/**
  * Add an instance of the selected class
  * @return void
  */
 public function addInstance()
 {
     if (!tao_helpers_Request::isAjax()) {
         throw new Exception("wrong request mode");
     }
     $response = array();
     $clazz = new core_kernel_classes_Class($this->getRequestParameter('id'));
     $label = $this->service->createUniqueLabel($clazz);
     $instance = $this->service->createInstance($clazz, $label);
     if (!is_null($instance) && $instance instanceof core_kernel_classes_Resource) {
         $response = array('label' => $instance->getLabel(), 'uri' => $instance->getUri());
     }
     $this->returnJson($response);
 }