client.js

var socket = io.connect('/');

//////////////
// Handlers //
//////////////

// fire when socket.io is connected to the back-end
socket.on('connect', function() {
    getEntries(3);
});

// fire when a "newEntry" event is broadcasted
socket.on('newEntry-' + currentLocation, function(data) {
    getEntries(3);
});

function getEntries(number) {
  // do something client side
}

controller.js

// create an entry
router.post('/', function(req, res, next) {

    // our parameters
    // TODO: attach client id and to entries

    var payload = {
        message: req.body.entryMessage,
        position: {
            currentState: parseInt(req.body.entryCurrentState),
            currentChapter: parseInt(req.body.entryCurrentChapter)
        },
        location: req.body.entryLocation || 'unknown',
        user: req.body.entryUser || 'unknown', //TODO: our client need to send a unique client id
        timestamp: new Date()
    };

    // our model's method
    Entry.create(payload, function(err, doc) {
        if (err) {
            next(helpers.generateError(req.originalUrl, 503, err));
        }

        res.io.emit('newEntry-' + payload.location, doc); // our socket.io event broadcast
        res.io.emit('updateEntries', doc); // a general event for our admin page
        res.json(doc);
    });
});