Microsoft KB Archive/94561

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WM_COMMNOTIFY is Obsolete for Win32-Based Applications

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Q94561

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The information in this article applies to:


 * Microsoft Win32 Application Programming Interface (API), included with:
 * the operating system: Microsoft Windows NT, versions 3.1, 3.5, 3.51
 * Microsoft Windows 95

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SUMMARY
Under Windows version 3.1, the WM_COMMNOTIFY message is posted by a communication device driver whenever a COM port event occurs. The message indicates the status of a window's input or output queue.

This message is not supported for Win32-based applications. However, WOW supports the EnableCommNotification API for 16-bit Windows-based applications running on Windows NT.

MORE INFORMATION
To duplicate the Windows 3.1 functionality for a Win32-based application, refer to the TTY sample, included with the SDK. The TTY sample is a common code base sample, which uses EnableCommNotification under Windows 3.1 to tell COMM.DRV to post messages to the TTY window.

In Win32, this behavior is simulated with a secondary thread which uses WaitCommEvent to block on the port and PostMessage to indicate when the desired event has occurred.

TTY.C defines WM_COMMNOTIFY if WIN32 is defined. Using this method, WM_COMMNOTIFY notifications are simulated but use the same message definition as Windows 3.1.

The TTY sample is located on the Win32 SDK CD in \MSTOOLS\SAMPLES\COMM.

Additional query words: 3.10 3.50 4.00

Keywords : kbOSWinNT310 kbOSWinNT350 kbOSWinNT351 kbOSWin95

Issue type :

Technology : kbAudDeveloper kbWin32sSearch kbWin32API