draft-ietf-httpbis-cice-00.txt   draft-ietf-httpbis-cice-01.txt 
HTTP Working Group J. Reschke HTTP Working Group J. Reschke
Internet-Draft greenbytes Internet-Draft greenbytes
Intended status: Standards Track April 11, 2015 Intended status: Standards Track May 30, 2015
Expires: October 13, 2015 Expires: December 1, 2015
Hypertext Transfer Protocol (HTTP) Client-Initiated Content-Encoding Hypertext Transfer Protocol (HTTP) Client-Initiated Content-Encoding
draft-ietf-httpbis-cice-00 draft-ietf-httpbis-cice-01
Abstract Abstract
In HTTP, "Content Codings" allow for payload encodings such as for In HTTP, content codings allow for payload encodings such as for
compression or integrity checks. In particular, the "gzip" content compression or integrity checks. In particular, the "gzip" content
coding is widely used for payload data sent in response messages. coding is widely used for payload data sent in response messages.
Content Codings can be used in request messages as well, however Content codings can be used in request messages as well, however
discoverability is not on par with response messages. This document discoverability is not on par with response messages. This document
extends the HTTP "Accept-Encoding" header field for use in responses. extends the HTTP "Accept-Encoding" header field for use in responses,
to indicate that content codings are supported in requests.
Editorial Note (To be removed by RFC Editor before publication) Editorial Note (To be removed by RFC Editor before publication)
Discussion of this draft takes place on the HTTPBIS working group Discussion of this draft takes place on the HTTPBIS working group
mailing list (ietf-http-wg@w3.org), which is archived at mailing list (ietf-http-wg@w3.org), which is archived at
<https://lists.w3.org/Archives/Public/ietf-http-wg/>. <https://lists.w3.org/Archives/Public/ietf-http-wg/>.
Working Group information can be found at Working Group information can be found at
<https://tools.ietf.org/wg/httpbis/> and <http://httpwg.github.io/>; <https://tools.ietf.org/wg/httpbis/> and <http://httpwg.github.io/>;
source code and issues list for this draft can be found at source code and issues list for this draft can be found at
<https://github.com/httpwg/http-extensions>. <https://github.com/httpwg/http-extensions>.
The changes in this draft are summarized in Appendix A.3. The changes in this draft are summarized in Appendix A.4.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 1, 2015.
This Internet-Draft will expire on October 13, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
3. Extensions to 'Accept-Encoding' Header Field . . . . . . . . . 3 3. Using the 'Accept-Encoding' Header Field in Responses . . . . . 3
4. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Deployment Considerations . . . . . . . . . . . . . . . . . . . 5 5. Deployment Considerations . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . . 6 8.2. Informative References . . . . . . . . . . . . . . . . . . 6
Appendix A. Change Log (to be removed by RFC Editor before Appendix A. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . . 6 publication) . . . . . . . . . . . . . . . . . . . . . 6
A.1. Since draft-reschke-http-cice-00 . . . . . . . . . . . . . 6 A.1. Since draft-reschke-http-cice-00 . . . . . . . . . . . . . 6
A.2. Since draft-reschke-http-cice-01 . . . . . . . . . . . . . 6 A.2. Since draft-reschke-http-cice-01 . . . . . . . . . . . . . 6
A.3. Since draft-reschke-http-cice-02 . . . . . . . . . . . . . 6 A.3. Since draft-reschke-http-cice-02 . . . . . . . . . . . . . 6
A.4. Since draft-ietf-httpbis-cice-00 . . . . . . . . . . . . . 7
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . . 7 Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
In HTTP, "Content Codings" allow for payload encodings such as for In HTTP, content codings allow for payload encodings such as for
compression or integrity checks ([RFC7231], Section 3.1.2). In compression or integrity checks ([RFC7231], Section 3.1.2). In
particular, the "gzip" content coding is widely used for payload data particular, the "gzip" content coding is widely used for payload data
sent in response messages. sent in response messages.
Content Codings can be used in request messages as well, however Content codings can be used in request messages as well, however
discoverability is not on par with response messages. This document discoverability is not on par with response messages. This document
extends the HTTP "Accept-Encoding" header field ([RFC7231], Section extends the HTTP "Accept-Encoding" header field ([RFC7231], Section
5.3.4) for use in responses. 5.3.4) for use in responses, to indicate that content codings are
supported in requests.
2. Notational Conventions 2. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
This document reuses terminology used in the base HTTP This document reuses terminology defined in the base HTTP
specifications, namely Section 2 of [RFC7230] and Section 3.1.2 of specifications, namely Section 2 of [RFC7230] and Section 3.1.2 of
[RFC7231]. [RFC7231].
