draft-ietf-netmod-yang-json-10.txt		rfc7951.txt
	NETMOD Working Group L. Lhotka		Internet Engineering Task Force (IETF) L. Lhotka
	Internet-Draft CZ.NIC		Request for Comments: 7951 CZ.NIC
	Intended status: Standards Track March 26, 2016		Category: Standards Track August 2016
	Expires: September 27, 2016		ISSN: 2070-1721
	JSON Encoding of Data Modeled with YANG		JSON Encoding of Data Modeled with YANG
	draft-ietf-netmod-yang-json-10
	Abstract		Abstract
	This document defines encoding rules for representing configuration		This document defines encoding rules for representing configuration
	data, state data, parameters of RPC operations or actions, and		data, state data, parameters of Remote Procedure Call (RPC)
	notifications defined using YANG as JavaScript Object Notation (JSON)		operations or actions, and notifications defined using YANG as
	text.		JavaScript Object Notation (JSON) text.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This is an Internet Standards Track document.
	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		This document is a product of the Internet Engineering Task Force
	and may be updated, replaced, or obsoleted by other documents at any		(IETF). It represents the consensus of the IETF community. It has
	time. It is inappropriate to use Internet-Drafts as reference		received public review and has been approved for publication by the
	material or to cite them other than as "work in progress."		Internet Engineering Steering Group (IESG). Further information on
			Internet Standards is available in Section 2 of RFC 7841.
	This Internet-Draft will expire on September 27, 2016.		Information about the current status of this document, any errata,
			and how to provide feedback on it may be obtained at
			http://www.rfc-editor.org/info/rfc7951.
	Copyright Notice		Copyright Notice
	Copyright (c) 2016 IETF Trust and the persons identified as the		Copyright (c) 2016 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 13 ¶		skipping to change at page 2, line 13 ¶
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Terminology and Notation . . . . . . . . . . . . . . . . . . 3		2. Terminology and Notation . . . . . . . . . . . . . . . . . . 3
	3. Properties of the JSON Encoding . . . . . . . . . . . . . . . 4		3. Properties of the JSON Encoding . . . . . . . . . . . . . . . 4
	4. Names and Namespaces . . . . . . . . . . . . . . . . . . . . 5		4. Names and Namespaces . . . . . . . . . . . . . . . . . . . . 5
	5. Encoding of YANG Data Node Instances . . . . . . . . . . . . 7		5. Encoding of YANG Data Node Instances . . . . . . . . . . . . 7
	5.1. The "leaf" Data Node . . . . . . . . . . . . . . . . . . 7		5.1. The "leaf" Data Node . . . . . . . . . . . . . . . . . . 7
	5.2. The "container" Data Node . . . . . . . . . . . . . . . . 7		5.2. The "container" Data Node . . . . . . . . . . . . . . . . 8
	5.3. The "leaf-list" Data Node . . . . . . . . . . . . . . . . 8		5.3. The "leaf-list" Data Node . . . . . . . . . . . . . . . . 8
	5.4. The "list" Data Node . . . . . . . . . . . . . . . . . . 8		5.4. The "list" Data Node . . . . . . . . . . . . . . . . . . 9
	5.5. The "anydata" Data Node . . . . . . . . . . . . . . . . . 9		5.5. The "anydata" Data Node . . . . . . . . . . . . . . . . . 9
	5.6. The "anyxml" Data Node . . . . . . . . . . . . . . . . . 10		5.6. The "anyxml" Data Node . . . . . . . . . . . . . . . . . 10
	5.7. Metadata Objects . . . . . . . . . . . . . . . . . . . . 10		5.7. Metadata Objects . . . . . . . . . . . . . . . . . . . . 11
	6. Representing YANG Data Types in JSON Values . . . . . . . . . 10		6. Representing YANG Data Types in JSON Values . . . . . . . . . 11
	6.1. Numeric Types . . . . . . . . . . . . . . . . . . . . . . 11		6.1. Numeric Types . . . . . . . . . . . . . . . . . . . . . . 11
	6.2. The "string" Type . . . . . . . . . . . . . . . . . . . . 11		6.2. The "string" Type . . . . . . . . . . . . . . . . . . . . 11
	6.3. The "boolean" Type . . . . . . . . . . . . . . . . . . . 11		6.3. The "boolean" Type . . . . . . . . . . . . . . . . . . . 11
	6.4. The "enumeration" Type . . . . . . . . . . . . . . . . . 11		6.4. The "enumeration" Type . . . . . . . . . . . . . . . . . 12
	6.5. The "bits" Type . . . . . . . . . . . . . . . . . . . . . 11		6.5. The "bits" Type . . . . . . . . . . . . . . . . . . . . . 12
	6.6. The "binary" Type . . . . . . . . . . . . . . . . . . . . 12		6.6. The "binary" Type . . . . . . . . . . . . . . . . . . . . 12
	6.7. The "leafref" Type . . . . . . . . . . . . . . . . . . . 12		6.7. The "leafref" Type . . . . . . . . . . . . . . . . . . . 12
	6.8. The "identityref" Type . . . . . . . . . . . . . . . . . 12		6.8. The "identityref" Type . . . . . . . . . . . . . . . . . 12
	6.9. The "empty" Type . . . . . . . . . . . . . . . . . . . . 13		6.9. The "empty" Type . . . . . . . . . . . . . . . . . . . . 13
	6.10. The "union" Type . . . . . . . . . . . . . . . . . . . . 13		6.10. The "union" Type . . . . . . . . . . . . . . . . . . . . 14
	6.11. The "instance-identifier" Type . . . . . . . . . . . . . 14		6.11. The "instance-identifier" Type . . . . . . . . . . . . . 15
	7. I-JSON Compliance . . . . . . . . . . . . . . . . . . . . . . 14		7. I-JSON Compliance . . . . . . . . . . . . . . . . . . . . . . 15
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 15		8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
	9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . 15		9.1. Normative References . . . . . . . . . . . . . . . . . . 16
	10.1. Normative References . . . . . . . . . . . . . . . . . . 16		9.2. Informative References . . . . . . . . . . . . . . . . . 17
