BaseHTTPServer, ThreadingMixIn and COM.

Paul Robinson paul.robinson at quantisci.co.uk
Tue Mar 14 14:36:51 CET 2000


Is there some inherant problem with using code such as...

ExcelApp=win32com.client.Dispatch("Excel.Application")
ExcelApp.visible = 0
workbook = ExcelApp.Workbooks.Add()
worksheet=workbook.Worksheets.Add()
cell = worksheet.Cells(1, 1)
val = unquote('=(2+3)*7')
cell.Value = val
val = cell.Value
ExcelApp.DisplayAlerts=0
workbook.Close()
ExcelApp.DisplayAlerts=1
ExcelApp.Quit()

...inside the request handler of a server that looks like:
from BaseHTTPServer import HTTPServer
from SocketServer import ThreadingMixIn
class AServer(ThreadingMixIn, HTTPServer):
	pass
The request handler is subclassed from BaseHTTPRequestHandler and I'm
simply overriding the do_GET method.

When the server does not include the ThreadingMixIn then all is well,
but it seems that I'm running into problems opening these Excel objects
in threads.
I presume that it's my code being thread-un-safe rather than the
win32com stuff in general.
What precautions should I be taking and/or how can I avoid this problem?

The actual error I get is as follows:
[Note that it's after one succesful request to the server]

D:\Temp\pySERV>python server.py
localhost - - [14/Mar/2000 13:33:28] "GET /%3d%282%2b7%29%2a12 HTTP/1.1"
200 -
Unhandled exception in thread:
Traceback (innermost last):
  File "C:\PROGRA~1\PYTHON\LIB\SocketServer.py", line 243, in
finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "C:\PROGRA~1\PYTHON\LIB\SocketServer.py", line 366, in __init__
    self.handle()
  File "C:\PROGRA~1\PYTHON\LIB\BaseHTTPServer.py", line 258, in handle
    method()
  File "simpleExcel.py", line 10, in behaviourGET
    ExcelApp=win32com.client.Dispatch("Excel.Application")
  File "C:\Program Files\Python\win32com\client\__init__.py", line 13,
in Dispatch
    dispatch, userName =
dynamic._GetGoodDispatchAndUserName(dispatch,userName,clsctx)
  File "C:\Program Files\Python\win32com\client\dynamic.py", line 67, in
_GetGoodDispatchAndUserName
    return (_GetGoodDispatch(IDispatch, clsctx), userName)
  File "C:\Program Files\Python\win32com\client\dynamic.py", line 58, in
_GetGoodDispatch
    IDispatch = pythoncom.CoCreateInstance(IDispatch, None, clsctx,
pythoncom.IID_IDispatch)
pywintypes.com_error: (-2147221008, 'CoInitialize has not been called.',
None, None)

[WinNT 4, SP4, Python 1.5.2, PythonWin Build 127]
Any help would be appreciated.

	Paul.

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Enviros Software Solutions
http://www.businesscollaborator.com
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