XTYP_UNREGISTER

A DDE callback function, DdeCallback, receives the XTYP_UNREGISTER transaction whenever a DDEML server application uses the DdeNameService function to unregister a service name, or whenever a non-DDEML application that supports the System topic is terminated.

HDDEDATA CALLBACK DdeCallback(
  UINT uType,     // XTYP_UNREGISTER
  UINT uFmt,      // clipboard data format
  HCONV hconv,    // handle to the conversation
  HSZ hsz1,       // handle to a string
  HSZ hsz2,       // handle to a string
  HDDEDATA hdata, // handle to a global memory object
  DWORD dwData1,  // transaction-specific data
  DWORD dwData2   // transaction-specific data
);

Parameters

uType

Specifies the transaction type.

uFmt

Not used.

hconv

Not used.

hsz1

Handle to the base service name being unregistered.

hsz2

Handle to the instance-specific service name being unregistered.

hdata

Not used.

dwData1

Not used.

dwData2

Not used.

Remarks

This transaction is filtered if the application specified the CBF_SKIP_REGISTRATIONS flag in the DdeInitialize function.

A application cannot block this transaction type; the CBR_BLOCK return code is ignored.

An application should use the hsz1 parameter to remove the service name from the list of servers available to the user. An application should use the hsz2 parameter to identify which application instance has terminated.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Windows 95/98: Requires Windows 95 or later.
  Header: Declared in Ddeml.h; include Windows.h.

See Also

Dynamic Data Exchange Management Library Overview, Dynamic Data Exchange Management Transactions, DdeInitialize, DdeNameService