	10.2. Informative References . . . . . . . . . . . . . . . . . 16		Appendix A. A Complete Example . . . . . . . . . . . . . . . . . 18
	Appendix A. A Complete Example . . . . . . . . . . . . . . . . . 17		Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 20
	Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 19		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 20
	B.1. Changes Between Revisions -09 and -10 . . . . . . . . . . 19
	B.2. Changes Between Revisions -08 and -09 . . . . . . . . . . 19
	B.3. Changes Between Revisions -07 and -08 . . . . . . . . . . 20
	B.4. Changes Between Revisions -06 and -07 . . . . . . . . . . 20
	B.5. Changes Between Revisions -05 and -06 . . . . . . . . . . 20
	B.6. Changes Between Revisions -04 and -05 . . . . . . . . . . 20
	B.7. Changes Between Revisions -03 and -04 . . . . . . . . . . 20
	B.8. Changes Between Revisions -02 and -03 . . . . . . . . . . 20
	B.9. Changes Between Revisions -01 and -02 . . . . . . . . . . 20
	B.10. Changes Between Revisions -00 and -01 . . . . . . . . . . 21
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 21
	1. Introduction		1. Introduction
	The NETCONF protocol [RFC6241] uses XML [W3C.REC-xml-20081126] for		The Network Configuration Protocol (NETCONF) [RFC6241] uses XML [XML]
	encoding data in its Content Layer. Other management protocols might		for encoding data in its Content Layer. Other management protocols
	want to use other encodings while still benefiting from using YANG		might want to use other encodings while still benefiting from using
	[I-D.ietf-netmod-rfc6020bis] as the data modeling language.		YANG [RFC7950] as the data modeling language.
	For example, the RESTCONF protocol [I-D.ietf-netconf-restconf]		For example, the RESTCONF protocol [RESTCONF] supports two encodings:
	supports two encodings: XML (media type "application/yang.data+xml")		XML (media type "application/yang.data+xml") and JavaScript Object
	and JSON (media type "application/yang.data+json").		Notation (JSON) (media type "application/yang.data+json").
	The specification of YANG 1.1 data modelling language		The specification of the YANG 1.1 data modeling language [RFC7950]
	[I-D.ietf-netmod-rfc6020bis] defines only XML encoding of data trees,		defines only XML encoding of data trees, i.e., configuration data,
	i.e., configuration data, state data, input/output parameters of RPC		state data, input/output parameters of Remote Procedure Call (RPC)
	operations or actions, and notifications. The aim of this document		operations or actions, and notifications. The aim of this document
	is to define rules for encoding the same data as JavaScript Object		is to define rules for encoding the same data as JSON text [RFC7159].
	Notation (JSON) text [RFC7159].
	2. Terminology and Notation		2. Terminology and Notation
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC2119].		document are to be interpreted as described in [RFC2119].
	The following terms are defined in [I-D.ietf-netmod-rfc6020bis]:		The following terms are defined in [RFC7950]:
	o action,		o action
	o anydata,		o anydata
	o anyxml,		o anyxml
	o augment,		o augment
	o container,		o container
	o data node,		o data node
	o data tree,		o data tree
	o identity,		o identity
	o instance identifier,		o instance identifier
	o leaf,		o leaf
	o leaf-list,		o leaf-list
	o list,
	o module,		o list
			o module
	o RPC operation,		o RPC operation
	o submodule.		o submodule
	The following terms are defined in [RFC6241]:		The following terms are defined in [RFC6241]:
	o configuration data,		o configuration data
	o notification,		o notification
	o state data.		o state data
	3. Properties of the JSON Encoding		3. Properties of the JSON Encoding
	This document defines JSON encoding for YANG data trees and their		This document defines JSON encoding for YANG data trees and their
	subtrees. It is always assumed that the top-level structure in JSON-		subtrees. It is always assumed that the top-level structure in JSON-
	encoded data is an object.		encoded data is an object.
	Instances of YANG data nodes (leafs, containers, leaf-lists, lists,		Instances of YANG data nodes (leafs, containers, leaf-lists, lists,
	anydata and anyxml nodes) are encoded as members of a JSON object,		anydata nodes, and anyxml nodes) are encoded as members of a JSON
	i.e., name/value pairs. Section 4 defines how the name part is		object, i.e., name/value pairs. Section 4 defines how the name part
	formed, and the following sections deal with the value part. The		is formed, and the following sections deal with the value part. The
	encoding rules are identical for all types of data trees, i.e.,		encoding rules are identical for all types of data trees, i.e.,
	configuration data, state data, parameters of RPC operations,		configuration data, state data, parameters of RPC operations,
	actions, and notifications.		actions, and notifications.
	With the exception of "anydata" encoding (Section 5.5), all rules in		With the exception of "anydata" encoding (Section 5.5), all rules in
	this document are also applicable to YANG 1.0 [RFC6020].		this document are also applicable to YANG 1.0 [RFC6020].
	Unlike XML element content, JSON values carry partial type		Unlike XML element content, JSON values carry partial type
	information (number, string, boolean). The JSON encoding is defined		information (number, string, boolean). The JSON encoding is defined
	so that this information is never in conflict with the data type of		so that this information is never in conflict with the data type of
	the corresponding YANG leaf or leaf-list.		the corresponding YANG leaf or leaf-list.
