Internet DRAFT - draft-ietf-core-comi
draft-ietf-core-comi
CoRE M. V. Veillette, Ed.
Internet-Draft Trilliant Networks Inc.
Intended status: Standards Track P. van der Stok, Ed.
Expires: 5 September 2024 consultant
A. Pelov, Ed.
IMT Atlantique
A. Bierman
YumaWorks
C. Bormann, Ed.
Universität Bremen TZI
4 March 2024
CoAP Management Interface (CORECONF)
draft-ietf-core-comi-17
Abstract
This document describes a network management interface for
constrained devices and networks, called CoAP Management Interface
(CORECONF). The Constrained Application Protocol (CoAP) is used to
access datastore and data node resources specified in YANG, or SMIv2
converted to YANG. CORECONF uses the YANG to CBOR mapping and
converts YANG identifier strings to numeric identifiers for payload
size reduction. CORECONF extends the set of YANG based protocols,
NETCONF and RESTCONF, with the capability to manage constrained
devices and networks.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at https://core-
wg.github.io/comi/draft-ietf-core-comi.html. Status information for
this document may be found at https://datatracker.ietf.org/doc/draft-
ietf-core-comi/.
Discussion of this document takes place on the core Working Group
mailing list (mailto:core@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/core/. Subscribe at
https://www.ietf.org/mailman/listinfo/core/.
Source for this draft and an issue tracker can be found at
https://github.com/core-wg/comi.
Veillette, et al. Expires 5 September 2024 [Page 1]
Internet-Draft CORECONF March 2024
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 5 September 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Example syntax . . . . . . . . . . . . . . . . . . . . . 5
2. CORECONF Architecture . . . . . . . . . . . . . . . . . . . . 5
2.1. Major differences between RESTCONF and CORECONF . . . . . 7
2.1.1. Differences due to CoAP and its efficient usage . . . 7
2.1.2. Differences due to the use of CBOR . . . . . . . . . 7
2.2. Compression of YANG identifiers . . . . . . . . . . . . . 8
2.2.1. Instance-identifiers . . . . . . . . . . . . . . . . 8
2.3. Media-Types . . . . . . . . . . . . . . . . . . . . . . . 8
2.4. Unified datastore . . . . . . . . . . . . . . . . . . . . 10
3. CoAP Interface . . . . . . . . . . . . . . . . . . . . . . . 10
3.1. Data Retrieval . . . . . . . . . . . . . . . . . . . . . 11
3.1.1. Using the 'c' query parameter . . . . . . . . . . . . 12
3.1.2. Using the 'd' query parameter . . . . . . . . . . . . 12
Veillette, et al. Expires 5 September 2024 [Page 2]
Internet-Draft CORECONF March 2024
3.1.3. FETCH . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2. Data Editing . . . . . . . . . . . . . . . . . . . . . . 14
3.2.1. Data Ordering . . . . . . . . . . . . . . . . . . . . 15
3.2.2. POST . . . . . . . . . . . . . . . . . . . . . . . . 15
3.2.3. iPATCH . . . . . . . . . . . . . . . . . . . . . . . 15
3.3. Full datastore access . . . . . . . . . . . . . . . . . . 16
3.3.1. Full datastore examples . . . . . . . . . . . . . . . 17
3.4. Event stream . . . . . . . . . . . . . . . . . . . . . . 17
3.4.1. Filtering Notifications . . . . . . . . . . . . . . . 18
3.4.2. Notify Examples . . . . . . . . . . . . . . . . . . . 19
3.5. RPC and Action statements . . . . . . . . . . . . . . . . 21
3.5.1. RPC Example . . . . . . . . . . . . . . . . . . . . . 21
3.5.2. Action Example . . . . . . . . . . . . . . . . . . . 22
4. Use of Block-wise Transfers . . . . . . . . . . . . . . . . . 24
5. Application Discovery . . . . . . . . . . . . . . . . . . . . 25
5.1. YANG library . . . . . . . . . . . . . . . . . . . . . . 25
5.2. Resource Discovery . . . . . . . . . . . . . . . . . . . 25
5.2.1. Datastore Resource Discovery . . . . . . . . . . . . 25
5.2.2. Data node Resource Discovery . . . . . . . . . . . . 26
5.2.3. Event stream Resource Discovery . . . . . . . . . . . 27
6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 27
7. Security Considerations . . . . . . . . . . . . . . . . . . . 31
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31
8.1. Resource Type (rt=) Link Target Attribute Values
Registry . . . . . . . . . . . . . . . . . . . . . . . . 31
8.2. CoAP Content-Formats Registry . . . . . . . . . . . . . . 32
8.3. Media Types Registry . . . . . . . . . . . . . . . . . . 32
8.4. YANG Namespace and Module Name Registration . . . . . . . 34
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 34
9.1. Normative References . . . . . . . . . . . . . . . . . . 34
9.2. Informative References . . . . . . . . . . . . . . . . . 37
Appendix A. ietf-coreconf YANG module . . . . . . . . . . . . . 38
Appendix B. ietf-coreconf .sid file . . . . . . . . . . . . . . 44
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 47
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 48
1. Introduction
The Constrained Application Protocol (CoAP) [RFC7252] is designed for
Machine to Machine (M2M) applications such as smart energy, smart
city, and building control. Constrained devices need to be managed
in an automatic fashion to handle the large quantities of devices
that are expected in future installations. Messages between devices
need to be as small and infrequent as possible. The implementation
complexity and runtime resources need to be as small as possible.
Veillette, et al. Expires 5 September 2024 [Page 3]
Internet-Draft CORECONF March 2024
This specification describes the CoAP Management Interface (CORECONF)
which uses CoAP methods to access structured data defined in YANG
[RFC7950]. This specification is complementary to [RFC8040] which
describes a REST-like interface called RESTCONF, which uses HTTP
methods to access structured data defined in YANG.
The use of standardized data models specified in a standardized
language, such as YANG, promotes interoperability between devices and
applications from different manufacturers.
CORECONF and RESTCONF are intended to work in a stateless client-
server fashion. They use a single round-trip to complete a single
editing transaction, where NETCONF needs multiple round trips.
To promote small messages, CORECONF uses a YANG to CBOR mapping
[RFC9254] and numeric identifiers [I-D.ietf-core-sid] to minimize
CBOR payloads and URI length.
1.1. Terminology
The following terms are defined in the YANG data modeling language
[RFC7950]: action, anydata, anyxml, client, container, data model,
data node, identity, instance identifier, leaf, leaf-list, list,
module, RPC, schema node, server, submodule.
The following terms are defined in [RFC6241]: configuration data,
datastore, state data.
The following term is defined in [I-D.ietf-core-sid]: YANG schema
item identifier (YANG SID, often shortened to simply SID).
The following terms are defined in the CoAP protocol [RFC7252]:
Confirmable Message, Content-Format, Endpoint.
The following terms are defined in this document:
data node resource: a CoAP resource that models a YANG data node.
datastore resource: a CoAP resource that models a YANG datastore.
event stream resource: a CoAP resource used by clients to observe
YANG notifications.
notification instance: An instance of a schema node of type
notification, specified in a YANG module implemented by the
server. The instance is generated in the server at the occurrence
of the corresponding event and reported by an event stream
resource.
Veillette, et al. Expires 5 September 2024 [Page 4]
Internet-Draft CORECONF March 2024
list instance identifier: Handle used to identify a YANG data node
that is an instance of a YANG "list", specified with the values of
the key leaves of the list.
single instance identifier: Handle used to identify a specific data
node which can be instantiated only once. This includes data
nodes defined at the root of a YANG module and data nodes defined
within a container. This excludes data nodes defined within a
list or any children of these data nodes.
instance-identifier: List instance identifier or single instance
identifier.
instance-value: The value assigned to a data node instance.
Instance-values are serialized into the payload according to the
rules defined in Section 4 of [RFC9254]. In a yang-instances data
item, the reference SID applying to the instance-value is provided
by the SID in the corresponding instance-identifier.
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.
1.2. Example syntax
CBOR is used to encode CORECONF request and response payloads. The
CBOR syntax of the YANG payloads is specified in [RFC9254], based on
[RFC8949] and [RFC8742]. The payload examples are notated in
Diagnostic notation (defined in Section 8 of [RFC8949] and Appendix G
of [RFC8610]), which can be automatically converted to CBOR.
2. CORECONF Architecture
This section describes the CORECONF architecture to use CoAP for
reading and modifying the content of datastore(s) used for the
management of the instrumented node.
