Socket.IO is a layer on top of the WebSocket protocol that makes it easy to send and receive messages between a client and a server. It has a few extra features that make it ideal for real-time communication. Examples of these features include:

  • Automatic reconnection
  • Multiplexing
  • Binary support
  • Acknowledgements
  • Broadcasts

The Engine.IO library is also worth looking at. It is the underlying library that Socket.IO uses to handle the WebSocket protocol. It is a standalone library that can be used without Socket.IO.

Socket.IO Breakdown

The entire Socket.IO protocol is documented in the Socket.IO Protocol page.

  1. Socket.IO Packet
  2. Packet Encoding
  3. Session Lifecycle
  4. Sample Session