Howdy folks,
I believe I may have found the one thing that’s impossible to program (without "cheating"). I'm using VB.NET 2003, on a winXP Pro machine. Here's what I'm trying to do:
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Using a service without a GUI, I'd like to detect when Windows is shutting down, restarting, or logging off. I need to differentiate between shutdowns, restarts, and log offs.
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As soon as one of these actions is detected, I need to cancel/postpone it, do some tasks (which may take awhile), and then resume the shutdown/restart/log off.
This must be done with a service, using no windows or GUI. That means no cheating, like using "CreateWindowEx" APIs – that's a GUI.
I guess I'll probably have to settle for compromises, but if there is a solid solution out there, pleeeeeeease help!
Cheers!
Detect and STOP shutdown in a VB.net 2003 Service
Shawn Songer
OK... I'll come with a bold suggestion: Make your process a service instead. A service exposes the OnStop and OnShutdown events. In these event handlers you can do your job, and then let the service stop and the OS to complete the logoff/restart/shutdown without you having to find out which action has been taken.
So... the big question is: Do you really need to stop the logoff/restart/shutdown Or do you just want time enough to do any tear-down before the process is ended
Agus Ilmi Kurniawan
I take your second point - but by the time they do so, hopefully they'll have provided adequate alternatives.
On your first point - don't create a .net form - just create a simple window using the Windows API directly - the impact on size will be negligible, and you can then use WM_QUERYENDSESSION.
Alternatively, if you really, really are sqeamish about using your own window, don't. FROM A DLL, hook the message loop and subclass the main desktop window, then examine it's messages.
Tomas Floyd
Thanks Claes,
That actually did help a bit, but I still can’t differentiate between a shutdown and a restart. Also, I can’t even detect or cancel the logoff event. Here’s what I’m doing:
Guillermo Díaz
Why no GUI
What's wrong with a hidden window for the purpose
Good-man
Take a look on the Microsoft.Win32.SystemEvents Class. There is a SessionEnding event that you might find useful.
chpe
Well, for starters, it actually is a service. OnShutdown “works,” but I still can’t differentiate between shutdowns, restarts, and it doesn’t even trap logoffs at all.
I need to do all this because it has to be up to the user when to perform the long cleanup tasks: during shutdown (most likely choice), restart, or log off. The choice has to be the user.
As for why no forms Well, two big reasons:
Surely there must be an actual way to detect and postpone a shutdown, restart, and logoff in a service (while differentiating between the three).