Internet Engineering Task Force G. LuffInternet-DraftIntended status: Informational H. Andrews, Ed.Expires: June 11, 2021 B. Hutton, Ed. December 8, 2020Relative JSON Pointersdraft-bhutton-relative-json-pointer-00Abstract JSON Pointer is a syntax for specifying locations in a JSON document, starting from the document root. This document defines an extension to the JSON Pointer syntax, allowing relative locations from within the document.Status of This Memo This Internet-Draft is submitted in full conformance with the provisions ofBCP 78 andBCP 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 athttps://datatracker.ietf.org/drafts/current/. 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 June 11, 2021.Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject toBCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://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 inSection 4.e ofLuff, et al. Expires June 11, 2021 [Page 1]
Internet-Draft Relative JSON Pointers December 2020 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.Table of Contents1. Introduction . . . . . . . . . . . . . . . . . . . . . . . .22. Conventions and Terminology . . . . . . . . . . . . . . . . .23. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . .24. Evaluation . . . . . . . . . . . . . . . . . . . . . . . . .35. JSON String Representation . . . . . . . . . . . . . . . . .45.1. Examples . . . . . . . . . . . . . . . . . . . . . . . .46. Non-use in URI Fragment Identifiers . . . . . . . . . . . . .57. Error Handling . . . . . . . . . . . . . . . . . . . . . . .58. Relationship to JSON Pointer . . . . . . . . . . . . . . . .59. Acknowledgements . . . . . . . . . . . . . . . . . . . . . .610. Security Considerations . . . . . . . . . . . . . . . . . . .611. References . . . . . . . . . . . . . . . . . . . . . . . . .611.1. Normative References . . . . . . . . . . . . . . . . . .611.2. Informative References . . . . . . . . . . . . . . . . .6Appendix A. ChangeLog . . . . . . . . . . . . . . . . . . . . .7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . .71. Introduction JSON Pointer (RFC 6901 [RFC6901]) is a syntax for specifying locations in a JSON document, starting from the document root. This document defines a related syntax allowing identification of relative locations from within the document.2. Conventions and Terminology 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 inRFC 2119 [RFC2119].3. Syntax A Relative JSON Pointer is a Unicode string in UTF-8 encoding (seeRFC 8259, Section 8 [RFC8259]), comprising a non-negative integer, followed by either a '#' (%x23) character or a JSON Pointer (RFC 6901 [RFC6901]). The separation between the integer prefix and the JSON Pointer will always be unambiguous, because a JSON Pointer must be either zero- length or start with a '/' (%x2F). Similarly, a JSON Pointer will never be ambiguous with the '#'.Luff, et al. Expires June 11, 2021 [Page 2]
Internet-Draft Relative JSON Pointers December 2020 The ABNF syntax of a Relative JSON Pointer is: relative-json-pointer = non-negative-integer [index-manipulation] <json-pointer> relative-json-pointer =/ non-negative-integer "#" index-manipulation = ("+" / "-") non-negative-integer non-negative-integer = %x30 / %x31-39 *( %x30-39 ) ; "0", or digits without a leading "0" where <json-pointer> follows the production defined inRFC 6901, Section 3 [RFC6901] ("Syntax").4. Evaluation Evaluation of a Relative JSON Pointer begins with a reference to a value within a JSON document, and completes with either a value within that document, a string corresponding to an object member, or integer value representing an array index. Evaluation begins by processing the non-negative-integer prefix. This can be found by taking the longest continuous sequence of decimal digits available, starting from the beginning of the string, taking the decimal numerical value. If this value is more than zero, then the following steps are repeated that number of times: If the current referenced value is the root of the document, then evaluation fails (see below). If the referenced value is an item within an array, then the new referenced value is that array. If the referenced value is an object member within an object, then the new referenced value is that object. If the next character is a plus ("+") or minus ("-"), followed by another continuous sequence of decimal digits, the following steps are taken using the decimal numeric value of that plus or minus sign and decimal sequence: If the current referenced value is not an item of an array, then evaluation fails (see below). If the referenced value is an item of an array, then the new referenced value is the item of the array indexed by adding the decimal value (which may be negative), to the index of the current referenced value.Luff, et al. Expires June 11, 2021 [Page 3]
