Using Socket.io for Building Real-Time Applications

Socket.IO is a library for real-time messaging that has two halves, a server package for Node.js and a client package for browsers and other programs. Each message has a name, called an event, and the receiving side runs the handler registered for that name. The ws server from the previous lesson moved raw messages; Socket.IO adds named events, reconnection after a dropped connection, and a fallback for networks that block WebSockets.

These features come with one condition. Socket.IO uses its own protocol on top of WebSocket, so a Socket.IO server talks only to Socket.IO clients. A plain