checked)
	{
	    Pxy = new clsProxy();
	    Pxy.ProxyURL = txtProxy.Text;
	    Pxy.ProxyUsr = txtProxyUsr.Text;
	    Pxy.ProxyPwd = txtProxyPwd.Text;
	    Pxy.ProxyPort = txtProxyPort.Text;
	}

	if(chkBasicAuth.Checked)
	{
	    HTTPBasic = new clsHTTPBasicAuthorization();
	    HTTPBasic.Domini = txtDominiBasicAuth.Text;
	    HTTPBasic.Usr = txtUsuariBasicAuth.Text;
	    HTTPBasic.Pwd = txtPwdBasicAuth.Text;
	}

	for (int i = 0; i < Iteracions; i++)
	{
	    txtResultats.Text += Environment.NewLine + DateTime.Now.ToLongTimeString()
		+ SendRequest(SOAPString, URL, SOAPAction, cboContentType.Text, Pxy, HTTPBasic);
	    Application.DoEvents();
	}

	txtResultats.Text += Environment.NewLine
                  + DateTime.Now.ToLongTimeString()
                  + " ----------------------" + Environment.NewLine;

    }
    catch (Exception E)
    {
	txtResultats.Text += Environment.NewLine
                  + "--------- ERRRORRR -------------" + Environment.NewLine;
	txtResultats.Text += Environment.NewLine + E.Message;
    }
    btnPOST.Enabled = true;
}