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Versions: 00 01 02 03 04 draft-ietf-appsawg-json-patch

Internet Engineering Task Force                            P. Bryan, Ed.
Internet-Draft                                        ForgeRock US, Inc.
Intended status: Informational                          December 4, 2011
Expires: June 6, 2012


                               JSON Patch
                       draft-pbryan-json-patch-04

Abstract

   JSON Patch defines the media type "application/json-patch", a JSON
   document structure for expressing a sequence of operations to apply
   to 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/.

   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 6, 2012.

Copyright Notice

   Copyright (c) 2011 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.  Document Structure . . . . . . . . . . . . . . . . . . . . . .  3
   4.  Operations . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     4.1.  add  . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     4.2.  remove . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     4.3.  replace  . . . . . . . . . . . . . . . . . . . . . . . . .  4
     4.4.  move . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     4.5.  test . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   5.  Error Handling . . . . . . . . . . . . . . . . . . . . . . . .  6
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  6
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  7
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  7
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     9.1.  Normative References . . . . . . . . . . . . . . . . . . .  7
     9.2.  Informative References . . . . . . . . . . . . . . . . . .  8
   Appendix A.  Examples  . . . . . . . . . . . . . . . . . . . . . .  8
     A.1.  Adding an Object Member  . . . . . . . . . . . . . . . . .  8
     A.2.  Adding an Array Element  . . . . . . . . . . . . . . . . .  8
     A.3.  Removing an Object Member  . . . . . . . . . . . . . . . .  9
     A.4.  Removing an Array Element  . . . . . . . . . . . . . . . .  9
     A.5.  Replacing a Value  . . . . . . . . . . . . . . . . . . . . 10
     A.6.  Moving a Value . . . . . . . . . . . . . . . . . . . . . . 10
     A.7.  Moving an Array Element  . . . . . . . . . . . . . . . . . 11
     A.8.  Testing a Value: Success . . . . . . . . . . . . . . . . . 11
     A.9.  Testing a Value: Error . . . . . . . . . . . . . . . . . . 12
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12






















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1.  Introduction

   JavaScript Object Notation (JSON) [RFC4627] is a common format for
   the exchange and storage of structured data.  HTTP PATCH [RFC5789]
   extends HTTP [RFC2616] with a method to perform partial modifications
   to resources.

   The JSON Patch media type "application/json-patch" is a JSON document
   structure for expressing a sequence of operations to apply to a
   target JSON document, suitable for use with the HTTP PATCH method.


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 RFC 2119 [RFC2119].


3.  Document Structure

   A JSON Patch document contains a JSON array of objects.  Each object
   contains a single operation to apply to the target JSON document.

   An example JSON Patch document:

   [
       { "test": "/a/b/c", value: "foo" },
       { "remove": "/a/b/c" },
       { "add": "/a/b/c", "value": [ "foo", "bar" ] },
       { "replace": "/a/b/c", "value": 42 },
       { "move": "/a/b/c", to: "/a/b/d" }
   ]

   Evaluation of a JSON Patch document begins with a target JSON
   document.  Operations are applied sequentially in the order they
   appear in the array.  Each operation in the sequence is applied to
   the target document; the resulting document becomes the target of the
   next operation.  Evaluation continues until all operations are
   successfully applied or an error condition is encountered.


4.  Operations

   The operation to apply is expressed in a member of the operation
   object.  The name of the operation member is one of: "add", "remove",
   "replace", "move" or "test".  The member value is a string containing
   a [JSON Pointer], which references the location in the target



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   document to apply the operation.  It is an error condition if an
   operation object contains no operation member, or more than one
   operation member.

4.1.  add

   The "add" operation adds a new value to the target document at the
   specified location.  The location must reference one of: the root of
   the target document, a member to add to an existing object, or an
   element to add to an existing array.  The operation object contains a
   "value" member, which specifies the value to be added.

   Example:

       { "add": "/a/b/c", "value": [ "foo", "bar" ] }

   If the location references the root of the target document or a
   member of an existing object, it is an error condition if a value at
   the specified location already exists.

   If the location references an element of an existing array, any
   elements at or above the specified index are shifted one position to
   the right.  It is an error condition if the specified index is
   greater than the number of elements in the array.

4.2.  remove

   The "remove" operation removes the value in the target document at
   the specified location.

   Example:

       { "remove": "/a/b/c" }

   If removing an element from an array, any elements above the
   specified index are shifted one position to the left.

   It is an error condition if a value at the specified location does
   not exist.

4.3.  replace

   The "replace" operation replaces the value in the target document at
   the specified location with a new value.  The operation object
   contains a "value" member, which specifies the replacement value.






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   Example:

       { "replace": "/a/b/c", "value": 42 }

   This operation is identical to expressing a "remove" operation for a
   value, followed immediately by an "add" operation at the same
   location with the replacement value.

   It is an error condition if a value at the specified location does
   not exist.

4.4.  move

   The "move" operation removes the value at one location and adds it to
   another location in the target document.

   The operation object contains a "to" member, a string containing a
   JSON Pointer which references the location in the target document to
   move the value to.  This location must reference one of: the member
   to add to an existing object, or an element to add to an existing
   array.

   Example:

       { "move": "/a/b/c", to: "/a/b/d" }

   This operation is identical to expressing a "remove" operation,
   followed immediately by an "add" operation at the new location with
   the value that was just removed.

   If the location in the "to" member references a member of an existing
   object in the target document, it is an error condition if a value at
   the specified location already exists.

