Pneuma

The vital spirit, soul, or creative force of a person.
"In Stoic philosophy, the pneuma penetrates all things, holding things together."
Wikipedia

Basically, yet another server framework, that provides middleware architecture and possibility to write MVC backend applications. Fast and very simple. Kickoff in a minute. If you used expressjs before then this framework will not be hard for you to understand.

Installation & setup

Put dart_pneuma package into your pubspec.yaml dependencies section and run pub get. Import the dependency inside your main file

import 'package:pneuma/pneuma.dart';

void main() {
  Pneuma app = new Pneuma();

  app.start();
}

This will start basic http server on default host and port 127.0.0.1:8080 You can either provide host and port named parametes into the constructor or use environment variables: IP and PORT

Usage

Pneuma could be used in three ways:

  1. Writing routed handlers
  2. Using middlewares
  3. Writing controllers with route maps

Writing routed handlers

Idea is the same as in nodejs's expressjs library. You can just map paths to a specific handler which will process the request or pass it forward by calling next callback.

import 'package:pneuma/pneuma.dart';

final RegExp allRoutes = new RegExp('.*');

void main() {
  Pneuma app = new Pneuma()
    ..get('/user', (req, res, next) {
      res.send('Hello user');
    })
    .post('/user', (req, res, next) async {
      dynamic body = await req.body;
      
      print(body);
      res.send('User has been updated');
    })
    .match(allRoutes, (req, res, next) {
      res.send('Not found');
    });

  app.start();
}

Using middlewares

Middleware abstract class should be extended to create your middleware. You will need to override run method, which will receive Request and Response instances as an arguments and should return Future of null or next Middleware usually accessible with this.next property, as Middleware is LinkedListEntity

import 'package:pneuma/pneuma.dart';

class LogMiddleware extends Middleware {
  @override
  Future<Middleware> run(Request req, Response res) {
    DateTime start = new DateTime.now();
    
    res.done.then((_res) {
      DateTime sent = new DateTime.now();
      String stamp = sent.toIso8601String();
      double timeTaken = (sent.millisecondsSinceEpoch - start.millisecondsSinceEpoch) / 1000;

      print('[$stamp]: ${req.method.name} ${_res.statusCode} ${req.uri.toString()} took ${timeTaken} sec.');
    });

    return new Future.value(this.next);
  }
}

void main() {
  Pneuma app = new Pneuma()
    ..use(new LogMiddleware())
    ..get('/user', (req, res, next) {
      res.send('Hello user');
    });

  app.start();
}

Writing controllers with route map

As once popular and still widely used, MVC architectural pattern is very usefull to build large scale applications. Extended from Middleware, Controller class can also be extended to let you map application routes to specific action methods, which should process the request as an endpoints of the app.

class UserController extends Controller {
  TestController() {
    routeMap = {
      new RegExp(r'^\/user'): indexAction,
    };
  }

  void indexAction(Request req, Response res) {
    res.send('Index Page');
  }
}

void main() {
  Pneuma app = new Pneuma()
    ..use(new UserController());

  app.start();
}

routeMap is a Map<RegExp, Invocation> which, in oreder for actions to be mapped to specified paths, should be defined.

Next step for the controllers will be defining annotations to marks actions for a specific route in a more friendlier manner.

class UserController extends Controller {
  @Route(r'^\/user')
  void indexAction(Request req, Response res) {
    res.send('Index Page');
  }
}

Libraries

pneuma