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Versions: 00 01 02 03 04 05 06 07 RFC 7238

Network Working Group                                         J. Reschke
Internet-Draft                                                greenbytes
Intended status: Experimental                           February 1, 2012
Expires: August 4, 2012


   The Hypertext Transfer Protocol (HTTP) Status Code 308 (Permanent
                               Redirect)
                    draft-reschke-http-status-308-03

Abstract

   This document specifies the additional HyperText Transfer Protocol
   (HTTP) Status Code 308 (Permanent Redirect).

Editorial Note (To be removed by RFC Editor before publication)

   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 [1], which may be joined by sending a message
   with subject "subscribe" to ietf-http-wg-request@w3.org [2].

   Discussions of the HTTPbis Working Group are archived at
   <http://lists.w3.org/Archives/Public/ietf-http-wg/>.

   XML versions, latest edits, and the issues list for this document are
   available from
   <http://greenbytes.de/tech/webdav/#draft-reschke-http-status-308>.

   Test cases related to redirection in general and the status code 308
   in particular can be found at
   <http://greenbytes.de/tech/tc/httpredirects/#l-308>.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."



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   This Internet-Draft will expire on August 4, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . . . 3
   3.  308 Permanent Redirect  . . . . . . . . . . . . . . . . . . . . 3
   4.  Deployment Considerations . . . . . . . . . . . . . . . . . . . 4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   8.  Normative References  . . . . . . . . . . . . . . . . . . . . . 5
   Appendix A.  Implementations (to be removed by RFC Editor
                before publication)  . . . . . . . . . . . . . . . . . 6
   Appendix B.  Change Log (to be removed by RFC Editor before
                publication) . . . . . . . . . . . . . . . . . . . . . 6
     B.1.  Since draft-reschke-http-status-308-00  . . . . . . . . . . 6
     B.2.  Since draft-reschke-http-status-308-01  . . . . . . . . . . 6
     B.3.  Since draft-reschke-http-status-308-02  . . . . . . . . . . 6
   Appendix C.  Resolved issues (to be removed by RFC Editor
                before publication)  . . . . . . . . . . . . . . . . . 7
     C.1.  respformat  . . . . . . . . . . . . . . . . . . . . . . . . 7
   Appendix D.  Open issues (to be removed by RFC Editor prior to
                publication) . . . . . . . . . . . . . . . . . . . . . 7
     D.1.  edit  . . . . . . . . . . . . . . . . . . . . . . . . . . . 7











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1.  Introduction

   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 7.3 of
   [draft-ietf-httpbis-p2-semantics], 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   | 301       | 302       |
   | POST to GET                               |           |           |
   | Does not allow changing the request       | -         | 307       |
   | method from POST to GET                   |           |           |
   +-------------------------------------------+-----------+-----------+

   Section 7.3.8 of [draft-ietf-httpbis-p2-semantics] states that HTTP
   does not define a permanent variant of status code 307; this
   specification adds the status code 308, defining this missing variant
   (Section 3).

2.  Notational Conventions

   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 [RFC2119].

3.  308 Permanent Redirect

   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 (Section 4.3 of
   [draft-ietf-httpbis-p1-messaging]) 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 ([draft-ietf-httpbis-p2-semantics], Section 9.5).  A
   response payload can contain a short hypertext note with a hyperlink
   to the new URI(s)..

   If the 308 status code is received in response to a request method
   that is known to be "safe", as defined in Section 6.1.1 of



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   [draft-ietf-httpbis-p2-semantics], 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.

4.  Deployment Considerations

   Section 4 of [draft-ietf-httpbis-p2-semantics] requires recipients to
   treat unknown 3xx status codes the same way as status code 300
   Multiple Choices ([draft-ietf-httpbis-p2-semantics], Section 7.3.1).
   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 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: 443

   <!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>






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5.  Security Considerations

   All security considerations that apply to HTTP redirects apply to the
   308 status code as well (see Section 11 of
   [draft-ietf-httpbis-p2-semantics]).

