This document specifies the additional Hypertext Transfer Protocol (HTTP) status code 308 (Permanent Redirect).
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This is a temporary document for the purpose of tracking the editorial changes made during the AUTH48 (RFC publication) phase.
This document is not an Internet Standards Track specification; it is published for examination, experimental implementation, and evaluation.
This document defines an Experimental Protocol for the Internet community. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 7841.
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HTTP defines a set of status codes for the purpose of redirecting a request to a different URI ([RFC3986]). The history of these status codes is summarized in Section 6.4 of [RFC7231], which also classifies the existing status codes into four categories.¶
The first of these categories contains the status codes 301 (Moved Permanently), 302 (Found), and 307 (Temporary Redirect), which can be classified as below:¶
|Allows changing the request method from POST to GET||301||302|
|Does not allow changing the request method from POST to GET||-||307|
The 308 (Permanent Redirect) status code indicates that the target resource has been assigned a new permanent URI and any future references to this resource ought to use one of the enclosed URIs. Clients with link editing capabilities ought to automatically re-link references to the effective request URI (Section 5.5 of [RFC7230]) to one or more of the new references sent by the server, where possible.¶
The server SHOULD generate a Location header field ([RFC7231], Section 7.1.2) in the response containing a preferred URI reference for the new permanent URI. The user agent MAY use the Location field value for automatic redirection. The server's response payload usually contains a short hypertext note with a hyperlink to the new URI(s).¶
Section 6 of [RFC7231] requires recipients to treat unknown 3xx status codes the same way as status code 300 Multiple Choices ([RFC7231], Section 6.4.1). Thus, servers will not be able to rely on automatic redirection happening similar to status codes 301, 302, or 307.¶
Therefore, initial use of status code 308 will be restricted to cases where the server has sufficient confidence in the client's understanding the new code or when a fallback to the semantics of status code 300 is not problematic. Server implementers are advised not to vary the status code based on characteristics of the request, such as the User-Agent header field ("User-Agent Sniffing") — doing so usually results in code that is both hard to maintain and hard to debug and would also require special attention to caching (i.e., setting a "Vary" response header field, as defined in Section 7.1.4 of [RFC7231]).¶
GET / HTTP/1.1 Host: example.com
HTTP/1.1 308 Permanent Redirect Content-Type: text/html; charset=UTF-8 Location: http://example.com/new Content-Length: 454 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>Permanent Redirect</title> <meta http-equiv="refresh" content="0; url=http://example.com/new"> </head> <body> <p> The document has been moved to <a href="http://example.com/new" >http://example.com/new</a>. </p> </body> </html>
The registration below has been added to the "Hypertext Transfer Protocol (HTTP) Status Code Registry" (defined in Section 8.2 of [RFC7231] and located at <http://www.iana.org/assignments/http-status-codes>):¶
|308||Permanent Redirect||Section 3 of this specification|
The definition for the new status code 308 reuses text from the HTTP/1.1 definitions of status codes 301 and 307.¶
Furthermore, thanks to Ben Campbell, Cyrus Daboo, Eran Hammer-Lahav, Bjoern Hoehrmann, Subramanian Moonesamy, Peter Saint-Andre, and Robert Sparks for feedback on this document.¶