push-server.js

var app = require('express')()
  , server = require('http').createServer(app)
  , io = require('socket.io').listen(server);

server.listen(80);

var subscribers = {};

var publishMessage = function(channel, message) {
  var sockets = subscribers[channel];
  if (sockets) {
    sockets.forEach(function(socket) {
      socket.emit('message', message); // 'messsage' is just something arbitrary I decided to call this "event"
    });
  }
};

var subscribe = function(channel, socket) {
  if (!subscribers[channel]) {
    subscribers[channel] = [];
  }
  subscribers[channel].push(socket);
}

app.get('/api/publish/:channel', function (req, res) {
  var message = {
    type: req.param('type')
  };
  publishMessage(req.param('channel'), message);
});

io.sockets.on('connection', function (socket) {
  socket.on('subscribe', function (channel) {
    subscribe(channel, socket);
  });
});