draft-ietf-netmod-yang-instance-file-format-01.txt   draft-ietf-netmod-yang-instance-file-format-02.txt 
Netmod B. Lengyel Netmod B. Lengyel
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track B. Claise Intended status: Standards Track B. Claise
Expires: June 9, 2019 Cisco Systems, Inc. Expires: August 30, 2019 Cisco Systems, Inc.
December 6, 2018 February 26, 2019
YANG Instance Data File Format YANG Instance Data File Format
draft-ietf-netmod-yang-instance-file-format-01 draft-ietf-netmod-yang-instance-file-format-02
Abstract Abstract
There is a need to document data defined in YANG models when a live There is a need to document data defined in YANG models when a live
YANG server is not available. Data is often needed already in design YANG server is not available. Data is often needed already at design
time or needed by groups that do not have a live running YANG server or implementation time or needed by groups that do not have a live
available. This document specifies a standard file format for YANG running YANG server available. This document specifies a standard
instance data, which follows the syntax and semantic from existing file format for YANG instance data (which follows the syntax and
YANG models, re-using existing formats from <get> operation/request semantic from existing YANG models, re-using the same format as the
and decorates them with metadata. reply to a <get> operation/request) and decorates it with metadata.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 9, 2019. This Internet-Draft will expire on August 30, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. High Level Principles . . . . . . . . . . . . . . . . . . 4 2.1. High Level Principles . . . . . . . . . . . . . . . . . . 4
3. Instance Data File Format . . . . . . . . . . . . . . . . . . 4 3. Instance Data File Format . . . . . . . . . . . . . . . . . . 4
3.1. Specifying the Target YANG Modules: target-ptr . . . . . 6 3.1. Specifying the Target YANG Modules: target-ptr . . . . . 6
3.1.1. IN-LINE Method . . . . . . . . . . . . . . . . . . . 7 3.1.1. INLINE Method . . . . . . . . . . . . . . . . . . . . 7
3.1.2. URI Method . . . . . . . . . . . . . . . . . . . . . 7 3.1.2. URI Method . . . . . . . . . . . . . . . . . . . . . 8
3.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 8
4. Data Life cycle . . . . . . . . . . . . . . . . . . . . . . . 11 4. Data Life cycle . . . . . . . . . . . . . . . . . . . . . . . 12
5. Delivery of Instance Data . . . . . . . . . . . . . . . . . . 12 5. Delivery of Instance Data . . . . . . . . . . . . . . . . . . 13
6. YANG Model . . . . . . . . . . . . . . . . . . . . . . . . . 12 6. Backwards Compatibility . . . . . . . . . . . . . . . . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 7. YANG Model . . . . . . . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 8. Security Considerations . . . . . . . . . . . . . . . . . . . 17
8.1. URI Registration . . . . . . . . . . . . . . . . . . . . 15 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
8.2. YANG Module Name Registration . . . . . . . . . . . . . . 15 9.1. URI Registration . . . . . . . . . . . . . . . . . . . . 17
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 9.2. YANG Module Name Registration . . . . . . . . . . . . . . 17
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
10.1. Normative References . . . . . . . . . . . . . . . . . . 16 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.2. Informative References . . . . . . . . . . . . . . . . . 16 11.1. Normative References . . . . . . . . . . . . . . . . . . 18
Appendix A. Open Issues . . . . . . . . . . . . . . . . . . . . 17 11.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix B. Changes between revisions . . . . . . . . . . . . . 17 Appendix A. Open Issues . . . . . . . . . . . . . . . . . . . . 19
Appendix C. Detailed Use Cases - Non-Normative . . . . . . . . . 19 Appendix B. Changes between revisions . . . . . . . . . . . . . 19
C.1. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 19 Appendix C. Detailed Use Cases - Non-Normative . . . . . . . . . 21
C.1. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 21
C.1.1. Use Case 1: Early Documentation of Server C.1.1. Use Case 1: Early Documentation of Server
Capabilities . . . . . . . . . . . . . . . . . . . . 19 Capabilities . . . . . . . . . . . . . . . . . . . . 22
C.1.2. Use Case 2: Preloading Data . . . . . . . . . . . . . 20 C.1.2. Use Case 2: Preloading Data . . . . . . . . . . . . . 23
C.1.3. Use Case 3: Documenting Factory Default Settings . . 20 C.1.3. Use Case 3: Documenting Factory Default Settings . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Terminology 1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they 14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
appear in all capitals, as shown here. appear in all capitals, as shown here.
Design time: A time during which a YANG model and the implementation Instance Data Set: A named set of data items decorated with metadata
behind it is created. Sometimes in other documents this period is that can be used as instance data in a YANG data tree.
divided into design and implementation time.
Instance Data Set: A named set of data items that can be used as
instance data in a YANG data tree.
Instance Data File: A file containing an instance data set formatted Instance Data File: A file containing an instance data set formatted
according to the rules described in this document. according to the rules described in this document.
Target YANG Module: A YANG module for which the instance data set Target YANG Module: A YANG module for which the instance data set
contains instance data, like ietf-yang-library in the examples. contains instance data, like ietf-yang-library in the examples.
YANG Instance Data, or just instance data for short, is data that YANG Instance Data, or just instance data for short, is data that
could be stored in a datastore and whose syntax and semantics is could be stored in a datastore and whose syntax and semantics is
defined by YANG models. defined by YANG models.
