MAY"> MUST"> MUST NOT"> OPTIONAL"> RECOMMENDED"> REQUIRED"> SHALL"> SHALL NOT"> SHOULD"> SHOULD NOT"> ]> The Hypertext Transfer Protocol (HTTP) Status Code 308 (Permanent Redirect) greenbytes GmbH
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HTTP redirect status code This document specifies the additional HyperText Transfer Protocol (HTTP) Status Code 308 (Permanent Redirect). Distribution of this document is unlimited. Although this is not a work item of the HTTPbis Working Group, comments should be sent to the Hypertext Transfer Protocol (HTTP) mailing list at ietf-http-wg@w3.org, which may be joined by sending a message with subject "subscribe" to ietf-http-wg-request@w3.org. Discussions of the HTTPbis Working Group are archived at . XML versions, latest edits, and the issues list for this document are available from . Test cases related to redirection in general and the status code 308 in particular can be found at . Umbrella issue for editorial fixes/enhancements.
HTTP defines a set of status codes for the purpose of redirecting a request to a different URI (). The history of these status codes is summarized in , 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: Permanent Temporary Allows changing the request method from POST to GET 301 302 Does not allow changing the request method from POST to GET - 307 states that HTTP does not define a permanent variant of status code 307; this specification adds the status code 308, defining this missing variant ().
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in .
According to HTTPbis Part 2, need to explain the request conditions, interactions with response headers, and implications for caches. If certain default behavior is assumed, it would be good to make that explicit. Added missing caching considerations. The target resource has been assigned a new permanent URI and any future references to this resource &SHOULD; use one of the returned URIs. Clients with link editing capabilities ought to automatically re-link references to the effective request URI () to one or more of the new references returned by the server, where possible. Caches MAY use a heuristic (see ) to determine freshness for 308 responses. The new permanent URI &SHOULD; be given by the Location field in the response (). A response payload can contain a short hypertext note with a hyperlink to the new URI(s).
requires recipients to treat unknown 3xx status codes the same way as status code 300 Multiple Choices (). 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 clients understanding the new code, or when a fallback to the semantics of status code 300 is not problematic. Note that many existing HTML-based user agents will emulate a refresh when encountering an HTML <meta> refresh directive. This can be used as another fallback. For example:
For example: HTTP/1.1 308 Permanent Redirect Content-Type: text/html; charset=UTF-8 Location: http://example.com/new Content-Length: <!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>
Client request: GET / HTTP/1.1 Host: example.com
Server response: HTTP/1.1 308 Permanent Redirect Content-Type: text/html; charset=UTF-8 Location: http://example.com/new Content-Length: <!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>
All security considerations that apply to HTTP redirects apply to the 308 status code as well (see ).
The registration below shall be added to the HTTP Status Code Registry (defined in and located at ): Value Description Reference 308 Permanent Redirect of this specification
The definition for the new status code 308 re-uses text from the HTTP/1.1 definitions of status codes 301 and 307. Furthermore, thanks to Cyrus Daboo, Bjoern Hoehrmann and, Subramanian Moonesamy, and Peter Saint-Andre for feedback on this document.
Key words for use in RFCs to Indicate Requirement Levels Harvard University
sob@harvard.edu
 Uniform Resource Identifier (URI): Generic Syntax World Wide Web Consortium
timbl@w3.org http://www.w3.org/People/Berners-Lee/
Day Software
fielding@gbiv.com http://roy.gbiv.com/
Adobe Systems Incorporated
LMM@acm.org http://larry.masinter.net/
HTTP/1.1, part 1: URIs, Connections, and Message Parsing Adobe Systems Incorporated
fielding@gbiv.com
 Alcatel-Lucent Bell Labs
jg@freedesktop.org
 Hewlett-Packard Company
JeffMogul@acm.org
 Microsoft Corporation
henrikn@microsoft.com
 Adobe Systems Incorporated
LMM@acm.org
 Microsoft Corporation
paulle@microsoft.com
 World Wide Web Consortium
timbl@w3.org
 World Wide Web Consortium
ylafon@w3.org
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julian.reschke@greenbytes.de
 HTTP/1.1, part 2: Message Semantics Adobe Systems Incorporated
fielding@gbiv.com
 One Laptop per Child
jg@laptop.org
 Hewlett-Packard Company
JeffMogul@acm.org
 Microsoft Corporation
henrikn@microsoft.com
 Adobe Systems, Incorporated
LMM@acm.org
 Microsoft Corporation
paulle@microsoft.com
 World Wide Web Consortium
timbl@w3.org
 World Wide Web Consortium
ylafon@w3.org
 greenbytes GmbH
julian.reschke@greenbytes.de
 HTTP/1.1, part 6: Caching Adobe Systems Incorporated
fielding@gbiv.com
 Alcatel-Lucent Bell Labs
jg@freedesktop.org
 Hewlett-Packard Company
JeffMogul@acm.org
 Microsoft Corporation
henrikn@microsoft.com
 Adobe Systems Incorporated
LMM@acm.org
 Microsoft Corporation
paulle@microsoft.com
 World Wide Web Consortium
timbl@w3.org
 World Wide Web Consortium
ylafon@w3.org
 Rackspace
mnot@mnot.net
 greenbytes GmbH
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Chrome: Feature requested in Chromium Issue 109012 (). Curl (the library): no change was needed (test case: ). Firefox: Feature requested in Bugzilla bug 714302 (), patch available. Safari: Safari automatically redirects 3xx status codes when a Location header field is present, thus no change is needed but does not preserve the request method.
Updated HTTPbis reference. Added . Added and resolved issue "refresh".
Added URI spec reference.
Tune HTML example. Expand "Implementations" section. Added and resolved issue "respformat" (align with new proposed text for 307 in HTTPbis P2).
Added and resolved issue "uaconfirm".
Added and resolved issue "missingconsiderations". Added request message to example. Updated the Safari implementation note.