Internet Engineering Task Force P. Bryan, Ed.
Internet-Draft ForgeRock US, Inc.
Intended status: Informational June 9, 2011
Expires: December 11, 2011
A JSON Media Type for Describing Partial Modifications to JSON Documents
draft-pbryan-json-patch-01
Abstract
JSON (JavaScript Object Notation) Patch defines the media type
"application/patch+json", a JSON-based document structure for
specifying partial modifications 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.
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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.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivations . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Patch Object Structure . . . . . . . . . . . . . . . . . . . . 3
5. Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5.1. add . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.2. remove . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.3. replace . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
9. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . . 5
10.2. Informative References . . . . . . . . . . . . . . . . . . 5
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . . 5
A.1. Adding an Object Property . . . . . . . . . . . . . . . . . 6
A.2. Adding an Array Element . . . . . . . . . . . . . . . . . . 6
A.3. Removing an Object Property . . . . . . . . . . . . . . . . 6
A.4. Removing an Array Element . . . . . . . . . . . . . . . . . 7
A.5. Replacing a Value . . . . . . . . . . . . . . . . . . . . . 7
Appendix B. Changelog . . . . . . . . . . . . . . . . . . . . . . 8
Appendix C. Open Issues . . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
This Internet-Draft proposes the JSON-Patch media type "application/
patch+json", a JSON structure for specifying partial modifications to
apply to a JSON document.
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. Motivations
JavaScript Object Notation (JSON) [RFC4627] is a popular format for
the storage and transmission of structured data. As a result,
numerous web service APIs support the JSON media type.
The HTTP PATCH [RFC5789] specification extends HTTP with a new method
to perform partial modifications to resources. A JSON-based patch
document type is required to modify JSON documents using this method.
4. Patch Object Structure
A JSON Patch document is a JSON document that contains an array of
objects. Each object contains a patch operation to apply to a target
JSON document.
A sample JSON Patch document:
[
{ "remove": "/a/b/c" },
{ "add": "/a/b/c", "value": "foo" },
{ "replace": "/a/b/c", "value": "bar" }
]
Patch operations are applied sequentially in the order they appear in
the array. After a patch operation has been applied, the resulting
JSON document becomes the target for the next patch operation. This
process repeats until all patches are successfully applied.
5. Operations
Operations are specified in the name of a property in the patch
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operation object, with that property's value being a string
containing the [JSON Pointer] that references the node to be
affected.
Adds a new value into an object or array. The value to be added to
the object or array is specified in the "value" property.
If adding to an object, it is an error condition if the property to
be added in the object already exists.
If adding to an array, any elements at or above the specified index
are shifted one position to the right (i.e. indexes are incremented).
It is an error condition if the addition would result in sparse
allocation of any array elements.
5.2. remove
Removes the value specified by the JSON Pointer value.
If removing an element from an array, any elements above the
specified index are shifted one position to the left (i.e. indexes
are decremented).
It is an error condition if the value to be removed does not exist.
5.3. replace
Replaces the value referenced by the JSON Pointer with a new value.
Syntacically equivalent to performing a "remove" operation, followed
immediately by an "add" operation. The value to be replaced is
specified in the "value" property.
It is an error condition if the value to be replaced does not exist.
6. Error Handling
In the event of an error condition, evaluation of the JSON Patch
document ceases. Enforcing safety and/or idempotency of a JSON Patch
document is specified by and enforced by the implementation.
7. Acknowledgements
The structure of a JSON Patch document was informed by the XML Patch
document [RFC5261] specification.
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8. IANA Considerations
The proposed MIME media type for the JSON Patch document is
"application/patch+json".
Type name: application
Subtype name: patch+json
Required parameters: none
Optional parameters: none
9. Security Considerations
This specification is based on the JSON format, therefore has the
same security considerations as [RFC4627].
10. References
10.1. Normative References
[JSON Pointer]
Bryan, P. and K. Zyp, "JSON Pointer", June 2011, <http://
tools.ietf.org/html/draft-pbryan-zyp-json-pointer-00>.
[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.
10.2. Informative References
[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.
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A.1. Adding an Object Property
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:
[
{ "add": "/foo/1", "value": "qux" }
]
The resulting JSON document:
{
"foo": [ "bar", "qux", "baz" ]
}
A.3. Removing an Object Property
An example target JSON document:
{
"baz": "qux",
"foo": "bar"
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}
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:
{
"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" }
]
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}
The resulting JSON document:
{
"baz": "boo",
"foo": "bar"
}
Draft 00
o Initial draft.
Draft 01
o Switched from JSONPath to JSON Pointer to reference nodes.
o Removed "op"; property name now contains operation to perform.
o Removed "element"; JSON Pointer now contains target node.
o Added "replace" operation to decrease operation verbosity.
Interest has been expressed in conforming to a uniform PUT/DELETE
interface, and providing for idempotent and non-idempotent operations
within the patch document format.
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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