2. Introduction 2. Introduction
There is a need to document data defined in YANG models when a live There is a need to document data defined in YANG models when a live
YANG server is not available. Data is often needed already in design YANG server is not available. Data is often needed already at design
time or needed by groups that do not have a live running YANG server or implementation time or needed by groups that do not have a live
available. To facilitate this off-line delivery of data this running YANG server available. To facilitate this off-line delivery
document specifies a standard format for YANG instance data sets and of data this document specifies a standard format for YANG instance
YANG instance data files. data sets and YANG instance data files.
The following is a list of already implemented and potential use The following is a list of already implemented and potential use
cases. cases.
UC1 Documentation of server capabilities UC1 Documentation of server capabilities
UC2 Preloading default configuration data UC2 Preloading default configuration data
UC3 Documenting Factory Default Settings UC3 Documenting Factory Default Settings
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outside the instance data set itself will define specific use cases. outside the instance data set itself will define specific use cases.
Use cases are listed here only to indicate the need for this work. Use cases are listed here only to indicate the need for this work.
2.1. High Level Principles 2.1. High Level Principles
The following is a list of the basic principles of the instance data The following is a list of the basic principles of the instance data
format: format:
P1 Two standard formats are based on the XML and the JSON encoding P1 Two standard formats are based on the XML and the JSON encoding
P2 Re-use existing formats from the <get> operation/request P2 Re-use existing formats similar to the <get> operation/request
P3 Add metadata about the instance data set P3 Add metadata about the instance data set
P4 A YANG instance data file shall contain only a single YANG P4 A YANG instance data file shall contain only a single YANG
instance data set instance data set
P5 A YANG instance data set may contain data for many target YANG P5 A YANG instance data set may contain data for many target YANG
modules modules
P6 Instance data may include configuration data, state data or a mix P6 Instance data may include configuration data, state data or a mix
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instance-data YANG module. The content-data is all data inside the instance-data YANG module. The content-data is all data inside the
anydata datanode, this carries the "real data" that we want to anydata datanode, this carries the "real data" that we want to
document/provide. The syntax and semantics of content-data is document/provide. The syntax and semantics of content-data is
defined by the target YANG modules. defined by the target YANG modules.
Two formats are specified that can be used to represent YANG instance Two formats are specified that can be used to represent YANG instance
data based on the XML and JSON encoding. Later as other YANG data based on the XML and JSON encoding. Later as other YANG
encodings (e.g. CBOR) are defined further instance data formats may encodings (e.g. CBOR) are defined further instance data formats may
be specified. be specified.
The content-data part of the XML format SHALL follow the format The content-data part of the XML format SHALL follow the encoding
returned for a NETCONF GET operation. The <content-data> anydata rules defined in [RFC7950] for XML and [RFC7951] for JSON and MUST
node SHALL contain all elements that would be inside the <data> use UTF-8 character encoding.
wrapper element of a reply to the <get> operation. Some XML
attributes (e.g. metadata like origin) MAY be absent. SW handling
YANG instance data MUST ignore XML attributes unknown to it, allowing
them to be used later for other purposes.
The content-data part of the JSON format SHALL follow the format of It MAY include metadata as defined by [RFC7952].
the payload of the reply returned for a RESTCONF GET request directed
at the datastore resource: {+restconf}/data or
{+restconf}/ds/<datastore>.
Instance data MUST conform to the corresponding target YANG Modules It MAY include entity-tags and timestamps as defined in [RFC8040]
and follow the XML/JSON encoding rules as defined in [RFC7950] and
[RFC7951] and MUST use UTF-8 character encoding. A single instance It MAY include an explicit tag for default values as defined in
data set MAY contain data for any number of target YANG modules; if [RFC6243] and [RFC8040]
needed it MAY carry the complete configuration and state data set for
a YANG server. Default values SHOULD NOT be included. It MAY include the origin metadata as specified in
[I-D.ietf-netconf-nmda-netconf] and
[I-D.ietf-netconf-nmda-restconf]
It MAY include implementation specific metadata. Unknown metadata
MUST be ignored by users of YANG instance data, allowing it to be
used later for other purposes.
It MAY include implementation specific XML attributes. Unknown
attributes MUST be ignored by users of YANG instance data,
allowing them to be used later for other purposes.
The content-data part will be very similar to the result returned for
a NETCONF <get-data> or for a RESTCONF get operation.
The content-data part MUST conform to the corresponding target YANG
Modules. A single instance data set MAY contain data for any number
of target YANG modules; if needed it MAY carry the complete
configuration and state data set for a YANG server. Default values
SHOULD NOT be included.
Config=true and config=false data MAY be mixed in the instance data Config=true and config=false data MAY be mixed in the instance data
file. file.
Instance data files MAY contain partial data sets. This means Instance data files MAY contain partial data sets. This means
mandatory, min-elements or require-instance=true constrains MAY be mandatory, min-elements or require-instance=true constrains MAY be
violated. violated.
The name of the file SHALL be of the form: The name of the file SHALL be of the form:
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The revision date is optional. ".filetype" SHALL be ".json" or ".xml" The revision date is optional. ".filetype" SHALL be ".json" or ".xml"
according to the format used. according to the format used.