3. Extensions to 'Accept-Encoding' Header Field 3. Using the 'Accept-Encoding' Header Field in Responses
Section 5.3.4 of [RFC7231] defines "Accept-Encoding" as a request Section 5.3.4 of [RFC7231] defines "Accept-Encoding" as a request
header field only. header field only.
This specification extends that definition to allow "Accept-Encoding" This specification expands that definition to allow "Accept-Encoding"
as a response header field as well. When present, it indicates what as a response header field as well. When present in a response, it
content codings a resource was willing to accept at the time of the indicates what content codings the resource was willing to accept in
response. A field value that only contains "identity" implies that the associated request. A field value that only contains "identity"
no content codings are supported. implies that no content codings were supported.
Note that this information is specific to the specific request. The Note that this information is specific to the associated request; the
set of supported encodings might be different for other resources on set of supported encodings might be different for other resources on
the same server, could also change depending on other aspects of the the same server, and could change over time or depend on other
request (such as the request method), or might change in the future. aspects of the request (such as the request method).
Section 6.5.13 of [RFC7231] defines status code 415 (Unsupported Section 6.5.13 of [RFC7231] defines status code 415 (Unsupported
Media Type) to apply to both media type and content coding related Media Type) to apply to both media type and content coding related
problems. problems.
Servers that fail a request due to an unsupported content coding Servers that fail a request due to an unsupported content coding
SHOULD respond with a 415 status and SHOULD include an "Accept- SHOULD respond with a 415 status and SHOULD include an "Accept-
Encoding" header field in that response, allowing clients to Encoding" header field in that response, allowing clients to
distinguish between content coding related issues and media type distinguish between content coding related issues and media type
related issues. In order to avoid confusion with media type related related issues. In order to avoid confusion with media type related
problems, servers that fail a request with a 415 status for reasons problems, servers that fail a request with a 415 status for reasons
unrelated to content codings SHOULD NOT include the "Accept-Encoding" unrelated to content codings SHOULD NOT include the "Accept-Encoding"
header field. header field.
While sending "Accept-Encoding" in a 415 (Unsupported Media Type) It is expected that the most common use of "Accept-Encoding" in
response will be the most common use case, it is not restricted to responses will have the 415 (Unsupported Media Type) status code, in
this particular status code. For instance, a server might include it response to optimistic use of a content coding by clients. However,
in a 2xx response when a request payload was big enough to justify the header field can also be used to indicate to clients that content
use of a compression coding, but the client failed to do so. codings are supported, to optimize future interactions. For example,
a resource might include it in a 2xx response when the request
payload was big enough to justify use of a compression coding, but
the client failed do so.
4. Example 4. Example
Client submits a POST request using Content-Encoding "compress" A client submits a POST request using the "compress" content coding
([RFC7231], Section 3.1.2.1): ([RFC7231], Section 3.1.2.1):
POST /edit/ HTTP/1.1 POST /edit/ HTTP/1.1
Host: example.org Host: example.org
Content-Type: application/atom+xml;type=entry Content-Type: application/atom+xml;type=entry
Content-Encoding: compress Content-Encoding: compress
...compressed payload... ...compressed payload...
Server rejects request because it only allows the "gzip" content The server rejects request because it only allows the "gzip" content
coding: coding:
HTTP/1.1 415 Unsupported Media Type HTTP/1.1 415 Unsupported Media Type
Date: Fri, 09 May 2014 11:43:53 GMT Date: Fri, 09 May 2014 11:43:53 GMT
Accept-Encoding: gzip Accept-Encoding: gzip
Content-Length: 68 Content-Length: 68
Content-Type: text/plain Content-Type: text/plain
This resource only supports the "gzip" content coding in requests. This resource only supports the "gzip" content coding in requests.
skipping to change at page 4, line 47 skipping to change at page 5, line 4
"gzip" content coding. "gzip" content coding.
Alternatively, a server that does not support any content codings in Alternatively, a server that does not support any content codings in
requests could answer with: requests could answer with:
HTTP/1.1 415 Unsupported Media Type HTTP/1.1 415 Unsupported Media Type
Date: Fri, 09 May 2014 11:43:53 GMT Date: Fri, 09 May 2014 11:43:53 GMT
Accept-Encoding: identity Accept-Encoding: identity
Content-Length: 61 Content-Length: 61
Content-Type: text/plain Content-Type: text/plain
This resource does not support content codings in requests. This resource does not support content codings in requests.