Veillette, et al. Expires 5 September 2024 [Page 5]
Internet-Draft CORECONF March 2024
+----------------------------------------------------------------+
| SMIv2 specification (optional) (2) |
+------------------------------+---------------------------------+
|
v
+----------------------------------------------------------------+
| YANG specification (1) |
+--------+--------------------------------------------+----------+
| |
Client v Server v
+--------------+ +-------------------------+
| Request +--> CoAP request(3) -->| Indication |
| Confirm |<-- CoAP response(3)<--+ Response (4) |
| | | |
| |<==== Security (7) ===>| +---------------------+ |
+--------------+ | | Datastore(s) (5) | |
| +---------------------+ |
| |
| +---------------------+ |
| | Event stream(s) (6) | |
| +---------------------+ |
+-------------------------+
Figure 1: Abstract CORECONF architecture
Figure 1 is a high-level representation of the main elements of the
CORECONF management architecture. The different numbered components
of Figure 1 are discussed according to the component number.
(1) YANG specification: contains a set of named and versioned
modules.
(2) SMIv2 specification: Optional part that consists of a named
module which, specifies a set of variables and "conceptual
tables". There is an algorithm to translate SMIv2 specifications
to YANG specifications.
(3) CoAP request/response messages: The CORECONF client sends
request messages to and receives response messages from the
CORECONF server.
(4) Request, Indication, Response, Confirm: Processes performed by
the CORECONF clients and servers.
(5) Datastore: A resource used to access configuration data, state
Veillette, et al. Expires 5 September 2024 [Page 6]
Internet-Draft CORECONF March 2024
data, RPCs, and actions. A CORECONF server supports a single
unified datastore. Multiple datastores, for instance as those
defined by Network Management Datastore Architecture (NMDA)
[RFC8342], are out of scope of this specification.
(6) Event stream: A resource used to get real-time notifications. A
CORECONF server may support multiple Event streams serving
different purposes such as normal monitoring, diagnostic, syslog,
security monitoring.
(7) Security: The server MUST prevent unauthorized users from
reading or writing any CORECONF resources. CORECONF relies on
security protocols such as DTLS [RFC6347][RFC9147] or OSCORE
[RFC8613] to secure CoAP communications.
2.1. Major differences between RESTCONF and CORECONF
CORECONF is a RESTful protocol for small devices where saving bytes
to transport a message is very important. Contrary to RESTCONF, many
design decisions are motivated by the saving of bytes. Consequently,
CORECONF is not a RESTCONF over CoAP protocol, but differs more
significantly from RESTCONF.
2.1.1. Differences due to CoAP and its efficient usage
* CORECONF uses CoAP/UDP as transport protocol and CBOR as payload
format [RFC9254]. RESTCONF uses HTTP/TCP as transport protocol
and JSON or XML as payload formats.
* CORECONF uses the methods FETCH and iPATCH to access data nodes.
RESTCONF uses instead the HTTP method PATCH and the HTTP method
GET with the "fields" Query parameter.
* RESTCONF uses the HTTP methods HEAD, and OPTIONS, which are not
supported by CoAP.
* CORECONF does not support "insert" query parameter (first, last,
before, after) and the "point" query parameter which are supported
by RESTCONF.
* CORECONF does not support the "start-time" and "stop-time" query
parameters to retrieve past notifications.
2.1.2. Differences due to the use of CBOR
* CORECONF encodes YANG identifier strings as numbers, where
RESTCONF does not.
Veillette, et al. Expires 5 September 2024 [Page 7]
Internet-Draft CORECONF March 2024
* CORECONF also differs in the handling of default values, only
'report-all' and 'trim' options are supported.
2.2. Compression of YANG identifiers
In the YANG specification, items are identified with a name string.
In order to significantly reduce the size of identifiers used in
CORECONF, numeric identifiers called YANG Schema Item iDentifier
(YANG SID or simply SID) are used instead.
2.2.1. Instance-identifiers
Instance-identifiers are used to uniquely identify data node
instances within a datastore. This YANG built-in type is defined in
Section 9.13 of [RFC7950]. An instance-identifier is composed of the
data node identifier (i.e., a SID) and, for data nodes within
list(s), the keys used to index within these list(s).
In CORECONF, instance-identifiers are carried in the payload of FETCH
and PATCH requests. They are encoded in CBOR based on the rules
defined in Section 6.13.1 of [RFC9254].
2.3. Media-Types
CORECONF uses Media-Types based on the YANG to CBOR mapping specified
in [RFC9254].
The following new Media-Types based on CBOR sequences [RFC8742] are
defined in this document:
application/yang-identifiers+cbor-seq: This Media-Type represents a
CBOR YANG document containing a list of instance-identifiers used
to target specific data node instances within a datastore.
FORMAT: CBOR sequence of instance-identifiers
The message payload of Media-Type 'application/yang-
identifiers+cbor-seq' is encoded using a CBOR sequence. Each item
of this CBOR sequence contains an instance-identifier encoded as
defined in Section 6.13.1 of [RFC9254].
application/yang-instances+cbor-seq: This Media-Type represents a
CBOR YANG document containing a list of data node instances. Each
data node instance is identified by its associated instance-
identifier.
FORMAT: CBOR sequence of CBOR maps of instance-identifier,
instance-value
Veillette, et al. Expires 5 September 2024 [Page 8]
Internet-Draft CORECONF March 2024
The message payload of Media-Type 'application/yang-
instances+cbor-seq' is encoded using a CBOR sequence. Each item
within this CBOR sequence contains a CBOR map carrying an
instance-identifier and associated instance-value. Instance-
identifiers are encoded using the rules defined in Section 6.13.1
of [RFC9254], instance-values are encoded using the rules defined
in Section 4 of [RFC9254]. The reference SID applying to the
instance-value is provided by the SID in the instance-identifier.
When present in an iPATCH request payload, this Media-Type carry a
list of data node instances to be replaced, created, or deleted.
For each data node instance D, for which the instance-identifier
is the same as a data node instance I, in the targeted datastore
resource: the value of D replaces the value of I. When the value
of D is null, the data node instance I is removed. When the
targeted datastore resource does not contain a data node instance
with the same instance-identifier as D, a new instance is created
with the same instance-identifier and value as D (unless the value
of D is null).
The different Media-Type usages are summarized in the table below:
+===============+===========+=======================================+
| Method | Resource | Media-Type |
+===============+===========+=======================================+
| FETCH request | datastore | application/yang- |
| | | identifiers+cbor-seq |
+---------------+-----------+---------------------------------------+
| FETCH | datastore | application/yang- |
| response | | instances+cbor-seq |
+---------------+-----------+---------------------------------------+
| iPATCH | datastore | application/yang- |
| request | | instances+cbor-seq |
+---------------+-----------+---------------------------------------+
| GET response | event | application/yang- |
| | stream | instances+cbor-seq |
+---------------+-----------+---------------------------------------+
| POST request | rpc, | application/yang- |
| | action | instances+cbor-seq |
+---------------+-----------+---------------------------------------+
| POST response | rpc, | application/yang- |
| | action | instances+cbor-seq |
+---------------+-----------+---------------------------------------+
Table 1: Summary of Media-Type Usages
Veillette, et al. Expires 5 September 2024 [Page 9]
Internet-Draft CORECONF March 2024
2.4. Unified datastore
CORECONF supports a simple datastore model consisting of a single
unified datastore. This datastore provides access to both
configuration and operational data. Configuration updates performed
on this datastore are reflected immediately or with a minimal delay
as operational data.
More complex datastore models such as the Network Management
Datastore Architecture (NMDA) as defined by [RFC8342] are out of
scope of the present specification.
Characteristics of the unified datastore are summarized in the table
below:
+==============+===================================================+
| Name | Value |
+==============+===================================================+
| Name | unified |
+--------------+---------------------------------------------------+
| YANG modules | all modules |
+--------------+---------------------------------------------------+
| YANG nodes | all data nodes ("config true" and "config false") |
+--------------+---------------------------------------------------+
| Access | read-write |
+--------------+---------------------------------------------------+
| How applied | changes applied in place immediately or with a |
| | minimal delay |
+--------------+---------------------------------------------------+
| Protocols | CORECONF |
+--------------+---------------------------------------------------+
| Defined in | "ietf-coreconf" |
+--------------+---------------------------------------------------+
Table 2: Characteristics of the Unified Datastore
3. CoAP Interface
This document specifies a Management Interface. CoAP endpoints that
implement the CORECONF management protocol, support at least one
discoverable management resource of resource type (rt): core.c.ds.
