How to use multiple instances of the same COM object at the sametime


J

Jan

Dear Usenet readers,

Our company wants to implement about 40 biometric access control devices
which have a proprietary DLL with a COM object in it.

I've done some research about COM objects and how to use them.
Now, I need to connect to every device separately and register for real
time events. So, I need about 40 instances of the COM object
simultaneously connected and registered to catch all events of all devices.

I assumed I needed threading for this, and I have done a simple
implementation.

All I want to ask is: Does anybody see something that I could have done
in a better way? I'm new to COM objects in Python!

The program runs fine, it is very basic and I tested it with 3 devices
connected at the same time. In production this will be 40!

Thanks in advance

Jan

Source code:

# Based on eventappartmentthreading from the win32com demo

import sys, os, time
import win32com.client
import win32api
import win32event
# sys.coinit_flags not set, so pythoncom initializes apartment-threaded.
import pythoncom
from threading import Thread

threadlist = dict() # this stores the device ids
# using the threadid as the key field

class ZkEvents:
def __init__(self):
self.event = win32event.CreateEvent(None, 0, 0, None)
thread = win32api.GetCurrentThreadId()
print "thread %s " % thread

self.dev_id = threadlist[thread]
print "Thread Connected For ID %s " % self.dev_id

def OnFinger(self):
print self.dev_id,
print "OnFinger"

def OnVerify(self, iUserID=pythoncom.Empty):
print self.dev_id,
print "OnVerify: %s" % iUserID

def OnKeyPress(self, iKey=pythoncom.Empty):
print self.dev_id,
print "KeyPress: %s" % iKey

def WaitWhileProcessingMessages(event, timeout = 60):
start = time.clock()
while True:
# Wake 4 times a second - we can't just specify the
# full timeout here, as then it would reset for every
# message we process.
rc = win32event.MsgWaitForMultipleObjects( (event,), 0,
250,
win32event.QS_ALLEVENTS)
if rc == win32event.WAIT_OBJECT_0:
# event signalled - stop now!
return True
if (time.clock() - start) > timeout:
# Timeout expired.
return False
# must be a message.
pythoncom.PumpWaitingMessages()

def TestZkEvents(ip, dev_id):
thread = win32api.GetCurrentThreadId()
print 'TestZkEvents created ZK object on thread %d'%thread
threadlist[thread] = dev_id

pythoncom.CoInitialize()
zk = win32com.client.DispatchWithEvents("zkemkeeper.ZKEM", ZkEvents)

if zk.Connect_Net(ip, 4370):
print "Connect %s OK" % ip
else:
print "Connect %s Failed" % ip
try:
if zk.RegEvent(1, 65535): # 65535 = register for all events
print "RegEvent %s, %s OK" % (ip, dev_id)
else:
print "RegEvent %s, %s Failed" % (ip, dev_id)
except pythoncom.com_error, details:
print "Warning - could not open the test HTML file", details

# Wait for the event to be signaled while pumping messages.
while True:
if not WaitWhileProcessingMessages(zk.event):
print "No Events From %s During Last Minute" % dev_id

zk = None

if __name__=='__main__':
# this should be a for loop with database fields...
t1 = Thread(target=TestZkEvents, args=('192.168.1.211',40))
t1.start()

t2 = Thread(target=TestZkEvents, args=('192.168.1.212',45))
t2.start()

t3 = Thread(target=TestZkEvents, args=('192.168.1.213',49))
t3.start()
 
Ad

Advertisements


Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question

Top