Terminating a Data Link

If the client requests that a specific data link be terminated, the client sends the server a WM_DDE_UNADVISE message, as shown in the following example.

if ((atomItem = GlobalAddAtom(szItemName)) != 0) 
{ 
    if (!PostMessage(hwndServerDDE, 
            WM_DDE_UNADVISE, 
            (WPARAM) hwndClientDDE, 
            PackDDElParam(WM_DDE_UNADVISE, 0, atomItem))) 
    { 
        GlobalDeleteAtom(atomItem); 
        FreeDDElParam(WM_DDE_UNADVISE, lParam); 
    } 
} 
 
if (atomItem == 0) 
{ 

    // Handle errors. 

} 

The server checks whether the client currently has a link to the specific item in this conversation. If a link exists, the server sends the client a positive WM_DDE_ACK message; the server is then no longer required to send updates about the item. If no link exists, the server sends the client a negative WM_DDE_ACK message.

The WM_DDE_UNADVISE message specifies a data format. A format of zero informs the server to stop all links for the specified item, even if several hot links are established and each uses a different format.

To terminate all links for a conversation, the client application sends the server a WM_DDE_UNADVISE message with a null item atom. The server determines whether the conversation has at least one link currently established. If a link exists, the server sends the client a positive WM_DDE_ACK message; the server then no longer has to send any updates in the conversation. If no link exists, the server sends the client a negative WM_DDE_ACK message.