def get_param_names
      code, message, value = @server.call("getParamNames", @caller_id)
      case code
      when 1
        return value
      when -1
        raise message
      else
        return false
      end
    end
def get_param_names
      code, message, value = @server.call("getParamNames", @caller_id)
      case code
      when 1
        return value
      when -1
        raise message
      else
        return false
      end
    end
get the all keys of parameters
 @return [Array] all keys