CBOR Encoding of Data Modeled with YANG
draft-ietf-core-yang-cbor-15
Internet Engineering Task Force M. Veillette, Ed.
Internet-Draft Trilliant Networks Inc.
Intended status: Standards Track I. Petrov, Ed.
Expires: 28 July 2021 Google Switzerland GmbH
A. Pelov
Acklio
24 January 2021
CBOR Encoding of Data Modeled with YANG
draft-ietf-core-yang-cbor-15
Abstract
This document defines encoding rules for serializing configuration
data, state data, RPC input and RPC output, action input, action
output, notifications and yang-data extension defined within YANG
modules using the Concise Binary Object Representation (CBOR, RFC
8949).
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 https://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 28 July 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 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 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. Terminology and Notation . . . . . . . . . . . . . . . . . . 3
3. Properties of the CBOR Encoding . . . . . . . . . . . . . . . 5
3.1. CBOR diagnostic notation . . . . . . . . . . . . . . . . 6
3.2. YANG Schema Item iDentifier . . . . . . . . . . . . . . . 8
3.3. Name . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4. Encoding of YANG Schema Node Instances . . . . . . . . . . . 10
4.1. The 'leaf' . . . . . . . . . . . . . . . . . . . . . . . 10
4.1.1. Using SIDs in keys . . . . . . . . . . . . . . . . . 10
4.1.2. Using names in keys . . . . . . . . . . . . . . . . . 11
4.2. The 'container' and other nodes from the data tree . . . 11
4.2.1. Using SIDs in keys . . . . . . . . . . . . . . . . . 12
4.2.2. Using names in keys . . . . . . . . . . . . . . . . . 13
4.3. The 'leaf-list' . . . . . . . . . . . . . . . . . . . . . 15
4.3.1. Using SIDs in keys . . . . . . . . . . . . . . . . . 15
4.3.2. Using names in keys . . . . . . . . . . . . . . . . . 15
4.4. The 'list' and 'list' instance(s) . . . . . . . . . . . . 16
4.4.1. Using SIDs in keys . . . . . . . . . . . . . . . . . 17
4.4.2. Using names in keys . . . . . . . . . . . . . . . . . 19
4.5. The 'anydata' . . . . . . . . . . . . . . . . . . . . . . 21
4.5.1. Using SIDs in keys . . . . . . . . . . . . . . . . . 22
4.5.2. Using names in keys . . . . . . . . . . . . . . . . . 23
4.6. The 'anyxml' . . . . . . . . . . . . . . . . . . . . . . 24
4.6.1. Using SIDs in keys . . . . . . . . . . . . . . . . . 24
4.6.2. Using names in keys . . . . . . . . . . . . . . . . . 25
5. Encoding of 'yang-data' extension . . . . . . . . . . . . . . 25
5.1. Using SIDs in keys . . . . . . . . . . . . . . . . . . . 26
5.2. Using names in keys . . . . . . . . . . . . . . . . . . . 27
6. Representing YANG Data Types in CBOR . . . . . . . . . . . . 28
6.1. The unsigned integer Types . . . . . . . . . . . . . . . 28
6.2. The integer Types . . . . . . . . . . . . . . . . . . . . 29
6.3. The 'decimal64' Type . . . . . . . . . . . . . . . . . . 29
6.4. The 'string' Type . . . . . . . . . . . . . . . . . . . . 30
6.5. The 'boolean' Type . . . . . . . . . . . . . . . . . . . 30
6.6. The 'enumeration' Type . . . . . . . . . . . . . . . . . 31
6.7. The 'bits' Type . . . . . . . . . . . . . . . . . . . . . 32
6.8. The 'binary' Type . . . . . . . . . . . . . . . . . . . . 34
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6.9. The 'leafref' Type . . . . . . . . . . . . . . . . . . . 34
6.10. The 'identityref' Type . . . . . . . . . . . . . . . . . 35
6.10.1. SIDs as identityref . . . . . . . . . . . . . . . . 35
6.10.2. Name as identityref . . . . . . . . . . . . . . . . 36
6.11. The 'empty' Type . . . . . . . . . . . . . . . . . . . . 36
6.12. The 'union' Type . . . . . . . . . . . . . . . . . . . . 37
6.13. The 'instance-identifier' Type . . . . . . . . . . . . . 38
6.13.1. SIDs as instance-identifier . . . . . . . . . . . . 38
6.13.2. Names as instance-identifier . . . . . . . . . . . . 41
7. Content-Types . . . . . . . . . . . . . . . . . . . . . . . . 43
8. Security Considerations . . . . . . . . . . . . . . . . . . . 43
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 43
9.1. Media-Types Registry . . . . . . . . . . . . . . . . . . 43
9.2. CoAP Content-Formats Registry . . . . . . . . . . . . . . 44
9.3. CBOR Tags Registry . . . . . . . . . . . . . . . . . . . 44
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 45
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 45
11.1. Normative References . . . . . . . . . . . . . . . . . . 45
11.2. Informative References . . . . . . . . . . . . . . . . . 46
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 47
1. Introduction
The specification of the YANG 1.1 data modeling language [RFC7950]
defines an XML encoding for data instances, i.e. contents of
configuration datastores, state data, RPC inputs and outputs, action
inputs and outputs, and event notifications.
An additional set of encoding rules has been defined in [RFC7951]
based on the JavaScript Object Notation (JSON) Data Interchange
Format [RFC8259].
The aim of this document is to define a set of encoding rules for the
Concise Binary Object Representation (CBOR) [RFC8949]. The resulting
encoding is more compact compared to XML and JSON and more suitable
for Constrained Nodes and/or Constrained Networks as defined by
[RFC7228].
2. Terminology and Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The following terms are defined in [RFC7950]:
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* action
* anydata
* anyxml
* data node
* data tree
* datastore
* feature
* identity
* module
* notification
* RPC
* schema node
* schema tree
* submodule
The following terms are defined in [RFC8040]:
* yang-data extension
This specification also makes use of the following terminology:
* child: A schema node defined as a child node of a container, a
list, a case, a notification, an RPC input, an RPC output, an
action input, an action output.
* delta: Difference between the current YANG SID and a reference
YANG SID. A reference YANG SID is defined for each context for
which deltas are used.
* item: A schema node, an identity, a module, a submodule or a
feature defined using the YANG modeling language.
* parent: The container, list, case, notification, RPC input, RPC
output, action input or action output node in which a schema node
is defined.
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* YANG Schema Item iDentifier (YANG SID or simply SID): Unsigned
integer used to identify different YANG items.
3. Properties of the CBOR Encoding
This document defines CBOR encoding rules for YANG data trees and
their subtrees.
