Using this support function, you can set a special callback function that will be used for handling asynchronous I/O operations.
BOOL ServerSupportFunction( HCONN ConnID, DWORD dwServerSupportFunction, PFN_HSE_IO_COMPLETION pfnIOCompletion, LPDWORD lpdwSizeofBuffer, LPDWORD lpdwContext );
Note that this support function does not actually perform any asynchronous I/O operations itself.
If the callback function is set to NULL, the callback function will never be called by IIS. If this support function is called multiple times, only the callback function specified by the last function call will be honored by IIS. All previous callback function settings will be lost.
If there is an error performing an asynchronous I/O operation, IIS will make exactly one call to the callback function that is specified by pfnIOCompletion in this support function. It is then your ISAPI extension's responsibility to do the necessary cleanup of any allocated resources associated with that operation.
Client: Requires Windows XP Professional, Windows 2000 Professional, or Windows NT Workstation 4.0.
Server: Requires Windows Server 2003, Windows 2000 Server, or Windows NT Server 4.0.
Header: Declared in httpext.h.