The logged in user session did not time out and appeared to remain logged in indefinitely.
Referencing the KB article to modify the timeout value in web.config file does not cause the end user to time out. KB article as follows:
The KB article, How to increase the web portal timeout duration?, is still valid; The timeout parameter in the 'sessionState' session is still the correct parameter to set for timeout period for end user in webportal
However, since version 8.1.0 there was a new feature for the web portal that allows different status messages to be shown as browser messages. This is achieved by allowing the browser to poll for notifications from the web servers.
To enable this polling and allow configuration of the polling interval, 2 parameters has been implemented in Web Designer, namely: VI_Common_EnableNotifications and VI_Common_NotificationPollingInterval.
Refer also to release notes for version 8.1.0 where this is also stated: New features.
By default VI_Common_EnableNotifications = 'True' and VI_Common_NotificationPollingInterval = 20000 which means the browser will poll the web server every 20 seconds.
The polling for notifications has kept the logged in session to remain alive. Hence the timeout parameter in web.config file appears to have no effect to the end user.
To make sure session timeout still works for the end user, there are 2 workarounds. These are as follows:
Turn off Notification polling for the browser by setting zero '0' (from Default 20000) on VI_Common_NotificationPollingInterval parameter in Web Designer. Where VI_Common_NotificationPollingInterval parameter is defined in VI_Session:
In case if browser notification and session is required, then the notification polling time interval (E.g. VI_Common_NotificationPollingInterval ) needs to be longer than the time out time setting.
For example: Set the browser-notification-time (e.g.VI_Common_NotificationPollingInterval parameter) to 7 min and and session-timeout in web.config file to 5 min then the the end user will have both browser status notification and session time out is also possible.