Python printing as a service - migration from WinXP to Win7/8 - issue with Win service privileges?

[Kristof Keßler]

Dear all,

this is my first post to the list, so if I am not sufficiently detailed 
let me know. Not even sure if this is the best list to send this to as 
it seems to be an issue with Windows service privileges.

We have been running a package of python scripts as services on a 
Windows XP machine for several years. These scripts include one that 
checks a mail server, processes mails and then prints to the 
attachements to the default printer. This is the only part that does not 
work, as a service, when migrating the package to Win7/8. The printing 
script works fine when executing it from the console. An odd thing also 
is that the script runs smoothly through as a service with not error 
message, but does not print.

The inital script was in Python 2.4:
--------

print_service.py
---
...
printcmd = "C:/Python24/python.exe C:/Application/printpostdelivery.py"
...
cmd = "%s %s" % (printcmd ,pdfname  )
(stdout, stdin, stderr) = popen2.popen3( cmd )
screen = stdout.read()
err_screen = stderr.read()
...
---

printpostdelivery.py
---
...
win32api.ShellExecute(0, "print", dateiname, None, ".", 0);
...
---
--------

I upgraded to Python 2.7 and changed to lines in print_service.py 
accordingly:
--------

print_service.py
---
...
printcmd = "C:/Python27/python.exe C:/Application/printpostdelivery.py"
...
cmd = "%s %s" % (printcmd ,pdfname )
p = subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE, 
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
(child_stdin,  child_stdout, child_stderr) = (p.stdin, p.stdout, p.stderr)
screen = child_stdout.read()
err_screen = child_stderr.read()
...
---
--------

I played around with the service settings and ran it as administrator, 
but that did not help...well, only that initially there was an error 
message when running the service with Python 2.7:
pywintypes.error: (31, 'ShellExecute', 'A device attached to the
system is not functioning.')
But that disappeared when I ran the service as an administrator.
Then it was the same all over again. Script runs through smoothly with 
no error, but the documents were not printed.

Any suggestions?
Thanks!

All the best

Kristof