问题
What's the difference between these two response statuses:
HTTP/1.1 101 Web Socket Protocol Handshake
HTTP/1.1 101 Switching Protocols
Does it matter which one I get?
回答1:
There is no difference whatsoever. What is important is the 101 response code to indicate the handshake is progressing. This is defined in RFC 6455:
The leading line from the client follows the Request-Line format. The leading line from the server follows the Status-Line format. The Request-Line and Status-Line productions are defined in [RFC2616].
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The handshake from the server is much simpler than the client handshake. The first line is an HTTP Status-Line, with the status code 101:
HTTP/1.1 101 Switching Protocols
Any status code other than 101 indicates that the WebSocket handshake has not completed and that the semantics of HTTP still apply.
The text of the Status-Line is arbitrary, the server can use whatever text it wants, per RFC 2616:
Status-Line = HTTP-Version SP Status-Code SP Reason-Phrase CRLF
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The Status-Code element is a 3-digit integer result code of the attempt to understand and satisfy the request. These codes are fully defined in section 10. The Reason-Phrase is intended to give a short textual description of the Status-Code. The Status-Code is intended for use by automata and the Reason-Phrase is intended for the human user. The client is not required to examine or display the Reason-Phrase.
Switching Protocols just happens to be what the examples in RFC 6455 use, but that is not a requirement.
来源：https://stackoverflow.com/questions/22410903/web-socket-protocol-handshake-vs-switching-protocols