Metadata, information about the data set itself SHALL be included in Metadata, information about the data set itself SHALL be included in
the instance data set. This data will be children of the top level the instance data set. This data will be children of the top level
instance-data-set container as defined in the ietf-instance-data YANG instance-data-set container as defined in the ietf-instance-data YANG
module. Metadata MUST include: module. Metadata MUST include:
o name of the instance data set o name of the instance data set
Metadata SHOULD include: Metadata SHOULD include:
o target-ptr: A pointer to the list of target YANG modules their o target-ptr: A pointer to the list of target YANG modules their
revision, supported features and deviations. revision, supported features and deviations.
o Revision date of the instance data set. If both this date and and o An inline definition of target-modules, when the INLINE method is
the date in the instance data file name are present they MUST have used for the target-ptr
the same value.
o Description of the instance data set. The description SHOULD o Description of the instance data set. The description SHOULD
contain information whether and how the data can change during the contain information whether and how the data can change during the
lifetime of the YANG server. lifetime of the YANG server.
Metadata MAY include: Metadata MAY include:
o Organization responsible for the instance data set o Organization responsible for the instance data set
o Contact information o Contact information
o Information about the datastore associated with the instance data o Information about the datastore associated with the instance data
set e.g. the datastore from where the data was read or the set e.g. the datastore from where the data was read or the
datastore where the data could be loaded or the datastore which is datastore where the data could be loaded or the datastore which is
being documented. This information is optional, as often a single being documented. This information is optional, as often a single
datastore can not be specified. datastore can not be specified.
o Revision date of the instance data set. If both this date and and
the date in the instance data file name are present they MUST have
the same value.
o Timestamp: The date and time when the instance data set was last o Timestamp: The date and time when the instance data set was last
modified. modified.
o It is anticipated that different organizations will have the need o It is anticipated that different organizations will have the need
to augment the metadata with various other data nodes. to augment the metadata with various other data nodes.
3.1. Specifying the Target YANG Modules: target-ptr 3.1. Specifying the Target YANG Modules: target-ptr
To properly understand and use an instance data set the user needs to To properly understand and use an instance data set the user needs to
know the list of target YANG modules their revision, supported know the list of target YANG modules their revision, supported
features and deviations. The metadata "target-ptr" is used to features and deviations. The metadata "target-ptr" is used to
specify the YANG target module list. One of the following 3 options specify the YANG target module list. One of the following options
SHALL be used: SHOULD be used:
IN-LINE method: Include the needed information as part of instance INLINE method: Include the needed information as part of instance
data as defined by ietf-yang-library data set as defined by e.g. ietf-yang-library
URI method: Include a URI that points to the target module set. URI method: Include a URI that points to the target module set.
(if you don't want to repeat the info again and again) (if you don't want to repeat the info again and again)
EXTERNAL Method: Do not include the target-ptr as the target YANG EXTERNAL Method: Do not include the target-ptr as the target YANG
module set is already known, or the information is available module set is already known, or the information is available
through external documents. through external documents.
Additional methods e.g. a YANG-package based solution may be added
later.
Note, the specified target YANG modules only indicate the set of Note, the specified target YANG modules only indicate the set of
modules that were used to define this YANG instance data set. modules that were used to define this YANG instance data set.
Sometimes instance data may be used for a YANG server supporting a Sometimes instance data may be used for a YANG server supporting a
different YANG module set e.g. for UC2 preloading data the instance different YANG module set e.g. for "UC2 Preloading Data" the instance
data set may not be updated every time the YANG modules on the YANG data set may not be updated every time the YANG modules on the YANG
server are updated, an unchanged instance data set may still be server are updated, an unchanged instance data set may still be
usable. Whether the instance data set is usable for a possibly usable. Whether the instance data set is usable for a possibly
different real-life target YANG module set depends on the different real-life target YANG module set depends on many factors
compatibility between the specified target and the real-life target including the compatibility between the specified target and the
YANG module set (considering modules, revisions, features, real-life target YANG module set (considering modules, revisions,
deviations). features, deviations), the scope of the instance data, etc.
3.1.1. IN-LINE Method 3.1.1. INLINE Method
Target-ptr MUST bet set to: One or more inline-target-spec elements SHALL be specified. The
first one specifies ietf-yang-library or a similar YANG module
listing target YANG modules with their name, revision-date,
supported-features and deviations. Deviations or unsupported
features MUST NOT remove any of the above data from the module.
Using ietf-yang-library MUST be supported.
'inline:ietf-yang-library@' revision-date '.yang' E.g. ietf-yang-library@2016-06-21.yang
E.g. inline:ietf-yang-library@2016-06-21.yang As some versions of ietf-yang-library MAY contain different module-
sets for different datastores, if multiple module-sets are defined,
the instance data set's meta-data MUST contain the datastore
information and instance data for the ietf-yang library MUST also
contain information specifying the module-set for the relevant
datastore.
The revision date in the inline target-ptr is mandatory, it specifies Subsequent inline-target-spec elements MAY specify YANG modules
the revision of the ietf-yang-library used. The first group of data augmenting the first module with useful data (e.g. a semantic
inside the "anydata data" element MUST be instance data targeted at version).
the ietf-yang-library. This data SHALL specify the target YANG
modules, revisions, supported features and deviations for this and When using the inline method a 'target-modules' element MUST be
all the other target YANG modules. present. This SHALL contain instance data corresponding to the YANG
modules specified in the inline-target-spec elements specifying the
set of target YANG modules for this instance-data-set.
3.1.2. URI Method 3.1.2. URI Method
Target-ptr MUST bet set to a URI that references another YANG A target-uri element SHALL contain a URI that references another YANG
instance data file. The current instance data file will use the same instance data file. The current instance data file will use the same
set of target YANG modules, revisions, supported features and set of target YANG modules, revisions, supported features and
deviations as the other referenced YANG instance data file. deviations as the referenced YANG instance data file.
