Add server-side communications channel

pkg/analyzer_plugin/lib/channel/channel.dart

 // Copyright (c) 2017, 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.
 
 import 'package:analyzer_plugin/protocol/protocol.dart';
 
 /**
- * The object that allows a [ServerPlugin] to receive [Request]s and to return
- * both [Response]s and [Notification]s.
+ * A communication channel that allows a [ServerPlugin] to receive [Request]s
+ * from, and to return both [Response]s and [Notification]s to, an analysis
+ * server.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class PluginCommunicationChannel {
   /**
    * Close the communication channel.
    */
   void close();
 
   /**
    * 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. Only one listener is allowed per
    * channel.
    */
   void listen(void onRequest(Request request),
       {Function onError, void onDone()});
 
   /**
    * Send the given [notification] to the server.
    */
   void sendNotification(Notification notification);
 
   /**
    * Send the given [response] to the server.
    */
   void sendResponse(Response response);
 }
+
+/**
+ * A communication channel that allows an analysis server to send [Request]s
+ * to, and to receive both [Response]s and [Notification]s from, a plugin.
+ *
+ * Clients may not extend, implement or mix-in this class.
+ */
+abstract class ServerCommunicationChannel {
+  /**
+   * Close the communication channel.
+   */
+  void close();
+
+  /**
+   * 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. Only one

[scheglov, 2017/02/02 18:25:04]

Is "the client" here code that uses ServerCommunicationChannel, or the plugin
this channel is used to talk to?

[Brian Wilkerson, 2017/02/02 18:46:39]

The plugin. I'll fix the wording, thanks.

+   * listener is allowed per channel.
+   */
+  void listen(void onResponse(Response response),
+      void onNotification(Notification notification),
+      {Function onError, void onDone()});
+
+  /**
+   * Send the given [request] to the plugin.
+   */
+  void sendRequest(Request request);
+}