pkg/shelf

pkg/shelf/lib/shelf_io.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.
+
+/// A Shelf adapter for handling [HttpRequest] objects from `dart:io`.
+///
+/// One can provide an instance of [HttpServer] as the `requests` parameter in
+/// [serveRequests].
+library shelf.io;
+
+import 'dart:async';
+import 'dart:io';
+
+import 'package:stack_trace/stack_trace.dart';
+
+import 'shelf.dart';
+import 'src/util.dart';
+
+/// Starts an [HttpServer] that listens on the specified [address] and
+/// [port] and sends requests to [handler].
+///
+/// See the documentation for [HttpServer.bind] for more details on [address],
+/// [port], and [backlog].
+Future<HttpServer> serve(Handler handler, address, int port,
+    {int backlog}) {
+  if (backlog == null) backlog = 0;
+  return HttpServer.bind(address, port, backlog: backlog).then((server) {
+    serveRequests(server, handler);
+    return server;
+  });
+}
+
+/// Serve a [Stream] of [HttpRequest]s.
+///
+/// [HttpServer] implements [Stream<HttpRequest>] so it can be passed directly
+/// to [serveRequests].
+void serveRequests(Stream<HttpRequest> requests, Handler handler) {
+  requests.listen((request) => handleRequest(request, handler));
+}
+
+/// Uses [handler] to handle [request].
+///
+/// Returns a [Future] which completes when the request has been handled.
+Future handleRequest(HttpRequest request, Handler handler) {
+  var shelfRequest = _fromHttpRequest(request);
+
+  return syncFuture(() => handler(shelfRequest))
+      .catchError((error, stackTrace) {
+    var chain = new Chain.current();
+    if (stackTrace != null) {
+      chain = new Chain.forTrace(stackTrace)
+          .foldFrames((frame) => frame.isCore || frame.package == 'shelf')
+          .terse;
+    }
+
+    return _logError('Error thrown by handler\n$error\n$chain');
+  }).then((response) {
+    if (response == null) {
+      response = _logError('null response from handler');
+    }
+
+    return _writeResponse(response, request.response);
+  });
+}
+
+/// Creates a new [Request] from the provided [HttpRequest].
+Request _fromHttpRequest(HttpRequest request) {
+  //TODO(kevmoo): make headers case-insensitive
+  var headers = {};
+  request.headers.forEach((k, v) {
+    // Multiple header values are joined with commas.
+    // See http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-21#page-22
+    headers[k] = v.join(',');
+  });
+
+  return new Request(request.uri.path, request.uri.query, request.method,
+      '', request.protocolVersion, request.requestedUri,
+      headers, body: request);
+}
+
+Future _writeResponse(Response response, HttpResponse httpResponse) {
+  httpResponse.statusCode = response.statusCode;
+
+  response.headers.forEach((header, value) {
+    if (value == null) return;
+    httpResponse.headers.set(header, value);
+  });
+
+  if (response.headers[HttpHeaders.SERVER] == null) {
+    var value = httpResponse.headers.value(HttpHeaders.SERVER);
+    httpResponse.headers.set(HttpHeaders.SERVER, '$value with Shelf');
+  }
+  return httpResponse.addStream(response.read())
+      .then((_) => httpResponse.close());
+}
+
+// TODO(kevmoo) A developer mode is needed to include error info in response
+// TODO(kevmoo) Make error output plugable. stderr, logging, etc
+Response _logError(String message) {
+  stderr.writeln('ERROR - ${new DateTime.now()}');
+  stderr.writeln(message);
+  return new Response.internalServerError();
+}