Socket.IO [SEP] programming language
Socket.IO
Socket.IO is a JavaScript library for realtime web applications. It enables realtime, bi-directional communication between web clients and servers. It has two parts: a client-side library that runs in the browser, and a server-side library for Node.js. Both components have a nearly identical API. Like Node.js, it is event-driven.
Socket.IO primarily uses the WebSocket protocol with polling as a fallback option, while providing the same interface. Although it can be used as
to only have Socket.IO knowledge.
Socket.IO is not a WebSocket library with fallback options to other realtime protocols. It is a custom realtime transport protocol implementation on top of other realtime protocols. 
A Socket.IO implementing server cannot connect to a non-Socket.IO WebSocket client. A Socket.IO implementing client cannot talk to a non-Socket.IO WebSocket or Long Polling Comet server.
Socket.IO requires using the Socket.IO libraries on both client and server side