draft-ietf-httpbis-jfv-02.txt   draft-ietf-httpbis-jfv-latest.txt 
HTTP Working Group J. Reschke HTTP Working Group J. Reschke
Internet-Draft greenbytes Internet-Draft greenbytes
Intended status: Standards Track October 24, 2016 Intended status: Standards Track February 20, 2017
Expires: April 27, 2017 Expires: August 24, 2017
A JSON Encoding for HTTP Header Field Values A JSON Encoding for HTTP Header Field Values
draft-ietf-httpbis-jfv-02 draft-ietf-httpbis-jfv-latest
Abstract Abstract
This document establishes a convention for use of JSON-encoded field This document establishes a convention for use of JSON-encoded field
values in HTTP header fields. values in HTTP header fields.
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 <http://httpwg.github.io/>; Working Group information can be found at <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. The changes in this draft are summarized in Appendix C.
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.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on April 27, 2017. This Internet-Draft will expire on August 24, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Data Model and Format . . . . . . . . . . . . . . . . . . . . 3 2. Data Model and Format . . . . . . . . . . . . . . . . . . . . 3
3. Sender Requirements . . . . . . . . . . . . . . . . . . . . . 4 3. Sender Requirements . . . . . . . . . . . . . . . . . . . . . 4
4. Recipient Requirements . . . . . . . . . . . . . . . . . . . . 5 4. Recipient Requirements . . . . . . . . . . . . . . . . . . . . 5
5. Using this Format in Header Field Definitions . . . . . . . . 5 5. Using this Format in Header Field Definitions . . . . . . . . 5
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Deployment Considerations . . . . . . . . . . . . . . . . . . 5
6.1. Content-Length . . . . . . . . . . . . . . . . . . . . . . 5 7. Interoperability Considerations . . . . . . . . . . . . . . . 5
6.2. Content-Disposition . . . . . . . . . . . . . . . . . . . 6 7.1. Encoding and Characters . . . . . . . . . . . . . . . . . 5
6.3. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 7 7.2. Numbers . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.4. Accept-Encoding . . . . . . . . . . . . . . . . . . . . . 8 7.3. Object Constraints . . . . . . . . . . . . . . . . . . . . 6
7. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8. Internationalization Considerations . . . . . . . . . . . . . 6
8. Deployment Considerations . . . . . . . . . . . . . . . . . . 9 9. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. Interoperability Considerations . . . . . . . . . . . . . . . 9 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Encoding and Characters . . . . . . . . . . . . . . . . . 9 10.1. Normative References . . . . . . . . . . . . . . . . . . . 7
9.2. Numbers . . . . . . . . . . . . . . . . . . . . . . . . . 10 10.2. Informative References . . . . . . . . . . . . . . . . . . 7
9.3. Object Constraints . . . . . . . . . . . . . . . . . . . . 10 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 8
10. Internationalization Considerations . . . . . . . . . . . . . 10 A.1. Content-Length . . . . . . . . . . . . . . . . . . . . . . 8
11. Security Considerations . . . . . . . . . . . . . . . . . . . 10 A.2. Content-Disposition . . . . . . . . . . . . . . . . . . . 9
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 A.3. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 10
12.1. Normative References . . . . . . . . . . . . . . . . . . . 11 A.4. Accept-Encoding . . . . . . . . . . . . . . . . . . . . . 11
12.2. Informative References . . . . . . . . . . . . . . . . . . 11 Appendix B. Discussion . . . . . . . . . . . . . . . . . . . . . 12
Appendix A. Change Log (to be removed by RFC Editor before Appendix C. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 12 publication) . . . . . . . . . . . . . . . . . . . . 12
A.1. Since draft-reschke-http-jfv-00 . . . . . . . . . . . . . 12 C.1. Since draft-reschke-http-jfv-00 . . . . . . . . . . . . . 12
A.2. Since draft-reschke-http-jfv-01 . . . . . . . . . . . . . 12 C.2. Since draft-reschke-http-jfv-01 . . . . . . . . . . . . . 12
A.3. Since draft-reschke-http-jfv-02 . . . . . . . . . . . . . 12 C.3. Since draft-reschke-http-jfv-02 . . . . . . . . . . . . . 12
A.4. Since draft-reschke-http-jfv-03 . . . . . . . . . . . . . 13 C.4. Since draft-reschke-http-jfv-03 . . . . . . . . . . . . . 13
A.5. Since draft-reschke-http-jfv-04 . . . . . . . . . . . . . 13 C.5. Since draft-reschke-http-jfv-04 . . . . . . . . . . . . . 13
