To determine the number of bytes already sent, use the BytesSent property.
Uploading data to a server may result in a download from the server. For example, suppose your application uploads a POST request to a Web server. The resulting download will update BytesReceived and TotalBytesToReceive.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2