#Server Documentation
App.js is a standard Express-Node.js with Socket.io integration with the exception of process.env.PORT which is needed for deployment, please refer to whatever service this App.js is planning to be deployed on for port information.
io.set('log level', 2) sets Socket.io to report to the Node.js console all information regarding connecting and disconnecting. To set it to debug, change the second argument to 3. Socket.io logging
app.get('/rooms'...) The pair of functions deals with Redis, please refer to Redis implementation
var socketManager and io.sockets.on is an abstraction of socket.on('connection', function{ socket.on(event, function(socket) {...} ) }), please refer to io manager documentation and server events.