6.  IANA Considerations

   The registration below shall be added to the HTTP Status Code
   Registry (defined in Section 4.2 of [draft-ietf-httpbis-p2-semantics]
   and located at <http://www.iana.org/assignments/http-status-codes>):

   +-------+--------------------+-----------+
   | Value | Description        | Reference |
   +-------+--------------------+-----------+
   | 308   | Permanent Redirect | Section 3 |
   +-------+--------------------+-----------+

7.  Acknowledgements

   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.

8.  Normative References

   [RFC2119]                          Bradner, S., "Key words for use in
                                      RFCs to Indicate Requirement
                                      Levels", BCP 14, RFC 2119,
                                      March 1997.

   [RFC3986]                          Berners-Lee, T., Fielding, R., and
                                      L. Masinter, "Uniform Resource
                                      Identifier (URI): Generic Syntax",
                                      STD 66, RFC 3986, January 2005.

   [draft-ietf-httpbis-p1-messaging]  Fielding, R., Ed., Gettys, J.,
                                      Mogul, J., Frystyk, H., Masinter,
                                      L., Leach, P., Berners-Lee, T.,
                                      Lafon, Y., Ed., and J. Reschke,
                                      Ed., "HTTP/1.1, part 1: URIs,
                                      Connections, and Message Parsing",
                                      draft-ietf-httpbis-p1-messaging-18
                                      (work in progress), January 2012.

   [draft-ietf-httpbis-p2-semantics]  Fielding, R., Ed., Gettys, J.,



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                                      Mogul, J., Frystyk, H., Masinter,
                                      L., Leach, P., Berners-Lee, T.,
                                      Lafon, Y., Ed., and J. Reschke,
                                      Ed., "HTTP/1.1, part 2: Message
                                      Semantics",
                                      draft-ietf-httpbis-p2-semantics-18
                                      (work in progress), January 2012.

   [1]  <mailto:ietf-http-wg@w3.org>

   [2]  <mailto:ietf-http-wg-request@w3.org?subject=subscribe>

Appendix A.  Implementations (to be removed by RFC Editor before
             publication)

   Chrome: Feature requested in Chromium Issue 109012
   (<http://code.google.com/p/chromium/issues/detail?id=109012>).

   Curl (the library): no change was needed (test case:
   <https://github.com/bagder/curl/blob/master/tests/data/test1325>).

   Firefox: Feature requested in Bugzilla bug 714302
   (<https://bugzilla.mozilla.org/show_bug.cgi?id=714302>), patch
   available.

   Safari: Safari automatically redirects 3xx status codes when a
   Location header field is present, thus no change is needed.

Appendix B.  Change Log (to be removed by RFC Editor before publication)

B.1.  Since draft-reschke-http-status-308-00

   Updated HTTPbis reference.  Added Appendix A.  Added and resolved
   issue "refresh".

B.2.  Since draft-reschke-http-status-308-01

   Added URI spec reference.

B.3.  Since draft-reschke-http-status-308-02

   Tune HTML example.  Expand "Implementations" section.  Added and
   resolved issue "respformat" (align with new proposed text for 307 in
   HTTPbis P2).







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Appendix C.  Resolved issues (to be removed by RFC Editor before
             publication)

   Issues that were either rejected or resolved in this version of this
   document.

C.1.  respformat

   Type: change

   <http://lists.w3.org/Archives/Public/ietf-http-wg/2012JanMar/
   0041.html>

   derhoermi@gmx.net (2012-01-14): "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."

   julian.reschke@greenbytes.de (2012-01-29): 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.

   Resolution (2012-01-31): The spec has been aligned with HTTPbis,
   relaxing the requirement.

Appendix D.  Open issues (to be removed by RFC Editor prior to
             publication)

D.1.  edit

   Type: edit

   julian.reschke@greenbytes.de (2011-04-15): Umbrella issue for
   editorial fixes/enhancements.







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Author's Address

   Julian F. Reschke
   greenbytes GmbH
   Hafenweg 16
   Muenster, NW  48155
   Germany

   EMail: julian.reschke@greenbytes.de
   URI:   http://greenbytes.de/tech/webdav/









































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