Platform SDK: Interprocess Communications

DdeQueryConvInfo

The DdeQueryConvInfo function retrieves information about a dynamic data exchange (DDE) transaction and about the conversation in which the transaction takes place.

UINT DdeQueryConvInfo(
  HCONV hConv,          // handle to conversation
  DWORD idTransaction,  // transaction identifier
  PCONVINFO pConvInfo   // conversation data
);

Parameters

hConv: [in] Handle to the conversation.
idTransaction: [in] Specifies the transaction. For asynchronous transactions, this parameter should be a transaction identifier returned by the DdeClientTransaction function. For synchronous transactions, this parameter should be QID_SYNC.
pConvInfo: [in/out] Pointer to the CONVINFO structure that receives information about the transaction and conversation. The cb member of the CONVINFO structure must specify the length of the buffer allocated for the structure.

Return Values

If the function succeeds, the return value is the number of bytes copied into the CONVINFO structure.

If the function fails, the return value is FALSE.

Errors

The DdeGetLastError function can be used to get the error code, which can be one of the following values:

DMLERR_DLL_NOT_INITIALIZED
DMLERR_NO_CONV_ESTABLISHED
DMLERR_NO_ERROR
DMLERR_UNFOUND_QUEUE_ID

Remarks

An application should not free a string handle referenced by the CONVINFO structure. If an application must use one of these string handles, it should call the DdeKeepStringHandle function to create a copy of the handle.

If the idTransaction parameter is set to QID_SYNC, the hUser member of the CONVINFO structure is associated with the conversation and can be used to hold data associated with the conversation. If idTransaction is the identifier of an asynchronous transaction, the hUser member is associated only with the current transaction and is valid only for the duration of the transaction.

Requirements