A node from the data tree such as container, list instance,
notification, RPC input, RPC output, action input and action output
is serialized using a CBOR map in which each child schema node is
encoded using a key and a value. This specification supports two
types of CBOR keys; YANG Schema Item iDentifier (YANG SID) as defined
in Section 3.2 and names as defined in Section 3.3. Each of these
key types is encoded using a specific CBOR type which allows their
interpretation during the deserialization process. Protocols or
mechanisms implementing this specification can mandate the use of a
specific key type.
In order to minimize the size of the encoded data, the proposed
mapping avoids any unnecessary meta-information beyond those natively
supported by CBOR. For instance, CBOR tags are used solely in the
case of SID not encoded as delta, anyxml schema nodes and the union
datatype to distinguish explicitly the use of different YANG
datatypes encoded using the same CBOR major type.
Unless specified otherwise by the protocol or mechanism implementing
this specification, the indefinite lengths encoding as defined in
Section 3.2 of [RFC8949] SHALL be supported by CBOR decoders.
Data nodes implemented using a CBOR array, map, byte string, and text
string can be instantiated but empty. In this case, they are encoded
with a length of zero.
When schema node are serialized using the rules defined by this
specification as part of an application payload, the payload SHOULD
include information that would allow a stateless way to identify each
node, such as the SID number associated with the node, SID delta from
another SID in the application payload, the namespace qualified name
or the instance-identifier.
Examples in Section 4 include a root CBOR map with a single entry
having a key set to either a namespace qualified name or a SID. This
root CBOR map is provided only as a typical usage example and is not
part of the present encoding rules. Only the value within this CBOR
map is compulsory.
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3.1. CBOR diagnostic notation
Within this document, CBOR binary contents are represented using an
equivalent textual form called CBOR diagnostic notation as defined in
Section 8 of [RFC8949]. This notation is used strictly for
documentation purposes and is never used in the data serialization.
Table 1 below provides a summary of this notation.
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+==========+======+====================+===========+==========+
| CBOR | CBOR | Diagnostic | Example | CBOR |
| content | type | notation | | encoding |
+==========+======+====================+===========+==========+
| Unsigned | 0 | Decimal digits | 123 | 18 7B |
| integer | | | | |
+----------+------+--------------------+-----------+----------+
| Negative | 1 | Decimal digits | -123 | 38 7A |
| integer | | prefixed by a | | |
| | | minus sign | | |
+----------+------+--------------------+-----------+----------+
| Byte | 2 | Hexadecimal value | h'F15C' | 42 F15C |
| string | | enclosed between | | |
| | | single quotes and | | |
| | | prefixed by an 'h' | | |
+----------+------+--------------------+-----------+----------+
| Text | 3 | String of Unicode | "txt" | 63 |
| string | | characters | | 747874 |
| | | enclosed between | | |
| | | double quotes | | |
+----------+------+--------------------+-----------+----------+
| Array | 4 | Comma-separated | [ 1, 2 ] | 82 01 02 |
| | | list of values | | |
| | | within square | | |
| | | brackets | | |
+----------+------+--------------------+-----------+----------+
| Map | 5 | Comma-separated | { 1: 123, | A2 |
| | | list of key : | 2: 456 } | 01187B |
| | | value pairs within | | 021901C8 |
| | | curly braces | | |
+----------+------+--------------------+-----------+----------+
| Boolean | 7/20 | false | false | F4 |
+----------+------+--------------------+-----------+----------+
| | 7/21 | true | true | F5 |
+----------+------+--------------------+-----------+----------+
| Null | 7/22 | null | null | F6 |
+----------+------+--------------------+-----------+----------+
| Not | 7/23 | undefined | undefined | F7 |
| assigned | | | | |
+----------+------+--------------------+-----------+----------+
Table 1: CBOR diagnostic notation summary
Note: CBOR binary contents shown in this specification are annotated
with comments. These comments are delimited by slashes ("/") as
defined in [RFC8610] Appendix G.6.
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3.2. YANG Schema Item iDentifier
Some of the items defined in YANG [RFC7950] require the use of a
unique identifier. In both NETCONF [RFC6241] and RESTCONF [RFC8040],
these identifiers are implemented using strings. To allow the
implementation of data models defined in YANG in constrained devices
and constrained networks, a more compact method to identify YANG
items is required. This compact identifier, called YANG Schema Item
iDentifier, is an unsigned integer. The following items are
identified using YANG SIDs (often shortened to SIDs):
* identities
* data nodes
* RPCs and associated input(s) and output(s)
* actions and associated input(s) and output(s)
* notifications and associated information
* YANG modules, submodules and features
To minimize their size, SIDs used as keys in inner CBOR maps are
typically encoded using deltas. Conversion from SIDs to deltas and
back to SIDs are stateless processes solely based on the data
serialized or deserialized. These SIDs may also be encoded as
absolute number when enclosed by CBOR tag 47.
Mechanisms and processes used to assign SIDs to YANG items and to
guarantee their uniqueness are outside the scope of the present
specification. If SIDs are to be used, the present specification is
used in conjunction with a specification defining this management.
One example for such a specification is [I-D.ietf-core-sid].
3.3. Name
This specification also supports the encoding of YANG item
identifiers as string, similar as those used by the JSON Encoding of
Data Modeled with YANG [RFC7951]. This approach can be used to avoid
the management overhead associated to SIDs allocation. The main
drawback is the significant increase in size of the encoded data.
YANG item identifiers implemented using names MUST be in one of the
following forms:
* simple - the identifier of the YANG item (i.e. schema node or
identity).
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* namespace qualified - the identifier of the YANG item is prefixed
with the name of the module in which this item is defined,
separated by the colon character (":").
The name of a module determines the namespace of all YANG items
defined in that module. If an item is defined in a submodule, then
the namespace qualified name uses the name of the main module to
which the submodule belongs.
ABNF syntax [RFC5234] of a name is shown in Figure 1, where the
production for "identifier" is defined in Section 14 of [RFC7950].
name = [identifier ":"] identifier
Figure 1: ABNF Production for a simple or namespace qualified name
A namespace qualified name MUST be used for all members of a top-
level CBOR map and then also whenever the namespaces of the data node
and its parent node are different. In all other cases, the simple
form of the name SHOULD be used.
Definition example:
module example-foomod {
container top {
leaf foo {
type uint8;
}
}
}
module example-barmod {
import example-foomod {
prefix "foomod";
}
augment "/foomod:top" {
leaf bar {
type boolean;
}
}
}
A valid CBOR encoding of the 'top' container is as follows.
CBOR diagnostic notation:
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{
"example-foomod:top": {
"foo": 54,
"example-barmod:bar": true
}
}
Both the 'top' container and the 'bar' leaf defined in a different
YANG module as its parent container are encoded as namespace
qualified names. The 'foo' leaf defined in the same YANG module as
its parent container is encoded as simple name.