A.6. Since draft-ietf-httpbis-jfv-00 . . . . . . . . . . . . . 13 C.6. Since draft-ietf-httpbis-jfv-00 . . . . . . . . . . . . . 13
A.7. Since draft-ietf-httpbis-jfv-01 . . . . . . . . . . . . . 13 C.7. Since draft-ietf-httpbis-jfv-01 . . . . . . . . . . . . . 13
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 13 C.8. Since draft-ietf-httpbis-jfv-02 . . . . . . . . . . . . . 13
Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
Defining syntax for new HTTP header fields ([RFC7230], Section 3.2) Defining syntax for new HTTP header fields ([RFC7230], Section 3.2)
is non-trivial. Among the commonly encountered problems are: is non-trivial. Among the commonly encountered problems are:
o There is no common syntax for complex field values. Several well- o There is no common syntax for complex field values. Several well-
known header fields do use a similarly looking syntax, but it is known header fields do use a similarly looking syntax, but it is
hard to write generic parsing code that will both correctly handle hard to write generic parsing code that will both correctly handle
valid field values but also reject invalid ones. valid field values but also reject invalid ones.
skipping to change at page 5, line 34 skipping to change at page 5, line 34
The result of the parsing operation is either an error (in which case The result of the parsing operation is either an error (in which case
the header field values needs to be considered invalid), or a JSON the header field values needs to be considered invalid), or a JSON
array. array.
5. Using this Format in Header Field Definitions 5. Using this Format in Header Field Definitions
[[anchor5: Explain what a definition of a new header field needs to [[anchor5: Explain what a definition of a new header field needs to
do precisely to use this format, mention must-ignore extensibility]] do precisely to use this format, mention must-ignore extensibility]]
6. Examples 6. Deployment Considerations
This JSON-based syntax will only apply to newly introduced header
fields, thus backwards compatibility is not a problem. That being
said, it is conceivable that there is existing code that might trip
over double quotes not being used for HTTP's quoted-string syntax
(Section 3.2.6 of [RFC7230]).
7. Interoperability Considerations
The "I-JSON Message Format" specification ([RFC7493]) addresses known
JSON interoperability pain points. This specification borrows from
the requirements made over there:
7.1. Encoding and Characters
This specification requires that field values use only US-ASCII
characters, and thus by definition use a subset of UTF-8 (Section 2.1
of [RFC7493]).
7.2. Numbers
Be aware of the issues around number precision, as discussed in
Section 2.2 of [RFC7493].
7.3. Object Constraints
As described in Section 4 of [RFC7159], JSON parser implementations
differ in the handling of duplicate object names. Therefore, senders
MUST NOT use duplicate object names, and recipients SHOULD either
treat field values with duplicate names as invalid (consistent with
[RFC7493], Section 2.3) or use the lexically last value (consistent
with [ECMA-262], Section 24.3.1.1).
Furthermore, ordering of object members is not significant and can
not be relied upon.
8. Internationalization Considerations
In HTTP/1.1, header field values are represented by octet sequences,
usually used to transmit ASCII characters, with restrictions on the
use of certain control characters, and no associated default
character encoding, nor a way to describe it ([RFC7230], Section
3.2). HTTP/2 does not change this.
This specification maps all characters which can cause problems to
JSON escape sequences, thereby solving the HTTP header field
internationalization problem.
Future specifications of HTTP might change to allow non-ASCII
characters natively. In that case, header fields using the syntax
defined by this specification would have a simple migration path (by
just stopping to require escaping of non-ASCII characters).
9. Security Considerations
Using JSON-shaped field values is believed to not introduce any new
threads beyond those described in Section 12 of [RFC7159], namely the
risk of recipients using the wrong tools to parse them.
Other than that, any syntax that makes extensions easy can be used to
smuggle information through field values; however, this concern is
shared with other widely used formats, such as those using parameters
in the form of name/value pairs.
