production

Helpers for concurrency, message-passing, rotating loggers, and other production functionality in Angel.

This will become the de-facto way to run Angel applications in deployed environments, as it takes care of inter-isolate communication, respawning dead processes, and other housekeeping for you automatically.

Most users will want to use the Runner class.

Runner

Runner is a utility, powered by package:args, that is intended to be the entry point of your application.

Instantiate it as follows, and your file will become a command-line executable that spawns multiple instances of your application:

import 'dart:async';
import 'dart:isolate';
import 'package:angel_framework/angel_framework.dart';
import 'package:angel_production/angel_production.dart';

main(List<String> args) => new Runner('example', configureServer).run(args);

Future configureServer(Angel app) async {
  app.get('/', (req, res) => 'Hello, production world!');

  app.get('/crash', (req, res) {
    // We'll crash this instance deliberately, but the Runner will auto-respawn for us.
    new Timer(const Duration(seconds: 3), Isolate.current.kill);
    return 'Crashing in 3s...';
  });
}

Runner will automatically re-spawn crashed instances, unless --no-respawn is passed. This can prevent your server from entirely going down at the first error, and adds a layer of fault tolerance to your infrastructure.

When combined with systemd, deploying Angel applications on Linux can be very simple.

Message Passing

The Runner class uses package:pub_sub to coordinate message passing between isolates.

When one isolate sends a message, all other isolates will receive the same message, except for the isolate that sent it.

It is injected into your application's Container as pub_sub.Client, so you can use it as follows: