Advanced MFC Programming

Chapter 16. Context Sensitive Help
conversation must be terminated. Either the server or the client can terminate the conversion. This can be
implemented by calling function ::DdeDisconnect(…) using the conversion handle. This function can be
called either from the server or from the client side. Once the message is sent, the other side will be notified
of the disconnection by receiving an XTYP_DISCONNECT message.
In the sample, once the connection is set up, it can be terminated from the client side by pressing
“Disconnect” button or from the server side through executing DDE | Disconnect command. This is
implemented as follows:
The server side:
void CMainFrame::OnDdeDisconnect()
{
if(m_hConvServer != 0)
{
::DdeDisconnect(m_hConvServer);
m_hConvServer=0;
Printf("Disconnected by the server.\r\n");
}
}
The client side:
……
void CDDECliDlg::OnButtonConnect()
{
if(m_hConvClient == 0)
{
}
}
else
{
::DdeDisconnect(m_hConvClient);
m_hConvClient=0;
UnobtainHsz(m_hszTopicName);
m_hszTopicName=0;
m_btnConnect.SetWindowText("Connect");
Printf("Disconnected by the client!\r\n");
}
The following shows how message XTYP_DISCONNECT is handled in both sides:
The client side:
……
……
case XTYP_DISCONNECT:
{
m_hConvClient=0;
UnobtainHsz(m_hszTopicName);
m_hszTopicName=0;
((CDDECliDlg *)(AfxGetApp()->m_pMainWnd))->m_btnConnect.SetWindowText("Connect");
Printf("Disconnected by the server.\r\n");
return (HDDEDATA)NULL;
}
The server side:
……
case XTYP_DISCONNECT:
{
if(m_hConvServer == hConv)
{
m_hConvServer=0;
Printf("Disconnected by the client.\r\n");
}
return (HDDEDATA)FALSE;
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