JSON Pointer
draft-pbryan-zyp-json-pointer-00

Abstract

JSON Pointer provides a syntax for identifying a specific node 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 http://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on December 11, 2011.

Copyright Notice

Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

• 1. Introduction
• 2. Conventions
• 3. Syntax
• 4. Evaluation
• 5. Error Handling
• 6. Acknowledgements
• 7. IANA Considerations
• 8. Security Considerations
• 9. References
• 9.1. Normative References
• 9.2. Informative References
• Appendix A. Examples
• Appendix B. Changelog
• Appendix C. Open Issues
• Authors' Addresses

1. Introduction

This Internet-Draft proposes JSON Pointer, a syntax for identifying a specific node within a JSON [RFC4627] document. The syntax is intended to be expressed in a JSON string value or in a URL fragment identifier for a resource with 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].

3. Syntax

A JSON Pointer is a sequence of zero or more property reference tokens, starting with and separated by the "/" (\x2F) character. Each property reference token is a sequence of unreserved characters or escape sequences per [RFC2396].

pointer = "/" 0*1( token *( "/" token ) )
token = 1*<URI unreserved character or escape sequence>
         

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

4. Evaluation

A JSON Pointer is evaluated against a target JSON document and yields a target node. Evaluation begins with the initial target node being the JSON document itself. For each property reference token, a new target node is selected from the current target node.

If the current target node is a JSON object, then the new target is the value of the property with the name identified by the next property reference token. If the current target node is a JSON array, then the new target is the value of the item in the array with the zero-based index identified by the next property reference token (which MUST be a non-negative integer number value).

It is an error condition if a property reference token fails to resolve a value for the current target node. The target node is successively updated for each property reference token until the entire sequence of property reference tokens is evaluated.

Property names SHOULD be URI encoded per [RFC2396]. In particular, any "/" character in a property name MUST be encoded as "%2F" to avoid being interpreted as a property reference token separator.

5. Error Handling

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

6. Acknowledgements

This specification originated from the [JSON Schema] specification.

7. IANA Considerations

This draft includes no request to IANA.

8. Security Considerations

This draft includes no security considerations.

9. References

9.1. Normative References

9.2. Informative References

Appendix A. Examples

For example, for the following JSON representation:

{
    "foo": {
        "anArray": [
            { "prop": 44 }
        ],
        "another prop": {
            "baz": "A string"
        }
    }
}
                 

The following JSON Pointers would be resolved:

JSON Pointer             resolution
-------------------      ----------
/                        self, the root of the resource itself
/foo                     the object referred to by the foo property
/foo/another%20prop      the object referred to by the "another prop"
                         property of the object referred to by the
                         "foo" property
/foo/another%20prop/baz  the string referred to by the value of "baz"
                         property of the "another prop" property of
                         the object referred to by the "foo" property
/foo/anArray/0           the first object in the "anArray" array
             

Appendix B. Changelog

draft-00

• Initial draft.

Appendix C. Open Issues

TBD

Authors' Addresses