The path of the discoverable management resource is left to
implementers to select (see Section 5).
YANG data node instances are accessible by performing FETCH and
iPATCH operations on the datastore resource.
Veillette, et al. Expires 5 September 2024 [Page 10]
Internet-Draft CORECONF March 2024
CORECONF also supports event stream resources used to observe
notification instances. Event stream resources can be discovered
using resource type (rt): core.c.ev.
The description of the CORECONF management interface is shown in the
table below:
+===============================+==============+===========+
| CoAP resource | Example path | rt |
+===============================+==============+===========+
| Datastore resource | /c | core.c.ds |
+-------------------------------+--------------+-----------+
| Default event stream resource | /s | core.c.ev |
+-------------------------------+--------------+-----------+
Table 3: Resources, example paths, and resource types (rt)
The path values in the table are example ones. On discovery, the
server makes the actual path values known for these resources.
The methods used by CORECONF are:
+===========+=============================================+
| Operation | Description |
+===========+=============================================+
| FETCH | Retrieve specific data nodes within a |
| | datastore resource or event stream resource |
+-----------+---------------------------------------------+
| iPATCH | Idempotently create, replace, and delete |
| | data node(s) within a datastore resource |
+-----------+---------------------------------------------+
| POST | Invoke an RPC or action |
+-----------+---------------------------------------------+
| GET | Retrieve the datastore resource or event |
| | stream resource |
+-----------+---------------------------------------------+
| PUT | Create or replace a datastore resource |
+-----------+---------------------------------------------+
| DELETE | Delete a datastore resource |
+-----------+---------------------------------------------+
Table 4: CoAP Methods in CORECONF
3.1. Data Retrieval
One or more data nodes can be retrieved by the client. The operation
is mapped to the FETCH method defined in Section 2 of [RFC8132].
Veillette, et al. Expires 5 September 2024 [Page 11]
Internet-Draft CORECONF March 2024
There are two additional query parameters for the FETCH method:
+==================+=============================================+
| query parameters | Description |
+==================+=============================================+
| c | Control selection of configuration and non- |
| | configuration data nodes (GET and FETCH) |
+------------------+---------------------------------------------+
| d | Control retrieval of default values. |
+------------------+---------------------------------------------+
Table 5
3.1.1. Using the 'c' query parameter
The 'c' (content) option controls how descendant nodes of the
requested data nodes will be processed in the reply.
The allowed values are:
+=======+=====================================================+
| Value | Description |
+=======+=====================================================+
| c | Return only configuration descendant data nodes |
+-------+-----------------------------------------------------+
| n | Return only non-configuration descendant data nodes |
+-------+-----------------------------------------------------+
| a | Return all descendant data nodes |
+-------+-----------------------------------------------------+
Table 6: Values for the 'c' query parameter
This option is only allowed for GET and FETCH methods on datastore
and data node resources. A 4.02 (Bad Option) error is returned if
used for other methods or resource types.
If this query parameter is not present, the default value is "a" (the
quotes are added for readability, but they are not part of the
payload).
3.1.2. Using the 'd' query parameter
The 'd' (with-defaults) option controls how the default values of the
descendant nodes of the requested data nodes will be processed.
The allowed values are:
Veillette, et al. Expires 5 September 2024 [Page 12]
Internet-Draft CORECONF March 2024
+=======+======================================================+
| Value | Description |
+=======+======================================================+
| a | All data nodes are reported. Defined as 'report- |
| | all' in Section 3.1 of [RFC6243]. |
+-------+------------------------------------------------------+
| t | Data nodes set to the YANG default are not reported. |
| | Defined as 'trim' in Section 3.2 of [RFC6243]. |
+-------+------------------------------------------------------+
Table 7: Values for the 'd' query parameter
If the target of a GET or FETCH method is a data node that represents
a leaf that has a default value, and the leaf has not been given a
value by any client yet, the server MUST return the default value of
the leaf.
If the target of a GET method is a data node that represents a
container or list that has child resources with default values, and
these have not been given a value yet,
The server MUST NOT return the child resource if d=t.
The server MUST return the child resource if d=a.
If this query parameter is not present, the default value is "t" (the
quotes are added for readability, but they are not part of the
payload).
3.1.3. FETCH
The FETCH method is used to retrieve one or more instance-values.
The FETCH request payload contains the list of instance-identifiers
of the data node instances requested.
The return response payload contains a list of data node instance-
values in the same order as requested. A CBOR null is returned for
each data node requested by the client, not supported by the server
or not currently instantiated.
For compactness, indexes of the list instance identifiers returned by
the FETCH response SHOULD be elided, only the SID is provided. That
means that the client is responsible for remembering the full
instance-identifiers in its request since no key values will be in
the response. This approach may also help reduce implementation
complexity since the format of each entry within the CBOR sequence of
the FETCH response is identical to the format of the corresponding
GET response.
Veillette, et al. Expires 5 September 2024 [Page 13]
Internet-Draft CORECONF March 2024
FORMAT:
FETCH <datastore resource>
(Content-Format: application/yang-identifiers+cbor-seq)
CBOR sequence of instance-identifiers
2.05 Content (Content-Format: application/yang-instances+cbor-seq)
CBOR sequence of CBOR maps of SID, instance-value
3.1.3.1. FETCH examples
This example uses the current-datetime leaf from module ietf-system
[RFC7317] and the interface list from module ietf-interfaces
[RFC8343]. In this example the value of current-datetime (SID 1723)
and the interface list (SID 1533) instance identified with
name="eth0" are queried.
REQ: FETCH </c>
(Content-Format: application/yang-identifiers+cbor-seq)
1723, / current-datetime (SID 1723) /
[1533, "eth0"] / interface (SID 1533) with name = "eth0" /
RES: 2.05 Content
(Content-Format: application/yang-instances+cbor-seq)
{
1723 : "2014-10-26T12:16:31Z" / current-datetime (SID 1723) /
},
{
1533 : {
4 : "eth0", / name (SID 1537) /
1 : "Ethernet adaptor", / description (SID 1534) /
5 : 1880, / type (SID 1538), identity /
/ ethernetCsmacd (SID 1880) /
2 : true, / enabled (SID 1535) /
11 : 3 / oper-status (SID 1544), value is testing /
}
}
3.2. Data Editing
CORECONF allows datastore contents to be created, modified and
deleted using CoAP methods.
Veillette, et al. Expires 5 September 2024 [Page 14]
Internet-Draft CORECONF March 2024
3.2.1. Data Ordering
A CORECONF server MUST preserve the relative order of all user-
ordered list and leaf-list entries that are received in a single edit
request. As per [RFC9254], these YANG data node types are encoded as
CBOR arrays, so messages will preserve their order.
3.2.2. POST
The CoAP POST operation is used in CORECONF for the invocation of
"ACTION" and "RPC" resources. Refer to Section 3.5 for details on
"ACTION" and "RPC" resources.
3.2.3. iPATCH
One or multiple data node instances are replaced with the idempotent
CoAP iPATCH method [RFC8132].
There are no query parameters for the iPATCH method.
The processing of the iPATCH command is specified by Media-Type
application/yang-instances+cbor-seq. In summary, if the CBOR patch
payload contains a data node instance that is not present in the
target, this instance is added. If the target contains the specified
instance, the content of this instance is replaced with the value of
the payload. A null value indicates the removal of an existing data
node instance.
FORMAT:
iPATCH <datastore resource>
(Content-Format: application/yang-instances+cbor-seq)
CBOR sequence of CBOR maps of instance-identifier, instance-value
2.04 Changed
3.2.3.1. iPATCH example
In this example, a CORECONF client requests the following operations:
* Set "/ietf-system:system/ntp/enabled" (SID 1755) to true.
* Remove the server "tac.nrc.ca" from the "/ietf-system:system/ntp/
server" (SID 1756) list.
* Add/set the server "NTP Pool server 2" to the list "/ietf-
system:system/ntp/server" (SID 1756).
Veillette, et al. Expires 5 September 2024 [Page 15]
Internet-Draft CORECONF March 2024
REQ: iPATCH </c>
(Content-Format: application/yang-instances+cbor-seq)
{
1755 : true / enabled (SID 1755) /
},
{
[1756, "tac.nrc.ca"] : null / server (SID 1756) /
},
{
1756 : { / server (SID 1756) /
3 : "tic.nrc.ca", / name (SID 1759) /
4 : true, / prefer (SID 1760) /
5 : { / udp (SID 1761) /
1 : "132.246.11.231" / address (SID 1762) /
}
}
}
RES: 2.04 Changed
A data node resource is deleted using an iPATCH with a null value, as
seen in this example.