10. References
10.1. Normative References
[RFC0020] Cerf, V., "ASCII format for network interchange",
STD 80, RFC 20, DOI 10.17487/RFC0020, October 1969,
<http://www.rfc-editor.org/info/rfc20>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>.
[RFC7159] Bray, T., "The JavaScript Object Notation (JSON)
Data Interchange Format", RFC 7159, DOI 10.17487/
RFC7159, March 2014,
<http://www.rfc-editor.org/info/rfc7159>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Message Syntax and
Routing", RFC 7230, DOI 10.17487/RFC7230,
June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Semantics and
Content", RFC 7231, DOI 10.17487/RFC7231,
June 2014,
<http://www.rfc-editor.org/info/rfc7231>.
[RFC7493] Bray, T., Ed., "The I-JSON Message Format",
RFC 7493, DOI 10.17487/RFC7493, March 2015,
<http://www.rfc-editor.org/info/rfc7493>.
10.2. Informative References
[ECMA-262] Ecma International, "ECMA-262 6th Edition, The
ECMAScript 2015 Language Specification",
Standard ECMA-262, June 2015,
<http://www.ecma-international.org/ecma-262/6.0/>.
[ISO-8859-1] International Organization for Standardization,
"Information technology -- 8-bit single-byte coded
graphic character sets -- Part 1: Latin alphabet
No. 1", ISO/IEC 8859-1:1998, 1998.
[KEY] Fielding, R. and M. Nottingham, "The Key HTTP
Response Header Field", draft-ietf-httpbis-key-01
(work in progress), March 2016.
[RFC5987] Reschke, J., "Character Set and Language Encoding
for Hypertext Transfer Protocol (HTTP) Header Field
Parameters", RFC 5987, DOI 10.17487/RFC5987,
August 2010,
<http://www.rfc-editor.org/info/rfc5987>.
[RFC6266] Reschke, J., "Use of the Content-Disposition Header
Field in the Hypertext Transfer Protocol (HTTP)",
RFC 6266, DOI 10.17487/RFC6266, June 2011,
<http://www.rfc-editor.org/info/rfc6266>.
[RFC6365] Hoffman, P. and J. Klensin, "Terminology Used in
Internationalization in the IETF", BCP 166,
RFC 6365, DOI 10.17487/RFC6365, September 2011,
<http://www.rfc-editor.org/info/rfc6365>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Authentication",
RFC 7235, DOI 10.17487/RFC7235, June 2014,
<http://www.rfc-editor.org/info/rfc7235>.
[XMLHttpRequest] WhatWG, "XMLHttpRequest",
<https://xhr.spec.whatwg.org/>.
Appendix A. Examples
This section shows how some of the existing HTTP header fields would This section shows how some of the existing HTTP header fields would
look like if they would use the format defined by this specification. look like if they would use the format defined by this specification.
6.1. Content-Length A.1. Content-Length
"Content-Length" is defined in Section 3.3.2 of [RFC7230], with the "Content-Length" is defined in Section 3.3.2 of [RFC7230], with the
field value's ABNF being: field value's ABNF being:
Content-Length = 1*DIGIT Content-Length = 1*DIGIT
So the field value is similar to a JSON number ([RFC7159], Section So the field value is similar to a JSON number ([RFC7159], Section
6). 6).
Content-Length is restricted to a single field instance, as it Content-Length is restricted to a single field instance, as it
skipping to change at page 6, line 20 skipping to change at page 9, line 15
...and the prose definition would: ...and the prose definition would:
o restrict all numbers to be non-negative integers without o restrict all numbers to be non-negative integers without
fractions, and fractions, and
o require that the array of values is of length 1 (but allow the o require that the array of values is of length 1 (but allow the
case where the array is longer, but all members represent the same case where the array is longer, but all members represent the same
value) value)
6.2. Content-Disposition A.2. Content-Disposition
Content-Disposition field values, defined in [RFC6266], consist of a Content-Disposition field values, defined in [RFC6266], consist of a
"disposition type" (a string), plus multiple parameters, of which at "disposition type" (a string), plus multiple parameters, of which at
least one ("filename") sometime needs to carry non-ASCII characters. least one ("filename") sometime needs to carry non-ASCII characters.