Internet-Draft Relative JSON Pointers December 2020 If the remainder of the Relative JSON Pointer is a JSON Pointer, then evaluation proceeds as perRFC 6901, Section 5 [RFC6901] with the modification that the initial reference being used is the reference currently being held (which may not be root of the document). Otherwise (when the remainder of the Relative JSON Pointer is the character '#'), the final result is determined as follows: If the current referenced value is the root of the document, then evaluation fails (see below). If the referenced value is an item within an array, then the final evaluation result is the value's index position within the array. If the referenced value is an object member within an object, then the new referenced value is the corresponding member name.5. JSON String Representation The concerns surrounding JSON String representation of a Relative JSON Pointer are identical to those laid out inRFC 6901, Section 5 [RFC6901].5.1. Examples For example, given the JSON document: { "foo": ["bar", "baz"], "highly": { "nested": { "objects": true } } }Luff, et al. Expires June 11, 2021 [Page 4]
Internet-Draft Relative JSON Pointers December 2020 Starting from the value "baz" (inside "foo"), the following JSON strings evaluate to the accompanying values: "0" "baz" "1/0" "bar" "0-1" "bar" "2/highly/nested/objects" true "0#" 1 "0-1#" 0 "1#" "foo" Starting from the value {"objects":true} (corresponding to the member key "nested"), the following JSON strings evaluate to the accompanying values: "0/objects" true "1/nested/objects" true "2/foo/0" "bar" "0#" "nested" "1#" "highly"6. Non-use in URI Fragment Identifiers Unlike a JSON Pointer, a Relative JSON Pointer can not be used in a URI fragment identifier. Such fragments specify exact positions within a document, and therefore Relative JSON Pointers are not suitable.7. Error Handling In the event of an error condition, evaluation of the JSON Pointer fails to complete. Evaluation may fail due to invalid syntax, or referencing a non- existent value. This specification does not define how errors are handled. An application of JSON Relative Pointer SHOULD specify the impact and handling of each type of error.8. Relationship to JSON Pointer Relative JSON Pointers are intended as a companion to JSON Pointers. Applications MUST specify the use of each syntax separately. Defining either JSON Pointer or Relative JSON Pointer as anLuff, et al. Expires June 11, 2021 [Page 5]
Internet-Draft Relative JSON Pointers December 2020 acceptable syntax does not imply that the other syntax is also acceptable.9. Acknowledgements The language and structure of this specification are based heavily on [RFC6901], sometimes quoting it outright. This draft remains primarily as written and published by Geraint Luff, with only minor subsequent alterations under new editorship.10. Security Considerations Evaluation of a given Relative JSON Pointer is not guaranteed to reference an actual JSON value. Applications using Relative JSON Pointer should anticipate this situation by defining how a pointer that does not resolve ought to be handled. As part of processing, a composite data structure may be assembled from multiple JSON documents (in part or in full). In such cases, applications SHOULD ensure that a Relative JSON Pointer does not evaluate to a value outside the document for which is was written. Note that JSON pointers can contain the NUL (Unicode U+0000) character. Care is needed not to misinterpret this character in programming languages that use NUL to mark the end of a string.11. References11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels",BCP 14,RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. [RFC6901] Bryan, P., Ed., Zyp, K., and M. Nottingham, Ed., "JavaScript Object Notation (JSON) Pointer",RFC 6901, DOI 10.17487/RFC6901, April 2013, <https://www.rfc-editor.org/info/rfc6901>.11.2. Informative References [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90,RFC 8259, DOI 10.17487/RFC8259, December 2017, <https://www.rfc-editor.org/info/rfc8259>.Luff, et al. Expires June 11, 2021 [Page 6]
Internet-Draft Relative JSON Pointers December 2020Appendix A. ChangeLog [[CREF1: This section to be removed before leaving Internet-Draft status.]]draft-bhutton-relative-json-pointer-00 * Add array forward and backward index manipulationdraft-handrews-relative-json-pointer-02 * Update to the latest JSON RFCdraft-handrews-relative-json-pointer-01 * The initial number is "non-negative", not "positive"draft-handrews-relative-json-pointer-00 * Revived draft with identical wording and structure. * Clarified how to use alongside JSON Pointer.draft-luff-relative-json-pointer-00 * Initial draft.Authors' Addresses Geraint Luff Cambridge UK EMail: luffgd@gmail.com Henry Andrews (editor) EMail: andrews_henry@yahoo.com Ben Hutton (editor) EMail: ben@jsonschema.dev URI:https://jsonschema.devLuff, et al. Expires June 11, 2021 [Page 7]
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| Document | Document type | Replaced Internet-Draft (individual) Expired & archived This document is an Internet-Draft (I-D). Anyone may submit an I-D to the IETF. This I-D isnot endorsed by the IETF and hasno formal standing in theIETF standards process. | |
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| Authors | Geraint Luff,Henry Andrews,Ben Hutton Email authors | ||
| Replaces | draft-handrews-relative-json-pointer | ||
| Replaced by | draft-hha-relative-json-pointer | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
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