HTML5 web sockets - how to communicate with them?

Question

I've tested many socket examples and communication between them was pretty simple: socket is opened and stays open until you close it and no information is being sent except the one you have sent.

With HTML5 web sockets these two moments are different.

At first, as soon as the client HTML5 socket connects to server socket it sends a bunch of information:

GET /echo HTTP/1.1
Upgrade: websocket
Connection: Upgrade
Host: localhost:2002
Origin: null
Pragma: no-cache
Cache-Control: no-cache
Sec-WebSocket-Key: iYzsmhdzg6h6/UGtCLLGVA==
Sec-WebSocket-Version: 13
Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits, x-webkit-deflate-frame
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.114 Safari/537.36
Cookie: _rails-socket-listener_session=dGtleFYxNjhIaUZrZVpOWUNIMHdFZFd6WW9wY2FJYjIwOWdSMFVPR1ZkYkZUakExdVlhNzMvWEphNG1IRUIvT1JsQ0N6bHF4REFXTkJUemE4R2RjOER6bXdhSEt6M0tIYmRwV0w3VzkrVGt4MzN2Z0M3MXMyYndZR3hvOGMySTJTZmdEMW9JdEE5ZERuSDB4VCtROFNnPT0tLTlheG1KamlBSVVmT0tUZ1F5bmQ0OUE9PQ%3D%3D--23413749a30295f08d277292837c76187a02a332

How to interpret this information? What to do with it?

At second, when I send some string from debugging server (Hercules setup utility), socket's onmessage event is not fired and client socket closes the connection immediately after this.

So, I suppose that HTML5 web socket expects some handshaking before it could be used. Where to read about it?

BTW: I am using Ruby as server-side language.

Answer 1

I've tested many web socket examples ....

From what you describe you did not use "web sockets" but simply "sockets", e.g. direct TCP/IP. WebSockets (e.g. what you call "HTML web sockets") are different: they are used to create something socket like over an established HTTP connection. Therefore you see the HTTP query with the "Upgrade: websocket" header, with the "Sec-WebSocket-Key" etc.

After establishing the connection (server sends response with code 101) the WebSocket connection has their own framing and scrambling of the data, so you cannot just use it with the normal socket tools.

See https://www.rfc-editor.org/rfc/rfc6455 for the specification and use "WebSockets" as the keyword if you look for more documentation, usage...