The referenced instance data file will usually contain data only for The referenced instance data file will usually contain data only for
ietf-yang-library to specify the target YANG modules for the original ietf-yang-library to specify the target YANG modules for the original
instance data file. instance data file.
The URI method is advantageous when the user wants to avoid the The URI method is advantageous when the user wants to avoid the
overhead of specifying the target YANG modules in the instance data overhead of specifying the target YANG modules in the instance data
file: E.g. In Use Case 6, when the system creates a diagnostic file file: E.g. In Use Case 6, when the system creates a diagnostic file
every 10 minutes to document the state of the YANG server. every 10 minutes to document the state of the YANG server.
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or might use the URI method to reference further instance data or might use the URI method to reference further instance data
file(s). However at the end of this reference chain there MUST be an file(s). However at the end of this reference chain there MUST be an
instance data file using the in-line method. instance data file using the in-line method.
If a referenced instance data file is not available the revision If a referenced instance data file is not available the revision
data, supported features and deviations for the target YANG modules data, supported features and deviations for the target YANG modules
are unknown. are unknown.
3.2. Examples 3.2. Examples
The following example is based on UC1, documenting server The following example is based on "UC1, Documenting Server
capabilities. It provides (a shortened) list of supported YANG Capabilities". It provides (a shortened) list of supported YANG
modules for a YANG server. It uses the inline method for the target- modules and Netconf capabilities for a YANG server. It uses the
ptr. inline method for the target-ptr.
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<instance-data-set xmlns= <instance-data-set xmlns=
"urn:ietf:params:xml:ns:yang:ietf-yang-instance-data"> "urn:ietf:params:xml:ns:yang:ietf-yang-instance-data">
<name>acme-router-modules</name> <name>acme-router-modules</name>
<target-ptr>inline:ietf-yang-library@2016-06-21.yang</target-ptr> <inline-target-spec>
ietf-yang-library@2016-06-21.yang
</inline-target-spec>
<target-modules>
<module-state xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library">
<module>
<name>ietf-yang-library</name>
<revision>2016-06-21</revision>
</module>
<module>
<name>ietf-netconf-monitoring</name>
<revision>2010-10-04</revision>
</module>
</module-state>
</target-modules>
<revision> <revision>
<date>2108-01-25</date> <date>2108-01-25</date>
<description>Initial version</description> <description>Initial version</description>
</revision> </revision>
<description>Defines the minimal set of modules that any acme-router <description>Defines the minimal set of modules that any acme-router
will contain.</description> will contain.</description>
<contact>info@acme.com</contact> <contact>info@acme.com</contact>
<content-data> <content-data>
<!-- The example lists only 4 modules, but it could list the <!-- The example lists only 4 modules, but it could list the
full set of supported modules for a YANG server, potentially many full set of supported modules for a YANG server, potentially many
dozens of modules --> dozens of modules -->
<module-state xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"> <module-state xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library">
<module> <module>
<name>ietf-yang-library</name> <name>ietf-yang-library</name>
<revision>2016-06-21</revision> <revision>2016-06-21</revision>
<namespace>urn:ietf:params:xml:ns:yang:ietf-yang-library</namespace> <namespace>
urn:ietf:params:xml:ns:yang:ietf-yang-library
</namespace>
<conformance-type>implement</conformance-type> <conformance-type>implement</conformance-type>
</module> </module>
<module> <module>
<name>ietf-system</name> <name>ietf-system</name>
<revision>2014-08-06</revision> <revision>2014-08-06</revision>
<namespace>urn:ietf:params:xml:ns:yang:ietf-system</namespace> <namespace>urn:ietf:params:xml:ns:yang:ietf-system</namespace>
<feature>sys:authentication</feature> <feature>sys:authentication</feature>
<feature>sys:local-users</feature> <feature>sys:local-users</feature>
<feature>sys:ntp</feature>
<deviation> <deviation>
<name>acme-system-ext</name> <name>acme-system-ext</name>
<revision>2018-08-06</revision> <revision>2018-08-06</revision>
</deviation> </deviation>
<conformance-type>implement</conformance-type> <conformance-type>implement</conformance-type>
</module> </module>
<module> <module>
<name>ietf-yang-types</name> <name>ietf-yang-types</name>
<revision>2013-07-15</revision> <revision>2013-07-15</revision>
<namespace>urn:ietf:params:xml:ns:yang:ietf-yang-types</namespace> <namespace>urn:ietf:params:xml:ns:yang:ietf-yang-types
</namespace>
<conformance-type>import</conformance-type> <conformance-type>import</conformance-type>
</module> </module>
<module> <module>
<name>acme-system-ext</name> <name>acme-system-ext</name>
<revision>2018-08-06</revision> <revision>2018-08-06</revision>
<namespace>urn:rdns:acme.com:oammodel:acme-system-ext</namespace> <namespace>urn:rdns:acme.com:oammodel:acme-system-ext
</namespace>
<conformance-type>implement</conformance-type> <conformance-type>implement</conformance-type>
</module> </module>
</module-state> </module-state>
<netconf-state>
<capabilities>
<capability>
urn:ietf:params:netconf:capability:validate:1.1
</capability>
</capabilities>
</netconf-state>
</content-data> </content-data>
</instance-data-set> </instance-data-set>
Figure 1: XML Instance Data Set - Use case 1, Documenting server Figure 1: XML Instance Data Set - Use case 1, Documenting server
capabilities capabilities
The following example is based on UC2, preloading default The following example is based on "UC2, Preloading Default
configuration. It provides (a shortened) default rule set for a Configuration". It provides a (shortened) default rule set for a
read-only operator role. It uses the inline method for the target- read-only operator role. It uses the inline method for the target-
ptr. ptr.
