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Called by the framework to notify the receiving socket that the sending socket has out-of-band data to send.

virtual void OnOutOfBandData(
   int nErrorCode 



The most recent error on a socket. The following error codes apply to the OnOutOfBandData member function:

  • 0   The function executed successfully.

  • WSAENETDOWN   The Windows Sockets implementation detected that the network subsystem failed.

Out-of-band data is a logically independent channel that is associated with each pair of connected sockets of type SOCK_STREAM. The channel is generally used to send urgent data.

MFC supports out-of-band data, but users of class CAsyncSocket are discouraged from using it. The easier way is to create a second socket for passing such data. For more information about out-of-band data, see Windows Sockets: Socket Notifications.