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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 HTTPbis Working Group J. Reschke 3 Internet-Draft greenbytes 4 Obsoletes: 7238 (if approved) January 14, 2015 5 Intended status: Standards Track 6 Expires: July 18, 2015 8 The Hypertext Transfer Protocol Status Code 308 (Permanent Redirect) 9 draft-ietf-httpbis-rfc7238bis-02 11 Abstract 13 This document specifies the additional Hypertext Transfer Protocol 14 (HTTP) status code 308 (Permanent Redirect). 16 Status of This Memo 18 This Internet-Draft is submitted in full conformance with the 19 provisions of BCP 78 and BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF). Note that other groups may also distribute 23 working documents as Internet-Drafts. The list of current Internet- 24 Drafts is at http://datatracker.ietf.org/drafts/current/. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 This Internet-Draft will expire on July 18, 2015. 33 Copyright Notice 35 Copyright (c) 2015 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents 40 (http://trustee.ietf.org/license-info) in effect on the date of 41 publication of this document. Please review these documents 42 carefully, as they describe your rights and restrictions with respect 43 to this document. Code Components extracted from this document must 44 include Simplified BSD License text as described in Section 4.e of 45 the Trust Legal Provisions and are provided without warranty as 46 described in the Simplified BSD License. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 51 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 52 3. 308 Permanent Redirect . . . . . . . . . . . . . . . . . . . . 3 53 4. Deployment Considerations . . . . . . . . . . . . . . . . . . . 4 54 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 55 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 56 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 57 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 58 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 59 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 61 1. Introduction 63 HTTP defines a set of status codes for the purpose of redirecting a 64 request to a different URI ([RFC3986]). The history of these status 65 codes is summarized in Section 6.4 of [RFC7231], which also 66 classifies the existing status codes into four categories. 68 The first of these categories contains the status codes 301 (Moved 69 Permanently), 302 (Found), and 307 (Temporary Redirect), which can be 70 classified as below: 72 +-------------------------------------------+-----------+-----------+ 73 | | Permanent | Temporary | 74 +-------------------------------------------+-----------+-----------+ 75 | Allows changing the request method from | 301 | 302 | 76 | POST to GET | | | 77 | Does not allow changing the request | - | 307 | 78 | method from POST to GET | | | 79 +-------------------------------------------+-----------+-----------+ 81 Section 6.4.7 of [RFC7231] states that it does not define a permanent 82 variant of status code 307; this specification adds the status code 83 308, defining this missing variant (Section 3). 85 This specification contains no technical changes from the 86 experimental RFC 7238, which it obsoletes. 88 2. Notational Conventions 90 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 91 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 92 document are to be interpreted as described in [RFC2119]. 94 3. 308 Permanent Redirect 96 The 308 (Permanent Redirect) status code indicates that the target 97 resource has been assigned a new permanent URI and any future 98 references to this resource ought to use one of the enclosed URIs. 99 Clients with link editing capabilities ought to automatically re-link 100 references to the effective request URI (Section 5.5 of [RFC7230]) to 101 one or more of the new references sent by the server, where possible. 103 The server SHOULD generate a Location header field ([RFC7231], 104 Section 7.1.2) in the response containing a preferred URI reference 105 for the new permanent URI. The user agent MAY use the Location field 106 value for automatic redirection. The server's response payload 107 usually contains a short hypertext note with a hyperlink to the new 108 URI(s). 110 A 308 response is cacheable by default; i.e., unless otherwise 111 indicated by the method definition or explicit cache controls (see 112 [RFC7234], Section 4.2.2). 114 Note: This status code is similar to 301 (Moved Permanently) 115 ([RFC7231], Section 6.4.2), except that it does not allow changing 116 the request method from POST to GET. 118 4. Deployment Considerations 120 Section 6 of [RFC7231] requires recipients to treat unknown 3xx 121 status codes the same way as status code 300 Multiple Choices 122 ([RFC7231], Section 6.4.1). Thus, servers will not be able to rely 123 on automatic redirection happening similar to status codes 301, 302, 124 or 307. 126 Therefore, the use of status code 308 is restricted to cases where 127 the server has sufficient confidence in the client's understanding 128 the new code or when a fallback to the semantics of status code 300 129 is not problematic. Server implementers are advised not to vary the 130 status code based on characteristics of the request, such as the 131 User-Agent header field ("User-Agent Sniffing") -- doing so usually 132 results in code that is both hard to maintain and hard to debug and 133 would also require special attention to caching (i.e., setting a 134 "Vary" response header field, as defined in Section 7.1.4 of 135 [RFC7231]). 137 Note that many existing HTML-based user agents will emulate a refresh 138 when encountering an HTML refresh directive ([HTML], Section 139 4.2.5.3). This can be used as another fallback. For example: 141 Client request: 143 GET / HTTP/1.1 144 Host: example.com 146 Server response: 148 HTTP/1.1 308 Permanent Redirect 149 Content-Type: text/html; charset=UTF-8 150 Location: http://example.com/new 151 Content-Length: 356 153 154 155 156 Permanent Redirect 157 159 160 161

162 The document has been moved to 163 http://example.com/new. 165

166 167 169 5. Security Considerations 171 All security considerations that apply to HTTP redirects apply to the 172 308 status code as well (see Section 9 of [RFC7231]). 174 6. IANA Considerations 176 The "Hypertext Transfer Protocol (HTTP) Status Code Registry" 177 (defined in Section 8.2 of [RFC7231] and located at 178 ) needs to be 179 updated with the registration below: 181 +-------+--------------------+---------------------------------+ 182 | Value | Description | Reference | 183 +-------+--------------------+---------------------------------+ 184 | 308 | Permanent Redirect | Section 3 of this specification | 185 +-------+--------------------+---------------------------------+ 187 7. Acknowledgements 189 The definition for the new status code 308 reuses text from the 190 HTTP/1.1 definitions of status codes 301 and 307. 192 Furthermore, thanks to Ben Campbell, Cyrus Daboo, Adrian Farrell, 193 Eran Hammer-Lahav, Bjoern Hoehrmann, Barry Leiba, Subramanian 194 Moonesamy, Peter Saint-Andre, and Robert Sparks for feedback on this 195 document. 197 8. References 199 8.1. Normative References 201 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 202 Requirement Levels", BCP 14, RFC 2119, March 1997. 204 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 205 Resource Identifier (URI): Generic Syntax", STD 66, 206 RFC 3986, January 2005. 208 [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 209 Protocol (HTTP/1.1): Message Syntax and Routing", 210 RFC 7230, June 2014. 212 [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 213 Protocol (HTTP/1.1): Semantics and Content", RFC 7231, 214 June 2014. 216 [RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, 217 Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching", 218 RFC 7234, June 2014. 220 8.2. Informative References 222 [HTML] Hickson, I., Berjon, R., Faulkner, S., Leithead, T., Doyle 223 Navara, E., O'Connor, E., and S. Pfeiffer, "HTML5", W3C 224 Recommendation REC-html5-20141028, October 2014, 225 . 227 Latest version available at . 229 Author's Address 231 Julian F. Reschke 232 greenbytes GmbH 233 Hafenweg 16 234 Muenster, NW 48155 235 Germany 237 EMail: julian.reschke@greenbytes.de 238 URI: http://greenbytes.de/tech/webdav/