For instance, the first example in Section 5 of [RFC6266]: For instance, the first example in Section 5 of [RFC6266]:
Attachment; filename=example.html Attachment; filename=example.html
has a disposition type of "Attachment", with filename parameter value has a disposition type of "Attachment", with filename parameter value
skipping to change at page 7, line 10 skipping to change at page 10, line 7
defined in [RFC5987], representing a filename starting with the defined in [RFC5987], representing a filename starting with the
Unicode character U+20AC (EURO SIGN), followed by " rates". If the Unicode character U+20AC (EURO SIGN), followed by " rates". If the
definition of Content-Disposition would have used the format proposed definition of Content-Disposition would have used the format proposed
here, the workaround involving the "parameter*" syntax would not have here, the workaround involving the "parameter*" syntax would not have
been needed at all. been needed at all.
The JSON representation of this value could then be: The JSON representation of this value could then be:
{ "attachment": { "filename" : "\u20AC rates" } } { "attachment": { "filename" : "\u20AC rates" } }
6.3. WWW-Authenticate A.3. WWW-Authenticate
The WWW-Authenticate header field value is defined in Section 4.1 of The WWW-Authenticate header field value is defined in Section 4.1 of
[RFC7235] as a list of "challenges": [RFC7235] as a list of "challenges":
WWW-Authenticate = 1#challenge WWW-Authenticate = 1#challenge
...where a challenge consists of a scheme with optional parameters: ...where a challenge consists of a scheme with optional parameters:
challenge = auth-scheme [ 1*SP ( token68 / #auth-param ) ] challenge = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
skipping to change at page 8, line 5 skipping to change at page 11, line 5
} }
} }
] ]
...which would translate to a header field value of: ...which would translate to a header field value of:
{ "Newauth" : { "realm": "apps", "type" : 1, { "Newauth" : { "realm": "apps", "type" : 1,
"title": "Login to \"apps\"" }}, "title": "Login to \"apps\"" }},
{ "Basic" : { "realm": "simple"}} { "Basic" : { "realm": "simple"}}
6.4. Accept-Encoding A.4. Accept-Encoding
The Accept-Encoding header field value is defined in Section 5.3.4 of The Accept-Encoding header field value is defined in Section 5.3.4 of
[RFC7231] as a list of codings, each of which allowing a weight [RFC7231] as a list of codings, each of which allowing a weight
parameter 'q': parameter 'q':
Accept-Encoding = #( codings [ weight ] ) Accept-Encoding = #( codings [ weight ] )
codings = content-coding / "identity" / "*" codings = content-coding / "identity" / "*"
weight = OWS ";" OWS "q=" qvalue weight = OWS ";" OWS "q=" qvalue
qvalue = ( "0" [ "." 0*3DIGIT ] ) qvalue = ( "0" [ "." 0*3DIGIT ] )
/ ( "1" [ "." 0*3("0") ] ) / ( "1" [ "." 0*3("0") ] )
skipping to change at page 9, line 19 skipping to change at page 12, line 19
would be mapped to a member whose name is given by the string would be mapped to a member whose name is given by the string
literal, and the value is an empty object. literal, and the value is an empty object.
For what it's worth, one of the most common cases for 'Accept- For what it's worth, one of the most common cases for 'Accept-
Encoding' would become: Encoding' would become:
"gzip", "deflate" "gzip", "deflate"
which would be only a small overhead over the original format. which would be only a small overhead over the original format.
7. Discussion Appendix B. Discussion
This approach uses a default of "JSON array", using implicit array This approach uses a default of "JSON array", using implicit array
markers. An alternative would be a default of "JSON object". This markers. An alternative would be a default of "JSON object". This
would simplify the syntax for non-list-typed header fields, but all would simplify the syntax for non-list-typed header fields, but all
the benefits of having the same data model for both types of header the benefits of having the same data model for both types of header
fields would be gone. A hybrid approach might make sense, as long as fields would be gone. A hybrid approach might make sense, as long as
it doesn't require any heuristics on the recipient's side. it doesn't require any heuristics on the recipient's side.
