express.js 4 and sockets with express router

One option is to pass it in to req object.

app.js:

var express = require('express');var path = require('path');var logger = require('morgan');var api = require('./routes/api');var app = express();var io = require('socket.io').listen(app.listen(3000));app.use(logger('dev'));app.use(express.static(path.join(__dirname, 'public')));io.sockets.on('connection', function (socket) {    console.log('client connect');    socket.on('echo', function (data) {        io.sockets.emit('message', data);    });});// Make io accessible to our routerapp.use(function(req,res,next){    req.io = io;    next();});app.use('/api', api);// error handlers omittedmodule.exports = app;

./routes/api.js:

var express = require('express');var router = express.Router();router.put('/foo', function(req, res) {    /*       do stuff to update the foo resource       ...     */    // now broadcast the updated foo..    req.io.sockets.emit('update', foo); });module.exports = router;

I've modified your files a little bit, may you check if it works?

You can pass the io you've defined to your routes like below;

require('./routes/api')(app,io); 

I didn't test the Socket.IO parts but there is no syntax error and routes also working.

server.js file:

var express = require('express');var app = express();var path = require('path');var logger = require('morgan');var io = require('socket.io').listen(app.listen(3000)); app.use(logger('dev'));app.use(express.static(path.join(__dirname, 'public'))); io.sockets.on('connection', function (socket) {    console.log('client connect');    socket.on('echo', function (data) {    io.sockets.emit('message', data); });});require('./routes/api')(app,io);  console.log("Server listening at port 3000");

api.js:

module.exports = function(app,io) {app.put('/foo', function(req, res) {     /*        do stuff to update the foo resource        ...      */      // now broadcast the updated foo..        console.log("PUT OK!");     io.sockets.emit('update'); // how?    res.json({result: "update sent over IO"}); });}

Supposing you want to access the SocketIO from anywhere in your application, not just in the router, you could create a singleton for it. This is what works for me:

//socket-singletion.jsvar socket = require('socket.io');var SocketSingleton = (function() {  this.io = null;  this.configure = function(server) {    this.io = socket(server);  }  return this;})();module.exports = SocketSingleton;

Then, you need to configure it using your server:

//server config filevar SocketSingleton = require('./socket-singleton');var http = require('http');var server = http.createServer(app);SocketSingleton.configure(server); // <--hereserver.listen('3000');

Finally, use it wherever you want:

//router/index.jsvar express = require('express');var router = express.Router();var SocketSingleton = require('../socket-singleton');/* GET home page. */router.get('/', function(req, res, next) {  setTimeout(function(){    SocketSingleton.io.emit('news', {msg: 'success!'});  }, 3000);  res.render('index', { title: 'Express' });});module.exports = router;