Very simple version of Isolates.

tests/lib/async/timer_isolate_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library multiple_timer_test;
 
 import 'dart:isolate';
 import 'dart:async';
 import '../../../pkg/unittest/lib/unittest.dart';
 
 const Duration TIMEOUT = const Duration(milliseconds: 100);
 
-createTimer() {
-  port.receive((msg, replyTo) {
-    new Timer(TIMEOUT, () {
-      replyTo.send("timer_fired");
-    });
+createTimer(replyTo) {
+  new Timer(TIMEOUT, () {
+    replyTo.send("timer_fired");
   });
 }
 
 main() {
   test("timer in isolate", () {
     int startTime;
     int endTime;
 
-    port.receive(expectAsync2((msg, _) {
+    ReceivePort port = new ReceivePort();
+
+    port.first.then(expectAsync1((msg) {
       expect("timer_fired", msg);
       int endTime = (new DateTime.now()).millisecondsSinceEpoch;
       expect(endTime - startTime, greaterThanOrEqualTo(TIMEOUT.inMilliseconds));
-      port.close();
     }));
 
     startTime = (new DateTime.now()).millisecondsSinceEpoch;
-    var sendPort = spawnFunction(createTimer);
-    sendPort.send("sendPort", port.toSendPort());
+    var remote = Isolate.spawn(createTimer, port.sendPort);
   });
 }