4. Encoding of YANG Schema Node Instances
Schema node instances defined using the YANG modeling language are
encoded using CBOR [RFC8949] based on the rules defined in this
section. We assume that the reader is already familiar with both
YANG [RFC7950] and CBOR [RFC8949].
4.1. The 'leaf'
A 'leaf' MUST be encoded accordingly to its datatype using one of the
encoding rules specified in Section 6.
The following examples shows the encoding of a 'hostname' leaf using
a SID or a name.
Definition example from [RFC7317]:
leaf hostname {
type inet:domain-name;
}
4.1.1. Using SIDs in keys
CBOR diagnostic notation:
{
1752 : "myhost.example.com" / hostname (SID 1752) /
}
CBOR encoding:
A1 # map(1)
19 06D8 # unsigned(1752)
72 # text(18)
6D79686F73742E6578616D706C652E636F6D # "myhost.example.com"
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4.1.2. Using names in keys
CBOR diagnostic notation:
{
"ietf-system:hostname" : "myhost.example.com"
}
CBOR encoding:
A1 # map(1)
74 # text(20)
696574662D73797374656D3A686F73746E616D65
72 # text(18)
6D79686F73742E6578616D706C652E636F6D
4.2. The 'container' and other nodes from the data tree
Containers, list instances, notification contents, rpc inputs, rpc
outputs, action inputs and action outputs MUST be encoded using a
CBOR map data item (major type 5). A map is comprised of pairs of
data items, with each data item consisting of a key and a value.
Each key within the CBOR map is set to a schema node identifier, each
value is set to the value of this schema node instance according to
the instance datatype.
This specification supports two types of CBOR keys; SID as defined in
Section 3.2 and names as defined in Section 3.3.
The following examples shows the encoding of a 'system-state'
container instance using SIDs or names.
Definition example from [RFC7317]:
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typedef date-and-time {
type string {
pattern '\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?(Z|[\+\-]
\d{2}:\d{2})';
}
}
container system-state {
container clock {
leaf current-datetime {
type date-and-time;
}
leaf boot-datetime {
type date-and-time;
}
}
}
4.2.1. Using SIDs in keys
In the context of containers and other nodes from the data tree, CBOR
map keys within inner CBOR maps can be encoded using deltas or SIDs.
In the case of deltas, they MUST be encoded using a CBOR unsigned
integer (major type 0) or CBOR negative integer (major type 1),
depending on the actual delta value. In the case of SID, they are
encoded using the SID value enclosed by CBOR tag 47 as defined in
Section 9.3.
Delta values are computed as follows:
* In the case of a 'container', deltas are equal to the SID of the
current schema node minus the SID of the parent 'container'.
* In the case of a 'list', deltas are equal to the SID of the
current schema node minus the SID of the parent 'list'.
* In the case of an 'rpc input' or 'rpc output', deltas are equal to
the SID of the current schema node minus the SID of the 'rpc'.
* In the case of an 'action input' or 'action output', deltas are
equal to the SID of the current schema node minus the SID of the
'action'.
* In the case of an 'notification content', deltas are equal to the
SID of the current schema node minus the SID of the
'notification'.
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CBOR diagnostic notation:
{
1720 : { / system-state (SID 1720) /
1 : { / clock (SID 1721) /
2 : "2015-10-02T14:47:24Z-05:00", / current-datetime(SID 1723)/
1 : "2015-09-15T09:12:58Z-05:00" / boot-datetime (SID 1722) /
}
}
}
CBOR encoding:
A1 # map(1)
19 06B8 # unsigned(1720)
A1 # map(1)
01 # unsigned(1)
A2 # map(2)
02 # unsigned(2)
78 1A # text(26)
323031352D31302D30325431343A34373A32345A2D30353A3030
01 # unsigned(1)
78 1A # text(26)
323031352D30392D31355430393A31323A35385A2D30353A3030
Figure 2: System state clock encoding
4.2.2. Using names in keys
CBOR map keys implemented using names MUST be encoded using a CBOR
text string data item (major type 3). A namespace-qualified name
MUST be used each time the namespace of a schema node and its parent
differ. In all other cases, the simple form of the name MUST be
used. Names and namespaces are defined in [RFC7951] section 4.
The following example shows the encoding of a 'system' container
instance using names.
Definition example from [RFC7317]:
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typedef date-and-time {
type string {
pattern '\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?(Z|[\+\-]
\d{2}:\d{2})';
}
}
container system-state {
container clock {
leaf current-datetime {
type date-and-time;
}
leaf boot-datetime {
type date-and-time;
}
}
}
CBOR diagnostic notation:
{
"ietf-system:system-state" : {
"clock" : {
"current-datetime" : "2015-10-02T14:47:24Z-05:00",
"boot-datetime" : "2015-09-15T09:12:58Z-05:00"
}
}
}
CBOR encoding:
A1 # map(1)
78 18 # text(24)
696574662D73797374656D3A73797374656D2D7374617465
A1 # map(1)
65 # text(5)
636C6F636B # "clock"
A2 # map(2)
70 # text(16)
63757272656E742D6461746574696D65
78 1A # text(26)
323031352D31302D30325431343A34373A32345A2D30353A3030
6D # text(13)
626F6F742D6461746574696D65
78 1A # text(26)
323031352D30392D31355430393A31323A35385A2D30353A3030
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4.3. The 'leaf-list'
A leaf-list MUST be encoded using a CBOR array data item (major type
4). Each entry of this array MUST be encoded accordingly to its
datatype using one of the encoding rules specified in Section 6.
The following example shows the encoding of the 'search' leaf-list
instance containing two entries, "ietf.org" and "ieee.org".
Definition example [RFC7317]:
typedef domain-name {
type string {
length "1..253";
pattern '((([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9].)
*([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9]\.?
)|\.';
}
}
leaf-list search {
type domain-name;
ordered-by user;
}
4.3.1. Using SIDs in keys
CBOR diagnostic notation:
{
1746 : [ "ietf.org", "ieee.org" ] / search (SID 1746) /
}
CBOR encoding:
A1 # map(1)
19 06D2 # unsigned(1746)
82 # array(2)
68 # text(8)
696574662E6F7267 # "ietf.org"
68 # text(8)
696565652E6F7267 # "ieee.org"
4.3.2. Using names in keys
CBOR diagnostic notation:
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{
"ietf-system:search" : [ "ietf.org", "ieee.org" ]
}
CBOR encoding:
A1 # map(1)
72 # text(18)
696574662D73797374656D3A736561726368 # "ietf-system:search"
82 # array(2)
68 # text(8)
696574662E6F7267 # "ietf.org"
68 # text(8)
696565652E6F7267 # "ieee.org"
4.4. The 'list' and 'list' instance(s)
A list or a subset of a list MUST be encoded using a CBOR array data
item (major type 4). Each list instance within this CBOR array is
encoded using a CBOR map data item (major type 5) based on the
encoding rules of a collection as defined in Section 4.2.
