public function serviceCatalog($type = NULL) {
    // If no type is specified, return the entire
    // catalog.
    if (empty($type)) {
      return $this->serviceCatalog;
    }

    $list = array();
    foreach ($this->serviceCatalog as $entry) {
      if ($entry['type'] == $type) {
        $list[] = $entry;
      }
    }

    return $list;
  }