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The Hypertext Transfer Protocol (HTTP) Status Code 308 (Permanent Redirect)greenbytes GmbHHafenweg 16MuensterNW48155Germanyjulian.reschke@greenbytes.dehttp://greenbytes.de/tech/webdav/HTTPredirectstatus 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.
“The fallback requirement (…)
strikes me as a bad idea. It’s a transient problem so it should be con-
ditioned and how widely supported this is, and it’s only useful if you
have some HTML implementation on the other end or an interactive user; a
web service not meant for interactive use where you can be sure that the
code is supported, because, say, you control the client, is unaffected,
and if you add that as another exception you basically end up saying you
can do this so your site works better with legacy clients in some situ-
ations and making your site work good is probably a good idea, so I’d
prefer just saying that. I don’t really want to ponder whether I should
send this hypertext response in response to an OPTIONS request in 2015,
just because your specification says I should.”
See related HTTPbis issue http://trac.tools.ietf.org/wg/httpbis/trac/ticket/332 —
we should fix this in the base spec, then copy over the new text to this document.
Proposal: use final text from HTTPbis.
The spec has been aligned with HTTPbis, relaxing the requirement.
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:
PermanentTemporaryAllows changing the request method from POST to GET301302Does 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 .
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.
The 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).
Unless the request method was HEAD, the representation of the response
&SHOULD; contain a short hypertext note with a hyperlink to the new URI(s)
since most user agents do not understand the 308 status code yet. Therefore,
the note &SHOULD; contain the information necessary for a user to repeat
the original request on the new URI.
If the 308 status code is received in response to a request method that is
known to be “safe”, as defined in ,
then the request &MAY; be automatically redirected by the user agent without
confirmation. Otherwise, the user agent &MUST-NOT; automatically redirect
the request unless it can be confirmed by the user, since this might change
the conditions under which the request was issued.
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 existing user agents will emulate a refresh when encountering
an HTML <meta> refresh directive. This can be used as another
fallback.
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>
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 ):
ValueDescriptionReference308Permanent Redirect
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 Bjoern Hoehrmann and Subramanian Moonesamy for feedback on this document.
Key words for use in RFCs to Indicate Requirement LevelsHarvard Universitysob@harvard.eduUniform Resource Identifier (URI): Generic SyntaxWorld Wide Web Consortiumtimbl@w3.orghttp://www.w3.org/People/Berners-Lee/Day Softwarefielding@gbiv.comhttp://roy.gbiv.com/Adobe Systems IncorporatedLMM@acm.orghttp://larry.masinter.net/HTTP/1.1, part 1: URIs, Connections, and Message ParsingAdobe Systems Incorporatedfielding@gbiv.comAlcatel-Lucent Bell Labsjg@freedesktop.orgHewlett-Packard CompanyJeffMogul@acm.orgMicrosoft Corporationhenrikn@microsoft.comAdobe Systems IncorporatedLMM@acm.orgMicrosoft Corporationpaulle@microsoft.comWorld Wide Web Consortiumtimbl@w3.orgWorld Wide Web Consortiumylafon@w3.orggreenbytes GmbHjulian.reschke@greenbytes.deHTTP/1.1, part 2: Message SemanticsAdobe Systems Incorporatedfielding@gbiv.comOne Laptop per Childjg@laptop.orgHewlett-Packard CompanyJeffMogul@acm.orgMicrosoft Corporationhenrikn@microsoft.comAdobe Systems, IncorporatedLMM@acm.orgMicrosoft Corporationpaulle@microsoft.comWorld Wide Web Consortiumtimbl@w3.orgWorld Wide Web Consortiumylafon@w3.orggreenbytes GmbHjulian.reschke@greenbytes.deChrome: 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.
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).