	With the exception of anyxml and schema-less anydata nodes, it is		With the exception of anyxml and schema-less anydata nodes, it is
	possible to map a JSON-encoded data tree to XML encoding as defined		possible to map a JSON-encoded data tree to XML encoding as defined
	in [I-D.ietf-netmod-rfc6020bis], and vice versa. However, such		in [RFC7950], and vice versa. However, such conversions require the
	conversions require the YANG data model to be available.		YANG data model to be available.
	In order to achieve maximum interoperability while allowing		In order to achieve maximum interoperability while allowing
	implementations to use a variety of existing JSON parsers, the JSON		implementations to use a variety of existing JSON parsers, the JSON
	encoding rules follow, as much as possible, the constraints of the		encoding rules follow, as much as possible, the constraints of the
	I-JSON restricted profile [RFC7493]. Section 7 discusses I-JSON		I-JSON (Internet JSON) restricted profile [RFC7493]. Section 7
	conformance in more detail.		discusses I-JSON conformance in more detail.
	4. Names and Namespaces		4. Names and Namespaces
	A JSON object member name MUST be in one of the following forms:		A JSON object member name MUST be in one of the following forms:
	o simple - identical to the identifier of the corresponding YANG		o simple - identical to the identifier of the corresponding YANG
	data node;		data node.
	o namespace-qualified - the data node identifier is prefixed with		o namespace-qualified - the data node identifier is prefixed with
	the name of the module in which the data node is defined,		the name of the module in which the data node is defined,
	separated from the data node identifier by the colon character		separated from the data node identifier by the colon character
	(":").		(":").
	The name of a module determines the namespace of all data node names		The name of a module determines the namespace of all data node names
	defined in that module. If a data node is defined in a submodule,		defined in that module. If a data node is defined in a submodule,
	then the namespace-qualified member name uses the name of the main		then the namespace-qualified member name uses the name of the main
	module to which the submodule belongs.		module to which the submodule belongs.
	ABNF syntax [RFC5234] of a member name is shown in Figure 1, where		ABNF syntax [RFC5234] of a member name is shown in Figure 1, where
	the production for "identifier" is defined in sec. 13 of		the production for "identifier" is defined in Section 14 of
	[I-D.ietf-netmod-rfc6020bis].		[RFC7950].
	member-name = [identifier ":"] identifier		member-name = [identifier ":"] identifier
	Figure 1: ABNF production for a JSON member name.		Figure 1: ABNF Production for a JSON Member Name
	A namespace-qualified member name MUST be used for all members of a		A namespace-qualified member name MUST be used for all members of a
	top-level JSON object, and then also whenever the namespaces of the		top-level JSON object and then also whenever the namespaces of the
	data node and its parent node are different. In all other cases, the		data node and its parent node are different. In all other cases, the
	simple form of the member name MUST be used.		simple form of the member name MUST be used.
	For example, consider the following YANG module:		For example, consider the following YANG module:
	module example-foomod {		module example-foomod {
	namespace "http://example.com/foomod";		namespace "http://example.com/foomod";
	prefix "foomod";		prefix "foomod";
	skipping to change at page 5, line 49 ¶		skipping to change at page 6, line 4 ¶
	namespace "http://example.com/foomod";		namespace "http://example.com/foomod";
	prefix "foomod";		prefix "foomod";
	container top {		container top {
	leaf foo {		leaf foo {
	type uint8;		type uint8;
	}		}
	}		}
	}		}
	If the data model consists only of this module, then the following is		If the data model consists only of this module, then the following is
	a valid JSON-encoded configuration data:		valid JSON-encoded configuration data:
	{		{
	"example-foomod:top": {		"example-foomod:top": {
	"foo": 54		"foo": 54
	}		}
	}		}
	Note that the member of the top-level object uses the namespace-		Note that the member of the top-level object uses the namespace-
	qualified name but the "foo" leaf doesn't because it is defined in		qualified name but the "foo" leaf doesn't because it is defined in
	the same module as its parent container "top".		the same module as its parent container "top".
	Now, assume the container "top" is augmented from another module,		Now, assume that the container "top" is augmented from another
	"example-barmod":		module, "example-barmod":
	module example-barmod {		module example-barmod {
	namespace "http://example.com/barmod";		namespace "http://example.com/barmod";
	prefix "barmod";		prefix "barmod";
	import example-foomod {		import example-foomod {
	prefix "foomod";		prefix "foomod";
	}		}
	augment "/foo:top" {		augment "/foomod:top" {
	leaf bar {		leaf bar {
	type boolean;		type boolean;
	}		}
	}		}
	}		}
	A valid JSON-encoded configuration data containing both leafs may		Valid JSON-encoded configuration data containing both leafs may then
	then look like this:		look like this:
	{		{
	"example-foomod:top": {		"example-foomod:top": {
	"foo": 54,		"foo": 54,
	"example-barmod:bar": true		"example-barmod:bar": true
	}		}
	}		}
	The name of the "bar" leaf is prefixed with the namespace identifier		The name of the "bar" leaf is prefixed with the namespace identifier
	because its parent is defined in a different module.		because its parent is defined in a different module.
	Explicit namespace identifiers are sometimes needed when encoding		Explicit namespace identifiers are sometimes needed when encoding
	values of the "identityref" and "instances-identifier" types. The		values of the "identityref" and "instance-identifier" types. The
	same form of namespace-qualified name as defined above is then used.		same form of namespace-qualified name as defined above is then used.
	See Sections 6.8 and 6.11 for details.		See Sections 6.8 and 6.11 for details.