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<instance-data-set xmlns= <instance-data-set xmlns=
"urn:ietf:params:xml:ns:yang:ietf-yang-instance-data"> "urn:ietf:params:xml:ns:yang:ietf-yang-instance-data">
<name>read-only-acm-rules</name> <name>read-only-acm-rules</name>
<target-ptr>inline:ietf-yang-library@2016-06-21.yang</target-ptr> <inline-target-spec>ietf-yang-library@2016-06-21.yang
</inline-target-spec>
<target-modules>
<module-state xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library">
<module>
<name>ietf-netconf-acm</name>
<revision>2012-02-22</revision>
</module>
</module-state>
</target-modules>
<revision> <revision>
<date>2018-01-25</date> <date>2018-01-25</date>
<description>Initial version</description> <description>Initial version</description>
</revision> </revision>
<description>Access control rules for a read-only role.</description> <description>Access control rules for a read-only role.</description>
<contact>info@acme.com</contact> <contact>info@acme.com</contact>
<content-data> <content-data>
<module-state xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library">
<module>
<name>ietf-yang-library</name>
<revision>2016-06-21</revision>
</module>
<module>
<name>ietf-netconf-acm</name>
<revision>2012-02-22</revision>
</module>
</module-state>
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"> <nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm">
<enable-nacm>true</enable-nacm> <enable-nacm>true</enable-nacm>
<read-default>deny</read-default> <read-default>deny</read-default>
<exec-default>deny</exec-default> <exec-default>deny</exec-default>
<rule-list> <rule-list>
<name>read-only-role</name> <name>read-only-role</name>
<group>read-only-group</group> <group>read-only-group</group>
<rule> <rule>
<name>read-all</name> <name>read-all</name>
<module-name>*</module-name> <module-name>*</module-name>
skipping to change at page 10, line 50 skipping to change at page 11, line 49
</rule-list> </rule-list>
</nacm> </nacm>
</content-data> </content-data>
</instance-data-set> </instance-data-set>
Figure 2: XML Instance Data Set - Use case 2, Preloading access Figure 2: XML Instance Data Set - Use case 2, Preloading access
control data control data
The following example is based on UC6 Storing diagnostics data. An The following example is based on UC6 Storing diagnostics data. An
instance data set is produced by the YANG server every 15 minutes instance data set is produced by the YANG server every 15 minutes
that contains statistics about netconf. As a new set is produced that contains statistics about NETCONF. As a new set is produced
automatically a revision-date would be useless; instead a timestamp periodically multiple times a day a revision-date would be useless;
is included. instead a timestamp is included.
{ {
"ietf-yang-instance-data:instance-data-set": { "ietf-yang-instance-data:instance-data-set": {
"name": "acme-router-netconf-diagnostics", "name": "acme-router-netconf-diagnostics",
"target-ptr": "file:///acme-netconf-diagnostics-yanglib.json", "target-uri": "file:///acme-netconf-diagnostics-yanglib.json",
"timestamp": "2018-01-25T17:00:38Z", "timestamp": "2018-01-25T17:00:38Z",
"description": "description":
"Netconf statistics", "Netconf statistics",
"content-data": { "content-data": {
"ietf-netconf-monitoring:netconf-state": { "ietf-netconf-monitoring:netconf-state": {
"statistics": { "statistics": {
"netconf-start-time ": "2018-12-05T17:45:00Z", "netconf-start-time ": "2018-12-05T17:45:00Z",
"in-bad-hellos ": "32", "in-bad-hellos ": "32",
"in-sessions ": "397", "in-sessions ": "397",
"dropped-sessions ": "87", "dropped-sessions ": "87",
skipping to change at page 11, line 43 skipping to change at page 12, line 43
Data defined or documented in YANG instance data sets may be used for Data defined or documented in YANG instance data sets may be used for
preloading a YANG server with this data, but the server may populate preloading a YANG server with this data, but the server may populate
the data without using the actual file in which case the instance the data without using the actual file in which case the instance
data file is only used as documentation. data file is only used as documentation.
While such data will usually not change, data documented by instance While such data will usually not change, data documented by instance
data sets MAY be changed by the YANG server itself or by management data sets MAY be changed by the YANG server itself or by management
operations. It is out of scope for this document to specify a method operations. It is out of scope for this document to specify a method
to prevent this. Whether such data changes and if so, when and how, to prevent this. Whether such data changes and if so, when and how,
SHOULD be described either in the instance data file description SHOULD be described either in the instance data set's description
statement or in some other implementation specific manner. statement or in some other implementation specific manner.
YANG instance data is a snap-shot of information at a specific point YANG instance data is a snap-shot of information at a specific point
of time. If the data changes afterwards this is not represented in of time. If the data changes afterwards this is not represented in
the instance data set anymore, the valid values can be retrieved in the instance data set anymore, the valid values can be retrieved in
run-time via Netconf/Restconf run-time via NETCONF/RESTCONF.
Notifications about the change of data documented by instance data Notifications about the change of data documented by instance data
sets may be supplied by e.g. the Yang-Push mechanism, but it is out sets may be supplied by e.g. the Yang-Push mechanism, but it is out
of scope for this document. of scope for this document.
5. Delivery of Instance Data 5. Delivery of Instance Data
Instance data sets that are produced as a result of some sort of Instance data sets that are produced as a result of some sort of
specification or design effort SHOULD be available without the need specification or design effort SHOULD be available without the need
for a live YANG server e.g. via download from the vendor's website, for a live YANG server e.g. via download from the vendor's website,
or in any other way product documentation is distributed. or in any other way product documentation is distributed.
