Applications Area Working Group P. Bryan, Ed.
Internet-Draft ForgeRock
Intended status: Informational K. Zyp
Expires: January 02, 2013 SitePen (USA)
M. Nottingham, Ed.
July 03, 2012

JSON Pointer


JSON Pointer defines a string syntax for identifying a specific value within a JSON document.

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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on January 02, 2013.

Copyright Notice

Copyright (c) 2012 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 ( in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

Table of Contents

1. Introduction

This specification defines JSON Pointer, a string syntax for identifying a specific value within a JavaScript Object Notation (JSON) [RFC4627] document. It is intended to be easily expressed in JSON string values and Uniform Resource Identifier (URI) [RFC3986] fragment identifiers.

2. 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].

This specification expresses normative syntax rules using Augmented Backus-Naur Form [RFC5234] (ABNF) notation.

3. Syntax

A JSON Pointer is a [Unicode] string containing a sequence of zero or more reference tokens, each prefixed by a '/' (%x2F) character.

If a reference token contains '~' (%x7E) or '/' (%x2F) characters, they MUST be encoded as '~0' and '~1' respectively.

ABNF syntax:

json-pointer = *( "/" reference-token )
reference-token = *( unescaped / escaped )
unescaped = %x00-2E / %x30-7D / %x7F-10FFFF
escaped = "~" ( "0" / "1" )

It is an error condition if a JSON Pointer value does not conform to this syntax (see Section 7).

4. Evaluation

Evaluation of a JSON Pointer begins with a reference to the root value of a JSON text document and completes with a reference to some value within the document. Each reference token in the JSON Pointer is sequentially evaluated.

Evaluation of each reference token begins by decoding any escaped character sequence; this is performed by first transforming any occurrence of the sequence '~1' to '/', then transforming any occurrence of the sequence '~0' to '~'.

The reference token then modifies which value is referenced according to the following scheme:

If a reference token is being evaluated against a JSON document, the implementation MAY evaluate each token against a concrete value, and terminate evaluation with an error condition if a evaluation fails to resolve a concrete value (see Section 7).

5. JSON String Representation

A JSON Pointer can be represented in a JSON string value. Per [RFC4627], section 2.5, all instances of quotation mark '"' (%x22), reverse solidus '\' (%x5C) and control (%x00-1F) characters MUST be escaped.

For example, given the JSON document

   "foo": ["bar", "baz"],
   "": 0
   "a/b": 1,
   "c%d": 2,
   "e^f": 3,
   "g|h": 4,
   "i\\j": 5,
   "k\"l": 6,
   " ": 7,
   "m~n": 8

Then the following JSON strings evaluate to the accompanying values:

 ""         // the whole document
 "/foo"       ["bar", "baz"]
 "/foo/0"    "bar"
 "/"          0
 "/a~1b"      1
 "/c%d"       2
 "/e^f"       3
 "/g|h"       4
 "/i\\j"      5
 "/k\"l"      6
 " "          7
 "m~0n"       8

6. URI Fragment Identifier Representation

A JSON Pointer can be represented in a URI fragment identifier. by encoding it into octets, using UTF-8 [RFC3629], percent-encoding those characters not allowed by the fragment rule in [RFC3986].

Given the same example document as above, the following URI fragment identifiers evaluate to the accompanying values:

 #                  // the whole document
 #/foo            ["bar", "baz"]
 #/foo/0         "bar"
 #/               0
 #/a~1b           1
 #/c%25d          2
 #/e%5Ef          3
 #/g%7Ch          4
 #/i%5Cj          5
 #/k%22l          6
 #/%20            7
 #/m~0n           8

7. Error Handling

In the event of an error condition, evaluation of the JSON Pointer fails to complete.

This includes, but is not limited to:

This specification does not define how errors are handled; an application of JSON Pointer SHOULD specify the impact and handling of each type of error.

For example, some applications might stop pointer processing upon an error; others may attempt to recover from missing values by inserting default ones.

8. IANA Considerations


9. Security Considerations

A given JSON Pointer is not guaranteed to reference an actual JSON value. Implementations should be aware of this and take appropriate precautions.

Note that JSON pointers can contain the NUL (Unicode U+0000) character, which may not be representable in all programming languages.

10. Acknowledgements

The following individuals contributed ideas, feedback and wording to this specification:

11. References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, November 2003.
[RFC3986] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005.
[RFC4627] Crockford, D., "The application/json Media Type for JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008.
[Unicode] The Unicode Consortium, "The Unicode Standard, Version 6.0", October 2011.

Authors' Addresses

Paul C. Bryan editor ForgeRock Phone: +1 604 783 1481 EMail:
Kris Zyp SitePen (USA) Phone: +1 650 968 8787 EMail:
Mark Nottingham editor Rackspace EMail: