Re: Session ending shutdown problem

I have a number of MFC MDI applications that run constantly and
unattended, essentially as embedded systems, to monitor and control a
variety of system hardware. They do have a user interface to help
manage the system but every user action requires a password-controlled
logon. A password is also needed to exit the program by whatever
normal means.

The problem is that IT personnel do remote maintenance on all the
systems including these and they can't shut down the program easily --
a password entry box pops up on the remote system but nobody is there
to enter one! So they just shut down Windows and my application loses
data.

Of course I can detect the QueryEndSession and EndSession messages.
The problem (I think) is that my shutdown takes too long -- there are
perhaps a dozen socket connections and several database tables that
have to be closed cleanly and many score data structures with
internal states that all need serialization so the system can be
restored properly at startup.

Here are some details: If I initiate a program close at
QueryEndSession and return FALSE to halt further system shutdown,
everything works fine. If I initiate a program close at either
QueryEndSession or EndSession but allow the system to actually
shutdown, then my program is aborted before all the data can be saved.
Most of my system saving is done during ExitInstance but some is also
done at the d'tor of my CWinApp derived class.

My current workaround is to shut down on QueryEndSession, returning
FALSE and force the IT people to perform a second shutdown.
Alternatively I can provide them with a separate program that tells my
application to close cleanly, but there is no promise that I can get
all the IT staff to actually do that. I would like behave nicely,
though and shut down cleanly on a single EndSession.

Is this a known issue? Am I simply doing something wrong? I confess
(if it is not already obvious) that I really don't understand how
EndSession works. Actually, I don't understand how MFC shutdown
works, for example why posting WM_QUIT does not properly close the
program whereas posting WM_CLOSE does. It is exactly OnClose where I
require the password. Is there some way I can force EndSession
processing to wait until my program is completely done?