It is important to note that this encoding rule also apply to a
single 'list' instance.
The following examples show the encoding of a 'server' list using
SIDs or names.
Definition example from [RFC7317]:
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list server {
key name;
leaf name {
type string;
}
choice transport {
case udp {
container udp {
leaf address {
type host;
mandatory true;
}
leaf port {
type port-number;
}
}
}
}
leaf association-type {
type enumeration {
enum server;
enum peer;
enum pool;
}
default server;
}
leaf iburst {
type boolean;
default false;
}
leaf prefer {
type boolean;
default false;
}
}
4.4.1. Using SIDs in keys
The encoding rules of each 'list' instance are defined in
Section 4.2.1. Deltas of list members are equal to the SID of the
current schema node minus the SID of the 'list'.
CBOR diagnostic notation:
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{
1756 : [ / server (SID 1756) /
{
3 : "NRC TIC server", / name (SID 1759) /
5 : { / udp (SID 1761) /
1 : "tic.nrc.ca", / address (SID 1762) /
2 : 123 / port (SID 1763) /
},
1 : 0, / association-type (SID 1757) /
2 : false, / iburst (SID 1758) /
4 : true / prefer (SID 1760) /
},
{
3 : "NRC TAC server", / name (SID 1759) /
5 : { / udp (SID 1761) /
1 : "tac.nrc.ca" / address (SID 1762) /
}
}
]
}
CBOR encoding:
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A1 # map(1)
19 06DC # unsigned(1756)
82 # array(2)
A5 # map(5)
03 # unsigned(3)
6E # text(14)
4E52432054494320736572766572 # "NRC TIC server"
05 # unsigned(5)
A2 # map(2)
01 # unsigned(1)
6A # text(10)
7469632E6E72632E6361 # "tic.nrc.ca"
02 # unsigned(2)
18 7B # unsigned(123)
01 # unsigned(1)
00 # unsigned(0)
02 # unsigned(2)
F4 # primitive(20)
04 # unsigned(4)
F5 # primitive(21)
A2 # map(2)
03 # unsigned(3)
6E # text(14)
4E52432054414320736572766572 # "NRC TAC server"
05 # unsigned(5)
A1 # map(1)
01 # unsigned(1)
6A # text(10)
7461632E6E72632E6361 # "tac.nrc.ca"
4.4.2. Using names in keys
The encoding rules of each 'list' instance are defined in
Section 4.2.2.
CBOR diagnostic notation:
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{
"ietf-system:server" : [
{
"name" : "NRC TIC server",
"udp" : {
"address" : "tic.nrc.ca",
"port" : 123
},
"association-type" : 0,
"iburst" : false,
"prefer" : true
},
{
"name" : "NRC TAC server",
"udp" : {
"address" : "tac.nrc.ca"
}
}
]
}
CBOR encoding:
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A1 # map(1)
72 # text(18)
696574662D73797374656D3A736572766572
82 # array(2)
A5 # map(5)
64 # text(4)
6E616D65 # "name"
6E # text(14)
4E52432054494320736572766572
63 # text(3)
756470 # "udp"
A2 # map(2)
67 # text(7)
61646472657373 # "address"
6A # text(10)
7469632E6E72632E6361 # "tic.nrc.ca"
64 # text(4)
706F7274 # "port"
18 7B # unsigned(123)
70 # text(16)
6173736F63696174696F6E2D74797065
00 # unsigned(0)
66 # text(6)
696275727374 # "iburst"
F4 # primitive(20)
66 # text(6)
707265666572 # "prefer"
F5 # primitive(21)
A2 # map(2)
64 # text(4)
6E616D65 # "name"
6E # text(14)
4E52432054414320736572766572
63 # text(3)
756470 # "udp"
A1 # map(1)
67 # text(7)
61646472657373 # "address"
6A # text(10)
7461632E6E72632E6361 # "tac.nrc.ca"
4.5. The 'anydata'
An anydata serves as a container for an arbitrary set of schema nodes
that otherwise appear as normal YANG-modeled data. An anydata
instance is encoded using the same rules as a container, i.e., CBOR
map. The requirement that anydata content can be modeled by YANG
implies the following:
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* CBOR map keys of any inner schema nodes MUST be set to valid
deltas or names.
* The CBOR array MUST contain either unique scalar values (as a
leaf-list, see Section 4.3), or maps (as a list, see Section 4.4).
* CBOR map values MUST follow the encoding rules of one of the
datatypes listed in Section 4.
The following example shows a possible use of an anydata. In this
example, an anydata is used to define a schema node containing a
notification event, this schema node can be part of a YANG list to
create an event logger.
Definition example:
module event-log {
...
anydata last-event; # SID 60123
This example also assumes the assistance of the following
notification.
module example-port {
...
notification example-port-fault { # SID 60200
leaf port-name { # SID 60201
type string;
}
leaf port-fault { # SID 60202
type string;
}
}
}
4.5.1. Using SIDs in keys
CBOR diagnostic notation:
{
60123 : { / last-event (SID 60123) /
77 : { / example-port-fault (SID 60200) /
1 : "0/4/21", / port-name (SID 60201) /
2 : "Open pin 2" / port-fault (SID 60202) /
}
}
}
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CBOR encoding:
A1 # map(1)
19 EADB # unsigned(60123)
A1 # map(1)
18 4D # unsigned(77)
A2 # map(2)
18 4E # unsigned(78)
66 # text(6)
302F342F3231 # "0/4/21"
18 4F # unsigned(79)
6A # text(10)
4F70656E2070696E2032 # "Open pin 2"
In some implementations, it might be simpler to use the absolute SID
tag encoding for the anydata root element. The resulting encoding is
as follows:
{
60123 : { / last-event (SID 60123) /
47(60200) : { / event-port-fault (SID 60200) /
1 : "0/4/21", / port-name (SID 60201) /
2 : "Open pin 2" / port-fault (SID 60202) /
}
}
}
4.5.2. Using names in keys
CBOR diagnostic notation:
{
"event-log:last-event" : {
"example-port:example-port-fault" : {
"port-name" : "0/4/21",
"port-fault" : "Open pin 2"
}
}
}
CBOR encoding:
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A1 # map(1)
74 # text(20)
6576656E742D6C6F673A6C6173742D6576656E74
A1 # map(1)
78 20 # text(32)
6578616D706C652D706F72743A206578616D7
06C652D706F72742D6661756C74
A2 # map(2)
69 # text(9)
706F72742D6E616D65 # "port-name"
66 # text(6)
302F342F3231 # "0/4/21"
6A # text(10)
706F72742D6661756C74 # "port-fault"
6A # text(10)
4F70656E2070696E2032 # "Open pin 2"
4.6. The 'anyxml'
An anyxml schema node is used to serialize an arbitrary CBOR content,
i.e., its value can be any CBOR binary object. anyxml value MAY
contain CBOR data items tagged with one of the tags listed in
Section 9.3, these tags shall be supported.
