Table des matières
Each Status-Code is described below, including a description of which method(s) it can follow and any metainformation required in the response.
This class of status code indicates a provisional response, consisting only in the Status-Line and optional headers and terminated by an empty line. There are no required headers for this class of status code. Since HTTP/1.0 did not define any 1xx status codes, servers MUST NOT send a 1xx response to an HTTP/1.0 client except under experimental conditions.
A client MUST be prepared to accept one or more 1xx status responses prior to a regular response, even if the client does not expect a 100 (Continue) status message. Unexpected 1xx status responses MAY be ignored by a user agent.
Proxies MUST forward 1xx responses, unless the connection between the proxy and its client has been closed, or unless the proxy itself has requested the generation of the 1xx response. (For example, if a proxy adds a "Expect: 100-continue" field when it forwards a request, then it does not need to forward the corresponding 100 (Continue) response(s).)
The client SHOULD continue with its request. This interim response is used to inform the client that the initial part of the request has been received and that it has not been rejected by the server yet. The client SHOULD continue by sending the remainder of the request or, if the request has already been completed, ignore this response. The server MUST send a final response after the request has been completed. See [RFC 2068], section 8.2.3 for detailed discussion of the use and handling of this status code.
he server understands and is willing to comply with the client's request, via the Upgrade message header field ([RFC 2068], section 14.42), for a change in the application protocol being used on this connection. The server will switch protocols to those defined by the response of the Upgrade header field immediately after the empty line which terminates the 101 response.
The protocol SHOULD be switched only when it is advantageous to do so. For example, switching to a newer version of HTTP is advantageous over older versions, and switching to a real-time, synchronous protocol might be advantageous when delivering resources that use such features.