WebSocket Upgrade

WebSocket starts with an HTTP handshake and then upgrades the connection to a bidirectional protocol.

Validate the Origin and negotiate the requested subprotocol and extensions. A successful handshake returns 101 Switching Protocols.

httpwebsocketupgraderealtime

Reference (http)

GET /chat HTTP/1.1
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Version: 13
Sec-WebSocket-Key: <nonce>

Validate the Origin and negotiate the requested subprotocol and extensions. A successful handshake returns 101 Switching Protocols.

Common mistakes

Accepting every Origin or treating the WebSocket handshake as proof of user authentication.

Sources