The following example shows a valid CBOR encoded instance consisting
of a CBOR array containing the CBOR simple values 'true', 'null' and
'true'.
Definition example from [RFC7951]:
module bar-module {
...
anyxml bar; # SID 60000
4.6.1. Using SIDs in keys
CBOR diagnostic notation:
{
60000 : [true, null, true] / bar (SID 60000) /
}
CBOR encoding:
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A1 # map(1)
19 EA60 # unsigned(60000)
83 # array(3)
F5 # primitive(21)
F6 # primitive(22)
F5 # primitive(21)
4.6.2. Using names in keys
CBOR diagnostic notation:
{
"bar-module:bar" : [true, null, true] / bar (SID 60000) /
}
CBOR encoding:
A1 # map(1)
6E # text(14)
6261722D6D6F64756C653A626172 # "bar-module:bar"
83 # array(3)
F5 # primitive(21)
F6 # primitive(22)
F5 # primitive(21)
5. Encoding of 'yang-data' extension
The yang-data extension [RFC8040] is used to define data structures
in YANG that are not intended to be implemented as part of a
datastore.
The yang-data extension MUST be encoded using the encoding rules of
nodes of data trees as defined in Section 4.2.
Just like YANG containers, yang-data extension can be encoded using
either SIDs or names.
Definition example from [I-D.ietf-core-comi] Appendix A:
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module ietf-coreconf {
...
import ietf-restconf {
prefix rc;
}
rc:yang-data yang-errors {
container error {
leaf error-tag {
type identityref {
base error-tag;
}
}
leaf error-app-tag {
type identityref {
base error-app-tag;
}
}
leaf error-data-node {
type instance-identifier;
}
leaf error-message {
type string;
}
}
}
}
5.1. Using SIDs in keys
The yang-data extensions encoded using SIDs are carried in a CBOR map
containing a single item pair. The key of this item is set to the
SID assigned to the yang-data extension container, the value is set
the CBOR encoding of this container as defined in Section 4.2.
This example shows a serialization example of the yang-errors yang-
data extension as defined in [I-D.ietf-core-comi] using SIDs as
defined in Section 3.2.
CBOR diagnostic notation:
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{
1024 : { / error (SID 1024) /
4 : 1011, / error-tag (SID 1028) /
/ = invalid-value (SID 1011) /
1 : 1018, / error-app-tag (SID 1025) /
/ = not-in-range (SID 1018) /
2 : 1740, / error-data-node (SID 1026) /
/ = timezone-utc-offset (SID 1740) /
3 : "Maximum exceeded" / error-message (SID 1027) /
}
}
CBOR encoding:
A1 # map(1)
19 0400 # unsigned(1024)
A4 # map(4)
04 # unsigned(4)
19 03F3 # unsigned(1011)
01 # unsigned(1)
19 03FA # unsigned(1018)
02 # unsigned(2)
19 06CC # unsigned(1740)
03 # unsigned(3)
70 # text(16)
4D6178696D756D206578636565646564
5.2. Using names in keys
The yang-data extensions encoded using names are carried in a CBOR
map containing a single item pair. The key of this item is set to
the namespace qualified name of the yang-data extension container,
the value is set the CBOR encoding of this container as defined in
Section 3.3.
This example shows a serialization example of the yang-errors yang-
data extension as defined in [I-D.ietf-core-comi] using names as
defined Section 3.3.
CBOR diagnostic notation:
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{
"ietf-coreconf:error" : {
"error-tag" : "invalid-value",
"error-app-tag" : "not-in-range",
"error-data-node" : "timezone-utc-offset",
"error-message" : "Maximum exceeded"
}
}
CBOR encoding:
A1 # map(1)
73 # text(19)
696574662D636F7265636F6E663A6572726F72 # "ietf-coreconf:error"
A4 # map(4)
69 # text(9)
6572726F722D746167 # "error-tag"
6D # text(13)
696E76616C69642D76616C7565 # "invalid-value"
6D # text(13)
6572726F722D6170702D746167 # "error-app-tag"
6C # text(12)
6E6F742D696E2D72616E6765 # "not-in-range"
6F # text(15)
6572726F722D646174612D6E6F6465 # "error-data-node"
73 # text(19)
74696D657A6F6E652D7574632D6F6666736574
# "timezone-utc-offset"
6D # text(13)
6572726F722D6D657373616765 # "error-message"
70 # text(16)
4D6178696D756D206578636565646564
6. Representing YANG Data Types in CBOR
The CBOR encoding of an instance of a leaf or leaf-list schema node
depends on the built-in type of that schema node. The following sub-
section defines the CBOR encoding of each built-in type supported by
YANG as listed in [RFC7950] section 4.2.4. Each subsection shows an
example value assigned to a schema node instance of the discussed
built-in type.
6.1. The unsigned integer Types
Leafs of type uint8, uint16, uint32 and uint64 MUST be encoded using
a CBOR unsigned integer data item (major type 0).
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The following example shows the encoding of a 'mtu' leaf instance set
to 1280 bytes.
Definition example from [RFC8344]:
leaf mtu {
type uint16 {
range "68..max";
}
}
CBOR diagnostic notation: 1280
CBOR encoding: 19 0500
6.2. The integer Types
Leafs of type int8, int16, int32 and int64 MUST be encoded using
either CBOR unsigned integer (major type 0) or CBOR negative integer
(major type 1), depending on the actual value.
The following example shows the encoding of a 'timezone-utc-offset'
leaf instance set to -300 minutes.
Definition example from [RFC7317]:
leaf timezone-utc-offset {
type int16 {
range "-1500 .. 1500";
}
}
CBOR diagnostic notation: -300
CBOR encoding: 39 012B
6.3. The 'decimal64' Type
Leafs of type decimal64 MUST be encoded using a decimal fraction as
defined in Section 3.4.4 of [RFC8949].
The following example shows the encoding of a 'my-decimal' leaf
instance set to 2.57.
Definition example from [RFC7317]:
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leaf my-decimal {
type decimal64 {
fraction-digits 2;
range "1 .. 3.14 | 10 | 20..max";
}
}
CBOR diagnostic notation: 4([-2, 257])
CBOR encoding: C4 82 21 19 0101
6.4. The 'string' Type
Leafs of type string MUST be encoded using a CBOR text string data
item (major type 3).
The following example shows the encoding of a 'name' leaf instance
set to "eth0".