Note: a concrete proposal was made by Kazuho Oku in <https:// Note: a concrete proposal was made by Kazuho Oku in <https://
lists.w3.org/Archives/Public/ietf-http-wg/2016JanMar/0155.html>. lists.w3.org/Archives/Public/ietf-http-wg/2016JanMar/0155.html>.
[[anchor7: Use of generic libs vs compactness of field values..]] [[anchor15: Use of generic libs vs compactness of field values..]]
[[anchor8: Mention potential "Key" header field extension ([KEY]).]]
8. Deployment Considerations
This JSON-based syntax will only apply to newly introduced header
fields, thus backwards compatibility is not a problem. That being
said, it is conceivable that there is existing code that might trip
over double quotes not being used for HTTP's quoted-string syntax
(Section 3.2.6 of [RFC7230]).
9. Interoperability Considerations
The "I-JSON Message Format" specification ([RFC7493]) addresses known
JSON interoperability pain points. This specification borrows from
the requirements made over there:
9.1. Encoding and Characters
This specification requires that field values use only US-ASCII
characters, and thus by definition use a subset of UTF-8 (Section 2.1
of [RFC7493]).
9.2. Numbers
Be aware of the issues around number precision, as discussed in
Section 2.2 of [RFC7493].
9.3. Object Constraints
As described in Section 4 of [RFC7159], JSON parser implementations
differ in the handling of duplicate object names. Therefore, senders
MUST NOT use duplicate object names, and recipients SHOULD either
treat field values with duplicate names as invalid (consistent with
[RFC7493], Section 2.3) or use the lexically last value (consistent
with [ECMA-262], Section 24.3.1.1).
Furthermore, ordering of object members is not significant and can
not be relied upon.
10. Internationalization Considerations
In HTTP/1.1, header field values are represented by octet sequences,
usually used to transmit ASCII characters, with restrictions on the
use of certain control characters, and no associated default
character encoding, nor a way to describe it ([RFC7230], Section
3.2). HTTP/2 does not change this.
This specification maps all characters which can cause problems to
JSON escape sequences, thereby solving the HTTP header field
internationalization problem.
Future specifications of HTTP might change to allow non-ASCII
characters natively. In that case, header fields using the syntax
defined by this specification would have a simple migration path (by
just stopping to require escaping of non-ASCII characters).
11. Security Considerations
Using JSON-shaped field values is believed to not introduce any new
threads beyond those described in Section 12 of [RFC7159], namely the
risk of recipients using the wrong tools to parse them.
Other than that, any syntax that makes extensions easy can be used to
smuggle information through field values; however, this concern is
shared with other widely used formats, such as those using parameters
in the form of name/value pairs.
12. References
12.1. Normative References
[RFC0020] Cerf, V., "ASCII format for network interchange",
STD 80, RFC 20, DOI 10.17487/RFC0020, October 1969,
<http://www.rfc-editor.org/info/rfc20>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>.
[RFC7159] Bray, T., "The JavaScript Object Notation (JSON)
Data Interchange Format", RFC 7159, DOI 10.17487/
RFC7159, March 2014,
<http://www.rfc-editor.org/info/rfc7159>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Message Syntax and
Routing", RFC 7230, DOI 10.17487/RFC7230,
June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Semantics and
Content", RFC 7231, DOI 10.17487/RFC7231,
June 2014,
<http://www.rfc-editor.org/info/rfc7231>.
[RFC7493] Bray, T., Ed., "The I-JSON Message Format",
RFC 7493, DOI 10.17487/RFC7493, March 2015,
<http://www.rfc-editor.org/info/rfc7493>.
12.2. Informative References
[ECMA-262] Ecma International, "ECMA-262 6th Edition, The
ECMAScript 2015 Language Specification",
Standard ECMA-262, June 2015,
<http://www.ecma-international.org/ecma-262/6.0/>.
[ISO-8859-1] International Organization for Standardization,
"Information technology -- 8-bit single-byte coded
graphic character sets -- Part 1: Latin alphabet
No. 1", ISO/IEC 8859-1:1998, 1998.
[KEY] Fielding, R. and M. Nottingham, "The Key HTTP
Response Header Field", draft-ietf-httpbis-key-01
(work in progress), March 2016.
