WebSocket client for VM service

runtime/bin/vmservice/client.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;
+
+// A service client.
+abstract class Client {
+  /// Port that lives as long as the network client.
+  final RawReceivePort receivePort = new RawReceivePort();
+  final VMService service;
+
+  Client(this.service) {
+    receivePort.handler = (response) {
+      post(null, response);
+    };
+    service._addClient(this);
+  }
+
+  /// When implementing, call [close] when the network connection closes.
+  void close() {
+    receivePort.close();
+    service._removeClient(this);
+  }
+
+  /// Call to process a message. Response will be sent with 'seq'.
+  void onMessage(var seq, var message) {

[turnidge, 2013/12/11 17:56:07]

Could we type message here?  I assume it is Message.

[Cutch, 2013/12/12 22:37:42]

Done.

+    // Call post when the response arrives.
+    message.future.then((response) {
+      post(seq, response);
+    });
+    // Send message to service.
+    service.route(message);
+  }
+
+  /// When implementing, responsible for sending [response] to the client.
+  void post(var seq, String response);
+
+  Map toJson() {
+    return {
+    };

[turnidge, 2013/12/11 17:56:07]

Should we leave this abstract too?

[Cutch, 2013/12/12 22:37:42]

Done.

+  }
+}