Definition example from [RFC8343]:
leaf name {
type string;
}
CBOR diagnostic notation: "eth0"
CBOR encoding: 64 65746830
6.5. The 'boolean' Type
Leafs of type boolean MUST be encoded using a CBOR simple value
'true' (major type 7, additional information 21) or 'false' (major
type 7, additional information 20).
The following example shows the encoding of an 'enabled' leaf
instance set to 'true'.
Definition example from [RFC7317]:
leaf enabled {
type boolean;
}
CBOR diagnostic notation: true
CBOR encoding: F5
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6.6. The 'enumeration' Type
Leafs of type enumeration MUST be encoded using a CBOR unsigned
integer (major type 0) or CBOR negative integer (major type 1),
depending on the actual value. Enumeration values are either
explicitly assigned using the YANG statement 'value' or automatically
assigned based on the algorithm defined in [RFC7950] section 9.6.4.2.
The following example shows the encoding of an 'oper-status' leaf
instance set to 'testing'.
Definition example from [RFC7317]:
leaf oper-status {
type enumeration {
enum up { value 1; }
enum down { value 2; }
enum testing { value 3; }
enum unknown { value 4; }
enum dormant { value 5; }
enum not-present { value 6; }
enum lower-layer-down { value 7; }
}
}
CBOR diagnostic notation: 3
CBOR encoding: 03
Values of 'enumeration' types defined in a 'union' type MUST be
encoded using a CBOR text string data item (major type 3) and MUST
contain one of the names assigned by 'enum' statements in YANG. The
encoding MUST be enclosed by the enumeration CBOR tag as specified in
Section 9.3.
Definition example from [RFC7950]:
type union {
type int32;
type enumeration {
enum unbounded;
}
}
CBOR diagnostic notation: 44("unbounded")
CBOR encoding: D8 2C 69 756E626F756E646564
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6.7. The 'bits' Type
Keeping in mind that bit positions are either explicitly assigned
using the YANG statement 'position' or automatically assigned based
on the algorithm defined in [RFC7950] section 9.7.4.2, each element
of type bits could be seen as a set of bit positions (or offsets from
position 0), that have a value of ether 1, which represents the bit
being set or 0, which represents that the bit is not set.
Leafs of type bits MUST be encoded either using a CBOR array or byte
string (major type 2). In case CBOR array representation is used,
each element is either a positive integer (major type 0 with value 0
being disallowed) that can be used to calculate the offset of the
next byte string, or a byte string (major type 2) that carries the
information whether certain bits are set or not. The initial offset
value is 0 and each unsigned integer modifies the offset value of the
next byte string by the integer value multiplied by 8. For example,
if the bit offset is 0 and there is an integer with value 5, the
first byte of the byte string that follows will represent bit
positions 40 to 47 both ends included. If the byte string has a
second byte, it will carry information about bits 48 to 55 and so on.
Within each byte, bits are assigned from least to most significant.
After the byte string, the offset is modified by the number of bytes
in the byte string multiplied by 8. Bytes with no bits set at the
end of the byte string are removed. An example follows.
The following example shows the encoding of an 'alarm-state' leaf
instance with the 'critical', 'warning' and 'indeterminate' flags
set.
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typedef alarm-state {
type bits {
bit unknown;
bit under-repair;
bit critical;
bit major;
bit minor;
bit warning {
position 8;
}
bit indeterminate {
position 128;
}
}
}
leaf alarm-state {
type alarm-state;
}
CBOR diagnostic notation: [h'0401', 14, h'01']
CBOR encoding: 83 42 0401 0E 41 01
In a number of cases the array would only need to have one element -
a byte string with a small number of bytes inside. For this case, it
is expected to omit the array element and have only the byte array
that would have been inside. To illustrate this, let us consider the
same example yang definition, but this time encoding only 'under-
repair' and 'critical' flags. The result would be
CBOR diagnostic notation: h'06'
CBOR encoding: 41 06
Elements in the array MUST be either byte strings or positive
unsigned integers, where byte strings and integers MUST alternate,
i.e., adjacent byte strings or adjacent integers are an error. An
array with a single byte string MUST instead by encoded as just that
byte string. An array with a single positive integer is an error.
Values of 'bit' types defined in a 'union' type MUST be encoded using
a CBOR text string data item (major type 3) and MUST contain a space-
separated sequence of names of 'bit' that are set. The encoding MUST
be enclosed by the bits CBOR tag as specified in Section 9.3.
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The following example shows the encoding of an 'alarm-state' leaf
instance defined using a union type with the 'under-repair' and
'critical' flags set.
Definition example:
leaf alarm-state-2 {
type union {
type alarm-state;
type bits {
bit extra-flag;
}
}
}
CBOR diagnostic notation: 43("under-repair critical")
CBOR encoding: D8 2B 75 756E6465722D72657061697220637269746963616C
6.8. The 'binary' Type
Leafs of type binary MUST be encoded using a CBOR byte string data
item (major type 2).
The following example shows the encoding of an 'aes128-key' leaf
instance set to 0x1f1ce6a3f42660d888d92a4d8030476e.
Definition example:
leaf aes128-key {
type binary {
length 16;
}
}
CBOR diagnostic notation: h'1F1CE6A3F42660D888D92A4D8030476E'
CBOR encoding: 50 1F1CE6A3F42660D888D92A4D8030476E
6.9. The 'leafref' Type
Leafs of type leafref MUST be encoded using the rules of the schema
node referenced by the 'path' YANG statement.
The following example shows the encoding of an 'interface-state-ref'
leaf instance set to "eth1".
Definition example from [RFC8343]:
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typedef interface-state-ref {
type leafref {
path "/interfaces-state/interface/name";
}
}
container interfaces-state {
list interface {
key "name";
leaf name {
type string;
}
leaf-list higher-layer-if {
type interface-state-ref;
}
}
}
CBOR diagnostic notation: "eth1"
CBOR encoding: 64 65746831
6.10. The 'identityref' Type
This specification supports two approaches for encoding identityref,
a YANG Schema Item iDentifier as defined in Section 3.2 or a name as
defined in [RFC7951] section 6.8.
6.10.1. SIDs as identityref
When schema nodes of type identityref are implemented using SIDs,
they MUST be encoded using a CBOR unsigned integer data item (major
type 0). (Note that no delta mechanism is employed for SIDs as
identityref.)
The following example shows the encoding of a 'type' leaf instance
set to the value 'iana-if-type:ethernetCsmacd' (SID 1880).
Definition example from [RFC7317]:
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identity interface-type {
}
identity iana-interface-type {
base interface-type;
}
identity ethernetCsmacd {
base iana-interface-type;
}
leaf type {
type identityref {
base interface-type;
}
}
CBOR diagnostic notation: 1880
CBOR encoding: 19 0758
6.10.2. Name as identityref
Alternatively, an identityref MAY be encoded using a name as defined
in Section 3.3. When names are used, identityref MUST be encoded
using a CBOR text string data item (major type 3). If the identity
is defined in different module than the leaf node containing the
identityref data node, the namespace qualified form MUST be used.
