public static extern bool WinHttpSendRequest(
     SafeWinHttpHandle requestHandle,
     [In] StringBuilder headers,
     uint headersLength,
     IntPtr optional,
     uint optionalLength,
     uint totalLength,
     IntPtr context);

 public static extern SafeWinHttpHandleWithCallback WinHttpOpenRequestWithCallback(
     SafeWinHttpHandle connectHandle,
     string verb,
     string objectName,
     string version,
     string referrer,
     string acceptTypes,
     uint flags);

 public static void DisposeAndClearHandle(ref SafeWinHttpHandle safeHandle)
 {
     if (safeHandle != null)
     {
         safeHandle.Dispose();
         safeHandle = null;
     }
 }

 public static void DisposeAndClearHandle(ref SafeWinHttpHandle handle)
 {
     if (handle != null)
     {
         handle.Dispose();
         handle = null;
     }
 }

            public void SetParentHandle(SafeWinHttpHandle parentHandle)
            {
                Debug.Assert(_parentHandle == null);
                Debug.Assert(parentHandle != null);
                Debug.Assert(!parentHandle.IsInvalid);

                bool ignore = false;
                parentHandle.DangerousAddRef(ref ignore);
                
                _parentHandle = parentHandle;
            }

 public static extern uint WinHttpWebSocketClose(
     SafeWinHttpHandle webSocketHandle,
     ushort status,
     IntPtr reason,
     uint reasonLength);

 public static extern uint WinHttpWebSocketShutdown(
     SafeWinHttpHandle webSocketHandle,
     ushort status,
     byte[] reason,
     uint reasonLength);

 public static extern bool WinHttpWriteData(
     SafeWinHttpHandle requestHandle,
     IntPtr buffer,
     uint bufferSize,
     out uint bytesWritten);

 public static extern bool WinHttpQueryHeaders(
     SafeWinHttpHandle requestHandle,
     uint infoLevel,
     string name,
     ref uint number,
     ref uint bufferLength,
     IntPtr index);

 public static extern bool WinHttpQueryDataAvailable(
     SafeWinHttpHandle requestHandle,
     out uint bytesAvailable);

 public static extern bool WinHttpSetTimeouts(
     SafeWinHttpHandle handle,
     int resolveTimeout,
     int connectTimeout,
     int sendTimeout,
     int receiveTimeout);

 public static extern bool WinHttpQueryOption(
     SafeWinHttpHandle handle,
     uint option,
     [Out] StringBuilder buffer,
     ref uint bufferSize);

 public static extern bool WinHttpSetCredentials(
     SafeWinHttpHandle requestHandle,
     uint authTargets,
     uint authScheme,
     string userName,
     string password,
     IntPtr reserved);

 public static extern bool WinHttpQueryAuthSchemes(
     SafeWinHttpHandle requestHandle,
     out uint supportedSchemes,
     out uint firstScheme,
     out uint authTarget);

 public static extern bool WinHttpSetOption(
     SafeWinHttpHandle handle,
     uint option,
     IntPtr optionData,
     uint optionLength);

 public static extern uint WinHttpWebSocketQueryCloseStatus(
     SafeWinHttpHandle webSocketHandle,
     out ushort status,
     byte[] reason,
     uint reasonLength,
     out uint reasonLengthConsumed);

 public static extern bool WinHttpGetProxyForUrl(
     SafeWinHttpHandle sessionHandle, string url,
     ref WINHTTP_AUTOPROXY_OPTIONS autoProxyOptions,
     out WINHTTP_PROXY_INFO proxyInfo);

 public static extern SafeWinHttpHandleWithCallback WinHttpConnectWithCallback(
     SafeWinHttpHandle sessionHandle,
     string serverName,
     ushort serverPort,
     uint reserved);

 public static extern IntPtr WinHttpSetStatusCallback(
     SafeWinHttpHandle handle,
     WINHTTP_STATUS_CALLBACK callback,
     uint notificationFlags,
     IntPtr reserved);

 public static extern bool WinHttpAddRequestHeaders(
     SafeWinHttpHandle requestHandle,
     string headers,
     uint headersLength,
     uint modifiers);