INF: Communicating Between Windows Virtual Machines with DDE

ID Number: Q40620

2.03 2.10 3.00

WINDOWS

Summary:

Windows 286 supports DDE (dynamic data exchange) for DOS (non-Windows)

applications; however, Windows/386 and Windows versions 3.x real and

enhanced modes do not include this type of functionality. Currently,

there are no plans to add this type of functionality to a future

release of Windows.

The following methods describe several different ways for a DOS

(non-Windows) application to communicate with a Windows/386

application:

1. The Clipboard. DOS applications can read from or write to the

Clipboard. The methods for doing this are documented in the Windows

SDK (Software Development Kit). Microsoft Word incorporates this

capability. This would be the method of choice in most instances.

2. A shared file. This is not an extremely fast method, although the

programmer could use a file on a RAM disk or rely on SMARTDRV to

reduce actual file accesses. Remember to call SHARE.EXE from DOS

before starting Windows/386 to ensure that file sharing works

properly.

3. DOS TSR (terminate-and-stay-resident) program. Another method that

can be used is to start a DOS TSR program with a buffer at a fixed

location that can be read/written to by different applications. For

this method to work, the memory region used must be below the load

point of Windows/386, otherwise the different virtual machines will

have their own private copies of the address space.

4. Bridge/386. There is a program called Bridge/386 that is sold by

Softbridge Microsystems in Cambridge, Massachusetts, that provides

this type of functionality. There is a good description of this

program in the September 1988 issue of the "Microsoft Systems

Journal."