Home Original page

making a Windows NT service out of a python program

Mark Hammond MHammond at skippinet.com.au
Tue Jul 13 10:37:28 EDT 1999 
Christian Tismer wrote in message
<378B2AA8.58477120 at appliedbiometrics.com>...

>This is all great stuff if you have understood it already.
>For me, it is still unclear what makes up a service, and
>what I need at the minimum to turn a Python program into
>an NT service.
>
>I need nothing more than to run Medusa as a service. Did
>anybody do this before? Do I need special calls at all?

Here are services explained in as few lines as possible:

NT designed services to be capable of responding asynchronously to requests.
While a service is working, NT can send a stop/pause etc request.  The
service can take pretty much as long as it likes to complete the request,
but it must be very quick about telling NT it is responding, and the state
change is pending (and continue to tell it until the transition is
complete).

At the raw API level, a service starts up by passing a callback function
back to NT.  Whenever NT needs to control the service, it calls this
function.

Thus, services are almost always threaded - one thread doing the work of the
service, and another responding to service control messages.  Could be
single threaded, but the single thread must be fully asynchronous for this
to work.

So, the short answer is that to _really_ work as a service properly, a
program must be written as a service (then the next thing people want are
event log messages and performance monitor data!).  Short of that, it would
actually be trivial to write a service that could run any arbitary Python
script.  You would not have the same level of control (eg, how would you
shut down the script - you cant target exceptions at threads in Python).  It
would actually be even simpler to write a "srvany" in Python - it could use
the win32process functions to execute any arbitary program, and take
whatever action was necessary if it terminated prematurely.

Services get a decent going over in our book :-)

Mark.
More information about the Python-list mailing list