WebSockets were never fully based on HTTP; instead, they use HTTP as part of the initial handshake process to establish a connection but then operate independently of HTTP for ongoing communication. The WebSocket protocol, defined under RFC 6455, was designed to provide full-duplex communication channels over a single TCP connection. When a WebSocket connection is initiated, it starts with an HTTP-based handshake. This involves the client sending an HTTP request to the server including an “Upgrade” header, which signals the desire to switch from HTTP to WebSocket.

Upon receiving this request, the server can accept the upgrade by sending back an HTTP response with its own “Upgrade” header. Once the handshake is complete and the HTTP connection is upgraded to a WebSocket connection, the protocol switches from the HTTP protocol. This allows communication where both client and server can send and receive messages independently, without the request-response paradigm of HTTP, thereby achieving real-time communication—the main goal of the WebSocket protocol. Thus, while WebSockets start their lifecycle using HTTP, they are not fully based on it.