redstone_web_socket

redstone_web_socket is a web socket plugin for Redstone.dart. It uses the shelf_web_socket package to create web socket handlers.

Using @WebSocketHandler with functions

If a function is annotated with @WebSocketHandler, it'll be invoked with a CompatibleWebSocket object for every new established connection:

@WebSocketHandler("/ws")
onConnection(websocket) {
  websocket.listen((message) {
    websocket.add("echo $message");
  });
}

Using @WebSocketHandler with classes

If a class is annotated with @WebSocketHandler, the plugin will install a event listener for every method annotated with @OnOpen, @OnMessage, @OnError and @OnClose:

@WebSocketHandler("/ws")
class ServerEndPoint {

  @OnOpen()
  void onOpen(WebSocketSession session) {
    print("connection established");
  }

  @OnMessage()
  void onMessage(String message, WebSocketSession session) {
    print("message received: $message");
    session.connection.add("echo $message");
  }

  @OnError()
  void onError(error, WebSocketSession session) {
    print("error: $error");
  }

  @OnClose()
  void onClose(WebSocketSession session) {
    print("connection closed");
  }

}

Like redstone groups, the class will be instantiated only once, and it can request injectable objects with a constructor (see dependency injection).

Installing handlers

To install web socket handlers, you just have to import redstone_web_socket.dart and call getWebSocketPlugin():

import 'package:redstone/server.dart' as app;
import 'package:redstone_web_socket/redstone_web_socket.dart';

void main() {
  app.setupConsoleLog();
  
  //install web socket handlers
  app.addPlugin(getWebSocketPlugin());
  
  app.start();
}

Unit tests

This package also provides a simple mock client, which can be used in unit tests:

import 'package:redstone/server.dart' as app;
import 'package:redstone_web_socket/redstone_web_socket.dart';
import 'package:unittest/unittest.dart';

main() {
  
  test("Test echo service", () {
  
    var completer = new Completer();
    var socket = new MockWebSocket();
    
    socket.listen((message) {
      
      expect(message, equals("echo message"));
      
      completer.complete();
    });
    
    openMockConnection("/ws", socket);
    
    socket.add("message");
    
    return completer.future;
  
  });

}