After adding these settings in web.config for increasing session timeout:
<sessionState mode="InProc" stateConnectionString="tcpip=127.0.0.1:42424"
stateNetworkTimeout="240" cookieless="false" timeout="240"></sessionState>
<authentication mode="Forms">
<forms name="site" loginUrl="login.aspx" timeout="9999999"
slidingExpiration="true" protection="All" cookieless="AutoDetect"
requireSSL="false" enableCrossAppRedirects="true" defaultUrl="default.aspx">
</forms>
</authentication>
But the session of my webpage is always ended after 20 minutes. What did I miss?
Thanks in advance.
I have found the answer here: http://www.primaryobjects.com/CMS/Article86.aspx by adding an iFrame and open a webpage just before session ends.