3.3. Full datastore access
The methods GET, PUT, POST, and DELETE can be used to request,
replace, create, and delete a whole datastore respectively.
FORMAT:
GET <datastore resource>
2.05 Content (Content-Format: application/yang-data+cbor; id=sid)
CBOR map of SID, instance-value
FORMAT:
PUT <datastore resource>
(Content-Format: application/yang-data+cbor; id=sid)
CBOR map of SID, instance-value
2.04 Changed
FORMAT:
POST <datastore resource>
(Content-Format: application/yang-data+cbor; id=sid)
CBOR map of SID, instance-value
2.01 Created
Veillette, et al. Expires 5 September 2024 [Page 16]
Internet-Draft CORECONF March 2024
FORMAT:
DELETE <datastore resource>
2.02 Deleted
The content of the CBOR map represents the complete datastore of the
server at the GET indication of after a successful processing of a
PUT or POST request.
3.3.1. Full datastore examples
The example uses the interface list from module ietf-interfaces
[RFC8343] and the clock container from module ietf-system [RFC7317].
We assume that the datastore contains two modules ietf-system (SID
1700) and ietf-interfaces (SID 1500); they contain the 'interface'
list (SID 1533) with one instance and the 'clock' container (SID
1721). After invocation of GET, a CBOR map with data nodes from
these two modules is returned:
REQ: GET </c>
RES: 2.05 Content
(Content-Format: application/yang-data+cbor; id=sid)
{
1721 : { / Clock (SID 1721) /
2: "2016-10-26T12:16:31Z", / current-datetime (SID 1723) /
1: "2014-10-05T09:00:00Z" / boot-datetime (SID 1722) /
},
1533 : [
{ / interface (SID 1533) /
4 : "eth0", / name (SID 1537) /
1 : "Ethernet adaptor", / description (SID 1534) /
5 : 1880, / type (SID 1538), identity: /
/ ethernetCsmacd (SID 1880) /
2 : true, / enabled (SID 1535) /
11 : 3 / oper-status (SID 1544), value is testing /
}
]
}
3.4. Event stream
Event notification is an essential function for the management of
servers. CORECONF allows notifications specified in YANG [RFC5277]
to be reported to a list of clients. The path for the default event
stream can be discovered as described in Section 3. The server MAY
support additional event stream resources to address different
notification needs.
Veillette, et al. Expires 5 September 2024 [Page 17]
Internet-Draft CORECONF March 2024
Reception of notification instances is enabled with the CoAP Observe
[RFC7641] function. Clients subscribe to the notifications by
sending a GET request with an "Observe" option to the stream
resource.
Each response payload carries one or multiple notifications. The
number of notifications reported, and the conditions used to remove
notifications from the reported list are left to implementers. When
multiple notifications are reported, they MUST be ordered starting
from the newest notification at index zero. Note that this could
lead to notifications being sent multiple times, which increases the
probability for the client to receive them, but it might potentially
lead to messages that exceed the MTU of a single CoAP packet. If
such cases could arise, implementers should make sure appropriate
fragmentation is available - for example the one described in
Section 4.
The format of notifications is a CBOR sequence, where each item in
the sequence is a single notification as described in Section 4.2.1
of [RFC9254]. (Accordingly, a notification without any content is an
empty CBOR sequence, i.e., zero bytes.)
FORMAT:
GET <stream-resource> Observe(0)
2.05 Content (Content-Format: application/yang-instances+cbor-seq)
CBOR sequence of CBOR maps of instance-identifier, instance-value
The sequence of data node instances may contain identical items which
have been generated at different times.
An example implementation is:
Every time an event is generated, the generated notification
instance is appended to the chosen stream(s). After an
aggregation period, which may be limited by the maximum number of
notifications supported, the content of the instance is sent to
all clients observing the modified stream.
3.4.1. Filtering Notifications
If only a subset of all possible notifications is of interest, a
FETCH operation can be performed with a request payload of type
application/yang-identifiers+cbor-seq that indicates which subset.
Veillette, et al. Expires 5 September 2024 [Page 18]
Internet-Draft CORECONF March 2024
FORMAT:
FETCH <stream-resource> Observe(0)
(Content-Format: application/yang-identifiers+cbor-seq)
CBOR sequence of instance-identifiers
2.05 Content (Content-Format: application/yang-instances+cbor-seq)
CBOR sequence of CBOR maps of instance-identifier, instance-value
When filtering is not supported by a CORECONF server, the request
payload can be ignored: all event notifications are then reported
independently of the presence and content of the request payload.
3.4.2. Notify Examples
Let suppose the server generates the example-port-fault event as
defined below.
module example-port {
yang-version 1.1;
namespace "https://example.com/ns/example-port";
prefix "port";
notification example-port-fault { // SID 60010
description
"Event generated if a hardware fault is detected";
leaf port-name { // SID 60011
type string;
}
leaf port-fault { // SID 60012
type string;
}
}
}
In this example the default event stream resource path /s is an
example location discovered with a request similar to Figure 3. By
executing a GET with Observe 0 on the default event stream resource
the client receives the following response:
Veillette, et al. Expires 5 September 2024 [Page 19]
Internet-Draft CORECONF March 2024
REQ: GET </s> Observe(0)
RES: 2.05 Content
(Content-Format: application/yang-instances+cbor-seq)
Observe(12)
{
60010 : { / example-port-fault (SID 60010) /
1 : "0/4/21", / port-name (SID 60011) /
2 : "Open pin 2" / port-fault (SID 60012) /
}
},
{
60010 : { / example-port-fault (SID 60010) /
1 : "1/4/21", / port-name (SID 60011) /
2 : "Open pin 5" / port-fault (SID 60012) /
}
}
In the example, the request returns a success response with the
contents of the last two generated events. Consecutively the server
will regularly notify the client when a new event is generated.
A client that wants to filter notifications can use a FETCH payload:
REQ: FETCH </s> Observe(0)
(Content-Format: application/yang-identifiers+cbor-seq)
60010, 60020 /CBOR sequence with two notification identifiers/
RES: 2.05 Content
(Content-Format: application/yang-instances+cbor-seq)
Observe(12)
{
60010 : { / example-port-fault (SID 60010) /
1 : "0/4/21", / port-name (SID 60011) /
2 : "Open pin 2" / port-fault (SID 60012) /
}
},
{
60010 : { / example-port-fault (SID 60010) /
1 : "1/4/21", / port-name (SID 60011) /
2 : "Open pin 5" / port-fault (SID 60012) /
}
}
Veillette, et al. Expires 5 September 2024 [Page 20]
Internet-Draft CORECONF March 2024
Note that the notifications in this example are identical to the
unfiltered example as they are all using identifier SID 60010 and
this is included in the filter.
3.5. RPC and Action statements
The YANG "action" and "RPC" statements specify the execution of a
Remote Procedure Call (RPC) in the server. It is invoked using a
POST method to an "Action" or "RPC" resource instance.
The request payload contains the values assigned to the input
container when specified. The response payload contains the values
of the output container when specified. Both the input and output
containers are encoded in CBOR using the rules defined in
Section 4.2.1 of [RFC9254].
The returned success response code is 2.04 Changed.
FORMAT:
POST <datastore resource>
(Content-Format: application/yang-instances+cbor-seq)
CBOR sequence of CBOR maps of instance-identifier, instance-value
2.04 (Content-Format: application/yang-instances+cbor-seq)
CBOR sequence of CBOR maps of instance-identifier, instance-value
3.5.1. RPC Example
This example is based on Section 3.6.1 of [RFC8040], abbreviated and
annotated with SIDs as follows:
Veillette, et al. Expires 5 September 2024 [Page 21]
Internet-Draft CORECONF March 2024
module example-ops {
yang-version 1.1;
namespace "https://example.com/ns/example-ops";
prefix "ops";
rpc reboot { // SID 61000
description "Reboot operation.";
input { // SID 61009
leaf delay { // SID 61001
type uint32;
units "seconds";
default 0;
description
"Number of seconds to wait before initiating the
reboot operation.";
}
}
}
}
This example invokes the 'reboot' RPC (SID 61000).
