restructure client api to use streams

pkg/analysis_server/lib/src/protocol.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 protocol;
 
 import 'dart:convert' show JsonDecoder;
 
 /**
  * Instances of the class [Request] represent a request that was received.
@@ skipping 247 matching lines @@
    * by a [request] that cannot be handled by any known handlers.
    */
   Response.unknownRequest(Request request)
     : this(request.id, new RequestError(-7, 'Unknown request'));
 
   /**
    * Initialize a newly created instance based upon the given JSON data
    */
   factory Response.fromJson(Map<String, Object> json) {
     try {
-      // TODO process result
-      String id = json[Response.ID];
+      var id = json[Response.ID];
+      if (id is! String) {
+        return null;
+      }
       var error = json[Response.ERROR];
       var result = json[Response.RESULT];
       Response response;
       if (error is Map) {
         response = new Response(id, new RequestError.fromJson(error));
       } else {
         response = new Response(id);
       }
       if (result is Map) {
         result.forEach((String key, Object value) {
@@ skipping 292 matching lines @@
   /**
    * The response to be returned as a result of the failure.
    */
   final Response response;
 
   /**
    * Initialize a newly created exception to return the given reponse.
    */
   RequestFailure(this.response);
 }