HTTP is a stateless protocol as noted previously. This means that a new connection is established for every request and closed after every response. An HTML5 WebSocket is a communication interface that allows for a permanent bidirectional connection between client and server.
A WebSocket is opened by the client through a GET request such as the following:
GET /chat HTTP/1.1 Host: server.example.com Upgrade: websocket Connection: Upgrade Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw== Sec-WebSocket-Protocol: chat, superchat Sec-WebSocket-Version: 13 Origin: http://example.com
If the server understands the request and accepts the connection, its response would be as follows:
HTTP/1.1 101 Switching Protocols Upgrade: websocket Connection: ...