REQ: POST </c>
(Content-Format: application/yang-instances+cbor-seq)
{ 61000:
{
1 : 77
}
}
RES: 2.04 Changed
(Content-Format: application/yang-instances+cbor-seq)
{ 61000:
null
}
3.5.2. Action Example
The example is based on the YANG action "reset" as defined in
Section 7.15.3 of [RFC7950] and annotated below with SIDs.
Veillette, et al. Expires 5 September 2024 [Page 22]
Internet-Draft CORECONF March 2024
module example-server-farm {
yang-version 1.1;
namespace "urn:example:server-farm";
prefix "sfarm";
import ietf-yang-types {
prefix "yang";
}
list server { // SID 60000
key name;
leaf name { // SID 60001
type string;
}
action reset { // SID 60002
input { // SID 60008
leaf reset-at { // SID 60003
type yang:date-and-time;
mandatory true;
}
}
output { // SID 60009
leaf reset-finished-at { // SID 60004
type yang:date-and-time;
mandatory true;
}
}
}
}
}
This example invokes the 'reset' action (SID 60002), of the server
instance with name equal to "myserver".
Veillette, et al. Expires 5 September 2024 [Page 23]
Internet-Draft CORECONF March 2024
REQ: POST </c>
(Content-Format: application/yang-instances+cbor-seq)
{ [60002, "myserver"]:
{
1 : "2016-02-08T14:10:08Z" / reset-at (SID 60003) /
}
}
RES: 2.04 Changed
(Content-Format: application/yang-instances+cbor-seq)
{ [60002, "myserver"]:
{
2 : "2016-02-08T14:10:11Z" / reset-finished-at (SID 60004)/
}
}
4. Use of Block-wise Transfers
The CoAP protocol provides reliability by acknowledging the UDP
datagrams. However, when large pieces of data need to be
transported, datagrams get fragmented, thus creating constraints on
the resources in the client, server and intermediate routers. The
block option [RFC7959] allows the transport of the total payload in
individual blocks of which the size can be adapted to the underlying
transport sizes such as: (UDP datagram size ~64KiB, IPv6 MTU of 1280,
IEEE 802.15.4 payload of 60-80 bytes). Each block is individually
acknowledged to guarantee reliability.
Notice that the Block mechanism splits the data at fixed positions,
such that individual data fields may become fragmented. Therefore,
assembly of multiple blocks may be required to process complete data
fields.
Beware of race conditions. In case blocks are filled one at a time,
care should be taken that the whole and consistent data
representation is sent in multiple blocks sequentially without
interruption. On the server, values might change, lists might get
re-ordered, extended or reduced. When these actions happen during
the serialization of the contents of the resource, the transported
results do not correspond with a state having occurred in the server;
or worse the returned values are inconsistent. For example: array
length does not correspond with the actual number of items. It may
be advisable to use Indefinite-length CBOR arrays and maps, which are
foreseen for data streaming purposes. (Note that the outer structure
of yang-identifiers and yang-instances is a CBOR sequence, which
already behaves similar to an indefinite-length encoded array.)
Veillette, et al. Expires 5 September 2024 [Page 24]
Internet-Draft CORECONF March 2024
5. Application Discovery
Two application discovery mechanisms are supported by CORECONF, the
YANG library data model as defined by [I-D.ietf-core-yang-library]
and the CORE resource discovery [RFC6690]. Implementers may choose
to implement one or the other or both.
5.1. YANG library
The YANG library data model [I-D.ietf-core-yang-library] provides a
high-level description of the resources available. The YANG library
contains the list of modules, features, and deviations supported by
the CORECONF server. From this information, CORECONF clients can
infer the list of data nodes supported and the interaction model to
be used to access them. This module also contains the list of
datastores implemented.
As described in [RFC6690], the location of the YANG library can be
found by sending a GET request to "/.well-known/core" including a
resource type (RT) parameter with the value "core.c.yl". Upon
success, the return payload will contain the root resource of the
YANG library module.
The following example assumes that the SID of the YANG library is
2351 (kv after encoding as specified in Section 2.2) and that the
server uses /c as datastore resource path.
REQ: GET </.well-known/core?rt=core.c.yl>
RES: 2.05 Content (Content-Format: application/link-format)
</c/kv>;rt="core.c.yl"
5.2. Resource Discovery
As some CoAP interfaces and services might not support the YANG
library interface and still be interested to discover resources that
are available, implementations MAY choose to support discovery of all
available resources using "/.well-known/core" as defined by
[RFC6690].
5.2.1. Datastore Resource Discovery
The presence and location of (path to) each datastore implemented by
the CORECONF server can be discovered by sending a GET request to
"/.well-known/core" including a resource type (RT) parameter with the
value "core.c.ds".
Veillette, et al. Expires 5 September 2024 [Page 25]
Internet-Draft CORECONF March 2024
Upon success, the return payload contains the list of datastore
resources.
Each datastore returned is further qualified using the "ds" Link-
Format attribute. This attribute is set to the SID assigned to the
datastore identity. When a unified datastore is implemented, the ds
attribute is set to 1029 as specified in Appendix B. For other
examples of datastores, see the Network Management Datastore
Architecture (NMDA) [RFC7950].
link-extension = ( "ds" "=" sid )
; SID assigned to the datastore identity
sid = 1*DIGIT
The following example assumes that the server uses /c as datastore
resource path.
REQ: GET </.well-known/core?rt=core.c.ds>
RES: 2.05 Content (Content-Format: application/link-format)
</c>; rt="core.c.ds";ds=1029
Figure 2
5.2.2. Data node Resource Discovery
If implemented, the presence and location of (path to) each data node
implemented by the CORECONF server are discovered by sending a GET
request to "/.well-known/core" including a resource type (RT)
parameter with the value "core.c.dn".
Upon success, the return payload contains the SID assigned to each
data node and their location.
The example below shows the discovery of the presence and location of
data nodes. Data nodes '/ietf-system:system-state/clock/boot-
datetime' (SID 1722) and '/ietf-system:system-state/clock/current-
datetime' (SID 1723) are returned. The example assumes that the
server uses /c as datastore resource path.
REQ: GET </.well-known/core?rt=core.c.dn>
RES: 2.05 Content (Content-Format: application/link-format)
</c/a6>;rt="core.c.dn",
</c/a7>;rt="core.c.dn"
Veillette, et al. Expires 5 September 2024 [Page 26]
Internet-Draft CORECONF March 2024
Without additional filtering, the list of data nodes may become
prohibitively long. If this is the case implementations SHOULD
support a way to obtain all links using multiple GET requests (for
example through some form of pagination).
5.2.3. Event stream Resource Discovery
The presence and location of (path to) each event stream implemented
by the CORECONF server are discovered by sending a GET request to
"/.well-known/core" including a resource type (RT) parameter with the
value "core.c.es".
Upon success, the return payload contains the list of event stream
resources.
The following example assumes that the server uses /s as the default
event stream resource.
REQ: GET </.well-known/core?rt=core.c.es>
RES: 2.05 Content (Content-Format: application/link-format)
</s>;rt="core.c.es"
Figure 3
6. Error Handling
In case a request is received which cannot be processed properly, the
CORECONF server MUST return an error response. This error response
MUST contain a CoAP 4.xx or 5.xx response code. Requests that result
in an error response MUST NOT have an effect on the datastore.
Errors returned by a CORECONF server can be broken into two
categories, those associated with the CoAP protocol itself and those
generated during the validation of the YANG data model constraints as
described in Section 8 of [RFC7950].
The following list of common CoAP errors should be implemented by
CORECONF servers. This list is not exhaustive, other errors defined
by CoAP and associated RFCs may be applicable.
* Error 4.01 (Unauthorized) is returned by the CORECONF server when
the CORECONF client is not authorized to perform the requested
action on the targeted resource (i.e., data node, datastore, rpc,
action or event stream).
* Error 4.02 (Bad Option) is returned by the CORECONF server when
one or more CoAP options are unknown or malformed.
Veillette, et al. Expires 5 September 2024 [Page 27]
Internet-Draft CORECONF March 2024
* Error 4.04 (Not Found) is returned by the CORECONF server when the
CORECONF client is requesting a non-instantiated resource (i.e.,
data node, datastore, rpc, action or event stream).
* Error 4.05 (Method Not Allowed) is returned by the CORECONF server
when the CORECONF client is requesting a method not supported on
the targeted resource. (e.g., GET on an rpc, PUT or POST on a data
node with "config" set to false).
