subscribe method

Implementation

StompUnsubscribe subscribe({
  required String destination,
  required StompFrameCallback callback,
  Map<String, String>? headers,
}) {
  final subscriptionHeaders = {
    ...?headers,
    'destination': destination,
  };

  if (!subscriptionHeaders.containsKey('id')) {
    subscriptionHeaders['id'] = 'sub-${_currentSubscriptionIndex++}';
  }

  _subscriptionWatcher[subscriptionHeaders['id']!] = callback;
  _transmit(command: 'SUBSCRIBE', headers: subscriptionHeaders);

  return ({Map<String, String>? unsubscribeHeaders}) {
    if (!connected) return;
    final headers = {...?unsubscribeHeaders};
    if (!headers.containsKey('id')) {
      headers['id'] = subscriptionHeaders['id']!;
    }
    _subscriptionWatcher.remove(headers['id']);

    _transmit(command: 'UNSUBSCRIBE', headers: headers);
  };
}