private function addClass(EasyRdf_Graph $graph, core_kernel_classes_Class $resource)
    {
        $this->addResource($graph, $resource);
        foreach ($resource->getInstances() as $instance) {
            $this->addResource($graph, $instance);
        }
        foreach ($resource->getSubClasses() as $subclass) {
            $this->addClass($graph, $subclass);
        }
        foreach ($resource->getProperties() as $property) {
            $this->addResource($graph, $property);
        }

    }