call method

Future call(Map<String, dynamic>? req)

Call the service with a request (req).

Implementation

Future call(Map<String, dynamic>? req) {
  // The service can't be called if it's currently advertising.
  if (req == null) {
    Map<String, dynamic>? request = {};
    req = request;
  }

  if (isAdvertised) return Future.value(false);
  // Set up the response receiver by filtering data from the ROS node by the ID generated.
  final callId = ros.requestServiceCaller(name);
  final receiver = ros.stream
      .where((message) => message['id'] == callId)
      .map(
        (Map<String, dynamic> message) =>
            message['result'] == null
                ? Future.error(message['values']!)
                : Future.value(message['values']),
      );
  // Wait for the receiver to receive a single response and then return.
  final completer = Completer();

  listener = receiver.listen((d) {
    completer.complete(d);
    listener!.cancel();
  });
  // Actually send the request.
  ros.send(
    Request(
      op: 'call_service',
      id: callId,
      service: name,
      type: type,
      args: req,
    ),
  );
  return completer.future;
}