draft-ietf-appsawg-json-pointer-03.txt   draft-ietf-appsawg-json-pointer-04.txt 
Applications Area Working Group P. Bryan, Ed. Applications Area Working Group P. Bryan, Ed.
Internet-Draft ForgeRock Internet-Draft Salesforce.com
Intended status: Informational K. Zyp Intended status: Informational K. Zyp
Expires: February 12, 2013 SitePen (USA) Expires: March 9, 2013 SitePen (USA)
M. Nottingham, Ed. M. Nottingham, Ed.
Rackspace September 5, 2012
August 11, 2012
JSON Pointer JSON Pointer
draft-ietf-appsawg-json-pointer-03 draft-ietf-appsawg-json-pointer-04
Abstract Abstract
JSON Pointer defines a string syntax for identifying a specific value JSON Pointer defines a string syntax for identifying a specific value
within a JSON document. within a JSON document.
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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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 12, 2013. This Internet-Draft will expire on March 9, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 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
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. JSON String Representation . . . . . . . . . . . . . . . . . . 4 5. JSON String Representation . . . . . . . . . . . . . . . . . . 4
6. URI Fragment Identifier Representation . . . . . . . . . . . . 5 6. URI Fragment Identifier Representation . . . . . . . . . . . . 5
7. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 6 7. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
9. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 9. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. Normative References . . . . . . . . . . . . . . . . . . . 7 11.1. Normative References . . . . . . . . . . . . . . . . . . . 7
11.2. Informative References . . . . . . . . . . . . . . . . . . 7 11.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
This specification defines JSON Pointer, a string syntax for This specification defines JSON Pointer, a string syntax for
identifying a specific value within a JavaScript Object Notation identifying a specific value within a JavaScript Object Notation
(JSON) [RFC4627] document. It is intended to be easily expressed in (JSON) [RFC4627] document. It is intended to be easily expressed in
JSON string values as well as Uniform Resource Identifier (URI) JSON string values as well as Uniform Resource Identifier (URI)
[RFC3986] fragment identifiers. [RFC3986] fragment identifiers.
2. Conventions 2. 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 specification expresses normative syntax rules using Augmented This specification expresses normative syntax rules using Augmented
Backus-Naur Form [RFC5234] (ABNF) notation. Backus-Naur Form (ABNF) [RFC5234] notation.
3. Syntax 3. Syntax
A JSON Pointer is a [Unicode] string containing a sequence of zero or A JSON Pointer is a [Unicode] string containing a sequence of zero or
more reference tokens, each prefixed by a '/' (%x2F) character. more reference tokens, each prefixed by a '/' (%x2F) character.
If a reference token contains '~' (%x7E) or '/' (%x2F) characters, Since the characters '~' (%x7E) and '/' (%x2F) have a special meaning
they MUST be encoded as '~0' and '~1' respectively. in JSON Pointer, they need to be encoded as '~0' and '~1'
respectively, when appearing in a reference token.
Its ABNF syntax is: Its ABNF syntax is:
json-pointer = *( "/" reference-token ) json-pointer = *( "/" reference-token )
reference-token = *( unescaped / escaped ) reference-token = *( unescaped / escaped )
unescaped = %x00-2E / %x30-7D / %x7F-10FFFF unescaped = %x00-2E / %x30-7D / %x7F-10FFFF
escaped = "~" ( "0" / "1" ) escaped = "~" ( "0" / "1" )
It is an error condition if a JSON Pointer value does not conform to It is an error condition if a JSON Pointer value does not conform to
this syntax (see Section 7). this syntax (see Section 7).
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Evaluation of each reference token begins by decoding any escaped Evaluation of each reference token begins by decoding any escaped
character sequence; this is performed by first transforming any character sequence; this is performed by first transforming any
occurrence of the sequence '~1' to '/', then transforming any occurrence of the sequence '~1' to '/', then transforming any
occurrence of the sequence '~0' to '~'. occurrence of the sequence '~0' to '~'.
The reference token then modifies which value is referenced according The reference token then modifies which value is referenced according
to the following scheme: to the following scheme:
If the currently referenced value is a JSON object, the new If the currently referenced value is a JSON object, the new
referenced value is the object member with the name (after referenced value is the object member with the name identified by
unescaping any backslash escape sequences that can occur in a JSON the reference token. The member name is equal to the token if it
string) identified by the reference token. The member name is has the same number of Unicode characters as token and their code
equal to the token if it has the same number of Unicode characters points are position-wise equal. If a referenced member name is
as token and their code points are position-wise equal. If a not unique in an object, the member that is referenced is
referenced member name is not unique in an object, the member that undefined, and evaluation fails (see below).
is referenced is undefined, and evaluation fails (see below).
