Internet Engineering Task Force P. Bryan, Ed.
Internet-Draft ForgeRock US, Inc.
Intended status: Informational K. Zyp
Expires: April 22, 2012 SitePen (USA)
October 20, 2011
JSON Pointer
draft-pbryan-zyp-json-pointer-01
Abstract
JSON Pointer defines a syntax for identifying a specific value within
a JSON document.
Status of this Memo
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This Internet-Draft will expire on April 22, 2012.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
8. Normative References . . . . . . . . . . . . . . . . . . . . . 4
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
This specification defines JSON Pointer, a syntax for identifying a
specific value within a JSON [RFC4627] text document. The syntax is
intended to be expressed in a JSON string value or the URI fragment
identifier of a resource that has a JSON representation.
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 syntax rules using ABNF [RFC5234]
(Augmented Backus-Naur Form) notation. Additionally, it uses the
following rules from URI syntax [RFC3986]: "unreserved" and "pct-
encoded".
3. Syntax
A JSON Pointer is a sequence of zero or more reference tokens, each
prefixed by a "/" (%x2F) character. Each reference token is a
sequence of unreserved and/or percent-encoded characters, per
[RFC3986].
json-pointer = *( "/" reference-token )
reference-token = *( unreserved / pct-encoded )
Unreserved characters in reference tokens SHOULD be percent-encoded,
per [RFC3986], and MUST be so encoded as "%2F" if the character is
"/" to avoid being interpreted as a reference token prefix.
It is an error condition if a JSON Pointer does not conform to this
syntax.
4. Evaluation
Evaluation begins with a reference to the root value of a JSON text
document, and completes with a reference to some value within the
same document. Each token in the JSON Pointer sequence is evaluated,
changing the referenced value according to the following scheme:
If the currently referenced value is a JSON object, the new
referenced value is the object property with the name identified by
the token. If the currently referenced value is a JSON array, the
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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 concrete JSON text
document, the implementation MAY evaluate each token against the
currently referenced concrete value, and terminate evaluation with an
error condition should a reference token fail to resolve to a
concrete value.
5. Error Handling
In the event of an error condition, evaluation of the JSON Pointer
fails to complete.
6. IANA Considerations
This draft includes no request to IANA.
7. Security Considerations
A pointer is not guaranteed to resolve to a JSON value.
Implementations of JSON Pointer should be aware of this and take
appropriate precautions.
8. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[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.
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" property in the root
object.
http://example.com/example.json#/foo/inner%20object
Resolves to the object value of the "inner object" property 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" property in the "inner object" property in the "foo"
property 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" property in the root object.
Authors' Addresses
Paul C. Bryan (editor)
ForgeRock US, Inc.
201 NE Park Plaza Drive Suite 196
Vancouver, WA 98684
USA
Phone: +1 604 783 1481
Email: paul.bryan@forgerock.com
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Kris Zyp
SitePen (USA)
530 Lytton Avenue
Palo Alto, CA 94301
USA
Phone: +1 650 968 8787
Email: kris@sitepen.com
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