WM_DDE_REQUEST

A DDE client application posts a WM_DDE_REQUEST message to a DDE server application to request the value of a data item.

To post this message, call the PostMessage function with the following parameters.

PostMessage( 
  (HWND) hWnd,             // handle to destination window 
  WM_DDE_REQUEST,          // message to send
  (WPARAM) wParam,         // handle to client window (HWND)
  (LPARAM) lParam          // format and item atom
);

Parameters

wParam

Handle to the client window sending the message.

lParam

The low-order word specifies a standard or registered clipboard format.

The high-order word contains an atom that identifies the data item requested from the server.

Remarks

Posting

The client application allocates the atom 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 atom or it can delete the atom and create a new one.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Windows 95/98: Requires Windows 95 or later.
  Header: Declared in Dde.h; include Windows.h.

See Also

Dynamic Data Exchange Overview, Dynamic Data Exchange Messages, GlobalAddAtom, PackDDElParam, PostMessage, ReuseDDElParam, SendMessage, UnpackDDElParam, WM_DDE_ACK, WM_DDE_DATA