A DDE client application posts a WM_DDE_REQUEST message to a DDE server application to request the value of a data item.
WM_DDE_REQUEST
wParam = (WPARAM) hwnd; // handle of posting application
lParam = (LPARAM) lParam; // holds cfFormat and aItem
Parameters
hwnd
Value of wParam. Identifies the client window sending the message.
lParam
Holds the cfFormat and aItem parameters.
| Parameter | Description |
| cfFormat | This is the LOWORD of lParam. Specifies a standard or registered clipboard format. |
| aItem | This is the HIWORD of lParam. Contains an atom that identifies the data item requested from the server. |
Remarks
Posting
The client application posts the WM_DDE_REQUEST message by calling the PostMessage function, not the SendMessage function.
The client application allocates aItem by calling the GlobalAddAtom function.
Receiving
If the receiving (server) application can satisfy the request, it responds with a WM_DDE_DATA message containing the requested data. Otherwise, it responds with a negative WM_DDE_ACK message.
When responding with either a WM_DDE_DATA or WM_DDE_ACK message, the server application can either reuse the aItem atom or it can delete the atom and create a new one.
See Also
GlobalAddAtom, PackDDElParam, PostMessage, ReuseDDElParam, SendMessage, UnpackDDElParam, WM_DDE_ACK, WM_DDE_DATA