public function BulletinGetTopics($category_id)
 {
     // $category_id : base:IDType (NOT Array, only ONE id gives)
     $this->CheckAndSetHeader(__FUNCTION__);
     $reg_args["category_id"] = $category_id;
     $this->encodeString($reg_args);
     $results = parent::BulletinGetTopics($reg_args);
     $this->methodClose();
     return $this->RetvalConvertArray($results->category->topic);
 }