我希望学习更多关于WebSocket协议的知识。根据RFC 6455,该协议的步骤是握手,它开始于HTTP Upgrade请求:
GET /chat HTTP/1.1
Host: server.example.com
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
Origin: http://example.com
Sec-WebSocket-Protocol: chat, superchat
Sec-WebSocket-Version: 13
服务器将响应HTTP切换协议消息:
HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=
Sec-WebSocket-Protocol: chat
我用基于socketIO的简单程序尝试观察这个过程(socketIO是nodeJS的websocket库)。在捕获到流量后,我注意到客户端发送给服务器的第一条消息是:
GET /socket.io/?EIO=3&transport=polling&t=1443149751115-0 HTTP/1.1
Host: localhost
Connection: keep-alive
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.85 Safari/537.36
Origin: null
Accept: */*
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-US,en;q=0.8
服务器做出以下响应:
HTTP/1.1 200 OK
Content-Type: application/octet-stream
Content-Length: 101
Access-Control-Allow-Credentials: true
Access-Control-Allow-Origin: null
Set-Cookie: io=3Z_TCqv9LKKXcWCjAAAD
Date: Fri, 25 Sep 2015 02:55:51 GMT
Connection: keep-alive
....0{"sid":"3Z_TCqv9LKKXcWCjAAAD","upgrades": ["websocket"],"pingInterval":25000,"pingTimeout":60000}
SocketIO是否没有遵循WebSockets的RFC标准,还是我有所遗漏?