split client and server channels

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';
 
 /**
- * The abstract class [CommunicationChannel] defines the behavior of objects
- * that allow an [AnalysisServer] to receive [Request]s and to return both
- * [Response]s and [Notification]s.
+ * The abstract class [ClientCommunicationChannel] defines the behavior of
+ * objects that allows an object to send [Request]s to [AnalysisServer] and to
+ * receive both [Response]s and [Notification]s.
  */
-abstract class CommunicationChannel {
+abstract class ClientCommunicationChannel {
+  /**
+   * Listen to the channel for responses and notifications.
+   * If a response is received, invoke the [onResponse] function.
+   * If a notification is received, invoke the [onNotification] function.
+   * If an error is encountered while trying to read from
+   * the socket, invoke the [onError] function. If the socket is closed by the
+   * client, invoke the [onDone] function.
+   */
+  void listen(void onResponse(Response response),
+              void onNotification(Notification notification),
+              {void onError(), void onDone()});
+
+  /**
+   * Send the given [request] to the server.
+   */
+  void sendRequest(Request request);
+}
+
+/**
+ * The abstract class [ServerCommunicationChannel] defines the behavior of
+ * objects that allow an [AnalysisServer] to receive [Request]s and to return
+ * both [Response]s and [Notification]s.
+ */
+abstract class ServerCommunicationChannel {
   /**
    * Listen to the channel for requests. If a request is received, invoke the
    * [onRequest] function. If an error is encountered while trying to read from
    * the socket, invoke the [onError] function. If the socket is closed by the
    * 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.
+ * Instances of the class [WebSocketClientChannel] implement a
+ * [ClientCommunicationChannel] that uses a [WebSocket] to communicate with
+ * servers.
  */
-class WebSocketChannel implements CommunicationChannel {
+class WebSocketClientChannel implements ClientCommunicationChannel {
   /**
    * The socket being wrapped.
    */
+  final WebSocket socket;
+
+  final JsonEncoder jsonEncoder = const JsonEncoder(null);
+
+  final JsonDecoder jsonDecoder = const JsonDecoder(null);
+
+  /**
+   * Initialize a newly create [WebSocket] wrapper to wrap the given [socket].
+   */
+  WebSocketClientChannel(this.socket);
+
+  @override
+  void listen(void onResponse(Response response),
+              void onNotification(Notification notification),
+              {void onError(), void onDone()}) {
+    socket.listen((data) => _read(data, onResponse, onNotification),
+        onError: onError, onDone: onDone);
+  }
+
+  @override
+  void sendRequest(Request request) {
+    socket.add(jsonEncoder.convert(request.toJson()));
+  }
+
+  /**
+   * Read a request from the given [data] and use the given function to handle
+   * the request.
+   */
+  void _read(Object data,
+             void onResponse(Response response),
+             void onNotification(Notification notification)) {
+    if (data is String) {
+      // Parse the string as a JSON descriptor
+      var json;
+      try {
+        json = jsonDecoder.convert(data);
+        if (json is! Map) {
+          return;
+        }
+      } catch (error) {
+        return;
+      }
+      // Process the resulting structure as a response or notification.
+      if (json[Notification.EVENT] != null) {
+        Notification notification = new Notification.fromJson(json);
+        if (notification != null) {
+          onNotification(notification);
+        }
+      } else {
+        Response response = new Response.fromJson(json);
+        if (response != null) {
+          onResponse(response);
+        }
+      }
+    }
+  }
+}
+
+/**
+ * Instances of the class [WebSocketServerChannel] implement a
+ * [ServerCommunicationChannel] that uses a [WebSocket] to communicate with
+ * clients.
+ */
+class WebSocketServerChannel implements ServerCommunicationChannel {
+  /**
+   * 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);
+  WebSocketServerChannel(this.socket);
 
   @override
   void listen(void onRequest(Request request), {void onError(), void onDone()}) {
-    socket.listen((data) =>
-        _readRequest(data, onRequest), onError: onError, onDone: onDone);
+    socket.listen((data) => _readRequest(data, onRequest), onError: onError,
+        onDone: onDone);
   }
 
   @override
   void sendNotification(Notification notification) {
     socket.add(jsonEncoder.convert(notification.toJson()));
   }
 
   @override
-  void sendRequest(Request request) {
-    socket.add(jsonEncoder.convert(request.toJson()));
-  }
-
-  @override
   void sendResponse(Response response) {
     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);
     }
   }
 }