* Error 4.08 (Request Entity Incomplete) is returned by the CORECONF
server if one or multiple blocks of a block transfer request is
missing, see [RFC7959] for more details.
* Error 4.13 (Request Entity Too Large) may be returned by the
CORECONF server during a block transfer request, see [RFC7959] for
more details.
* Error 4.15 (Unsupported Content-Format) is returned by the
CORECONF server when the Content-Format used in the request does
not match those specified in Section 2.3.
The CORECONF server MUST also enforce the different constraints
associated with the YANG data models implemented. These constraints
are described in Section 8 of [RFC7950]. These errors are reported
using the CoAP error code 4.00 (Bad Request) and may have the
following error container as payload. The YANG definition and
associated .sid file are available in Appendix A and Appendix B. The
error container is encoded using the encoding rules of a YANG data
template as defined in Section 5 of [RFC9254].
+--rw error!
+--rw error-tag identityref
+--rw error-app-tag? identityref
+--rw error-data-node? instance-identifier
+--rw error-message? string
The following 'error-tag' and 'error-app-tag' are defined by the
ietf-coreconf YANG module, these tags are implemented as YANG
identity and can be extended as needed.
* error-tag 'operation-failed' is returned by the CORECONF server
when the operation request cannot be processed successfully.
- error-app-tag 'malformed-message' is returned by the CORECONF
server when the payload received from the CORECONF client does
not contain a well-formed CBOR content as defined in [RFC8949]
or does not comply with the CBOR structure defined within this
document.
Veillette, et al. Expires 5 September 2024 [Page 28]
Internet-Draft CORECONF March 2024
- error-app-tag 'data-not-unique' is returned by the CORECONF
server when the validation of the 'unique' constraint of a list
or leaf-list fails.
- error-app-tag 'too-many-elements' is returned by the CORECONF
server when the validation of the 'max-elements' constraint of
a list or leaf-list fails.
- error-app-tag 'too-few-elements' is returned by the CORECONF
server when the validation of the 'min-elements' constraint of
a list or leaf-list fails.
- error-app-tag 'must-violation' is returned by the CORECONF
server when the restrictions imposed by a 'must' statement are
violated.
- error-app-tag 'duplicate' is returned by the CORECONF server
when a client tries to create a duplicate list or leaf-list
entry.
* error-tag 'invalid-value' is returned by the CORECONF server when
the CORECONF client tries to update or create a leaf with a value
encoded using an invalid CBOR datatype or if the 'range',
'length', 'pattern' or 'require-instance' constrain is not
fulfilled.
- error-app-tag 'invalid-datatype' is returned by the CORECONF
server when CBOR encoding does not follow the rules set by the
YANG Build-In type or when the value is incompatible with it
(e.g., a value greater than 127 for an int8, undefined
enumeration).
- error-app-tag 'not-in-range' is returned by the CORECONF server
when the validation of the 'range' property fails.
- error-app-tag 'invalid-length' is returned by the CORECONF
server when the validation of the 'length' property fails.
- error-app-tag 'pattern-test-failed' is returned by the CORECONF
server when the validation of the 'pattern' property fails.
* error-tag 'missing-element' is returned by the CORECONF server
when the operation requested by a CORECONF client fails to comply
with the 'mandatory' constraint defined. The 'mandatory'
constraint is enforced for leafs and choices, unless the node or
any of its ancestors have a 'when' condition or 'if-feature'
expression that evaluates to 'false'.
Veillette, et al. Expires 5 September 2024 [Page 29]
Internet-Draft CORECONF March 2024
- error-app-tag 'missing-key' is returned by the CORECONF server
to further qualify a missing-element error. This error is
returned when the CORECONF client tries to create or list
instance, without all the 'key' specified or when the CORECONF
client tries to delete a leaf listed as a 'key'.
- error-app-tag 'missing-input-parameter' is returned by the
CORECONF server when the input parameters of an RPC or action
are incomplete.
* error-tag 'unknown-element' is returned by the CORECONF server
when the CORECONF client tries to access a data node of a YANG
module not supported, of a data node associated with an 'if-
feature' expression evaluated to 'false' or to a 'when' condition
evaluated to 'false'.
* error-tag 'bad-element' is returned by the CORECONF server when
the CORECONF client tries to create data nodes for more than one
case in a choice.
* error-tag 'data-missing' is returned by the CORECONF server when a
data node required to accept the request is not present.
- error-app-tag 'instance-required' is returned by the CORECONF
server when a leaf of type 'instance-identifier' or 'leafref'
marked with require-instance set to 'true' refers to an
instance that does not exist.
- error-app-tag 'missing-choice' is returned by the CORECONF
server when no nodes exist in a mandatory choice.
* error-tag 'error' is returned by the CORECONF server when an
unspecified error has occurred.
For example, the CORECONF server might return the following error.
Veillette, et al. Expires 5 September 2024 [Page 30]
Internet-Draft CORECONF March 2024
RES: 4.00 Bad Request
(Content-Format: application/yang-data+cbor; id=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 value exceeded" / error-message (SID 1027) /
}
}
7. Security Considerations
For secure network management, it is important to restrict access to
configuration variables only to authorized parties. CORECONF re-uses
the security mechanisms already available to CoAP, this includes DTLS
[RFC6347][RFC9147] and OSCORE [RFC8613] for protected access to
resources, as well as suitable authentication and authorization
mechanisms, for example those defined in ACE OAuth [RFC9200].
All the security considerations of [RFC7252], [RFC7959], [RFC8132]
and [RFC7641] apply to this document as well. The use of NoSec
(Section 9 of [RFC7252]), when OSCORE is not used, is NOT
RECOMMENDED.
In addition, mechanisms for authentication and authorization may need
to be selected if not provided with the CoAP security mode.
As [RFC9254] and [RFC4648] are used for payload and SID encoding, the
security considerations of those documents also need to be well-
understood.
8. IANA Considerations
8.1. Resource Type (rt=) Link Target Attribute Values Registry
This document adds the following resource type to the "Resource Type
(rt=) Link Target Attribute Values", within the "Constrained RESTful
Environments (CoRE) Parameters" registry.
Veillette, et al. Expires 5 September 2024 [Page 31]
Internet-Draft CORECONF March 2024
+===========+=====================+===========+
| Value | Description | Reference |
+===========+=====================+===========+
| core.c.ds | YANG datastore | RFC XXXX |
+-----------+---------------------+-----------+
| core.c.dn | YANG data node | RFC XXXX |
+-----------+---------------------+-----------+
| core.c.yl | YANG module library | RFC XXXX |
+-----------+---------------------+-----------+
| core.c.es | YANG event stream | RFC XXXX |
+-----------+---------------------+-----------+
Table 8
// RFC Ed.: replace RFC XXXX with this RFC number and remove this
note.
8.2. 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- | | TBD2 | RFC XXXX |
| identifiers+cbor-seq | | | |
+---------------------------+----------------+------+-----------+
| application/yang- | | TBD3 | RFC XXXX |
| instances+cbor-seq | | | |
+---------------------------+----------------+------+-----------+
Table 9
// RFC Ed.: replace TBD1, TBD2 and TBD3 with assigned IDs and remove
this note. // RFC Ed.: replace RFC XXXX with this RFC number and
remove this note.
8.3. Media Types Registry
This document adds the following media types to the "Media Types"
registry.
Veillette, et al. Expires 5 September 2024 [Page 32]
Internet-Draft CORECONF March 2024
+===========================+===========================+=========+
| Name | Template |Reference|
+===========================+===========================+=========+
| yang-identifiers+cbor-seq | application/yang- |RFC XXXX |
| | identifiers+cbor-seq | |
+---------------------------+---------------------------+---------+
| yang-instances+cbor-seq | application/yang- |RFC XXXX |
| | instances+cbor-seq | |
+---------------------------+---------------------------+---------+
Table 10
Each of these media types share the following information:
* Subtype name: <as listed in table>
* Required parameters: N/A
* Optional parameters: N/A
* Encoding considerations: binary
* Security considerations: See the Security Considerations section
of RFC XXXX
* Interoperability considerations: N/A
* Published specification: RFC XXXX
* Applications that use this media type: CORECONF
* Fragment identifier considerations: N/A
* Additional information:
* Deprecated alias names for this type: N/A
* Magic number(s): N/A
* File extension(s): N/A
* Macintosh file type code(s): N/A
* Person & email address to contact for further information:
iesg&ietf.org
* Intended usage: COMMON
Veillette, et al. Expires 5 September 2024 [Page 33]
Internet-Draft CORECONF March 2024
* Restrictions on usage: N/A
* Author: Michel Veillette
* Change Controller: IETF
* Provisional registration? No
// RFC Ed.: replace RFC XXXX with this RFC number and remove this
note.
