private IServerSession lookupScoutServerSessionOnVirtualSession(HttpServletRequest req, HttpServletResponse res, String ajaxSessionId, Subject subject, UserAgent userAgent) throws ProcessingException, ServletException {
    initializeAjaxSessionTimeout(req);
    IServerSession serverSession = m_ajaxSessionCache.get(ajaxSessionId);
    if (serverSession == null) {
      synchronized (m_ajaxSessionCache) {
        serverSession = m_ajaxSessionCache.get(ajaxSessionId);
        if (serverSession == null) { // double checking
          return createAndCacheNewServerSession(ajaxSessionId, subject, userAgent, req, res);
        }
      }
    }
    m_ajaxSessionCache.touch(ajaxSessionId);
    return serverSession;
  }

protected void beforeAccessToInternalMap() {
    if (System.currentTimeMillis() > m_nextMaintenance) {
      validateInternalMap();
      m_nextMaintenance = System.currentTimeMillis() + m_sessionTimeoutMillis / 2;
    }
  }


protected boolean isEntryValid(DynamicEntry e) {
    VirtualSessionEntry v = (VirtualSessionEntry) e;
    return v.getTimestamp() + v.getInactivityTimeout() >= System.currentTimeMillis();
  }

 /**
   * Initialize Ajax Session timeout only once from the HTTP session
   */
  protected void initializeAjaxSessionTimeout(HttpServletRequest req) {
    if (!m_isAjaxSessionTimeoutInitialized) {
      final long defaultSessionTimeout = 3600L;
      final long millisecondsInSeconds = 1000L;
      m_ajaxSessionCache.setSessionTimeoutMillis(Math.max(defaultSessionTimeout, millisecondsInSeconds * req.getSession().getMaxInactiveInterval()));
      m_isAjaxSessionTimeoutInitialized = true;
    }
  }

private IServerSession lookupScoutServerSessionOnVirtualSession(HttpServletRequest req, HttpServletResponse res, String ajaxSessionId, Subject subject, UserAgent userAgent) throws ProcessingException, ServletException {
synchronized (m_ajaxSessionCache) {
//update session timeout
int maxInactive = req.getSession().getMaxInactiveInterval();
if (maxInactive < 0) {
maxInactive = 3600;
}
m_ajaxSessionCache.setSessionTimeoutMillis(Math.max(1000L, 1000L * maxInactive));
IServerSession serverSession = m_ajaxSessionCache.get(ajaxSessionId);
if (serverSession == null) {
serverSession = SERVICES.getService(IServerSessionRegistryService.class).newServerSession(m_serverSessionClass, subject, userAgent);
m_ajaxSessionCache.put(ajaxSessionId, serverSession);
}
else {
m_ajaxSessionCache.touch(ajaxSessionId);
}
return serverSession;
}
}