One document matched: draft-richer-oauth-xml-00.txt
Network Working Group J. Richer, Ed.
Internet-Draft The MITRE Corporation
Intended status: Experimental November 7, 2010
Expires: May 11, 2011
XML Encoding for OAuth 2
draft-richer-oauth-xml-00
Abstract
This document describes a method of translating JSON structured
values to XML structured values in the context of the OAuth 2
protocol.
Requirements Language
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].
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 May 11, 2011.
Copyright Notice
Copyright (c) 2010 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
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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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Objects and Members . . . . . . . . . . . . . . . . . . . . 3
3.2. Root Element . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Type Identifiers . . . . . . . . . . . . . . . . . . . . . 4
3.4. Strings and Numbers . . . . . . . . . . . . . . . . . . . . 4
3.5. Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.6. Namespace . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.7. Information Loss . . . . . . . . . . . . . . . . . . . . . 4
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Standard OAuth Token . . . . . . . . . . . . . . . . . . . 5
4.2. Extensions . . . . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
8. Normative References . . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
The OAuth 2 Protocol [I-D.ietf-oauth-v2] makes use of JSON [RFC4627]
encoding for its structured return values, as defined by section 4.2
of the OAuth specification. However, JSON encoding is not always
desirable, particularly when OAuth is being used as part of an XML
[W3C.CR-xml11-20021015] API.
This extension describes a means for the client to request a
particular format and a method for the token endpoint to encode its
return values as XML documents as opposed to the default JSON
objects.
2. Transport
To select XML encoding, the client sends the following OPTIONAL
parameter
format
OPTIONAL. The format parameter specifies the client's desired
format for responses from the token endpoint. Valid values are
"json" and "xml", though other extensions MAY define other
valid values. If omitted, the parameter value defaults to
"json" and behavior is as defined in OAuth 2
[I-D.ietf-oauth-v2].
The server SHALL respond to a valid access grant containing an XML
format request with an HTTP 200 response and content type of
"application/xml".
3. Encoding
This section defines encodings for different parts of the JSON data
model in XML equivalents.
3.1. Objects and Members
JSON objects SHALL be encoded by using XML Elements. The object
itself SHALL be represented by the root elment of an XML subtree.
All members of the object SHALL be represented by sub-elements of the
root element. The key of the member pair SHALL be the node name of
the XML Element, and the value of the member pair SHALL be encoded as
the content of the XML Element. The root element of the overall JSON
object
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3.2. Root Element
The token endpoint SHALL use the root element with a node name
"oauth" to represent the anonymous root JSON object specified in the
OAuth specification.
3.3. Type Identifiers
All elements MAY have an OPTIONAL "type" attribute, which has a valid
value of "object", "string", "number", or "array". These attributes
can be used to differentiate between otherwise potentially ambiguous
encodings (Section 3.7), though the most common cases will not need
them.
3.4. Strings and Numbers
Strings and numbers SHALL be encoded as CDATA within their enclosing
element. These values MUST be properly escaped XML CDATA, and MAY be
represented using <[CDATA[ ... ]]> encoding.
3.5. Arrays
Arrays SHALL be represented using repeated, sibling XML Element nodes
(nodes with the same node name). The order of the array is encoded
using document order of the array elements.
3.6. Namespace
This extension does not define a required namespace for the OAuth XML
encoding.
3.7. Information Loss
This encoding scheme is intended to give a clear an intuitive mapping
between OAuth and XML data structures. However, the mapping between
the two formats is not exact and some information loss may occur, and
round-trip translation between the two formats MUST NOT be depended
upon.
1. Both strings and numbers (Section 3.4) in JSON are represented as
CDATA in XML. Without type identifiers (Section 3.3) there is no
clear way to differentiate between the two in the XML encoding.
2. Arrays (Section 3.5) in JSON are represented by repeated elements
in XML. There is therefore no reliable way to distinguish
between a single-element array and a standalone string or number
value in the XML encoding, as both would be encoded the same way.
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4. Examples
Below are examples of encoding different OAuth JSON objects with XML.
4.1. Standard OAuth Token
A standard OAuth JSON-encoded token response:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
{
"access_token":"SlAV32hkKG",
"expires_in":3600,
"refresh_token":"8xLOxBtZp8"
}
Can be encoded in as the following XML response document:
HTTP/1.1 200 OK
Content-Type: application/xml
Cache-Control: no-store
<oauth>
<access_token>SlAV32hkKG</access_token>
<expires_in>3600</expires_in>
<refresh_token>8xLOxBtZp8</refresh_token>
</oauth>
Or, with optional type attributes (Section 3.3) in place:
HTTP/1.1 200 OK
Content-Type: application/xml
Cache-Control: no-store
<oauth type="object">
<access_token type="string">SlAV32hkKG</access_token>
<expires_in type="number">3600</expires_in>
<refresh_token type="string">8xLOxBtZp8</refresh_token>
</oauth>
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4.2. Extensions
Extensions to the OAuth protocol MAY make use of JSON's extensible
data representation capabilities, including both objects and arrays,
to extend the data returned with the token. Using the encoding rules
(Section 3) recursively, one can represent the same structures in
XML.
This example uses both objects and arrays to support a complicated,
fictional example extension to the OAuth protocol:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
{
"access_token":"SlAV32hkKG",
"expires_in":3600,
"refresh_token":"8xLOxBtZp8",
"ext_value": "extension",
"ext_list": [ 1, 2, "three" ],
"ext_object": {
"member1": "value1",
"memberlist": [ "A", "B", "C"],
"member3": 3,
"memberobj": {
"a": "first",
"b": "second",
"c": "third"
}
}
}
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The above is encoded into XML as follows (without using type
attributes):
HTTP/1.1 200 OK
Content-Type: application/xml
Cache-Control: no-store
<oauth>
<access_token>SlAV32hkKG</access_token>
<expires_in>3600</expires_in>
<refresh_token>8xLOxBtZp8</refresh_token>
<ext_value>extension</ext_value>
<ext_list>1</ext_list>
<ext_list>2</ext_list>
<ext_list>three</ext_list>
<ext_object>
<member1>value1</member>
<memberlist>A</memberlist>
<memberlist>B</memberlist>
<memberlist>C</memberlist>
<member3>3</member3>
<memberobj>
<a>first</a>
<b>second</b>
<c>third</c>
</memberobj>
</ext_object>
</oauth>
5. IANA Considerations
This document makes no request of IANA.
6. Security Considerations
There are no additional security considerations.
7. Acknowledgements
Thanks to Eve Maler, Joseph Holsten, and the OAuth Working Group for
feedback.
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8. Normative References
[I-D.ietf-oauth-v2]
Hammer-Lahav, E., Recordon, D., and D. Hardt, "The OAuth
2.0 Protocol", draft-ietf-oauth-v2-10 (work in progress),
July 2010.
[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.
[W3C.CR-xml11-20021015]
Cowan, J., "Extensible Markup Language (XML) 1.1", W3C
CR CR-xml11-20021015, October 2002.
Author's Address
Justin Richer (editor)
The MITRE Corporation
Email: jricher@mitre.org
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