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

h.kheti.serpentcs at gmail.com h.kheti.serpentcs at gmail.com
Tue Dec 18 07:28:28 EST 2018


On Friday, March 22, 2013 at 11:43:50 PM UTC+5:30, Jan wrote:
> 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()




 I Found This Error Plz Help,
  File "C:\Python27\pyt32\lib\threading.py", line 801, in __bootstrap_inner
    self.run()
  File "C:\Python27\pyt32\lib\threading.py", line 754, in run
    self.__target(*self.__args, **self.__kwargs)
  File "C:\Users\Kasim-SCS\Desktop\hk\zkem\v10_biometric_ERPpeek.py", line 266,
in TestZkEvents
    zk = DispatchWithEvents("zkemkeeper.ZKEM", ZkEvents)
  File "C:\Python27\pyt32\lib\site-packages\win32com\client\__init__.py", line 2
53, in DispatchWithEvents
    disp = Dispatch(clsid)
  File "C:\Python27\pyt32\lib\site-packages\win32com\client\__init__.py", line 9
5, in Dispatch
    dispatch, userName = dynamic._GetGoodDispatchAndUserName(dispatch,userName,c
lsctx)
  File "C:\Python27\pyt32\lib\site-packages\win32com\client\dynamic.py", line 11
4, in _GetGoodDispatchAndUserName
    return (_GetGoodDispatch(IDispatch, clsctx), userName)
  File "C:\Python27\pyt32\lib\site-packages\win32com\client\dynamic.py", line 91
, in _GetGoodDispatch
    IDispatch = pythoncom.CoCreateInstance(IDispatch, None, clsctx, pythoncom.II
D_IDispatch)
com_error: (-2147221005, 'Invalid class string', None, None)


How To Solve DispatchWithEnvent Error ??



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