Other instance data sets may be read from or produced by the YANG Other instance data sets may be read from or produced by the YANG
server itself e.g. UC6 documenting diagnostic data. server itself e.g. UC6 documenting diagnostic data.
6. YANG Model 6. Backwards Compatibility
<CODE BEGINS> file "ietf-yang-instance-data.yang" The concept of backwards compatibility and what changes are backwards
compatible are not defined for instance data sets as it is highly
dependent on the specific use case and the target YANG model.
However as instance data does use the concept of managed entities
identified by key values the following guidelines are provided:
module ietf-yang-instance-data { o For list entries representing the same managed entity as
yang-version 1.1; previously key values SHOULD NOT be changed.
namespace
"urn:ietf:params:xml:ns:yang:ietf-yang-instance-data";
prefix yid ;
import ietf-yang-data-ext { prefix yd; } o The meaning of list entries, representing the same managed entity
import ietf-datastores { prefix ds; } as previously, SHOULD NOT be changed e.g. redefining an alarm-type
import ietf-inet-types { prefix inet; } but not changing its alarm-type-id should be avoided.
import ietf-yang-types { prefix yang; }
organization "IETF NETMOD Working Group"; o Keys for previously removed list entries SHOULD NOT be reused if
contact they represent a different meaning.
"WG Web: <https://datatracker.ietf.org/wg/netmodf/>
WG List: <mailto:netmod@ietf.org>
Author: Balazs Lengyel 7. YANG Model
<mailto:balazs.lengyel@ericsson.com>";
description "The module defines the structure and content of YANG <CODE BEGINS> file "ietf-yang-instance-data.yang"
instance data sets."; module ietf-yang-instance-data {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-yang-instance-data";
prefix yid ;
revision 2018-11-30 { import ietf-yang-data-ext { prefix yd; }
description "Initial revision."; import ietf-datastores { prefix ds; }
reference "RFC XXXX: YANG Instance Data Format"; import ietf-inet-types { prefix inet; }
} import ietf-yang-types { prefix yang; }
yd:yang-data instance-data-format { organization "IETF NETMOD Working Group";
container instance-data-set { contact
description "Auxiliary container to carry meta-data for "WG Web: <https://datatracker.ietf.org/wg/netmodf/>
the complete instance data set."; WG List: <mailto:netmod@ietf.org>
leaf name { Author: Balazs Lengyel
type string; <mailto:balazs.lengyel@ericsson.com>";
mandatory true;
description "Name of the YANG instance data set.";
}
leaf target-ptr { description "The module defines the structure and content of YANG
type union { instance data sets.";
type string {
pattern 'inline:ietf-yang-library@\d{4}-\d{2}-\d{2}\.yang';
}
type inet:uri;
}
description "A pointer to the list of target YANG modules
their revisions, supported features and deviations.
target-ptr SHALL use one of the following formats:
IN-LINE format: target-ptr should bet set to: revision 2019-02-20 {
'inline:ietf-yang-library@' revision-date '.yang' description "Initial revision.";
E.g. inline:ietf-yang-library@2016-06-21.yang reference "RFC XXXX: YANG Instance Data Format";
The revision date is mandatory. When using the in-line }
format the first group of data inside the content-data
node MUST be instance data targeted at the
ietf-yang-library. This data SHALL specify the target YANG
modules, revisions, supported features and deviations for
this and all the other target YANG modules of the set.
URI format. target-ptr MUST be a URI that references yd:yang-data instance-data-format {
another YANG instance data file. container instance-data-set {
This instance data file will use the same set of target description "Auxiliary container to carry meta-data for
YANG modules, revisions, supported features and deviations the complete instance data set.";
as this other referenced YANG instance data file.";
}
leaf description { type string; } leaf name {
type string;
mandatory true;
description "Name of the YANG instance data set.";
}
leaf contact { choice target-ptr {
type string; description "A pointer to the list of target YANG modules
description "Contact information for the person or their revisions, supported features and deviations.";
organization to whom queries concerning this
instance data set should be sent.";
}
leaf organization { case inline {
type string; leaf-list inline-target-spec {
description "Organization responsible for the instance type string {
data set."; pattern '.+@\d{4}-\d{2}-\d{2}\.yang';
} }
min-elements 1;
ordered-by user;
description
"Indicates that target modules are specified inline.
Each value MUST be a YANG Module name including the
revision-date as defined for YANG file names in RFC7950.
leaf datastore { E.g. ietf-yang-library@2016-06-21.yang
type ds:datastore-ref;
description "The identity of the datastore with which the
instance data set is associated. If a single specific
datastore can not be specified, the leaf MUST be absent.
If this leaf is absent, then the datastore to which the The first item is either ietf-yang-library or some other
instance data belongs is undefined."; YANG module that contains a list of YANG modules with
} their name, revision-date, supported-features and
deviations.
