Node.js Web Development - Fourth Edition

Initializing Socket.IO with Express

Socket.IO works by wrapping itself around an HTTP Server object. Think back to Chapter 4, HTTP Servers and Clients, where we wrote a module that hooked into HTTP Server methods so that we could spy on HTTP transactions. The HTTP Sniffer attaches a listener to every HTTP event to print out the events. But what if you used that idea to do real work? Socket.IO uses a similar concept, listening to HTTP requests and responding to specific ones by using the Socket.IO protocol to communicate with client code in the browser.

To get started, let's first make a duplicate of the code from the previous chapter. If you created a directory named chap08 for that code, create a new directory named chap09 and copy the source ...