D. Kellenberger D. Kellenberger - 1 year ago 200
TypeScript Question

Using inversify-express-utils, how can i integrate websockets?

We try to connect to extend our typescript application based on inversify-express-utils with websockets, but no luck so far:

import 'reflect-metadata';
import {interfaces, InversifyExpressServer, TYPE} from 'inversify-express-utils';
import { Kernel } from 'inversify';
import {UserController} from './controller/UserController';
import TYPES from './constant/types';
import * as socketIo from 'socket.io';

// set up kernel
let kernel = new Kernel();

// create server
let server = new InversifyExpressServer(kernel);
.listen(3000, 'localhost', () => console.log('listening on http://localhost:3000'));

// try to setup a socket io based websocket
let io = socketIo(server);
io.on('connect', (socket) => console.log('"connect" executed'));
io.on('connection', (socket) => console.log('"connection" executed'));

Server starts up as expected with
ts-node server.ts
But I can't connect to this web socket. Tried it with several tools, like for example Dark WebSocket Terminal chrome plugin and executing
\connect localhost:3000
Any idea?

Answer Source

I've got some similar issue some time ago. Here is what was worked for me:

let server: interfaces.InversifyExpressServer = new InversifyExpressServer(kernel);

server.setConfig((app) => {

let app = server.build();

let instance: any = app.listen(config.url.port);
console.log(`Server started on port ${config.url.port} :)`);

let socketIO = SocketIO.listen(instance);
socketIO.on('connection', (socket: SocketIO.Server) => {
    socket.emit('news', { hello: 'world' });
    socket.on('my other event', function (data: any) {

exports = module.exports = app;

As you can see, you have to create a running instance of your express server before you can attach Socket.IO on to it. Your server variable is not enough. I hope this will work for you.

Best regards
.... Simon

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