protected function _addResources(array $resources) {
        foreach ($resources as $resourceName => $properties) {
            // If the properties aren't set as an array, then we will consider
            // the value as the resource ID.
            if (!is_array($properties)) {
                $properties = array('id' => $properties);
            }

            $resourceName = strtolower($resourceName);
            $id = $properties['id'];

            if ($resourceName === 'all') {
                $id = 'all';
            }

            if (is_null($id) || empty($id)) {
                throw new Zend_Application_Resource_Exception(
                    sprintf(
                        $this->_missingPropertyMessage, 'ID', 'resource', $resourceName
                    )
                );
            }

            $this->_addResourceById($resources, $id);
        }
    }