Microsoft KB Archive/108402

DOCERR: WM_COPYDATA Is Also Supported on Win32s PSS ID Number: Q108402 Article last modified on 04-28-1994

3.10

WINDOWS NT

= SUMMARY =

There are a number of methods that two processes (both 32-bit, or one 32- bit and one 16-bit) can use to communicate on both Windows NT and Win32s. These methods include the use of dynamic data exchange (DDE), the clipboard, and object linking and embedding (OLE), all of which can involve some amount of overhead.

Windows NT introduces a new message, WM_COPYDATA, which can be used to pass data from one application to another. The Win32 “Programmer’s Reference” contains the following description

WM_COPYDATA wParam = (WPARAM) (HWND) hwndFrom; lParam = (LPARAM) (PCOPYDATASTRUCT) pcds;

where wParam is the handle of the sending window and pcds is a pointer to the structure that contains the data.

The documentation does not indicate that this message is supported under Win32s; however, WM_COPYDATA is supported under Win32s.

Note that under Win32s, WM_COPYDATA does not actually copy the data–it only translates the pointers to the data. If the receiving application changes the buffer, then the data is changed for both applications.

Additional reference words: 3.10 KBCategory: Prg KBSubcategory: BseMisc

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Copyright Microsoft Corporation 1994.