[Zope] Sessions question

[List Subscriber @ Neurobs]

Hi,

I recently updated my python UF product to use Zope's built in Sessions 
instead of CST. Now I am faced with two problems:

1. How to completely expire all session stuff on logout. At this point 
of time I am using the following terminate session function to do so:

def __terminate_session (Self,REQUEST):
        REQUEST.SESSION.invalidate()
        REQUEST.SESSION.getBrowserIdManager().flushBrowserIdCookie()

so the question is : Is this enough?? or do I have to something more??

2. How can I call my UF's user_logout function on expiry of the session??

In CST there was a field that allowed me to set up a method to be called 
on expiry. I didnt find any such option in the session_data_manager or 
browser_id_manager. So how do I do that??

TIA
AM