public void GetRequest(string requestUrl, EventHandler<WebEventArgs> callbackMethod, object requestState)
        {
            try
            {
                HttpWebRequest myHttpWebRequest1 = HttpWebRequest.CreateHttp(requestUrl);
                //myHttpWebRequest1.Accept = "text/html, application/xhtml+xml";
                //myHttpWebRequest1.Headers["User-Agent"] = "Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0; Touch; MASMJS";
                // Create an instance of the RequestState and assign the previous myHttpWebRequest1// object to it's request field.  
                RequestState myRequestState = new RequestState();
                myRequestState.request = myHttpWebRequest1;
                myRequestState.CallbackMethod = callbackMethod;
                myRequestState.userState = requestState;

                // Start the asynchronous request.
                IAsyncResult result = myHttpWebRequest1.BeginGetResponse(new AsyncCallback(RespCallback), myRequestState);
            }
            catch (WebException e)
            {
                throw e;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        internal void PostRequest(string requestUrl, string postData, EventHandler<WebEventArgs> callbackMethod, object userState)
        {
            try
            {
                HttpWebRequest myHttpWebRequest1 = HttpWebRequest.CreateHttp(requestUrl);

                // Create an instance of the RequestState and assign the previous myHttpWebRequest1// object to it's request field.  
                RequestState myRequestState = new RequestState();
                myRequestState.request = myHttpWebRequest1;
                myRequestState.CallbackMethod = callbackMethod;
                myRequestState.userState = userState;
                myRequestState.requestData = new StringBuilder(postData);

                // Start the asynchronous request.
                myHttpWebRequest1.Method = "POST";
                //myHttpWebRequest1.ContentType = "application/x-www-form-urlencoded";
                //myHttpWebRequest1.Accept = "text/html, application/xhtml+xml, */*";
                //myHttpWebRequest1.Referer = "http://websig.hidrografico.pt/website/icenc/jsForm.htm";
                IAsyncResult result = myHttpWebRequest1.BeginGetRequestStream(new AsyncCallback(PostStreamCallback), myRequestState);
            }
            catch (WebException e)
            {
            }
            catch (Exception e)
            {
            }
        }