Otherwise, both the simple and namespace qualified forms are
permitted. Names and namespaces are defined in Section 3.3.
The following example shows the encoding of the identity 'iana-if-
type:ethernetCsmacd' using its namespace qualified name. This
example is described in Section 6.10.1.
CBOR diagnostic notation: "iana-if-type:ethernetCsmacd"
CBOR encoding: 78 1b
69616E612D69662D747970653A65746865726E657443736D616364
6.11. The 'empty' Type
Leafs of type empty MUST be encoded using the CBOR null value (major
type 7, additional information 22).
The following example shows the encoding of a 'is-router' leaf
instance when present.
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Definition example from [RFC8344]:
leaf is-router {
type empty;
}
CBOR diagnostic notation: null
CBOR encoding: F6
6.12. The 'union' Type
Leafs of type union MUST be encoded using the rules associated with
one of the types listed. When used in a union, the following YANG
datatypes are enclosed by a CBOR tag to avoid confusion between
different YANG datatypes encoded using the same CBOR major type.
* bits
* enumeration
* identityref
* instance-identifier
See Section 9.3 for the assigned value of these CBOR tags.
As mentioned in Section 6.6 and in Section 6.7, 'enumeration' and
'bits' are encoded as CBOR text string data item (major type 3) when
defined within a 'union' type.
The following example shows the encoding of an 'ip-address' leaf
instance when set to "2001:db8:a0b:12f0::1".
Definition example from [RFC7317]:
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typedef ipv4-address {
type string {
pattern '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}
([0-9][1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(%[\p{N}
\p{L}]+)?';
}
}
typedef ipv6-address {
type string {
pattern '((:|[0-9a-fA-F]{0,4}):)([0-9a-fA-F]{0,4}:){0,5}((([0-9a
-fA-F]{0,4}:)?(:|[0-9a-fA-F]{0,4}))|(((25[0-5]|2[0-4][0
-9]|[01]?[0-9]?[0-9])\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0
-9]?[0-9])))(%[\p{N}\p{L}]+)?';
pattern '(([^:]+:){6}(([^:]+:[^:]+)|(.*\..*)))|((([^:]+:)*[^:]+)
?::(([^:]+:)*[^:]+)?)(%.+)?';
}
}
typedef ip-address {
type union {
type ipv4-address;
type ipv6-address;
}
}
leaf address {
type inet:ip-address;
}
CBOR diagnostic notation: "2001:db8:a0b:12f0::1"
CBOR encoding: 74 323030313A6462383A6130623A313266303A3A31
6.13. The 'instance-identifier' Type
This specification supports two approaches for encoding an instance-
identifier, one based on YANG Schema Item iDentifier as defined in
Section 3.2 and one based on names as defined in Section 3.3.
6.13.1. SIDs as instance-identifier
SIDs uniquely identify a schema node. In the case of a single
instance schema node, i.e. a schema node defined at the root of a
YANG module or submodule or schema nodes defined within a container,
the SID is sufficient to identify this instance.
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In the case of a schema node member of a YANG list, a SID is combined
with the list key(s) to identify each instance within the YANG
list(s).
Single instance schema nodes MUST be encoded using a CBOR unsigned
integer data item (major type 0) and set to the targeted schema node
SID.
Schema nodes member of a YANG list MUST be encoded using a CBOR array
data item (major type 4) containing the following entries:
* The first entry MUST be encoded as a CBOR unsigned integer data
item (major type 0) and set to the targeted schema node SID.
* The following entries MUST contain the value of each key required
to identify the instance of the targeted schema node. These keys
MUST be ordered as defined in the 'key' YANG statement, starting
from top level list, and follow by each of the subordinate
list(s).
Examples within this section assume the definition of a schema node
of type 'instance-identifier':
Definition example from [RFC7950]:
container system {
...
leaf reporting-entity {
type instance-identifier;
}
leaf contact { type string; }
leaf hostname { type inet:domain-name; } } ~~~~
*First example:*
The following example shows the encoding of the 'reporting-entity'
value referencing data node instance "/system/contact" (SID 1741).
Definition example from [RFC7317]:
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container system {
leaf contact {
type string;
}
leaf hostname {
type inet:domain-name;
}
}
CBOR diagnostic notation: 1741
CBOR encoding: 19 06CD
*Second example:*
The following example shows the encoding of the 'reporting-entity'
value referencing list instance "/system/authentication/user/
authorized-key/key-data" (SID 1734) for user name "bob" and
authorized-key "admin".
Definition example from [RFC7317]:
list user {
key name;
leaf name {
type string;
}
leaf password {
type ianach:crypt-hash;
}
list authorized-key {
key name;
leaf name {
type string;
}
leaf algorithm {
type string;
}
leaf key-data {
type binary;
}
}
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CBOR diagnostic notation: [1734, "bob", "admin"]
CBOR encoding:
83 # array(3)
19 06C6 # unsigned(1734)
63 # text(3)
626F62 # "bob"
65 # text(5)
61646D696E # "admin"
*Third example:*
The following example shows the encoding of the 'reporting-entity'
value referencing the list instance "/system/authentication/user"
(SID 1730) corresponding to user name "jack".
CBOR diagnostic notation: [1730, "jack"]
CBOR encoding:
82 # array(2)
19 06C2 # unsigned(1730)
64 # text(4)
6A61636B # "jack"
6.13.2. Names as instance-identifier
An "instance-identifier" value is encoded as a string that is
analogical to the lexical representation in XML encoding; see
Section 9.13.2 in [RFC7950]. However, the encoding of namespaces in
instance-identifier values follows the rules stated in Section 3.3,
namely:
* The leftmost (top-level) data node name is always in the namespace
qualified form.
* Any subsequent data node name is in the namespace qualified form
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
names appearing in predicates.
For example,
/ietf-interfaces:interfaces/interface[name='eth0']/ietf-ip:ipv4/ip
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is a valid instance-identifier value because the data nodes
"interfaces", "interface", and "name" are defined in the module
"ietf-interfaces", whereas "ipv4" and "ip" are defined in "ietf-ip".
The resulting xpath MUST be encoded using a CBOR text string data
item (major type 3).
*First example:*
This example is described in Section 6.13.1.
CBOR diagnostic notation: "/ietf-system:system/contact"
CBOR encoding:
78 1c 2F696574662D73797374656D3A73797374656D2F636F6E74616374
*Second example:*
This example is described in Section 6.13.1.
