Very simple version of Isolates.

samples/chat/chat_stress_client.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 chat_stress_client;
 import 'dart:io';
 import "dart:convert";
 
 
 class ChatStressClient {
@@ skipping 34 matching lines @@
     void leave() {
       void leaveResponseHandler(HttpClientResponse response, String data) {
         httpClient.close();
       }
 
       Map leaveRequest = new Map();
       leaveRequest["request"] = "leave";
       leaveRequest["sessionId"] = sessionId;
       httpClient.post("127.0.0.1", port, "/leave")
         .then((HttpClientRequest request) {
-          request.addString(JSON.encode(leaveRequest));
+          request.write(JSON.encode(leaveRequest));
           return request.close();
         })
         .then((HttpClientResponse response) {
           StringBuffer body = new StringBuffer();
           response.listen(
             (data) => body.write(new String.fromCharCodes(data)),
             onDone: () => leaveResponseHandler(response, body.toString()));
         });
     }
 
     var sendMessage;
     void receive() {
       void receiveResponseHandler(HttpClientResponse response, String data) {
         var responseData = parseResponse(response, data, "receive");
         if (responseData == null) return;
         if (responseData["disconnect"] == true) return;
 
         sendMessage();
       }
 
       Map messageRequest = new Map();
       messageRequest["request"] = "receive";
       messageRequest["sessionId"] = sessionId;
       messageRequest["nextMessage"] = receiveMessageCount;
       messageRequest["maxMessages"] = 100;
       httpClient.post("127.0.0.1", port, "/receive")
         .then((HttpClientRequest request) {
-          request.addString(JSON.encode(messageRequest));
+          request.write(JSON.encode(messageRequest));
           return request.close();
         })
         .then((HttpClientResponse response) {
           StringBuffer body = new StringBuffer();
           response.listen(
             (data) => body.write(new String.fromCharCodes(data)),
             onDone: () => receiveResponseHandler(response, body.toString()));
         });
     }
 
@@ skipping 14 matching lines @@
           leave();
         }
       }
 
       Map messageRequest = new Map();
       messageRequest["request"] = "message";
       messageRequest["sessionId"] = sessionId;
       messageRequest["message"] = "message $sendMessageCount";
       httpClient.post("127.0.0.1", port, "/message")
         .then((HttpClientRequest request) {
-          request.addString(JSON.encode(messageRequest));
+          request.write(JSON.encode(messageRequest));
           return request.close();
         })
         .then((HttpClientResponse response) {
           StringBuffer body = new StringBuffer();
           response.listen(
             (data) => body.write(new String.fromCharCodes(data)),
             onDone: () => sendResponseHandler(response, body.toString()));
         });
     };
 
     void join() {
       void joinResponseHandler(HttpClientResponse response, String data) {
         var responseData = parseResponse(response, data, "join");
         if (responseData == null) return;
         sessionId = responseData["sessionId"];
 
         messageCount = 0;
         sendMessageCount = 0;
         receiveMessageCount = 0;
         sendMessage();
       }
 
       Map joinRequest = new Map();
       joinRequest["request"] = "join";
       joinRequest["handle"] = "test1";
       httpClient.post("127.0.0.1", port, "/join")
         .then((HttpClientRequest request) {
-          request.addString(JSON.encode(joinRequest));
+          request.write(JSON.encode(joinRequest));
           return request.close();
         })
         .then((HttpClientResponse response) {
           StringBuffer body = new StringBuffer();
           response.listen(
             (data) => body.write(new String.fromCharCodes(data)),
             onDone: () => joinResponseHandler(response, body.toString()));
         });
     }
 
     // Create a HTTP client factory.
     httpClient = new HttpClient();
     port = 8123;
 
     // Start the client by joining the chat topic.
     join();
   }
 
   int messagesToSend;
   bool verbose;
 }
 
 
 void main () {
   ChatStressClient stresser = new ChatStressClient();
   stresser.run();
 }