With the Windows Web Services API (WWSAPI), you can connect your C/C++ client applications with web services. You can also create C/C++ server-side web service end-points. WWSAPI is new with Windows 7 (client) and Windows Server 2008 R2 (server). WWSAPI is also back-ported to all formally supported versions of Windows (client and server). The WWSAPI runtime library (WebServices.dll) is a native-code implementation of WS-* family of protocols for SOAP based web services.
More reading here: http://code.msdn.microsoft.com/wwsapi