CBOR diagnostic notation:
"/ietf-system:system/authentication/user[name='bob']/authorized-key
[name='admin']/key-data"
CBOR encoding:
78 59
2F696574662D73797374656D3A73797374656D2F61757468656E74696361
74696F6E2F757365725B6E616D653D27626F62275D2F617574686F72697A
65642D6B65790D0A5B6E616D653D2761646D696E275D2F6B65792D64617461
*Third example:*
This example is described in Section 6.13.1.
CBOR diagnostic notation:
"/ietf-system:system/authentication/user[name='jack']"
CBOR encoding:
78 33
2F696574662D73797374656D3A73797374656D2F61757468656E74696361
74696F6E2F757365725B6E616D653D27626F62275D
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7. Content-Types
The following Content-Type is defined:
application/yang-data+cbor; id=name: This Content-Type represents a
CBOR YANG document containing one or multiple data node values.
Each data node is identified by its associated namespace qualified
name as defined in Section 3.3.
FORMAT: CBOR map of name, instance-value
The message payload of Content-Type 'application/yang-data+cbor'
is encoded using a CBOR map. Each entry within the CBOR map
contains the data node identifier (i.e. its namespace qualified
name) and the associated instance-value. Instance-values are
encoded using the rules defined in Section 4
8. Security Considerations
The security considerations of [RFC8949] and [RFC7950] apply.
This document defines an alternative encoding for data modeled in the
YANG data modeling language. As such, this encoding does not
contribute any new security issues in addition of those identified
for the specific protocol or context for which it is used.
To minimize security risks, software on the receiving side SHOULD
reject all messages that do not comply to the rules of this document
and reply with an appropriate error message to the sender.
9. IANA Considerations
9.1. Media-Types Registry
This document adds the following Media-Type to the "Media Types"
registry.
+================+============================+===========+
| Name | Template | Reference |
+================+============================+===========+
| yang-data+cbor | application/yang-data+cbor | RFC XXXX |
+----------------+----------------------------+-----------+
Table 2
// RFC Ed.: please replace RFC XXXX with this RFC number and remove
this note.
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Type name: application
Subtype name: yang-data+cbor
Required parameters: none
Optional parameters: none
Encoding considerations: binary (CBOR)
Security considerations: see Section 8 of RFC XXXX
Published specification: RFC XXXX
Person & email address to contact for further information: CORE WG
mailing list (core@ietf.org), or IETF Applications and Real-Time
Area (art@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
9.2. CoAP Content-Formats Registry
This document adds the following Content-Format to the "CoAP Content-
Formats", within the "Constrained RESTful Environments (CoRE)
Parameters" registry.
+====================+================+======+===========+
| Media Type | Content Coding | ID | Reference |
+====================+================+======+===========+
| application/yang- | | TBD1 | RFC XXXX |
| data+cbor; id=name | | | |
+--------------------+----------------+------+-----------+
Table 3
// RFC Ed.: please replace TBD1 with assigned IDs and remove this
note. // RFC Ed.: please replace RFC XXXX with this RFC number and
remove this note.
9.3. CBOR Tags Registry
This specification requires the assignment of CBOR tags for the
following YANG datatypes. These tags are added to the CBOR Tags
Registry as defined in Section 9.2 of [RFC8949].
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+=====+==================+=============================+===========+
| Tag | Data Item | Semantics | Reference |
+=====+==================+=============================+===========+
| 43 | text string | YANG bits datatype | [this] |
+-----+------------------+-----------------------------+-----------+
| | | ; see Section 6.7. | |
+-----+------------------+-----------------------------+-----------+
| 44 | text string | YANG enumeration datatype | [this] |
+-----+------------------+-----------------------------+-----------+
| | | ; see Section 6.6. | |
+-----+------------------+-----------------------------+-----------+
| 45 | unsigned integer | YANG identityref datatype | [this] |
+-----+------------------+-----------------------------+-----------+
| | or text string | ; see Section 6.10. | |
+-----+------------------+-----------------------------+-----------+
| 46 | unsigned integer | YANG instance-identifier | [this] |
+-----+------------------+-----------------------------+-----------+
| | or text string | datatype; see Section 6.13. | [this] |
+-----+------------------+-----------------------------+-----------+
| | or array | | |
+-----+------------------+-----------------------------+-----------+
| 47 | unsigned integer | YANG Schema Item iDentifier | |
+-----+------------------+-----------------------------+-----------+
| | | ; see Section 3.2. | [this] |
+-----+------------------+-----------------------------+-----------+
Table 4
// RFC Ed.: please replace [this] with RFC number and remove this
note
10. Acknowledgments
This document has been largely inspired by the extensive works done
by Andy Bierman and Peter van der Stok on [I-D.ietf-core-comi].
[RFC7951] has also been a critical input to this work. The authors
would like to thank the authors and contributors to these two drafts.
The authors would also like to acknowledge the review, feedback, and
comments from Ladislav Lhotka and Juergen Schoenwaelder.
11. References
11.1. Normative References
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[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>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/info/rfc8949>.
11.2. Informative References
[I-D.ietf-core-comi]
Veillette, M., Stok, P., Pelov, A., Bierman, A., and I.
Petrov, "CoAP Management Interface (CORECONF)", Work in
Progress, Internet-Draft, draft-ietf-core-comi-11, 17
January 2021, <http://www.ietf.org/internet-drafts/draft-
ietf-core-comi-11.txt>.
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[I-D.ietf-core-sid]
Veillette, M., Pelov, A., and I. Petrov, "YANG Schema Item
iDentifier (YANG SID)", Work in Progress, Internet-Draft,
draft-ietf-core-sid-15, 17 January 2021,
<http://www.ietf.org/internet-drafts/draft-ietf-core-sid-
15.txt>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>.
[RFC7317] Bierman, A. and M. Bjorklund, "A YANG Data Model for
System Management", RFC 7317, DOI 10.17487/RFC7317, August
2014, <https://www.rfc-editor.org/info/rfc7317>.
[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",
RFC 7951, DOI 10.17487/RFC7951, August 2016,
<https://www.rfc-editor.org/info/rfc7951>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[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>.
[RFC8343] Bjorklund, M., "A YANG Data Model for Interface
Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
<https://www.rfc-editor.org/info/rfc8343>.
[RFC8344] Bjorklund, M., "A YANG Data Model for IP Management",
RFC 8344, DOI 10.17487/RFC8344, March 2018,
<https://www.rfc-editor.org/info/rfc8344>.
Authors' Addresses
Michel Veillette (editor)
Trilliant Networks Inc.
610 Rue du Luxembourg
Granby Quebec J2J 2V2
Canada
Email: michel.veillette@trilliantinc.com
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Ivaylo Petrov (editor)
Google Switzerland GmbH
Brandschenkestrasse 110
CH-8002 Zurich
Switzerland
Email: ivaylopetrov@google.com
Alexander Pelov
Acklio
1137A avenue des Champs Blancs
35510 Cesson-Sevigne
France
Email: a@ackl.io
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