	5. Encoding of YANG Data Node Instances		5. Encoding of YANG Data Node Instances
	Every data node instance is encoded as a name/value pair where the		Every data node instance is encoded as a name/value pair where the
	name is formed from the data node identifier using the rules of		name is formed from the data node identifier using the rules of
	Section 4. The value depends on the category of the data node as		Section 4. The value depends on the category of the data node, as
	explained in the following subsections.		explained in the following subsections.
	Character encoding MUST be UTF-8.		Character encoding MUST be UTF-8.
	5.1. The "leaf" Data Node		5.1. The "leaf" Data Node
	A leaf instance is encoded as a name/value pair where the value can		A leaf instance is encoded as a name/value pair where the value can
	be a string, number, literal "true" or "false", or the special array		be a string, number, literal "true" or "false", or the special array
	"[null]", depending on the type of the leaf (see Section 6 for the		"[null]", depending on the type of the leaf (see Section 6 for the
	type encoding rules).		type encoding rules).
	skipping to change at page 8, line 15 ¶		skipping to change at page 8, line 34 ¶
	5.3. The "leaf-list" Data Node		5.3. The "leaf-list" Data Node
	A leaf-list is encoded as a name/array pair, and the array elements		A leaf-list is encoded as a name/array pair, and the array elements
	are values of some scalar type, which can be a string, number,		are values of some scalar type, which can be a string, number,
	literal "true" or "false", or the special array "[null]", depending		literal "true" or "false", or the special array "[null]", depending
	on the type of the leaf-list (see Section 6 for the type encoding		on the type of the leaf-list (see Section 6 for the type encoding
	rules).		rules).
	The ordering of array elements follows the same rules as the ordering		The ordering of array elements follows the same rules as the ordering
	of XML elements representing leaf-list entries in the XML encoding.		of XML elements representing leaf-list entries in the XML encoding.
	Specifically, the "ordered-by" properties (sec. 7.7.7 in		Specifically, the "ordered-by" properties (Section 7.7.7 in
	[I-D.ietf-netmod-rfc6020bis]) MUST be observed.		[RFC7950]) MUST be observed.
	Example: For the leaf-list definition		Example: For the leaf-list definition
	leaf-list foo {		leaf-list foo {
	type uint8;		type uint8;
	}		}
	the following is a valid JSON-encoded instance:		the following is a valid JSON-encoded instance:
	"foo": [123, 0]		"foo": [123, 0]
	5.4. The "list" Data Node		5.4. The "list" Data Node
	A list instance is encoded as a name/array pair, and the array		A list instance is encoded as a name/array pair, and the array
	elements are JSON objects.		elements are JSON objects.
	The ordering of array elements follows the same rules as the ordering		The ordering of array elements follows the same rules as the ordering
	of XML elements representing list entries in the XML encoding.		of XML elements representing list entries in the XML encoding.
	Specifically, the "ordered-by" properties (sec. 7.7.7 in		Specifically, the "ordered-by" properties (Section 7.7.7 in
	[I-D.ietf-netmod-rfc6020bis]) MUST be observed.		[RFC7950]) MUST be observed.
	Unlike the XML encoding, where list keys are required to precede any		Unlike the XML encoding, where list keys are required to precede any
	other siblings within a list entry, and appear in the order specified		other siblings within a list entry and appear in the order specified
	by the data model, the order of members in a JSON-encoded list entry		by the data model, the order of members in a JSON-encoded list entry
	is arbitrary because JSON objects are fundamentally unordered		is arbitrary because JSON objects are fundamentally unordered
	collections of members.		collections of members.
	Example: For the list definition		Example: For the list definition
	list bar {		list bar {
	key foo;		key foo;
	leaf foo {		leaf foo {
	type uint8;		type uint8;
	}		}
	leaf baz {		leaf baz {
	type string;		type string;
	}		}
	}		}
	skipping to change at page 9, line 29 ¶		skipping to change at page 9, line 48 ¶
	"baz": "zig"		"baz": "zig"
	},		},
	{		{
	"baz": "zag",		"baz": "zag",
	"foo": 0		"foo": 0
	}		}
	]		]
	5.5. The "anydata" Data Node		5.5. The "anydata" Data Node
	Anydata data node serves as a container for an arbitrary set of nodes		The anydata data node serves as a container for an arbitrary set of
	that otherwise appear as normal YANG-modeled data. A data model for		nodes that otherwise appear as normal YANG-modeled data. A data
	anydata content may or may not be known at run time. In the latter		model for anydata content may or may not be known at runtime. In the
	case, converting JSON-encoded instances to the XML encoding defined		latter case, converting JSON-encoded instances to the XML encoding
	in [I-D.ietf-netmod-rfc6020bis] may be impossible.		defined in [RFC7950] may be impossible.
	An anydata instance is encoded in the same way as a container, i.e.,		An anydata instance is encoded in the same way as a container, i.e.,
	as a value/object pair. The requirement that anydata content can be		as a name/object pair. The requirement that anydata content can be
	modeled by YANG implies the following rules for the JSON text inside		modeled by YANG implies the following rules for the JSON text inside
	the object:		the object:
	o It is valid I-JSON [RFC7493].		o It is valid I-JSON [RFC7493].
	o All object member names satisfy the ABNF production in Figure 1.		o All object member names satisfy the ABNF production in Figure 1.
	o Any JSON array contains either only unique scalar values (as a		o Any JSON array contains either only unique scalar values (as a
	leaf-list, see Section 5.3), or only objects (as a list, see		leaf-list; see Section 5.3) or only objects (as a list; see
	Section 5.4).		Section 5.4).
	o The "null" value is only allowed in the single-element array		o The "null" value is only allowed in the single-element array
	"[null]" corresponding to the encoding of the "empty" type, see		"[null]" corresponding to the encoding of the "empty" type; see
	Section 6.9.		Section 6.9.
