@Override
 protected void doService(
     final HttpServletRequest request,
     final HttpServletResponse response,
     final HttpContext context)
     throws ServletException, IOException, LoginRequiredException, PermissionDeniedException {
   try {
     final SessionIdentifier sessionIdentifier =
         authenticationService.createSessionIdentifier(request);
     final MonitoringNodeIdentifier monitoringNodeIdentifier =
         monitoringService.createNodeIdentifier(
             request.getParameter(MonitoringGuiConstants.PARAMETER_NODE_ID));
     monitoringService.unsilentNode(sessionIdentifier, monitoringNodeIdentifier);
   } catch (final AuthenticationServiceException e) {
     logger.warn(e.getClass().getName(), e);
   } catch (MonitoringServiceException e) {
     logger.warn(e.getClass().getName(), e);
   }
   final RedirectWidget widget = new RedirectWidget(buildRefererUrl(request));
   widget.render(request, response, context);
 }
 @Override
 protected void doCheckPermission(final HttpServletRequest request)
     throws ServletException, IOException, PermissionDeniedException, LoginRequiredException {
   try {
     final SessionIdentifier sessionIdentifier =
         authenticationService.createSessionIdentifier(request);
     monitoringService.expectMonitoringAdminPermission(sessionIdentifier);
   } catch (final AuthenticationServiceException e) {
     throw new PermissionDeniedException(e);
   } catch (MonitoringServiceException e) {
     throw new PermissionDeniedException(e);
   }
 }