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

See also

Reference

CONVCONTEXT

DdeConnect

DdeInitialize

Conceptual

Dynamic Data Exchange Management Library