	Example: for the anydata definition		Example: For the anydata definition
	anydata data;		anydata data;
	the following is a valid JSON-encoded instance:		the following is a valid JSON-encoded instance:
	"data": {		"data": {
	"ietf-notification:notification": {		"ietf-notification:notification": {
	"eventTime": "2014-07-29T13:43:01Z",		"eventTime": "2014-07-29T13:43:01Z",
	"example-event:event": {		"example-event:event": {
	"event-class": "fault",		"event-class": "fault",
	skipping to change at page 10, line 41 ¶		skipping to change at page 11, line 9 ¶
	anyxml bar;		anyxml bar;
	the following is a valid JSON-encoded instance:		the following is a valid JSON-encoded instance:
	"bar": [true, null, true]		"bar": [true, null, true]
	5.7. Metadata Objects		5.7. Metadata Objects
	Apart from instances of YANG data nodes, a JSON document MAY contain		Apart from instances of YANG data nodes, a JSON document MAY contain
	special object members whose name starts with the "@" character		special object members whose name starts with the "@" character
	(COMMERCIAL AT). Such members are used for special purposes such as		(COMMERCIAL AT). Such members are used for special purposes, such as
	encoding metadata [I-D.ietf-netmod-yang-metadata]. Exact syntax and		encoding metadata [RFC7952]. The exact syntax and semantics of such
	semantics of such members are outside the scope of this document.		members are outside the scope of this document.
	6. Representing YANG Data Types in JSON Values		6. Representing YANG Data Types in JSON Values
	The type of the JSON value in an instance of the leaf or leaf-list		The type of the JSON value in an instance of the leaf or leaf-list
	data node depends on the type of that data node as specified in the		data node depends on the type of that data node, as specified in the
	following subsections.		following subsections.
	6.1. Numeric Types		6.1. Numeric Types
	A value of the types "int8", "int16", "int32", "uint8", "uint16" and		A value of the "int8", "int16", "int32", "uint8", "uint16", or
	"uint32" is represented as a JSON number.		"uint32" type is represented as a JSON number.
	A value of the "int64", "uint64" or "decimal64" type is represented		A value of the "int64", "uint64", or "decimal64" type is represented
	as a JSON string whose content is the lexical representation of the		as a JSON string whose content is the lexical representation of the
	corresponding YANG type as specified in sections 9.2.1 and 9.3.1 of		corresponding YANG type as specified in Sections 9.2.1 and 9.3.1 of
	[I-D.ietf-netmod-rfc6020bis].		[RFC7950].
	For example, if the type of the leaf "foo" in Section 5.1 was		For example, if the type of the leaf "foo" in Section 5.1 was
	"uint64" instead of "uint8", the instance would have to be encoded as		"uint64" instead of "uint8", the instance would have to be encoded as
	"foo": "123"		"foo": "123"
	The special handling of 64-bit numbers follows from the I-JSON		The special handling of 64-bit numbers follows from the I-JSON
	recommendation to encode numbers exceeding the IEEE 754-2008 double		recommendation to encode numbers exceeding the IEEE 754-2008
	precision range as strings, see sec. 2.2 in [RFC7493].		double-precision range [IEEE754-2008] as strings; see Section 2.2 in
			[RFC7493].
	6.2. The "string" Type		6.2. The "string" Type
	A "string" value is represented as a JSON string, subject to JSON		A "string" value is represented as a JSON string, subject to JSON
	string encoding rules.		string encoding rules.
	6.3. The "boolean" Type		6.3. The "boolean" Type
	A "boolean" value is represented as the corresponding JSON literal		A "boolean" value is represented as the corresponding JSON literal
	name "true" or "false".		name "true" or "false".
	6.4. The "enumeration" Type		6.4. The "enumeration" Type
	An "enumeration" value is represented as a JSON string - one of the		An "enumeration" value is represented as a JSON string -- one of the
	names assigned by "enum" statements in YANG.		names assigned by "enum" statements in YANG.
	The representation is identical to the lexical representation of the		The representation is identical to the lexical representation of the
	"enumeration" type in XML, see sec. 9.6 in		"enumeration" type in XML; see Section 9.6 in [RFC7950].
	[I-D.ietf-netmod-rfc6020bis].
	6.5. The "bits" Type		6.5. The "bits" Type
	A "bits" value is represented as a JSON string - a space-separated		A "bits" value is represented as a JSON string -- a space-separated
	sequence of names of bits that are set. The permitted bit names are		sequence of names of bits that are set. The permitted bit names are
	assigned by "bit" statements in YANG.		assigned by "bit" statements in YANG.
	The representation is identical to the lexical representation of the		The representation is identical to the lexical representation of the
	"bits" type, see sec. 9.7 in [I-D.ietf-netmod-rfc6020bis].		"bits" type; see Section 9.7 in [RFC7950].
	6.6. The "binary" Type		6.6. The "binary" Type
	A "binary" value is represented as a JSON string - base64-encoding of		A "binary" value is represented as a JSON string -- base64 encoding
	arbitrary binary data.		of arbitrary binary data.
	The representation is identical to the lexical representation of the		The representation is identical to the lexical representation of the
	"binary" type in XML, see sec. 9.8 in [I-D.ietf-netmod-rfc6020bis].		"binary" type in XML; see Section 9.8 in [RFC7950].
	6.7. The "leafref" Type		6.7. The "leafref" Type
	A "leafref" value is represented using the same rules as the type of		A "leafref" value is represented using the same rules as the type of
	the leaf to which the leafref value refers.		the leaf to which the leafref value refers.
