XTYP_CONNECT

A client uses the XTYP_CONNECT transaction to establish a conversation. A DDE server callback function, DdeCallback, receives this transaction when a client specifies a service name that the server supports (and a topic name that is not NULL) in a call to the DdeConnect function.

HDDEDATA CALLBACK DdeCallback(
  UINT uType,     // XTYP_CONNECT
  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 topic name.

hsz2

Handle to the service name.

hdata

Not used.

dwData1

Pointer to a CONVCONTEXT structure that contains context information for the conversation. If the client is not a Dynamic Data Exchange Management Library (DDEML) application, this parameter is 0.

dwData2

Specifies whether the client is the same application instance as the server. If the parameter is 1, the client is the same instance. If the parameter is 0, the client is a different instance.

Return Values

A server callback function should return TRUE to allow the client to establish a conversation on the specified service name and topic name pair, or the function should return FALSE to deny the conversation. If the callback function returns TRUE and a conversation is successfully established, the system passes the conversation handle to the server by issuing an XTYP_CONNECT_CONFIRM transaction to the server's callback function (unless the server specified the CBF_SKIP_CONNECT_CONFIRMS flag in the DdeInitialize function).

Remarks

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

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

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, CONVCONTEXT, DdeConnect, DdeInitialize