Hi Leticia,

The mixture of ``response.write()`` including JavaScript to drive the browser to a new location along with writing objects in ZODB all within the same transaction can break some of the promises that you'd normally expect Zope and a browser to keep.


My guess is that browser is being told to visit ``end`` before the transaction started by ``init2`` has finished. Perhaps a conflict error is causing that transaction to take longer than you expect. Normally this would not trip you up as your browser does not see anything until after the transaction has finished. (In this normal mode you might see a conflict error rendered in the browser if the publication machinery had to give up.)

For your example try breaking up ``init2`` into two scripts. The first that writes the session data and then redirects the browser to the second. The second then does not touch session data and manages all the ``response.write()``s. And remove the unused ``sessionData = context.REQUEST.SESSION`` from ``external``.

Cheers
Michael

On 21/06/2005, at 6:20 AM, Leticia Larrosa wrote:

Hi all:

I think that I found a ZOPE bug. Is really very important for me know what can I do for avoid it. The first 9 steps are to recreate the situation and the other steps are to provoke the error.

Step 1: Crate a folder called "reproducingError" in Zope Interface Manage

Step 2: create a page template called "index_html" in the "reproducingError" folder with the following content:
"
<!-- index_html page template -->
<form name="form1" method="post" action="reproducingError/init">
  <input type="text" name="user">
  <input type="submit" name="Submit" value="Submit">
</form>
"

Step 3: create a python script called "init" in the "reproducingError" folder with the following content:
"
# init script
sessionData = container.REQUEST.SESSION
sessionData.set("userId", container.REQUEST.user)
return context.init2_html()
"

Step 4: create a page template called "init2_html" in the "reproducingError" folder with the following content:
"
<!-- init2_html page template -->
<a href="init2">passing face 2</a>
"

Step 5: create a python script called "init2" in the "reproducingError" folder with the following content:
"
# init2 script
request = context.REQUEST
sessionData = request.SESSION
sessionData.set('idService', 'testService')
context.first()
return context.external(context)
"

Step 6: create a page template called "first_html" in the "reproducingError" folder with the following content:
"
First Response
"

Step 7: create a python script called "first" in the "reproducingError" folder with the following content:
"
# first script
response = container.REQUEST.RESPONSE
str = container.first_html()
response.write(str)
response.flush()
"

Step 8: create an external method called "external" in the "reproducingError" folder with the following content, in where the function of the external method is "communicationResponse" and the module is any name that you give to the file:
"
# external method
import time
def communicationResponse(context):
    response = context.REQUEST.RESPONSE
    sessionData = context.REQUEST.SESSION
strDetailEnd = "<script>window.location='reproducingError/end'</ script>"

    for item in range(1, 40):
        time.sleep(3)
        response.write("Response iteration:" + str(item))
        response.flush()
    response.write(strDetailEnd)
    response.flush()
"

Step 9: create a python script called "end" in the "reproducingError" folder with the following content:
"
# end script
idService = context.REQUEST.SESSION['idService']
return "Fin - " + idService
"

Step 10: open two explorer in wich call the object "reproducingError" (Example: localhost:8080/reproducingError)

Step 11: enter an example text in each one.

Step 12: clink in the link of one of them, and 5 second later clink on the link of the other explorer. The waiting for around 5 second is necesary because with other time interval not allways get the error.

Stpe 13: and wait the "Response iteration"... Please if the error don't appear in any of the pages, begins at Step 9 again. and try to count to 5 witch other velocity :)

The correct result is:
"
Fin - testService
"

The error is:
"
Site Error
An error was encountered while publishing this resource.
Error Type: KeyError
Error Value: 'idService'
"
The traceback:
"
Traceback (innermost last):
  Module ZPublisher.Publish, line 101, in publish
  Module ZPublisher.mapply, line 88, in mapply
  Module ZPublisher.Publish, line 39, in call_object
  Module Shared.DC.Scripts.Bindings, line 306, in __call__
  Module Shared.DC.Scripts.Bindings, line 343, in _bindAndExec
  Module Products.PythonScripts.PythonScript, line 323, in _exec
  Module None, line 2, in end
   - <PythonScript at /approach/reproducingError/end>
   - Line 2
  Module AccessControl.ZopeGuards, line 67, in guarded_getitem
  Module Products.Transience.TransientObject, line 176, in __getitem__
KeyError: 'idService'
"

I will appreciate if you try until the error appear, because I not always obtain the error. I thinks that it is bacause the time interval between the two request.

A curious thing is that when I obtain the error, if I wait around 15 second and refresh the page in wich i obtain the error, the correct result appear.. and no errors come.

Sorry for the extended message, but I need any help that you can give me, because this describe error environment imitate a funcionality that I must give in a system very import that i'm doing.

I'm using Zope 2.7.6 for Windows.

Thanks in advanced.
Leticia
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