System.Net.HttpWebRequest.BeginGetRequestStream C# (CSharp) Метод

        public override IAsyncResult BeginGetRequestStream(AsyncCallback callback, Object state)
        {
            CheckAbort();

            if (Interlocked.Exchange(ref _beginGetRequestStreamCalled, 1) != 0)
            {
                throw new InvalidOperationException(SR.net_repcall);
            }

            _requestStreamCallback = callback;
            _requestStreamOperation = GetRequestStreamTask().ToApm(callback, state);

            return _requestStreamOperation.Task;
        }      

 public void PostRegisterInfoAsync(RegisterInfo registerInfo)
 {
     _requestState = new RequestState();
     _registerInfo = registerInfo;
     _httpWebRequest = (HttpWebRequest)WebRequest.Create(_registerURL);
     _timer.Start();
     _requestState.request = _httpWebRequest;
     _httpWebRequest.Method = "POST";
     _httpWebRequest.ContentType = "application/x-www-form-urlencoded";
     _httpWebRequest.BeginGetRequestStream(new AsyncCallback(RequestCallback), _httpWebRequest);
 }