mod_dart: server-side Dart apps in Apache

Highly experimental, probably broken and insecure - proceed with caution :-)

Sample use

httpd.conf

LoadModule dart_module libexec/apache2/mod_dart.so
<Location />
  AddHandler dart .dart
  DartDebug on
</Location>

helloworld.dart

#import('apache:handler');
#import('dart:io');

main() {
  response.headers.contentType = new ContentType.fromString("text/html");
  response.outputStream.writeString("<h1>Hello, dart!</h1>\n");
  print("<dl>"); // shorthand to write a line to response.outputStream
  request.headers.forEach((name, values) {
    print("<dt>$name</dt>");
    values.forEach((v) => print("<dd>$v</dd>"));
  });
}

APIs provided

apache:handler provides top level constants, and a convenience function:

final HttpRequest request;
final HttpResponse response;
void print(s) => response.outputStream.writeString(s.toString());

The HttpRequest and HttpResponse emulation is mostly complete, see the dart:io documentation for details.

The major difference is that InputStream and OutputStream are blocking. This means InputStream.read will always return data unless end-of-stream has been reached, and registered listeners (onData, onError, etc) will never fire.

Date formatting and parsing in HttpHeaders is not yet implemented.

Each request is handled in its own isolate, spawning further isolates is untested and probably doesn't work.

Apache directives

• LoadModule dart_module libexec/apache2/mod_dart.so (or similar)
  • Load mod_dart
• AddHandler dart .dart
  • Tells Apache to process *.dart files with mod_dart
• DartDebug On
  • Exceptions and syntax errors will be sent to the browser in addition to the apache error log
  • The X-Dart-Snapshot header will be set, indicating whether the script was loaded from a VM snapshot
• DartSnapshot /path/to/script.dart
  • The script will be loaded at startup and snapshotted, so it doesn't need to be parsed for every page load
  • If the snapshot is stale (older than the script's mtime), it will not be used
• DartSnapshotForever /path/to/script.dart
  • Same as DartSnapshot, but doesn't check if the snapshot is stale (and thus avoids one stat())

Building and installing

You'll need:

• Mac or Linux
• g++ toolchain
• python
• Apache2, installed and configured
• The apache2-dev bits (apxs and the headers)
• Dart sources

First, build the Dart VM for the architecture (must match Apache):

dart/runtime $ ../tools/build.py -m release --arch x64

Edit build.config, and at least set DART_SRC. APXS and Apache will be automatically located if they're on your PATH with common names (apxs/apxs2, apache2/httpd). Otherwise set the appropriate variables.

./build.sh will build the library, install it, and restart apache.

Legal stuff

Copyright 2012 Google Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.