Dart: Isolate Example [Courtesy: Forian Loitsch]. NOTE: This example is not maintained. Please see https://github.com/dartlang-italia/dart-libraries-samples/tree/master/isolate for a working example.

spawn.dart

void echo(SendPort initialReplyTo) {
  var port = new ReceivePort();
  initialReplyTo(port.sendPort);
  port.listen((msg) {
    var data = msg[0];
    SendPort replyTo = msg[1];
    replyTo.send(data);
    if (data == "bar") port.close();
  });
}

Future sendReceive(SendPort port, msg) {
  ReceivePort response = new ReceivePort();
  port.send([msg, response.sendPort]);
  return response.first;
}

main() {
  var response = new ReceivePort();
  Future<Isolate> remote = Isolate.spawn(echo, response.sendPort);
  remote.then((_) => response.first).then((sendPort) {
    sendReceive(sendPort, "foo").then((msg) {
      print("received: $msg");
      return sendReceive(sendPort, "bar");
    }).then((msg) {
      print("received another: $msg");
    });
  });
}

spawnUri.dart

// == new file echo.dart.
void main(List<String> args, SendPort replyTo) {
  replyTo.send(args[0]);
}

// == new file start.dart
main() {
  var response = new ReceivePort();
  Future<Isolate> remote = Isolate.spawnUri(Uri.parse("echo.dart"), ["foo"], response.sendPort);
  remote.then((_) => response.first)
    .then((msg) { print("received: $msg"); });
}