WebSockets浅探及实践 - 1

• 确定状态码是不是101，如果不是则遵循HTTP的响应处理过程。否则往下走
• 确保响应头中必须包含Upgrade域，其中包含"websocket"值，否则连接失败；
• 确保响应头包含Connect域，且有值"Upgrade"，否则连接失败；
• 确保响应头包含Sec-WebSocket-Accept域，且其值应该等于Base64(SHA-1(|Sec-WebSocket-Key|)+"258EAFA5-E914-47DA-95CA-C5AB0DC85B11")；否则连接失败；

• 如果响应头中包含了Sec-WebSocket-Extensions域，而请求头并未包含，那么客户端必须中断连接；
• 如果响应头中包含Sec-WebSocket-Protocol域，但在请求头中并没有包含此子协议值，客户端必须中断连接.

GET /socket.io/1/websocket/1166156958668058955 HTTP/1.1
Host: localhost:8077
User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:12.0) Gecko/20100101 Firefox/12.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive, Upgrade
Sec-WebSocket-Version: 13
Origin: http://localhost:8077
Sec-WebSocket-Key: xQelQMxXk7J8q1whTHKPJA==
Pragma: no-cache
Cache-Control: no-cache
Upgrade: websocket

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: V6OpbVjbdllb6RNrRdFmG+pIzXk=

0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-------+-+-------------+-------------------------------+
     |F|R|R|R| opcode|M| Payload len |    Extended payload length    |
     |I|S|S|S|  (4)  |A|     (7)     |             (16/64)           |
     |N|V|V|V|       |S|             |   (if payload len==126/127)   |
     | |1|2|3|       |K|             |                               |
     +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
     |     Extended payload length continued, if payload len == 127  |
     + - - - - - - - - - - - - - - - +-------------------------------+
     |                               |Masking-key, if MASK set to 1  |
     +-------------------------------+-------------------------------+
     | Masking-key (continued)       |          Payload Data         |
     +-------------------------------- - - - - - - - - - - - - - - - +
     :                     Payload Data continued ...                :
     + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
     |                     Payload Data continued ...                |
     +---------------------------------------------------------------

[Constructor(DOMString url, optional (DOMString or DOMString[]) protocols)]
interface WebSocket : EventTarget {
  readonly attribute DOMString url;

  // ready state
  const unsigned short CONNECTING = 0;
  const unsigned short OPEN = 1;
  const unsigned short CLOSING = 2;
  const unsigned short CLOSED = 3;
  readonly attribute unsigned short readyState;
  readonly attribute unsigned long bufferedAmount;

  // networking
  [TreatNonCallableAsNull] attribute Function? onopen;
  [TreatNonCallableAsNull] attribute Function? onerror;
  [TreatNonCallableAsNull] attribute Function? onclose;
  readonly attribute DOMString extensions;
  readonly attribute DOMString protocol;
  void close([Clamp] optional unsigned short code, optional DOMString reason);

  // messaging
  [TreatNonCallableAsNull] attribute Function? onmessage;
           attribute DOMString binaryType;
  void send(DOMString data);
  void send(ArrayBufferView data);
  void send(Blob data);
};

• CONNECTING(0): 连接尚未建立
• OPEN(1): WebSocket连接已建立，可以进行通信
• CLOSING(2): 连接将要进行closing握手
• CLOSED(3): 连接已关闭或不能打开

exampleSocket.onmessage =  function  (event) {  
      console.log(event.data);  
}