Tell us how you're using Twisted (was Re: [Twisted-Python] Win32 IOCPReactor?)

[Berkstresser, Dan]

I am using twisted for an in-house production tracking system for a
large steel mill.  The twisted server handles communications between a
MySQL database, wireless barcode scanners that use WinCE/Python CE for
the clients, some networked industrial scales and interfaces with a
custom Quality Assurance database.

Lucas' response to my Windows NT Service question from the other day
worked like a charm BTW.  Not sure how to link/"re:" to it so I will
re-post it here for posterity:

>From: Lucas Taylor <lucas at lucaserve.com>
>Subject: Re: [Twisted-Python] Windows NT Service Problem
>To: Twisted general discussion <twisted-python at twistedmatrix.com>
>Message-ID: <464D3F74.1060403 at lucaserve.com>
>Content-Type: text/plain; charset=ISO-8859-1

>This isn't really relevant to the references you've mentioned, but
there
>is a simple way to create Windows services with a minor amount of code
>and it's not too onerous. You don't have to use py2exe, although it is
>certainly possible to do so once you've got the rest working. I'm not
>sure if this is the "best" way, but it has been successful for me in a
>couple of projects over the past 2 years.

>Below is a very simple example using the QOTD server from the core
docs.
>It doesn't use tac files, Application objects, or twistd, so it's very
>basic. A "real" project will differ, but the basic mechanics of
starting
>and stopping the service are illustrated in the SvcDoRun() and
>CheckForQuit() methods of the WindowsService object. The idea is to
have
>the reactor check for a Stop event periodically and exit if it is
raised.

>You should be able to install and remove it thusly:
>python qotdservice.py install
>python qotdservice.py remove

>You can then test it out with the sample Echo client from the core
docs.

"""qotdservice.py
Sample Twisted Windows Service
"""

# Service Utilities
import win32serviceutil
import win32service
import win32event

# Twisted imports
from twisted.internet.protocol import Protocol, Factory
from twisted.internet import reactor

class QOTD(Protocol):

    def connectionMade(self):
        self.transport.write("An apple a day keeps the doctor away\r\n")
        self.transport.loseConnection()


class WindowsService(win32serviceutil.ServiceFramework):
    _svc_name_ = "TwistedWin32Service"
    _svc_display_name_ = "Twisted Win32 Service"

    def __init__(self, args):
        win32serviceutil.ServiceFramework.__init__(self, args)
        self.hWaitStop = win32event.CreateEvent(None, 0, 0, None)

    def SvcStop(self):
        self.ReportServiceStatus(win32service.SERVICE_STOP_PENDING)
        win32event.SetEvent(self.hWaitStop)

    def SvcDoRun(self):
        import servicemanager

        self.CheckForQuit()

        factory = Factory()
        factory.protocol = QOTD

        reactor.listenTCP(8007, factory)
        reactor.run(installSignalHandlers=0)


    def CheckForQuit(self):
        retval = win32event.WaitForSingleObject(self.hWaitStop, 10)
        if not retval == win32event.WAIT_TIMEOUT:
            # Received Quit from Win32
            reactor.stop()

        reactor.callLater(1.0, self.CheckForQuit)

if __name__=='__main__':
    win32serviceutil.HandleCommandLine(WindowsService)