If the currently referenced value is a JSON array, the reference If the currently referenced value is a JSON array, the reference
token MUST contain characters that represent an unsigned base-10 token MUST contain characters that represent an unsigned base-10
integer value (possibly with leading zeros), and the new integer value (possibly with leading zeros), and the new
referenced value is the array element with the zero-based index referenced value is the array element with the zero-based index
identified by the token. identified by the token.
If a reference token is being evaluated against a JSON document, If a reference token is being evaluated against a JSON document,
implementations will evaluate each token against the document's implementations will evaluate each token against the document's
contents, and terminate evaluation with an error condition if it contents, and terminate evaluation with an error condition if it
fails to resolve a concrete value for any of the JSON pointer's fails to resolve a concrete value for any of the JSON pointer's
reference tokens. See Section 7 for details. reference tokens. See Section 7 for details.
5. JSON String Representation 5. JSON String Representation
A JSON Pointer can be represented in a JSON string value. Per A JSON Pointer can be represented in a JSON string value. Per
[RFC4627], section 2.5, all instances of quotation mark '"' (%x22), [RFC4627], Section 2.5, all instances of quotation mark '"' (%x22),
reverse solidus '\' (%x5C) and control (%x00-1F) characters MUST be reverse solidus '\' (%x5C) and control (%x00-1F) characters MUST be
escaped. escaped.
For example, given the JSON document Note that before processing a JSON string as a JSON Pointer,
backslash escape sequences must be unescaped.
For example, given the JSON document
{ {
"foo": ["bar", "baz"], "foo": ["bar", "baz"],
"": 0, "": 0,
"a/b": 1, "a/b": 1,
"c%d": 2, "c%d": 2,
"e^f": 3, "e^f": 3,
"g|h": 4, "g|h": 4,
"i\\j": 5, "i\\j": 5,
"k\"l": 6, "k\"l": 6,
" ": 7, " ": 7,
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"/c%d" 2 "/c%d" 2
"/e^f" 3 "/e^f" 3
"/g|h" 4 "/g|h" 4
"/i\\j" 5 "/i\\j" 5
"/k\"l" 6 "/k\"l" 6
"/ " 7 "/ " 7
"/m~0n" 8 "/m~0n" 8
6. URI Fragment Identifier Representation 6. URI Fragment Identifier Representation
A JSON Pointer can be represented in a URI fragment identifier. by A JSON Pointer can be represented in a URI fragment identifier by
encoding it into octets, using UTF-8 [RFC3629], percent-encoding encoding it into octets, using UTF-8 [RFC3629], percent-encoding
those characters not allowed by the fragment rule in [RFC3986]. those characters not allowed by the fragment rule in [RFC3986].
Note that a given media type needs to nominate JSON Pointer as its Note that a given media type needs to nominate JSON Pointer as its
fragment identifier syntax explicitly (usually, in its registration fragment identifier syntax explicitly (usually, in its registration
[RFC4288]); i.e., just because a document is JSON does not imply that [RFC4288]); i.e., just because a document is JSON does not imply that
JSON Pointer can be used as its fragment identifier syntax. JSON Pointer can be used as its fragment identifier syntax. In
particular, the fragment identifier syntax for application/json is
not JSON Pointer.
Given the same example document as above, the following URI fragment Given the same example document as above, the following URI fragment
identifiers evaluate to the accompanying values: identifiers evaluate to the accompanying values:
# // the whole document # // the whole document
#/foo ["bar", "baz"] #/foo ["bar", "baz"]
#/foo/0 "bar" #/foo/0 "bar"
#/ 0 #/ 0
#/a~1b 1 #/a~1b 1
#/c%25d 2 #/c%25d 2
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<http://www.unicode.org/versions/Unicode6.0.0/>. <http://www.unicode.org/versions/Unicode6.0.0/>.
11.2. Informative References 11.2. Informative References
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and [RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December 2005. Registration Procedures", BCP 13, RFC 4288, December 2005.
Authors' Addresses Authors' Addresses
Paul C. Bryan (editor) Paul C. Bryan (editor)
ForgeRock Salesforce.com
Phone: +1 604 783 1481 Phone: +1 604 783 1481
Email: pbryan@anode.ca Email: pbryan@anode.ca
Kris Zyp Kris Zyp
SitePen (USA) SitePen (USA)
Phone: +1 650 968 8787 Phone: +1 650 968 8787
Email: kris@sitepen.com Email: kris@sitepen.com
Mark Nottingham (editor) Mark Nottingham (editor)
Rackspace
Email: mnot@mnot.net Email: mnot@mnot.net
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