XTYP_REQUEST transaction

A client uses the XTYP_REQUEST transaction to request data from a server. A Dynamic Data Exchange (DDE) server callback function, DdeCallback, receives this transaction when a client specifies XTYP_REQUEST in the DdeClientTransaction function.


#define     XCLASS_DATA              0x2000
#define     XTYP_REQUEST            (0x00B0 | XCLASS_DATA          )

Parameters

uType

The transaction type.

uFmt

The format in which the server should submit data to the client.

hconv

A handle to the conversation.

hsz1

A handle to the topic name.

hsz2

A handle to the item name.

hdata

Not used.

dwData1

Not used.

dwData2

Not used.

Return value

The server should call the DdeCreateDataHandle function to create a data handle that identifies the data and then return the handle. The server should return NULL if it is unable to complete the transaction. If the server returns NULL, the client will receive a DDE_FNOTPROCESSED flag.

Remarks

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

If responding to this transaction requires lengthy processing, the server can return the CBR_BLOCK return code to suspend future transactions on the current conversation and then process the transaction asynchronously. When the server has finished and the data is ready to pass to the client, the server can call the DdeEnableCallback function to resume the conversation.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Ddeml.h (include Windows.h)

See also

Reference
DdeClientTransaction
DdeCreateDataHandle
DdeEnableCallback
DdeInitialize
Conceptual
Dynamic Data Exchange Management Library

 

 

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