Added README, a bin/serve example server which can be used locally.

example/src/examples/file_repository.dart

Index: example/src/examples/file_repository.dart
diff --git a/example/src/examples/file_repository.dart b/example/src/examples/file_repository.dart
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+++ b/example/src/examples/file_repository.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 appengine_pub.file_repository;
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:archive/archive.dart';
+import 'package:logging/logging.dart';
+import 'package:path/path.dart' as path;
+import 'package:pub_server/repository.dart';
+import 'package:yaml/yaml.dart';
+
+final Logger _logger = new Logger('pub_server.file_repository');
+
+/// Implements the [PackageRepository] by storing pub packages on a file system.
+class FileRepository extends PackageRepository {
+  final String baseDir;
+
+  FileRepository(this.baseDir);
+
+  Stream<PackageVersion> versions(String package) {
+    var directory = new Directory(path.join(baseDir, package));
+    if (directory.existsSync()) {
+      return directory
+          .list(recursive: false)
+          .where((fse) => fse is Directory)
+          .map((Directory dir) {
+        var version = path.basename(dir.path);
+        var pubspecFile = new File(pubspecFilePath(package, version));
+        var tarballFile = new File(packageTarballPath(package, version));
+        if (pubspecFile.existsSync() && tarballFile.existsSync()) {
+          var pubspec = pubspecFile.readAsStringSync();
+          return new PackageVersion(package, version, pubspec);
+        }
+      });
+    }
+
+    return new Stream.fromIterable([]);
+  }
+
+  // TODO: Could be optimized by searching for the exact package/version
+  // combination instead of enumerating all.
+  Future<PackageVersion> lookupVersion(String package, String version) {
+    return versions(package)
+        .where((pv) => pv.versionString == version)
+        .toList().then((List<PackageVersion> versions) {
+      if (versions.length >= 1) return versions.first;
+      return null;
+    });
+  }
+
+  bool get supportsUpload => true;
+
+  Future upload(Stream<List<int>> data) {
+    _logger.info('Start uploading package.');
+    return data.fold(new BytesBuilder(), (b, d) => b..add(d)).then((bb) {
+      var tarballBytes = bb.takeBytes();
+      var tarBytes = new GZipDecoder().decodeBytes(tarballBytes);
+      var archive = new TarDecoder().decodeBytes(tarBytes);
+      var pubspecArchiveFile;
+      for (var file in archive.files) {
+        if (file.name == 'pubspec.yaml') {
+          pubspecArchiveFile = file;
+          break;
+        }
+      }
+      if (pubspecArchiveFile != null) {
+        // TODO: Error handling.
+        var pubspec = loadYaml(UTF8.decode(pubspecArchiveFile.content));
+
+        var package = pubspec['name'];
+        var version = pubspec['version'];
+
+        var packageVersionDir =
+            new Directory(path.join(baseDir, package, version));
+        var pubspecFile = new File(pubspecFilePath(package, version));
+        var tarballFile = new File(packageTarballPath(package, version));
+
+        if (!packageVersionDir.existsSync()) {
+          packageVersionDir.createSync(recursive: true);
+        }
+        pubspecFile.writeAsBytesSync(pubspecArchiveFile.content);
+        tarballFile.writeAsBytesSync(tarballBytes);
+
+        _logger.info('Uploaded new $package/$version');
+      } else {
+        _logger.warning('Did not find any pubspec.yaml file in upload. '
+                        'Aborting.');
+        throw 'No pubspec file.';
+      }
+    });
+  }
+
+  bool get supportsDownloadUrl => false;
+
+  Future<Stream> download(String package, String version) {
+    var pubspecFile = new File(pubspecFilePath(package, version));
+    var tarballFile = new File(packageTarballPath(package, version));
+
+    if (pubspecFile.existsSync() && tarballFile.existsSync()) {
+      return new Future.value(tarballFile.openRead());
+    } else {
+      return new Future.error(
+          'package cannot be downloaded, because it does not exist');
+    }
+  }
+
+  String pubspecFilePath(String package, String version)
+      => path.join(baseDir, package, version, 'pubspec.yaml');
+
+  String packageTarballPath(String package, String version)
+      => path.join(baseDir, package, version, 'package.tar.gz');
+}