Using COM Objects with CherryPy

If you use COM objects with CherryPy (2.1 or greater) you might be greeted with a traceback similar to one of these:

Traceback (most recent call last):
...
  File "server.py", line 84, in test
    ou = GetObject('LDAP://OU=YourContainer, DC=YourSite, DC=com')
  File "c:\python24\lib\site-packages\win32com\client\__init__.py", line 73, in GetObject
    return Moniker(Pathname, clsctx)
  File "c:\python24\lib\site-packages\win32com\client\__init__.py", line 88, in Moniker
    moniker, i, bindCtx = pythoncom.MkParseDisplayName(Pathname)
com_error: (-2147221020, 'Invalid syntax', None, None)

or

Traceback (most recent call last):
...
  File "server.py", line 78, in test
    word = Dispatch('Word.Application')
  File "c:\python24\lib\site-packages\win32com\client\__init__.py", line 95, in Dispatch
    dispatch, userName = dynamic._GetGoodDispatchAndUserName(dispatch,userName,clsctx)
  File "C:\Python24\Lib\site-packages\win32com\client\dynamic.py", line 91, in _GetGoodDispatchAndUserName
    return (_GetGoodDispatch(IDispatch, clsctx), userName)
  File "C:\Python24\Lib\site-packages\win32com\client\dynamic.py", line 79, in _GetGoodDispatch
    IDispatch = pythoncom.CoCreateInstance(IDispatch, None, clsctx, pythoncom.IID_IDispatch)
com_error: (-2147221008, 'CoInitialize has not been called.', None, None)

CherryPy 2.1 and up uses a threaded HTTP server by default. CherryPy 2.0 did not, and thus you had to do nothing special to use COM objects. To use COM in threads, you have to make a few simple changes. Try adding these lines to your server file:

from pythoncom import CoInitialize, CoUninitialize

"""
Define your site classes here...
"""

def InitializeCOM(threadIndex):
    CoInitialize()

def UninitializeCOM(threadIndex):
    CoUninitialize()

cherrypy.engine.subscribe('start_thread', InitializeCOM)
cherrypy.engine.subscribe('stop_thread', UninitializeCOM)

That will setup COM access for each of your threads. See ticket 194 for more details.

Older versions

	replace this	with this
2.3	engine.subscribe('start_thread', f)	engine.on_start_thread_list.append(f)
	engine.subscribe('stop_thread', f)	engine.on_stop_thread_list.append(f)
2.2	engine.on_start_thread_list	server.on_start_thread_list
	engine.on_stop_thread_list	server.on_stop_thread_list
2.1	server.on_start_thread_list	server.onStartThreadList
	server.on_stop_thread_list	server.onStopThreadList