# File lib/stomp/connection.rb, line 244
    def ack(message_id, headers = {})
      raise Stomp::Error::NoCurrentConnection if closed?
      raise Stomp::Error::MessageIDRequiredError if message_id.nil? || message_id == ""
      headers = headers.symbolize_keys
      headers['message-id''message-id'] = message_id
      if @protocol >= Stomp::SPL_11
        raise Stomp::Error::SubscriptionRequiredError unless headers[:subscription]
      end
      _headerCheck(headers)
      transmit(Stomp::CMD_ACK, headers)
    end