From:    William A. Rowe, Jr. 
Date:    June 7th '00
Subject: service monitoring in Apache 1.3.13

The concept for a taskbar monitor has been thrown around
for a very long while.  1.3.13 introduced Win9x services,
and that added fuel to the mix.  Here are some sideband
observations I've made for other developers...

About Apache as a console, don't start Apache hidden without
any command line arguments if you want to launch it yourself
in a hidden window (it will do the classic test for 
AllocConsole/FreeConsole)... drop in some arguments such as
the -f or -r option and it will fly without thinking it is a 
service under 9x and NT.

Rule two, don't use --ntservice as an argument, ever.  Only
the Windows NT Service Control Manager is allowed to pass that
flag, and only that flag, when it runs Apache.exe.  Do use 
--ntservice as the sole argument to the executable name if 
you are installing an Apache NT service yourself.

Rule three, use -k start and -n name when maintaining the
HKLM/Software/Microsoft/Windows/CurrentVersion/RunServices
list, since there is no other way for Apache to know what 
the service is named :)  And look at any 9x installed service's 
RunServices entry in the registry for the start service semantic.

Rule four, use the WinNT Service Control Manager exclusively
for starting, stopping and restarting Apache as an NT service.
The restart signal is the value 128, as documented in service.h 
and service.c - this will continue to work in Apache 2.0.  If
it fails, you are handling an older version (pre 1.3.13) of
Apache, and need to stop and then start the service instead.

Rule five, use the legacy pid-named events to signal Win9x 
service Apache to restart and stop the service.  But don't
bother looking for httpd.pid files... you can get the pid
right from the hidden service control window.  Apache 1.3.13
and 2.x create a hidden window named for the name of the 
service (without the spaces), with a window class of
"ApacheWin95ServiceMonitor", so can use FindWindow to track 
down running Win9x services.  See the service.c code for how 
I accomplished this pretty simply in the -k stop/-k restart
handler.

Finally, to identify all installed Apache services, just query 
the registry key HKLM\SYSTEM\CurrentControlSet\Services for any 
key that has the ImagePath value of "...\Apache.exe"... or else
"...\httpd.exe"... (quotes are significant here, if the leading 
quote is ommitted the entire string ends with the text \Apache.exe
based on Apache's own service installer in every released version.)