update client to use channel rather than socket

pkg/analysis_server/lib/src/channel.dart

 // Copyright (c) 2014, 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 channel;
 
 import 'dart:convert';
 import 'dart:io';
 
 import 'package:analysis_server/src/protocol.dart';
@@ skipping 11 matching lines @@
    * client, invoke the [onDone] function.
    */
   void listen(void onRequest(Request request), {void onError(), void onDone()});
 
   /**
    * Send the given [notification] to the client.
    */
   void sendNotification(Notification notification);
 
   /**
+   * Send the given [request] to the server.
+   */
+  void sendRequest(Request request);
+
+  /**
    * Send the given [response] to the client.
    */
   void sendResponse(Response response);
 }
 
 /**
  * Instances of the class [WebSocketChannel] implement a [CommunicationChannel]
  * that uses a [WebSocket] to communicate with clients.
  */
 class WebSocketChannel implements CommunicationChannel {
   /**
    * The socket being wrapped.
    */
   final WebSocket socket;
 
+  final JsonEncoder jsonEncoder = const JsonEncoder(null);
+
   /**
    * Initialize a newly create [WebSocket] wrapper to wrap the given [socket].
    */
   WebSocketChannel(this.socket);
 
   @override
   void listen(void onRequest(Request request), {void onError(), void onDone()}) {
     socket.listen((data) =>
         _readRequest(data, onRequest), onError: onError, onDone: onDone);
   }
 
   @override
   void sendNotification(Notification notification) {
-    JsonEncoder encoder = const JsonEncoder(null);
-    socket.add(encoder.convert(notification.toJson()));
+    socket.add(jsonEncoder.convert(notification.toJson()));
+  }
+
+  @override
+  void sendRequest(Request request) {
+    socket.add(jsonEncoder.convert(request.toJson()));
   }
 
   @override
   void sendResponse(Response response) {
-    JsonEncoder encoder = const JsonEncoder(null);
-    socket.add(encoder.convert(response.toJson()));
+    socket.add(jsonEncoder.convert(response.toJson()));
   }
 
   /**
    * Read a request from the given [data] and use the given function to handle
    * the request.
    */
   void _readRequest(Object data, void onRequest(Request request)) {
     if (data is List<int>) {
       sendResponse(new Response.invalidRequestFormat());
       return;
     }
     if (data is String) {
       // Parse the string as a JSON descriptor and process the resulting
       // structure as a request.
       Request request = new Request.fromString(data);
       if (request == null) {
         sendResponse(new Response.invalidRequestFormat());
         return;
       }
       onRequest(request);
     }
   }
 }