8.4. YANG Namespace and Module Name Registration
This document registers the following XML namespace URN in the "IETF
XML Registry", following the format defined in [RFC3688]:
URI: please assign urn:ietf:params:xml:ns:yang:ietf-coreconf
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace.
Reference: RFC XXXX
IANA is requested to register the following YANG module in the "YANG
Module Names" registry [RFC6020]:
Name: ietf-coreconf
Namespace: urn:ietf:params:xml:ns:yang:ietf-coreconf
Prefix: coreconf
Reference: RFC XXXX
// RFC Ed.: please replace XXXX with RFC number and remove this note
The YANG module and SID file are in Appendix A and Appendix B,
respectively.
9. References
9.1. Normative References
Veillette, et al. Expires 5 September 2024 [Page 34]
Internet-Draft CORECONF March 2024
[I-D.ietf-core-sid]
Veillette, M., Pelov, A., Petrov, I., Bormann, C., and M.
Richardson, "YANG Schema Item iDentifier (YANG SID)", Work
in Progress, Internet-Draft, draft-ietf-core-sid-24, 22
December 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-core-sid-24>.
[I-D.ietf-core-yang-library]
Veillette, M. and I. Petrov, "Constrained YANG Module
Library", Work in Progress, Internet-Draft, draft-ietf-
core-yang-library-03, 11 January 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-core-
yang-library-03>.
[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/rfc/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/rfc/rfc3688>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/rfc/rfc4648>.
[RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event
Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008,
<https://www.rfc-editor.org/rfc/rfc5277>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/rfc/rfc6020>.
[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/rfc/rfc6241>.
[RFC6243] Bierman, A. and B. Lengyel, "With-defaults Capability for
NETCONF", RFC 6243, DOI 10.17487/RFC6243, June 2011,
<https://www.rfc-editor.org/rfc/rfc6243>.
Veillette, et al. Expires 5 September 2024 [Page 35]
Internet-Draft CORECONF March 2024
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/rfc/rfc7252>.
[RFC7641] Hartke, K., "Observing Resources in the Constrained
Application Protocol (CoAP)", RFC 7641,
DOI 10.17487/RFC7641, September 2015,
<https://www.rfc-editor.org/rfc/rfc7641>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/rfc/rfc7950>.
[RFC7959] Bormann, C. and Z. Shelby, Ed., "Block-Wise Transfers in
the Constrained Application Protocol (CoAP)", RFC 7959,
DOI 10.17487/RFC7959, August 2016,
<https://www.rfc-editor.org/rfc/rfc7959>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/rfc/rfc8040>.
[RFC8132] van der Stok, P., Bormann, C., and A. Sehgal, "PATCH and
FETCH Methods for the Constrained Application Protocol
(CoAP)", RFC 8132, DOI 10.17487/RFC8132, April 2017,
<https://www.rfc-editor.org/rfc/rfc8132>.
[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/rfc/rfc8174>.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore Architecture
(NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
<https://www.rfc-editor.org/rfc/rfc8342>.
[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/rfc/rfc8610>.
[RFC8742] Bormann, C., "Concise Binary Object Representation (CBOR)
Sequences", RFC 8742, DOI 10.17487/RFC8742, February 2020,
<https://www.rfc-editor.org/rfc/rfc8742>.
Veillette, et al. Expires 5 September 2024 [Page 36]
Internet-Draft CORECONF March 2024
[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/rfc/rfc8949>.
[RFC9254] Veillette, M., Ed., Petrov, I., Ed., Pelov, A., Bormann,
C., and M. Richardson, "Encoding of Data Modeled with YANG
in the Concise Binary Object Representation (CBOR)",
RFC 9254, DOI 10.17487/RFC9254, July 2022,
<https://www.rfc-editor.org/rfc/rfc9254>.
9.2. Informative References
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/rfc/rfc6347>.
[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link
Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,
<https://www.rfc-editor.org/rfc/rfc6690>.
[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/rfc/rfc7317>.
[RFC8343] Bjorklund, M., "A YANG Data Model for Interface
Management", RFC 8343, DOI 10.17487/RFC8343, March 2018,
<https://www.rfc-editor.org/rfc/rfc8343>.
[RFC8613] Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
"Object Security for Constrained RESTful Environments
(OSCORE)", RFC 8613, DOI 10.17487/RFC8613, July 2019,
<https://www.rfc-editor.org/rfc/rfc8613>.
[RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version
1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022,
<https://www.rfc-editor.org/rfc/rfc9147>.
[RFC9200] Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
H. Tschofenig, "Authentication and Authorization for
Constrained Environments Using the OAuth 2.0 Framework
(ACE-OAuth)", RFC 9200, DOI 10.17487/RFC9200, August 2022,
<https://www.rfc-editor.org/rfc/rfc9200>.
Veillette, et al. Expires 5 September 2024 [Page 37]
Internet-Draft CORECONF March 2024
Appendix A. ietf-coreconf YANG module
This appendix is normative.
<CODE BEGINS> file "ietf-coreconf@2024-03-04.yang"
module ietf-coreconf {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-coreconf";
prefix coreconf;
import ietf-datastores {
prefix ds;
reference
"RFC 8342: Network Management Datastore Architecture (NMDA)";
}
import ietf-restconf {
prefix rc;
description
"This import statement is required to access
the yang-data extension defined in RFC 8040.";
reference "RFC 8040: RESTCONF Protocol";
}
organization
"IETF Core Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/core/>
WG List: <mailto:core@ietf.org>
Michel Veillette
<mailto:michel.veillette@trilliantinc.com>
Alexander Pelov
<mailto:alexander.pelov@imt-atlantique.fr>
Peter van der Stok
<mailto:stokcons@kpnmail.nl>
Andy Bierman
<mailto:andy@yumaworks.com>";
description
"This module contains the different definitions required
by the CORECONF protocol.