As some versions of ietf-yang-library MAY contain
different module-sets for different datastores, if
multiple module-sets are defined, the instance data set's
meta-data MUST contain the datastore information and
instance data for the ietf-yang-library MUST also contain
information specifying the module-set for the relevant
datastore.
list revision { Subsequent items MAY specify YANG modules augmenting the
key date; first module with useful data (e.g. a semantic version).";
description "Instance data sets that are produced as }
a result of some sort of specification or design effort anydata target-modules {
SHOULD have at least one revision entry. For every mandatory true;
published editorial change, a new one SHOULD be added description "Instance data corresponding to the YANG modules
in front of the revisions sequence so that all specified in the inline-target-spec nodes defining the set
revisions are in reverse chronological order. of target YANG modules for this instance-data-set.";
}
}
For instance data sets that are read from case uri {
or produced by the YANG server or otherwise leaf target-uri {
subject to frequent updates or changes, revision type inet:uri;
SHOULD NOT be present"; description
"A reference to another YANG instance data file.
This instance data file will use the same set of target
YANG modules, revisions, supported features and deviations
as the referenced YANG instance data file.";
}
}
}
leaf date { leaf description { type string; }
type string {
pattern '\d{4}-\d{2}-\d{2}';
}
description "Specifies the date the instance data set
was last modified. Formatted as YYYY-MM-DD";
}
leaf description { type string; } leaf contact {
} type string;
description "Contact information for the person or
organization to whom queries concerning this
instance data set should be sent.";
}
leaf timestamp { leaf organization {
type yang:date-and-time; type string;
description "The date and time when the instance data set description "Organization responsible for the instance
was last modified. data set.";
}
For instance data sets that are read from or produced leaf datastore {
by the YANG server or otherwise subject to frequent type ds:datastore-ref;
updates or changes, timestamp SHOULD be present"; description "The identity of the datastore with which the
} instance data set is associated. If a single specific
anydata content-data { datastore can not be specified, the leaf MUST be absent.
mandatory true;
description "Contains the real instance data.
The data MUST conform to the relevant YANG Modules.";
}
}
}
}
<CODE ENDS> If this leaf is absent, then the datastore to which the
instance data belongs is undefined.";
}
7. Security Considerations list revision {
key date;
description "Instance data sets that are produced as
a result of some sort of specification or design effort
SHOULD have at least one revision entry. For every
published editorial change, a new one SHOULD be added
in front of the revisions sequence so that all
revisions are in reverse chronological order.
For instance data sets that are read from
or produced by the YANG server or otherwise
subject to frequent updates or changes, revision
SHOULD NOT be present";
leaf date {
type string {
pattern '\d{4}-\d{2}-\d{2}';
}
description "Specifies the date the instance data set
was last modified. Formatted as YYYY-MM-DD";
}
leaf description { type string; }
}
leaf timestamp {
type yang:date-and-time;
description "The date and time when the instance data set
was last modified.
For instance data sets that are read from or produced
by the YANG server or otherwise subject to frequent
updates or changes, timestamp SHOULD be present";
}
anydata content-data {
mandatory true;
description "Contains the real instance data.
The data MUST conform to the relevant YANG Modules.";
}
}
}
}
<CODE ENDS>
8. Security Considerations
Depending on the nature of the instance data, instance data files MAY Depending on the nature of the instance data, instance data files MAY
need to be handled in a secure way. The same type of handling should need to be handled in a secure way. The same type of handling should
be applied, that would be needed for the result of a <get> operation be applied, that would be needed for the result of a <get> operation
returning the same data. returning the same data.
8. IANA Considerations 9. IANA Considerations
This document registers one URI and one YANG module. This document registers one URI and one YANG module.
8.1. URI Registration 9.1. URI Registration
This document registers one URI in the IETF XML registry [RFC3688]. This document registers one URI in the IETF XML registry [RFC3688].
Following the format in RFC 3688, the following registration is Following the format in RFC 3688, the following registration is
requested to be made: requested to be made:
URI: urn:ietf:params:xml:ns:yang:ietf-yang-instance-data URI: urn:ietf:params:xml:ns:yang:ietf-yang-instance-data
Registrant Contact: The IESG. Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace. XML: N/A, the requested URI is an XML namespace.
8.2. YANG Module Name Registration 9.2. YANG Module Name Registration
This document registers one YANG module in the YANG Module Names This document registers one YANG module in the YANG Module Names
registry [RFC6020]. registry [RFC6020].
name: ietf-yang-instance-data name: ietf-yang-instance-data
namespace: urn:ietf:params:xml:ns:yang:ietf-yang-instance-data namespace: urn:ietf:params:xml:ns:yang:ietf-yang-instance-data
prefix: yid prefix: yid
reference: RFC XXXX reference: RFC XXXX
9. Acknowledgments 10. Acknowledgments
For their valuable comments, discussions, and feedback, we wish to For their valuable comments, discussions, and feedback, we wish to
acknowledge Andy Bierman, Juergen Schoenwaelder, Rob Wilton, Joe acknowledge Andy Bierman, Juergen Schoenwaelder, Rob Wilton, Joe
Clark, Martin Bjorklund, Ladislav Lhotka, Qin Wu and other members of Clark, Martin Bjorklund, Ladislav Lhotka, Qin Wu and other members of
the Netmod WG. the Netmod WG.
10. References 11. References
10.1. Normative References 11.1. Normative References
[I-D.ietf-netconf-nmda-netconf]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "NETCONF Extensions to Support the Network
Management Datastore Architecture", draft-ietf-netconf-
nmda-netconf-08 (work in progress), October 2018.
[I-D.ietf-netconf-nmda-restconf]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "RESTCONF Extensions to Support the Network
Management Datastore Architecture", draft-ietf-netconf-
nmda-restconf-05 (work in progress), October 2018.
