When does session is considered as inactive in websphere server

Vaadin 6 / 7 / 8
1

Hello,

The session time out of the application is set programatically via the method setMaxInactiveInterval(timeValue). The timeValue is being retrived from the database. In the web.xml, the heartbeatInterval is set to -1 and there is a filter set. Looks like this:

<context-param>
       <description>Vaadin heartbeat</description>
       <param-name>heartbeatInterval</param-name>
       <param-value>-1</param-value>
</context-param>

<filter>
       <filter-name>LoginFilter</filter-name>
       <filter-class>com.xx.web.filter.LoginFilter</filter-class>
</filter>

The session time out is set for 10 minutes. However, the application that is deployed on a websphere environment, times out after 11 minutes. Compared to the application deployed on a wildfly environment, it times out roughly after 10 mins and 30 seconds.

May I know why this happens? Thanks in advanced for your help.