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Network Working Group                                         J. Reschke
Internet-Draft                                                greenbytes
Intended status: Experimental                          December 19, 2011
Expires: June 21, 2012


   The Hypertext Transfer Protocol (HTTP) Status Code 308 (Permanent
                               Redirect)
                    draft-reschke-http-status-308-00

Abstract

   This document specifies the additional HyperText Transfer Protocol
   (HTTP) Status Codes 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 and latest edits for this document are available from <h
   ttp://greenbytes.de/tech/webdav/#draft-reschke-http-status-code-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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on June 21, 2012.

Copyright Notice




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Internet-Draft            HTTP Status Code 308             December 2011


   Copyright (c) 2011 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
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   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 . . . . . . . . . . . . . . . . . . . . 4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 4
   8.  Normative References  . . . . . . . . . . . . . . . . . . . . . 4




























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Internet-Draft            HTTP Status Code 308             December 2011


1.  Introduction

   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 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 this status code (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.  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 Section 6.1.1 of



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Internet-Draft            HTTP Status Code 308             December 2011


   [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 a fallback to the semantics of status
   code 300 is not problematic.

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.

8.  Normative References

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



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Internet-Draft            HTTP Status Code 308             December 2011


   [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-17
                                      (work in progress), October 2011.

   [draft-ietf-httpbis-p2-semantics]  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 2: Message
                                      Semantics",
                                      draft-ietf-httpbis-p2-semantics-17
                                      (work in progress), October 2011.

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

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

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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