[RFC5987] Reschke, J., "Character Set and Language Encoding
for Hypertext Transfer Protocol (HTTP) Header Field
Parameters", RFC 5987, DOI 10.17487/RFC5987,
August 2010,
<http://www.rfc-editor.org/info/rfc5987>.
[RFC6266] Reschke, J., "Use of the Content-Disposition Header
Field in the Hypertext Transfer Protocol (HTTP)",
RFC 6266, DOI 10.17487/RFC6266, June 2011,
<http://www.rfc-editor.org/info/rfc6266>.
[RFC6365] Hoffman, P. and J. Klensin, "Terminology Used in
Internationalization in the IETF", BCP 166,
RFC 6365, DOI 10.17487/RFC6365, September 2011,
<http://www.rfc-editor.org/info/rfc6365>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext
Transfer Protocol (HTTP/1.1): Authentication",
RFC 7235, DOI 10.17487/RFC7235, June 2014,
<http://www.rfc-editor.org/info/rfc7235>.
[XMLHttpRequest] van Kesteren, A., Aubourg, J., Song, J., and H.
Steen, "XMLHttpRequest Level 1", W3C Working
Draft WD-XMLHttpRequest-20140130, January 2014, <ht
tp://www.w3.org/TR/2014/
WD-XMLHttpRequest-20140130/>.
Latest version available at [[anchor16: Mention potential "Key" header field extension ([KEY]).]]
<http://www.w3.org/TR/XMLHttpRequest/>.
Appendix A. Change Log (to be removed by RFC Editor before publication) Appendix C. Change Log (to be removed by RFC Editor before publication)
A.1. Since draft-reschke-http-jfv-00 C.1. Since draft-reschke-http-jfv-00
Editorial fixes + working on the TODOs. Editorial fixes + working on the TODOs.
A.2. Since draft-reschke-http-jfv-01 C.2. Since draft-reschke-http-jfv-01
Mention slightly increased risk of smuggling information in header Mention slightly increased risk of smuggling information in header
field values. field values.
A.3. Since draft-reschke-http-jfv-02 C.3. Since draft-reschke-http-jfv-02
Mention Kazuho Oku's proposal for abbreviated forms. Mention Kazuho Oku's proposal for abbreviated forms.
Added a bit of text about the motivation for a concrete JSON subset Added a bit of text about the motivation for a concrete JSON subset
(ack Cory Benfield). (ack Cory Benfield).
Expand I18N section. Expand I18N section.
A.4. Since draft-reschke-http-jfv-03 C.4. Since draft-reschke-http-jfv-03
Mention relation to KEY header field. Mention relation to KEY header field.
A.5. Since draft-reschke-http-jfv-04 C.5. Since draft-reschke-http-jfv-04
Change to HTTP Working Group draft. Change to HTTP Working Group draft.
A.6. Since draft-ietf-httpbis-jfv-00 C.6. Since draft-ietf-httpbis-jfv-00
Added example for "Accept-Encoding" (inspired by Kazuho's feedback), Added example for "Accept-Encoding" (inspired by Kazuho's feedback),
showing a potential way to optimize the format when default values showing a potential way to optimize the format when default values
apply. apply.
A.7. Since draft-ietf-httpbis-jfv-01 C.7. Since draft-ietf-httpbis-jfv-01
Add interop discussion, building on I-JSON and ECMA-262 (see Add interop discussion, building on I-JSON and ECMA-262 (see
<https://github.com/httpwg/http-extensions/issues/225>). <https://github.com/httpwg/http-extensions/issues/225>).
Appendix B. Acknowledgements C.8. Since draft-ietf-httpbis-jfv-02
Move non-essential parts into appendix.
Updated XHR reference.
Appendix D. Acknowledgements
Thanks go to the Hypertext Transfer Protocol Working Group Thanks go to the Hypertext Transfer Protocol Working Group
participants. participants.
Author's Address Author's Address
Julian F. Reschke Julian F. Reschke
greenbytes GmbH greenbytes GmbH
Hafenweg 16 Hafenweg 16
Muenster, NW 48155 Muenster, NW 48155
 End of changes. 24 change blocks. 
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