Add admin server that supports web socket API.

sdk/lib/_internal/pub/lib/src/barback/base_server.dart

Index: sdk/lib/_internal/pub/lib/src/barback/base_server.dart
diff --git a/sdk/lib/_internal/pub/lib/src/barback/base_server.dart b/sdk/lib/_internal/pub/lib/src/barback/base_server.dart
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+// 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 pub.barback.base_server;
+
+import 'dart:async';
+import 'dart:io';
+
+import 'package:barback/barback.dart';
+import 'package:mime/mime.dart';
+import 'package:path/path.dart' as path;
+import 'package:stack_trace/stack_trace.dart';
+
+import '../barback.dart';
+import '../log.dart' as log;
+import '../utils.dart';
+import 'build_environment.dart';
+
+/// Base class for a pub-controlled server.
+abstract class BaseServer<T> {
+  /// The [BuildEnvironment] being served.
+  final BuildEnvironment environment;
+
+  /// The underlying HTTP server.
+  final HttpServer _server;
+
+  /// The server's port.
+  int get port => _server.port;
+
+  /// The servers's address.
+  InternetAddress get address => _server.address;
+
+  /// The server's base URL.
+  Uri get url => baseUrlForAddress(_server.address, port);
+
+  /// The results of requests handled by the server.
+  ///
+  /// These can be used to provide visual feedback for the server's processing.
+  /// This stream is also used to emit any programmatic errors that occur in the
+  /// server.
+  Stream<T> get results => _resultsController.stream;
+  final _resultsController = new StreamController<T>.broadcast();
+
+  BaseServer(this.environment, this._server) {
+    Chain.track(_server).listen(handleRequest, onError: (error, stackTrace) {
+      _resultsController.addError(error, stackTrace);
+      close();
+    });
+  }
+
+  /// Closes this server.
+  Future close() {
+    return Future.wait([_server.close(), _resultsController.close()]);
+  }
+
+  /// Handles an HTTP request.
+  void handleRequest(HttpRequest request);
+
+  /// Responds to [request] with a 405 response and closes it.
+  void methodNotAllowed(HttpRequest request) {
+    logRequest(request, "405 Method Not Allowed");
+    request.response.statusCode = 405;
+    request.response.reasonPhrase = "Method Not Allowed";
+    request.response.headers.add('Allow', 'GET, HEAD');
+    request.response.write(
+        "The ${request.method} method is not allowed for ${request.uri}.");
+    request.response.close();
+  }
+
+  /// Responds to [request] with a 404 response and closes it.
+  void notFound(HttpRequest request, message) {
+    logRequest(request, "404 Not Found");
+
+    // Force a UTF-8 encoding so that error messages in non-English locales are
+    // sent correctly.
+    request.response.headers.contentType =
+        ContentType.parse("text/plain; charset=utf-8");
+
+    request.response.statusCode = 404;
+    request.response.reasonPhrase = "Not Found";
+    request.response.write(message);
+    request.response.close();
+  }
+
+  /// Log [message] at [log.Level.FINE] with metadata about [request].
+  void logRequest(HttpRequest request, String message) =>
+    log.fine("$this ${request.method} ${request.uri}\n$message");
+
+  /// Adds [result] to the server's [results] stream.
+  void addResult(T result) {
+    _resultsController.add(result);
+  }
+
+  /// Adds [error] as an error to the server's [results] stream.
+  void addError(error, [stackTrace]) {
+    _resultsController.addError(error, stackTrace);
+  }
+}