[I-D.ietf-netmod-yang-data-ext] [I-D.ietf-netmod-yang-data-ext]
Bierman, A., Bjorklund, M., and K. Watsen, "YANG Data Bierman, A., Bjorklund, M., and K. Watsen, "YANG Data
Extensions", draft-ietf-netmod-yang-data-ext-01 (work in Extensions", draft-ietf-netmod-yang-data-ext-01 (work in
progress), March 2018. progress), March 2018.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004, DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>. <https://www.rfc-editor.org/info/rfc3688>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020, the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010, DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>. <https://www.rfc-editor.org/info/rfc6020>.
[RFC6243] Bierman, A. and B. Lengyel, "With-defaults Capability for
NETCONF", RFC 6243, DOI 10.17487/RFC6243, June 2011,
<https://www.rfc-editor.org/info/rfc6243>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016, RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>. <https://www.rfc-editor.org/info/rfc7950>.
[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",
RFC 7951, DOI 10.17487/RFC7951, August 2016, RFC 7951, DOI 10.17487/RFC7951, August 2016,
<https://www.rfc-editor.org/info/rfc7951>. <https://www.rfc-editor.org/info/rfc7951>.
10.2. Informative References [RFC7952] Lhotka, L., "Defining and Using Metadata with YANG",
RFC 7952, DOI 10.17487/RFC7952, August 2016,
<https://www.rfc-editor.org/info/rfc7952>.
[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>.
11.2. Informative References
[I-D.ietf-ccamp-alarm-module] [I-D.ietf-ccamp-alarm-module]
Vallin, S. and M. Bjorklund, "YANG Alarm Module", draft- Vallin, S. and M. Bjorklund, "YANG Alarm Module", draft-
ietf-ccamp-alarm-module-06 (work in progress), November ietf-ccamp-alarm-module-07 (work in progress), January
2018. 2019.
[I-D.ietf-netconf-rfc7895bis] [I-D.ietf-netconf-rfc7895bis]
Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K., Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K.,
and R. Wilton, "YANG Library", draft-ietf-netconf- and R. Wilton, "YANG Library", draft-ietf-netconf-
rfc7895bis-07 (work in progress), October 2018. rfc7895bis-07 (work in progress), October 2018.
[I-D.ietf-netconf-yang-push] [I-D.ietf-netconf-yang-push]
Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen- Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-
Nygaard, E., Bierman, A., and B. Lengyel, "Subscription to Nygaard, E., Bierman, A., and B. Lengyel, "Subscription to
YANG Datastores", draft-ietf-netconf-yang-push-20 (work in YANG Datastores", draft-ietf-netconf-yang-push-22 (work in
progress), October 2018. progress), February 2019.
[I-D.wu-netconf-restconf-factory-restore] [I-D.wu-netconf-restconf-factory-restore]
Wu, Q., Lengyel, B., and Y. Niu, "Factory default Wu, Q., Lengyel, B., and Y. Niu, "Factory default
Setting", draft-wu-netconf-restconf-factory-restore-03 Setting", draft-wu-netconf-restconf-factory-restore-03
(work in progress), October 2018. (work in progress), October 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 17, line 33 skipping to change at page 19, line 49
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Appendix A. Open Issues Appendix A. Open Issues
o Augmenting metadata must be possible. As of now it looks like o Augmenting metadata must be possible. As of now it looks like
yang-data-ext will solve that. If not, define instance data as yang-data-ext will solve that. If not, define instance data as
regular YANG instead of yd:yang-data. regular YANG instead of yd:yang-data.
Appendix B. Changes between revisions Appendix B. Changes between revisions
v01 - v02
o Removed design time from terminology
o Defined the format of the content-data part by referencing various
RFCs and drafts instead of the result of the get-data and get
operations.
o Changed target-ptr to a choice
o Inline target-ptr may include augmenting modules and alternatives
to ietf-yang-library
o Moved list of target modules into a separate <target-modules>
element.
o Added backwards compatibility considerations
v00 - v01 v00 - v01
o Added the target-ptr metadata with 3 methods o Added the target-ptr metadata with 3 methods
o Added timestamp metadata o Added timestamp metadata
o Removed usage of dedicated .yid file extension o Removed usage of dedicated .yid file extension
o Added list of use cases o Added list of use cases
skipping to change at page 20, line 11 skipping to change at page 22, line 49
this. Moreover the network operator's decision to buy a vendor's this. Moreover the network operator's decision to buy a vendor's
product may even be influenced by the network node's OAM feature set product may even be influenced by the network node's OAM feature set
documented as the Yang server's capabilities. documented as the Yang server's capabilities.
Beside NMS implementors, system integrators and many others also need Beside NMS implementors, system integrators and many others also need
the same information early. Examples could be model driven testing, the same information early. Examples could be model driven testing,
generating documentation, etc. generating documentation, etc.
Most server-capabilities are relatively stable and change only during Most server-capabilities are relatively stable and change only during
upgrade or due to licensing or addition or removal of HW. They are upgrade or due to licensing or addition or removal of HW. They are
usually defined by a vendor in design time, before the product is usually defined by a vendor at design time, before the product is
released. It feasible and advantageous to define/document them early released. It feasible and advantageous to define/document them early
e.g. in a YANG instance data File. e.g. in a YANG instance data File.
It is anticipated that a separate IETF document will define in detail It is anticipated that a separate IETF document will define in detail
how and which set of server capabilities should be documented. how and which set of server capabilities should be documented.
C.1.2. Use Case 2: Preloading Data C.1.2. Use Case 2: Preloading Data
There are parts of the configuration that must be fully configurable There are parts of the configuration that must be fully configurable
by the operator, however for which often a simple default by the operator, however for which often a simple default
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