@Override
  public UnsubscribeResponse unsubscribe(NotificationTopic topic, String id)
      throws UnsubscribeException {
    NotificationProducer port = createPort();

    Holder<Header> header = buildUnsubscribeHeader(endpoint);
    UnsubscribeRequest body = createUnsubscribeRequest(topic, id);

    return port.unsubscribe(header, body);
  }
  @Override
  public String subscribe(NotificationTopic topic, String consumerErp) throws SubscribeException {
    NotificationProducer port = createPort();

    Holder<Header> header = buildSubscribeHeader(endpoint);
    SubscribeRequest body = createSubscribeRequest(topic, consumerErp);

    SubscribeResponse response = port.subscribe(header, body);

    return response.getSubscriptionID();
  }