public void Init(HttpApplication application)
{
    application.PostRequestHandlerExecute += application_PostRequestHandlerExecute;
    SessionStateModule session = (SessionStateModule)application.Modules["Session"];
    session.Start += session_Start;
    session.End += session_End;
}

void session_End(object sender, EventArgs e)
{
    Visitor visitor = HttpContext.Current.Session["visitor"] as Visitor;

    if (visitor != null)
    {
        foreach (PageItem page in visitor.Pages)
        {
            page.UpdatePageViews();
        }
    }
}