Very simple version of Isolates.

runtime/bin/vmservice/running_isolate.dart

 // Copyright (c) 2013, 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.
 
 part of vmservice;
 
 class RunningIsolate implements ServiceRequestRouter {
   final SendPort sendPort;
   final String name;
 
   RunningIsolate(this.sendPort, this.name);
 
   Future sendMessage(List request) {
     final completer = new Completer.sync();
     final receivePort = new ReceivePort();
     sendServiceMessage(sendPort, receivePort, request);
-    receivePort.receive((value, ignoreReplyTo) {
-      receivePort.close();
+    receivePort.first.then((value) {
       if (value is Exception) {
         completer.completeError(value);
       } else {
         completer.complete(value);
       }
     });
     return completer.future;
   }
 
   Future route(ServiceRequest request) {
     // Send message to isolate.
     var message = request.toServiceCallMessage();
     return sendMessage(message).then((response) {
       request.setResponse(response);
       return new Future.value(request);
     });
   }
 }