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Versions: (draft-pbryan-zyp-json-pointer) 00 01 02 03 04 05 06 07 08 09 RFC 6901

Applications Area Working Group                            P. Bryan, Ed.
Internet-Draft                                                 ForgeRock
Intended status: Informational                                    K. Zyp
Expires: September 10, 2012                                SitePen (USA)
                                                           March 9, 2012


                              JSON Pointer
                   draft-ietf-appsawg-json-pointer-01

Abstract

   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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   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 September 10, 2012.

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
   (http://trustee.ietf.org/license-info) 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.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Syntax  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   4.  Evaluation  . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   5.  JSON String Representation  . . . . . . . . . . . . . . . . . . 4
   6.  URI Fragment Identifier Representation  . . . . . . . . . . . . 4
   7.  Error Handling  . . . . . . . . . . . . . . . . . . . . . . . . 4
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   9.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   11. Normative References  . . . . . . . . . . . . . . . . . . . . . 5
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . . . 5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 6




































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1.  Introduction

   This specification defines JSON Pointer, a string syntax for
   identifying a specific value within a JavaScript Object Notation
   (JSON) [RFC4627] text document.  This syntax 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 '/' (%x2F) or '^' (%x5E) characters,
   such characters MUST each be prefixed (escaped) with a '^' (%x5E)
   character.

   ABNF syntax:

   json-pointer = *( "/" reference-token )
   reference-token = *( unescaped / escaped )
   unescaped = %x00-2E / %x30-5B / %x5D-10FFFF
   escaped = "^" ( "/" / "^" )

   It is an error condition if a JSON Pointer value does not conform to
   this syntax.


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 unescaping any escaped
   character sequence; this is performed by removing the '^' (escape)



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

      If the currently referenced value is a JSON object, the new
      referenced value is the object member with the name identified by
      the reference token.  The member name is equal to the token if it
      has the same number of Unicode characters as token and their
      codepoints are positionwise equal.  If a referenced member name is
      not unique in an object, the member that is referenced is
      undefined.

      If the currently referenced value is a JSON array, the reference
      token MUST contain characters that represent an unsigned base-10
      integer value, and the new referenced value is the array element
      with the zero-based index identified by the token.

   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.


5.  JSON String Representation

   A JSON Pointer MAY 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.


6.  URI Fragment Identifier Representation

   A JSON Pointer MAY be represented in a URI fragment identifier.  The
   JSON pointer MUST be UTF-8 [RFC3629] encoded as octets; octets not in
   the URI "unreserved" set SHOULD be percent-encoded, per [RFC3986],
   section 2.5.


7.  Error Handling

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


8.  IANA Considerations

   This document has no IANA actions.




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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.


10.  Acknowledgements

   The following individuals contributed ideas, feedback and wording,
   which contributed to the content of this specification:

      Mike Acar, Carsten Bormann, Tim Bray, Jacob Davies, Martin J.
      Duerst, Bjoern Hoehrmann, James H. Manger, Mark Nottingham, Drew
      Perttula, Julian Reschke.


11.  Normative 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,
              <http://www.unicode.org/versions/Unicode6.0.0/>.


Appendix A.  Examples










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   The following examples illustrate the use of JSON Pointers in URI
   fragments for a JSON text document located at
   http://example.com/example.json, with the following value:

   {
       "foo": {
           "bar": [ "element0", "element1" ],
           "inner object": {
               "baz": "qux"
       }
   }

   http://example.com/example.json#
      Resolves to the object value at the root of the JSON text
      document.

   http://example.com/example.json#/foo
      Resolves to the object value of the "foo" member in the root
      object.

   http://example.com/example.json#/foo/inner%20object
      Resolves to the object value of the "inner object" member in the
      "foo" object value in the root object.

   http://example.com/example.json#/foo/inner%20object/baz
      Resolves to the string value "qux", which is the value of the
      "baz" member in the "inner object" member in the "foo" member in
      the root object.

   http://example.com/example.json#/foo/bar/0
      Resolves to the string value "element0", which is the first value
      in the "bar" array in the "foo" member in the root object.


Authors' Addresses

   Paul C. Bryan (editor)
   ForgeRock

   Phone: +1 604 783 1481
   Email: pbryan@anode.ca










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   Kris Zyp
   SitePen (USA)

   Phone: +1 650 968 8787
   Email: kris@sitepen.com














































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