	6.8. The "identityref" Type		6.8. The "identityref" Type
	An "identityref" value is represented as a string - the name of an		An "identityref" value is represented as a string -- the name of an
	identity. If the identity is defined in another module than the leaf		identity. If the identity is defined in a module other than the leaf
	node containing the identityref value, the namespace-qualified form		node containing the identityref value, the namespace-qualified form
	(Section 4) MUST be used. Otherwise, both the simple and namespace-		(Section 4) MUST be used. Otherwise, both the simple and namespace-
	qualified forms are permitted.		qualified forms are permitted.
	For example, consider the following schematic module:		For example, consider the following schematic module:
	module example-mod {		module example-mod {
	...		...
	import ietf-interfaces {		import ietf-interfaces {
	prefix if;		prefix if;
	}		}
	import iana-if-type {
	prefix ianaift;
	}
	...		...
	leaf type {		leaf type {
	type identityref {		type identityref {
	base "if:interface-type";		base "if:interface-type";
	}		}
	}		}
	}		}
	A valid instance of the "type" leaf is then encoded as follows:		A valid instance of the "type" leaf is then encoded as follows:
	skipping to change at page 13, line 33 ¶		skipping to change at page 14, line 12 ¶
	"foo": [null]		"foo": [null]
	6.10. The "union" Type		6.10. The "union" Type
	A value of the "union" type is encoded as the value of any of the		A value of the "union" type is encoded as the value of any of the
	member types.		member types.
	When validating a value of the "union" type, the type information		When validating a value of the "union" type, the type information
	conveyed by the JSON encoding MUST also be taken into account. JSON		conveyed by the JSON encoding MUST also be taken into account. JSON
	syntax thus provides additional means for resolving union member type		syntax thus provides additional means for resolving the member type
	that are not available in XML encoding.		of the union that are not available in XML encoding.
	For example, consider the following YANG definition:		For example, consider the following YANG definition:
	leaf bar {		leaf bar {
	type union {		type union {
	type uint16;		type uint16;
	type string;		type string;
	}		}
	}		}
	In RESTCONF [I-D.ietf-netconf-restconf], it is possible to set the		In RESTCONF [RESTCONF], it is possible to set the value of "bar" in
	value of "bar" in the following way when using the "application/		the following way when using the "application/yang.data+xml"
	yang.data+xml" media type:		media type:
	<bar>13.5</bar>		<bar>13.5</bar>
	because the value may be interpreted as a string, i.e., the second
	member type of the union. When using the "application/		because the value may be interpreted as a string, i.e., the
	yang.data+json" media type, however, this is an error:		second member type of the union. When using the
			"application/yang.data+json" media type, however, this is an error:
	"bar": 13.5		"bar": 13.5
	In this case, the JSON encoding indicates the value is supposed to be		In this case, the JSON encoding indicates that the value is supposed
	a number rather than a string, and it is not a valid "uint16" value.		to be a number rather than a string, and it is not a valid "uint16"
			value.
	Conversely, the value of		Conversely, the value of
	"bar": "1"		"bar": "1"
	is to be interpreted as a string.		is to be interpreted as a string.
	6.11. The "instance-identifier" Type		6.11. The "instance-identifier" Type
	An "instance-identifier" value is encoded as a string that is		An "instance-identifier" value is encoded as a string that is
	analogical to the lexical representation in XML encoding, see		analogical to the lexical representation in XML encoding; see
	sec. 9.13.3 in [I-D.ietf-netmod-rfc6020bis]. However, the encoding		Section 9.13.2 in [RFC7950]. However, the encoding of namespaces in
	of namespaces in instance-identifier values follows the rules stated		instance-identifier values follows the rules stated in Section 4,
	in Section 4, namely:		namely:
	o The leftmost (top-level) data node name is always in the		o The leftmost (top-level) data node name is always in the
	namespace-qualified form.		namespace-qualified form.
	o Any subsequent data node name is in the namespace-qualified form		o Any subsequent data node name is in the namespace-qualified form
	if the node is defined in another module than its parent node, and		if the node is defined in a module other than its parent node, and
	the simple form is used otherwise. This rule also holds for node		the simple form is used otherwise. This rule also holds for node
	names appearing in predicates.		names appearing in predicates.
	For example,		For example,
	/ietf-interfaces:interfaces/interface[name='eth0']/ietf-ip:ipv4/ip		/ietf-interfaces:interfaces/interface[name='eth0']/ietf-ip:ipv4/ip
	is a valid instance-identifer value because the data nodes		is a valid instance-identifier value because the data nodes
	"interfaces", "interface" and "name" are defined in the module "ietf-		"interfaces", "interface", and "name" are defined in the module
	interfaces", whereas "ipv4" and "ip" are defined in "ietf-ip".		"ietf-interfaces", whereas "ipv4" and "ip" are defined in "ietf-ip".
	7. I-JSON Compliance		7. I-JSON Compliance
	I-JSON [RFC7493] is a restricted profile of JSON that guarantees		I-JSON [RFC7493] is a restricted profile of JSON that guarantees
	maximum interoperability for protocols that use JSON in their		maximum interoperability for protocols that use JSON in their
	messages, no matter what JSON encoders/decoders are used in protocol		messages, no matter what JSON encoders/decoders are used in protocol
	implementations. The encoding defined in this document therefore		implementations. The encoding defined in this document therefore
	observes the I-JSON requirements and recommendations as closely as		observes the I-JSON requirements and recommendations as closely as
	possible.		possible.
	skipping to change at page 15, line 25 ¶		skipping to change at page 16, line 9 ¶
	The JSON encoding defined in this document deviates from I-JSON only		The JSON encoding defined in this document deviates from I-JSON only
	in the representation of the "binary" type. In order to remain		in the representation of the "binary" type. In order to remain
	compatible with XML encoding, the base64 encoding scheme is used		compatible with XML encoding, the base64 encoding scheme is used
	(Section 6.6), whilst I-JSON recommends base64url instead.		(Section 6.6), whilst I-JSON recommends base64url instead.