Veillette, et al. Expires 5 September 2024 [Page 38]
Internet-Draft CORECONF March 2024
Copyright (c) 2024 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Revised BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX;
see the RFC itself for full legal notices.";
revision 2024-03-04 {
description
"Initial revision.";
reference
"[I-D.ietf-core-comi] CoAP Management Interface";
}
identity unified {
base ds:datastore;
description
"Identifier of the unified configuration and operational
state datastore.";
}
identity error-tag {
description
"Base identity for error-tag.";
}
identity operation-failed {
base error-tag;
description
"Returned by the CORECONF server when the operation request
can't be processed successfully.";
}
identity invalid-value {
base error-tag;
description
"Returned by the CORECONF server when the CORECONF client tries
to update or create a leaf with a value encoded using an
invalid CBOR datatype or if the 'range', 'length',
'pattern' or 'require-instance' constrain is not
fulfilled.";
}
Veillette, et al. Expires 5 September 2024 [Page 39]
Internet-Draft CORECONF March 2024
identity missing-element {
base error-tag;
description
"Returned by the CORECONF server when the operation requested
by a CORECONF client fails to comply with the 'mandatory'
constraint defined. The 'mandatory' constraint is
enforced for leafs and choices, unless the node or any of
its ancestors have a 'when' condition or 'if-feature'
expression that evaluates to 'false'.";
}
identity unknown-element {
base error-tag;
description
"Returned by the CORECONF server when the CORECONF client tries
to access a data node of a YANG module not supported, of a
data node associated with an 'if-feature' expression
evaluated to 'false' or to a 'when' condition evaluated
to 'false'.";
}
identity bad-element {
base error-tag;
description
"Returned by the CORECONF server when the CORECONF client tries
to create data nodes for more than one case in a choice.";
}
identity data-missing {
base error-tag;
description
"Returned by the CORECONF server when a data node required to
accept the request is not present.";
}
identity error {
base error-tag;
description
"Returned by the CORECONF server when an unspecified error has
occurred.";
}
identity error-app-tag {
description
"Base identity for error-app-tag.";
}
identity malformed-message {
Veillette, et al. Expires 5 September 2024 [Page 40]
Internet-Draft CORECONF March 2024
base error-app-tag;
description
"Returned by the CORECONF server when the payload received
from the CORECONF client don't contain a well-formed CBOR
content as defined in [RFC8949] or don't
comply with the CBOR structure defined within this
document.";
}
identity data-not-unique {
base error-app-tag;
description
"Returned by the CORECONF server when the validation of the
'unique' constraint of a list or leaf-list fails.";
}
identity too-many-elements {
base error-app-tag;
description
"Returned by the CORECONF server when the validation of the
'max-elements' constraint of a list or leaf-list fails.";
}
identity too-few-elements {
base error-app-tag;
description
"Returned by the CORECONF server when the validation of the
'min-elements' constraint of a list or leaf-list fails.";
}
identity must-violation {
base error-app-tag;
description
"Returned by the CORECONF server when the restrictions
imposed by a 'must' statement are violated.";
}
identity duplicate {
base error-app-tag;
description
"Returned by the CORECONF server when a client tries to create
a duplicate list or leaf-list entry.";
}
identity invalid-datatype {
base error-app-tag;
description
"Returned by the CORECONF server when CBOR encoding is
Veillette, et al. Expires 5 September 2024 [Page 41]
Internet-Draft CORECONF March 2024
incorect or when the value encoded is incompatible with
the YANG Built-In type. (e.g., value greater than 127
for an int8, undefined enumeration).";
}
identity not-in-range {
base error-app-tag;
description
"Returned by the CORECONF server when the validation of the
'range' property fails.";
}
identity invalid-length {
base error-app-tag;
description
"Returned by the CORECONF server when the validation of the
'length' property fails.";
}
identity pattern-test-failed {
base error-app-tag;
description
"Returned by the CORECONF server when the validation of the
'pattern' property fails.";
}
identity missing-key {
base error-app-tag;
description
"Returned by the CORECONF server to further qualify a
missing-element error. This error is returned when the
CORECONF client tries to create a list instance, without all
the 'key' specified or when the CORECONF client tries to
delete a leaf listed as a 'key'.";
}
identity missing-input-parameter {
base error-app-tag;
description
"Returned by the CORECONF server when the input parameters
of a RPC or action are incomplete.";
}
identity instance-required {
base error-app-tag;
description
"Returned by the CORECONF server when a leaf of type
'instance-identifier' or 'leafref' marked with
Veillette, et al. Expires 5 September 2024 [Page 42]
Internet-Draft CORECONF March 2024
require-instance set to 'true' refers to an instance
that does not exist.";
}
identity missing-choice {
base error-app-tag;
description
"Returned by the CORECONF server when no nodes exist in a
mandatory choice.";
}
rc:yang-data coreconf-error {
container error {
description
"Optional payload of a 4.00 Bad Request CoAP error.";
leaf error-tag {
type identityref {
base error-tag;
}
mandatory true;
description
"The enumerated error-tag.";
}
leaf error-app-tag {
type identityref {
base error-app-tag;
}
description
"The application-specific error-tag.";
}
leaf error-data-node {
type instance-identifier;
description
"When the error reported is caused by a specific data node,
this leaf identifies the data node in error.";
}
leaf error-message {
type string;
description
"A message describing the error.";
}
}
}
}
Veillette, et al. Expires 5 September 2024 [Page 43]
Internet-Draft CORECONF March 2024
<CODE ENDS>
Figure 4: ietf-coreconf YANG module
Appendix B. ietf-coreconf .sid file
This appendix is normative.
<CODE BEGINS> file "ietf-coreconf@2024-03-04.sid"
{
"ietf-sid-file:sid-file": {
"module-name": "ietf-coreconf",
"module-revision": "2024-03-04",
"assignment-range": [
{
"entry-point": "1000",
"size": "100"
}
],
"item": [
{
"namespace": "module",
"identifier": "ietf-coreconf",
"sid": "1000"
},
{
"namespace": "identity",
"identifier": "bad-element",
"sid": "1001"
},
{
"namespace": "identity",
"identifier": "data-missing",
"sid": "1002"
},
{
"namespace": "identity",
"identifier": "data-not-unique",
"sid": "1003"
},
{
"namespace": "identity",
"identifier": "duplicate",
"sid": "1004"
},
{
"namespace": "identity",
"identifier": "error",
Veillette, et al. Expires 5 September 2024 [Page 44]
Internet-Draft CORECONF March 2024
"sid": "1005"
},
{
"namespace": "identity",
"identifier": "error-app-tag",
"sid": "1006"
},
{
"namespace": "identity",
"identifier": "error-tag",
"sid": "1007"
},
{
"namespace": "identity",
"identifier": "instance-required",
"sid": "1008"
},
{
"namespace": "identity",
"identifier": "invalid-datatype",
"sid": "1009"
},
{
"namespace": "identity",
"identifier": "invalid-length",
"sid": "1010"
},
{
"namespace": "identity",
"identifier": "invalid-value",
"sid": "1011"
},
{
"namespace": "identity",
"identifier": "malformed-message",
"sid": "1012"
},
{
"namespace": "identity",
"identifier": "missing-choice",
"sid": "1013"
},
{
"namespace": "identity",
"identifier": "missing-element",
"sid": "1014"
},
{
Veillette, et al. Expires 5 September 2024 [Page 45]
Internet-Draft CORECONF March 2024
"namespace": "identity",
"identifier": "missing-input-parameter",
"sid": "1015"
},
{
"namespace": "identity",
"identifier": "missing-key",
"sid": "1016"
},
{
"namespace": "identity",
"identifier": "must-violation",
"sid": "1017"
},
{
"namespace": "identity",
"identifier": "not-in-range",
"sid": "1018"
},
{
"namespace": "identity",
"identifier": "operation-failed",
"sid": "1019"
},
{
"namespace": "identity",
"identifier": "pattern-test-failed",
"sid": "1020"
},
{
"namespace": "identity",
"identifier": "too-few-elements",
"sid": "1021"
},
{
"namespace": "identity",
"identifier": "too-many-elements",
"sid": "1022"
},
{
"namespace": "identity",
"identifier": "unified",
"sid": "1029"
},
{
"namespace": "identity",
"identifier": "unknown-element",
"sid": "1023"
Veillette, et al. Expires 5 September 2024 [Page 46]
Internet-Draft CORECONF March 2024
},
{
"namespace": "data",
"identifier": "/ietf-coreconf:error",
"sid": "1024"
},
{
"namespace": "data",
"identifier": "/ietf-coreconf:error/error-app-tag",
"sid": "1025"
},
{
"namespace": "data",
"identifier": "/ietf-coreconf:error/error-data-node",
"sid": "1026"
},
{
"namespace": "data",
"identifier": "/ietf-coreconf:error/error-message",
"sid": "1027"
},
{
"namespace": "data",
"identifier": "/ietf-coreconf:error/error-tag",
"sid": "1028"
}
]
}
}
<CODE ENDS>
Figure 5: ietf-coreconf SID file
Acknowledgments
We are very grateful to Bert Greevenbosch who was one of the original
authors of the CORECONF specification.
Mehmet Ersue and Bert Wijnen explained the encoding aspects of PDUs
transported under SNMP. Koen Zandberg's implementation input
motivated massively simplifying (and fixing) the URI construction for
GET/PUT/POST requests.
The specification has further benefited from comments (alphabetical
order) by Rodney Cummings, Dee Denteneer, Esko Dijk, Klaus Hartke,
Michael van Hartskamp, Tanguy Ropitault, Jürgen Schönwälder, Anuj
Sehgal, Zach Shelby, Hannes Tschofenig, Michael Verschoor, and Thomas
Watteyne.
Veillette, et al. Expires 5 September 2024 [Page 47]
Internet-Draft CORECONF March 2024
Contributors
Ivaylo Petrov
Email: ivaylopetrov@google.com
Authors' Addresses
Michel Veillette (editor)
Trilliant Networks Inc.
610 Rue du Luxembourg
Granby Quebec J2J 2V2
Canada
Email: michel.veillette@trilliant.com
Peter van der Stok (editor)
consultant
Phone: +31625097806
Email: stokcons@kpnmail.nl
URI: https://vanderstok.tech
Alexander Pelov (editor)
IMT Atlantique
2 rue de la Châtaigneraie
35510 Cesson-Sevigne
France
Email: alexander.pelov@imt-atlantique.fr
Andy Bierman
YumaWorks
685 Cochran St.
Suite #160
Simi Valley, CA 93065
United States of America
Email: andy@yumaworks.com
Carsten Bormann (editor)
Universität Bremen TZI
Postfach 330440
D-28359 Bremen
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
Veillette, et al. Expires 5 September 2024 [Page 48]
