Application Layer Protocol - Web Socket Home : www.sharetechnote.com
What is WebSocket ?
WebSocket sounds like "A special socket that is specially designed/optimized for Web Application". It sounds OK.. but what it really mean ? The official definition of WebSocket is defined in RFC 6455 as stated below.
The WebSocket Protocol enables two-way communication between a client running untrusted code in a controlled environment to a remote host that has opted-in to communications from that code. The security model used for this is the origin-based security model commonly used by web browsers. The protocol consists of an opening handshake followed by basic message framing, layered over TCP. The goal of this technology is to provide a mechanism for browser-based applications that need two-way communication with servers that does not rely on opening multiple HTTP connections (e.g., using XMLHttpRequest or <iframe>s and long polling).
Whenever I try to clearly understand anything from RFC, I almost always have to rewrite things on my own format / words, otherwise it tend to be very confusing. Let me rewrite this statement from RFC document. It goes as follows.
(1) GET /protocol HTTP/1.1 (Host url etc)
GET /mqtt HTTP/1.1
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.110 Safari/537.36
Accept-Encoding: gzip, deflate, sdch
Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits
(2) HTTP/1.1 101 Switching Protocols
HTTP/1.1 101 Switching Protocols