	8. Security Considerations		8. Security Considerations
	This document defines an alternative encoding for data modeled in the		This document defines an alternative encoding for data modeled in the
	YANG data modeling language. As such, it doesn't contribute any new		YANG data modeling language. As such, it doesn't contribute any new
	security issues beyond those discussed in sec. 16 of		security issues beyond those discussed in Section 17 of [RFC7950].
	[I-D.ietf-netmod-rfc6020bis].
	This document defines no mechanisms for signing and encrypting data		This document defines no mechanisms for signing and encrypting data
	modeled with YANG. Under normal circumstances, data security and		modeled with YANG. Under normal circumstances, data security and
	integrity is guaranteed by the management protocol in use, such as		integrity are guaranteed by the management protocol in use, such as
	NETCONF [RFC6241] or RESTCONF [I-D.ietf-netconf-restconf]. If it is		NETCONF [RFC6241] or RESTCONF [RESTCONF]. If this is not the case,
	not the case, external mechanisms, such as PKCS #7 [RFC2315] or JOSE		external mechanisms, such as Public-Key Cryptography Standards (PKCS)
	([RFC7515] and [RFC7516]), need to be considered.		#7 [RFC2315] or JSON Object Signing and Encryption (JOSE) [RFC7515]
			[RFC7516], need to be considered.
	JSON processing is rather different from XML, and JSON parsers may		JSON processing is rather different from XML, and JSON parsers may
	thus suffer from other types of vulnerabilities than their XML		thus suffer from different types of vulnerabilities than their XML
	counterparts. To minimize these new security risks, software on the		counterparts. To minimize these new security risks, software on the
	receiving side SHOULD reject all messages that do not comply to the		receiving side SHOULD reject all messages that do not comply with the
	rules of this document and reply with an appropriate error message to		rules of this document and reply with an appropriate error message to
	the sender.		the sender.
	9. Acknowledgments		9. References
	The author wishes to thank Andy Bierman, Martin Bjorklund, Dean
	Bogdanovic, Balazs Lengyel, Juergen Schoenwaelder and Phil Shafer for
	their helpful comments and suggestions.
	10. References
	10.1. Normative References
	[I-D.ietf-netmod-rfc6020bis]		9.1. Normative References
	Bjorklund, M., "The YANG 1.1 Data Modeling Language",
	draft-ietf-netmod-rfc6020bis-11 (work in progress),
	February 2016.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<http://www.rfc-editor.org/info/rfc2119>.		<http://www.rfc-editor.org/info/rfc2119>.
	[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax		[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
	Specifications: ABNF", STD 68, RFC 5234,		Specifications: ABNF", STD 68, RFC 5234,
	DOI 10.17487/RFC5234, January 2008,		DOI 10.17487/RFC5234, January 2008,
	<http://www.rfc-editor.org/info/rfc5234>.		<http://www.rfc-editor.org/info/rfc5234>.
	skipping to change at page 16, line 34 ¶		skipping to change at page 17, line 5 ¶
	<http://www.rfc-editor.org/info/rfc6241>.		<http://www.rfc-editor.org/info/rfc6241>.
	[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data		[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
	Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March		Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
	2014, <http://www.rfc-editor.org/info/rfc7159>.		2014, <http://www.rfc-editor.org/info/rfc7159>.
	[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,		[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,
	DOI 10.17487/RFC7493, March 2015,		DOI 10.17487/RFC7493, March 2015,
	<http://www.rfc-editor.org/info/rfc7493>.		<http://www.rfc-editor.org/info/rfc7493>.
	10.2. Informative References		[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
			RFC 7950, DOI 10.17487/RFC7950, August 2016,
			<http://www.rfc-editor.org/info/rfc7950>.
	[I-D.ietf-netconf-restconf]		9.2. Informative References
	Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
	Protocol", draft-ietf-netconf-restconf-10 (work in
	progress), March 2016.
	[I-D.ietf-netmod-yang-metadata]		[IEEE754-2008]
	Lhotka, L., "Defining and Using Metadata with YANG",		IEEE, "IEEE Standard for Floating-Point Arithmetic",
	draft-ietf-netmod-yang-metadata-07 (work in progress),		IEEE 754-2008, DOI 10.1109/IEEESTD.2008.4610935, 2008,
	March 2016.		<http://standards.ieee.org/findstds/
			standard/754-2008.html>.
			[RESTCONF] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
			Protocol", Work in Progress,
			draft-ietf-netconf-restconf-16, August 2016.
	[RFC2315] Kaliski, B., "PKCS #7: Cryptographic Message Syntax		[RFC2315] Kaliski, B., "PKCS #7: Cryptographic Message Syntax
	Version 1.5", RFC 2315, DOI 10.17487/RFC2315, March 1998,		Version 1.5", RFC 2315, DOI 10.17487/RFC2315, March 1998,
	<http://www.rfc-editor.org/info/rfc2315>.		<http://www.rfc-editor.org/info/rfc2315>.
	[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for		[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
	the Network Configuration Protocol (NETCONF)", RFC 6020,		the Network Configuration Protocol (NETCONF)", RFC 6020,
	DOI 10.17487/RFC6020, October 2010,		DOI 10.17487/RFC6020, October 2010,
	<http://www.rfc-editor.org/info/rfc6020>.		<http://www.rfc-editor.org/info/rfc6020>.
	skipping to change at page 17, line 22 ¶		skipping to change at page 17, line 42 ¶
	<http://www.rfc-editor.org/info/rfc7223>.		<http://www.rfc-editor.org/info/rfc7223>.
