XTYP_CONNECT transaction
A client uses the XTYP_CONNECT transaction to establish a conversation. A Dynamic Data Exchange (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.
#define XCLASS_BOOL 0x1000
#define XTYPF_NOBLOCK 0x0002
#define XTYP_CONNECT (0x0060 | XCLASS_BOOL | XTYPF_NOBLOCK)
Parameters
-
uType
-
The transaction type.
-
uFmt
-
Not used.
-
hconv
-
Not used.
-
hsz1
-
A handle to the topic name.
-
hsz2
-
A handle to the service name.
-
hdata
-
Not used.
-
dwData1
-
A pointer to a CONVCONTEXT structure that contains context information for the conversation. If the client is not a 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 value
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
| Requirement | Value |
|---|---|
| Minimum supported client |
Windows 2000 Professional [desktop apps only] |
| Minimum supported server |
Windows 2000 Server [desktop apps only] |
| Header |
|
See also
-
Reference
-
Conceptual