5. Deployment Considerations 5. Deployment Considerations
Servers that do not support content codings in requests already are Servers that do not support content codings in requests already are
required to fail a request that does use a content coding. Section required to fail a request that does use a content coding. Section
6.5.13 of [RFC7231] recommends to use the status code 415 6.5.13 of [RFC7231] recommends using the status code 415 (Unsupported
(Unsupported Media Type), so the only change needed is to include the Media Type), so the only change needed is to include the "Accept-
"Accept-Encoding" header field with value "identity" in that Encoding" header field with value "identity" in that response.
response.
Servers that do support some content codings are required to fail Servers that do support some content codings are required to fail
requests with unsupported content codings as well. To be compliant requests with unsupported content codings as well. To be compliant
with this specification, servers will need to use the status code 415 with this specification, servers will need to use the status code 415
(Unsupported Media Type) to signal the problem, and will have to (Unsupported Media Type) to signal the problem, and will have to
include an "Accept-Encoding" header field that enumerates the content include an "Accept-Encoding" header field that enumerates the content
codings that are supported. As the set of supported content codings codings that are supported. As the set of supported content codings
usually is static and small, adding the header field ought to be is usually static and small, adding the header field ought to be
trivial. trivial.
6. Security Considerations 6. Security Considerations
This specification does not introduce any new security considerations This specification does not introduce any new security considerations
beyond those discussed in Section 9 of [RFC7231]. beyond those discussed in Section 9 of [RFC7231].
7. IANA Considerations 7. IANA Considerations
HTTP header fields are registered within the "Message Headers" HTTP header fields are registered within the "Message Headers"
skipping to change at page 5, line 44 skipping to change at page 5, line 44
This document updates the definition of the "Accept-Encoding" header This document updates the definition of the "Accept-Encoding" header
field, so the "Permanent Message Header Field Names" registry shall field, so the "Permanent Message Header Field Names" registry shall
be updated accordingly: be updated accordingly:
+-----------------+----------+----------+---------------------------+ +-----------------+----------+----------+---------------------------+
| Header Field | Protocol | Status | Reference | | Header Field | Protocol | Status | Reference |
| Name | | | | | Name | | | |
+-----------------+----------+----------+---------------------------+ +-----------------+----------+----------+---------------------------+
| Accept-Encoding | http | standard | [RFC7231], Section 5.3.4, | | Accept-Encoding | http | standard | [RFC7231], Section 5.3.4, |
| | | | extended by Section 3 of | | | | | and Section 3 of this |
| | | | this document | | | | | document |
+-----------------+----------+----------+---------------------------+ +-----------------+----------+----------+---------------------------+
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997, Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing", Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, June 2014, RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>. <http://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231, Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
June 2014, <http://www.rfc-editor.org/info/rfc7231>. DOI 10.17487/RFC7231, June 2014,
<http://www.rfc-editor.org/info/rfc7231>.
8.2. Informative References 8.2. Informative References
[BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration [BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864, Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004, <http://www.rfc-editor.org/info/rfc3864>. September 2004, <http://www.rfc-editor.org/info/bcp90>.
Appendix A. Change Log (to be removed by RFC Editor before publication) Appendix A. Change Log (to be removed by RFC Editor before publication)
A.1. Since draft-reschke-http-cice-00 A.1. Since draft-reschke-http-cice-00
Clarified that the information returned in Accept-Encoding is per Clarified that the information returned in Accept-Encoding is per
resource, not per server. resource, not per server.
Added some deployment considerations. Added some deployment considerations.
skipping to change at page 7, line 5 skipping to change at page 7, line 5
Mention use of A-E in responses other than 415. Mention use of A-E in responses other than 415.
Recommend not to include A-E in a 415 response unless there was Recommend not to include A-E in a 415 response unless there was
actually a problem related to content coding. actually a problem related to content coding.
A.3. Since draft-reschke-http-cice-02 A.3. Since draft-reschke-http-cice-02
First Working Group draft; updated boilerplate accordingly. First Working Group draft; updated boilerplate accordingly.
A.4. Since draft-ietf-httpbis-cice-00
Apply editorial improvements suggested by Mark Nottingham.
Appendix B. Acknowledgements Appendix B. Acknowledgements
Thanks go to the members of the and HTTPbis Working Group, namely Thanks go to the members of the and HTTPbis Working Group, namely
Amos Jeffries, Mark Nottingham, and Ted Hardie. Amos Jeffries, Mark Nottingham, and Ted Hardie.
Author's Address Author's Address
Julian F. Reschke Julian F. Reschke
greenbytes GmbH greenbytes GmbH
Hafenweg 16 Hafenweg 16
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