	[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web		[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
	Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May		Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
	2015, <http://www.rfc-editor.org/info/rfc7515>.		2015, <http://www.rfc-editor.org/info/rfc7515>.
	[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",		[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
	RFC 7516, DOI 10.17487/RFC7516, May 2015,		RFC 7516, DOI 10.17487/RFC7516, May 2015,
	<http://www.rfc-editor.org/info/rfc7516>.		<http://www.rfc-editor.org/info/rfc7516>.
	[W3C.REC-xml-20081126]		[RFC7952] Lhotka, L., "Defining and Using Metadata with YANG",
	Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and		RFC 7952, DOI 10.17487/RFC7952, August 2016,
			<http://www.rfc-editor.org/info/rfc7952>.
			[XML] Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
	F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth		F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
	Edition)", World Wide Web Consortium Recommendation REC-		Edition)", World Wide Web Consortium Recommendation
	xml-20081126, November 2008,		REC-xml-20081126, November 2008,
	<http://www.w3.org/TR/2008/REC-xml-20081126>.		<http://www.w3.org/TR/2008/REC-xml-20081126>.
	Appendix A. A Complete Example		Appendix A. A Complete Example
	The JSON document shown below represents the same data as the reply		The JSON document shown below represents the same data as the reply
	to the NETCONF <get> request appearing in Appendix D of [RFC7223].		to the NETCONF <get> request appearing in Appendix D of [RFC7223].
	The data model is a combination of two YANG modules: "ietf-		The data model is a combination of two YANG modules:
	interfaces" and "ex-vlan" (the latter is an example module from		"ietf-interfaces" and "ex-vlan" (the latter is an example module from
	Appendix C of [RFC7223]). The "if-mib" feature defined in the "ietf-		Appendix C of [RFC7223]). The "if-mib" feature defined in the
	interfaces" module is supported.		"ietf-interfaces" module is supported.
	{		{
	"ietf-interfaces:interfaces": {		"ietf-interfaces:interfaces": {
	"interface": [		"interface": [
	{		{
	"name": "eth0",		"name": "eth0",
	"type": "iana-if-type:ethernetCsmacd",		"type": "iana-if-type:ethernetCsmacd",
	"enabled": false		"enabled": false
	},		},
	{		{
	skipping to change at page 19, line 29 ¶		skipping to change at page 20, line 4 ¶
	}		}
	},		},
	{		{
	"name": "lo1",		"name": "lo1",
	"type": "iana-if-type:softwareLoopback",		"type": "iana-if-type:softwareLoopback",
	"admin-status": "up",		"admin-status": "up",
	"oper-status": "up",		"oper-status": "up",
	"if-index": 1,		"if-index": 1,
	"statistics": {		"statistics": {
	"discontinuity-time": "2013-04-01T03:00:00+00:00"		"discontinuity-time": "2013-04-01T03:00:00+00:00"
	}		}
	}		}
	]		]
	}		}
	}		}
	Appendix B. Change Log		Acknowledgements
	RFC Editor: Remove this section upon publication as an RFC.
	B.1. Changes Between Revisions -09 and -10
	o A sentence about signing and encrypting data was added, together
	with informative references to RFCs 2315, 7515 and 7516.
	B.2. Changes Between Revisions -08 and -09
	o References to RFC 6241 term in the Terminology section were added.
	o Prefixes in the example in Sec. 4 were changed so as to be
	different from node names.
	B.3. Changes Between Revisions -07 and -08
	o Changed the names of example modules so that they start with
	"example-".
	B.4. Changes Between Revisions -06 and -07
	o General permit on object members whose names start with "@".
	B.5. Changes Between Revisions -05 and -06
	o More text and a new example about resolving union-type values.
	B.6. Changes Between Revisions -04 and -05
	o Removed section "Validation of JSON-encoded Instance Data" and
	other text about XML-JSON mapping.
	o Added section "Properties of the JSON Encoding".
	B.7. Changes Between Revisions -03 and -04
	o I-D.ietf-netmod-rfc6020bis is used as a normative reference
	instead of RFC 6020.
	o Removed noncharacters as an I-JSON issue because it doesn't exist
	in YANG 1.1.
	o Section about anydata encoding was added.
	o Require I-JSON for anyxml encoding.
	o Use ABNF for defining qualified name.
	B.8. Changes Between Revisions -02 and -03
	o Namespace encoding is defined without using RFC 2119 keywords.
	o Specification for anyxml nodes was extended and clarified.
	o Text about ordering of list entries was corrected.
	B.9. Changes Between Revisions -01 and -02
	o Encoding of namespaces in instance-identifiers was changed.
	o Text specifying the order of array elements in leaf-list and list
	instances was added.
	B.10. Changes Between Revisions -00 and -01
	o Metadata encoding was moved to a separate I-D, draft-lhotka-
	netmod-yang-metadata.
	o JSON encoding is now defined directly rather than via XML-JSON
	mapping.
	o The rules for namespace encoding has changed. This affect both
	node instance names and instance-identifiers.
	o I-JSON-related changes. The most significant is the string
	encoding of 64-bit numbers.
	o When validating union type, the partial type info present in JSON
	encoding is taken into account.
	o Added section about I-JSON compliance.
	o Updated the example in appendix.
	o Wrote Security Considerations.
	o Removed IANA Considerations as there are none.		The author wishes to thank Andy Bierman, Martin Bjorklund, Dean
			Bogdanovic, Balazs Lengyel, Juergen Schoenwaelder, and Phil Shafer
			for their helpful comments and suggestions.
	Author's Address		Author's Address
	Ladislav Lhotka		Ladislav Lhotka
	CZ.NIC		CZ.NIC
	Email: lhotka@nic.cz		Email: lhotka@nic.cz
End of changes. 92 change blocks.
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