   If the location in the "to" member references an element of an
   existing array, any elements at or above the specified index are
   shifted one position to the right.  It is an error condition if the
   specified index is greater than the number of elements in the array.

4.5.  test

   The "test" operation tests that a value in the target document at the
   specified location is equal to a specified value.  The operation
   object contains a "value" member, which specifies the value to test
   for.






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   Example:

       { "test": "/a/b/c", value: "foo" }

   It is an error condition if the value in the target document is not
   equal to the specified value.


5.  Error Handling

   If an error condition occurs, evaluation of the JSON Patch document
   SHOULD terminate and application of the entire patch document SHALL
   NOT be deemed successful.


6.  IANA Considerations

   The Internet media type for a JSON Patch document is application/
   json-patch.

   Type name:  application

   Subtype name:  json-patch

   Required parameters:  none

   Optional parameters:   none

   Encoding considerations:
      Per JSON [RFC4627]: 8bit if UTF-8; binary if UTF-16 or UTF-32.

   Security considerations:
      See Security Considerations in section 7.

   Interoperability considerations:  N/A

   Published specification:
      draft-pbryan-json-patch-04

   Applications that use this media type:
      Applications that manipulate JSON documents.

   Additional information:

      Magic number(s):  N/A






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      File extension(s):  .json-patch

      Macintosh file type code(s):  TEXT

   Person & email address to contact for further information:
      Paul C. Bryan <paul.bryan@forgerock.com>

   Intended usage:  COMMON

   Restrictions on usage:  none

   Author:  Paul C. Bryan <paul.bryan@forgerock.com>

   Change controller:  Paul C. Bryan <paul.bryan@forgerock.com>


7.  Security Considerations

   This specification has the same security considerations as JSON
   [RFC4627] and JSON Pointer [JSON Pointer].


8.  Acknowledgements

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

      Mike Amundsen, Paul Davis, Dean Landolt, Randall Leeds, Mark
      Nottingham, Julian Reschke, Eli Stevens.

   The structure of a JSON Patch document was initially informed by the
   XML Patch document [RFC5261] specification.


9.  References

9.1.  Normative References

   [JSON Pointer]
              Bryan, P. and K. Zyp, "JSON Pointer", October 2011, <http:
              //tools.ietf.org/html/draft-pbryan-zyp-json-pointer-02>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627, July 2006.




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9.2.  Informative References

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC5261]  Urpalainen, J., "An Extensible Markup Language (XML) Patch
              Operations Framework Utilizing XML Path Language (XPath)
              Selectors", RFC 5261, September 2008.

   [RFC5789]  Dusseault, L. and J. Snell, "PATCH Method for HTTP",
              RFC 5789, March 2010.


Appendix A.  Examples

A.1.  Adding an Object Member

   An example target JSON document:

   {
       "foo": "bar"
   }

   A JSON Patch document:

   [
       { "add": "/baz", "value": "qux" }
   ]

   The resulting JSON document:

   {
       "baz": "qux",
       "foo": "bar"
   }

A.2.  Adding an Array Element

   An example target JSON document:

   {
       "foo": [ "bar", "baz" ]
   }

   A JSON Patch document:





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   [
       { "add": "/foo/1", "value": "qux" }
   ]

   The resulting JSON document:

   {
       "foo": [ "bar", "qux", "baz" ]
   }

A.3.  Removing an Object Member

   An example target JSON document:

   {
       "baz": "qux",
       "foo": "bar"
   }

   A JSON Patch document:

   [
       { "remove": "/baz" }
   ]

   The resulting JSON document:

   {
       "foo": "bar"
   }

A.4.  Removing an Array Element

   An example target JSON document:

   {
       "foo": [ "bar", "qux", "baz" ]
   }

   A JSON Patch document:

   [
       { "remove": "/foo/1" }
   ]

   The resulting JSON document:





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   {
       "foo": ["bar", "baz"]
   }

A.5.  Replacing a Value

   An example target JSON document:

   {
       "baz": "qux",
       "foo": "bar"
   }

   A JSON Patch document:

   [
         { "replace": "/baz", "value": "boo" }
   ]

   The resulting JSON document:

   {
       "baz": "boo",
       "foo": "bar"
   }

A.6.  Moving a Value

   An example target JSON document:

   {
       "foo": {
           "bar": "baz",
           "waldo": "fred"
       }
       "qux": {
           "corge": "grault"
       }
   }

   A JSON Patch document:

   [
       { "move": "/foo/waldo", to: "/qux/thud" }
   ]

   The resulting JSON document:




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   {
       "foo": {
           "bar": "baz"
       }
       "qux": {
           "corge": "grault",
           "thud": "fred"
       }
   }

A.7.  Moving an Array Element

   An example target JSON document:

   {
       "foo": [ "all", "grass", "cows", "eat" ]
   }

   A JSON Patch document:

   [
       { "move": "/foo/1", "to": "/foo/3" }
   ]

   The resulting JSON document:

   {
       "foo": [ "all", "cows", "eat", "grass" ]
   }

A.8.  Testing a Value: Success

   An example target JSON document:

   {
       "baz": "qux",
       "foo": [ "a", 2, "c" ]
   }

   A JSON Patch document, which will result in successful evaluation:

   [
       { "test": "/baz", "value": "qux" },
       { "test": "/foo/1", "value": 2 }
   ]






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A.9.  Testing a Value: Error

   An example target JSON document:

   {
       "baz": "qux",
   }

   A JSON Patch document, which will result in an error condition:

   [
       { "test": "/baz", "value": "bar" }
   ]


Author's Address

   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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