rfc9195xml2.original.xml   rfc9195.xml 
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ile-format-21">
<front> <front>
<title abbrev="YANG Instance Data">YANG Instance Data File Format</title> <title abbrev="YANG Instance Data">A File Format for YANG Instance Data</tit
le>
<seriesInfo name="RFC" value="9195"/>
<author initials="B." surname="Lengyel" fullname="Balazs Lengyel"> <author initials="B." surname="Lengyel" fullname="Balazs Lengyel">
<organization abbrev="Ericsson"> Ericsson </organization> <organization abbrev="Ericsson">Ericsson</organization>
<address> <address>
<postal>
<street>Magyar Tudosok korutja 11</street>
<city>Budapest</city>
<country>Hungary</country>
<code>1117</code>
</postal>
<email>balazs.lengyel@ericsson.com</email> <email>balazs.lengyel@ericsson.com</email>
</address> </address>
</author> </author>
<author fullname="Benoit Claise" initials="B" surname="Claise"> <author fullname="Benoit Claise" initials="B." surname="Claise">
<organization>Huawei</organization> <organization>Huawei</organization>
<address> <address>
<email>benoit.claise@huawei.com</email> <email>benoit.claise@huawei.com</email>
</address> </address>
</author> </author>
<date year="2021"/> <date year="2022" month="February"/>
<area>OPS</area> <area>OPS</area>
<workgroup>Netmod</workgroup> <workgroup>Netmod</workgroup>
<abstract>
<abstract>
<t> <t>
There is a need to document data defined in YANG models at design time, There is a need to document data defined in YANG models at design time,
implementation time or when a live server is unavailable. implementation time, or when a live server is unavailable.
This document specifies a standard This document specifies a standard
file format for YANG instance data, which follows the syntax and semanti cs file format for YANG instance data, which follows the syntax and semanti cs
of existing YANG models, and annotates it with metadata. of existing YANG models and annotates it with metadata.
</t> </t>
</abstract> </abstract>
</front> </front>
<middle> <middle>
<section anchor="intro" title="Introduction"> <section anchor="intro" numbered="true" toc="default">
<name>Introduction</name>
<t> <t>
There is a need to document data defined in YANG models when a live serv er is unavailable. There is a need to document data defined in YANG models when a live serv er is unavailable.
Data is often needed at design, implementation time or even later Data is often needed at design time, implementation time, or even later
when a live running server is unavailable. when a live running server is unavailable.
To facilitate this offline delivery of data, this document specifies a s tandard To facilitate this offline delivery of data, this document specifies a s tandard
format for YANG instance data sets and YANG instance data files. format for YANG instance data sets and YANG instance data files.
The format of the instance data set is defined by the "ietf-yang-instanc e-data" The format of the instance data set is defined by the "ietf-yang-instanc e-data"
YANG module, see <xref target="instance_data_yam"/>. YANG module; see <xref target="instance_data_yam" format="default"/>.
The YANG data model in this document conforms to the Network The YANG data model in this document conforms to the Network
Management Datastore Architecture (NMDA) defined in <xref target="RFC834 Management Datastore Architecture (NMDA) defined in <xref target="RFC834
2"/> 2" format="default"/>.
</t>
<t>The following is a list of already implemented and potential use case
s.
<list style="format UC%d">
<t>Documentation of server capabilities</t>
<t>Preloading default configuration data</t>
<t>Documenting factory default settings</t>
<t>Storing the configuration of a device, e.g., for backup, archive or
audit purposes</t>
<t>Storing diagnostics data</t>
<t>Allowing YANG instance data to potentially be carried within other
IPC message formats</t>
<t>Default instance data used as part of a templating solution</t>
<t>Providing data examples in RFCs or internet drafts</t>
</list>
</t> </t>
<t><xref target="detailed_use_cases"/> describes the first three use <t>The following is a list of already-implemented and potential use cases.
</t>
<ol spacing="normal" type="UC%d">
<li anchor="uc1">Documentation of server capabilities</li>
<li anchor="uc2">Preloading default configuration data</li>
<li anchor="uc3">Documenting factory default settings</li>
<li anchor="uc4">Storing the configuration of a device, e.g., for backup
, archive, or
audit purposes</li>
<li anchor="uc5">Storing diagnostics data</li>
<li anchor="uc6">Allowing YANG instance data to potentially be carried w
ithin other inter-process communication (IPC) message formats</li>
<li anchor="uc7">Default instance data used as part of a templating solu
tion</li>
<li anchor="uc8">Providing data examples in RFCs or internet drafts</li>
</ol>
<t><xref target="detailed_use_cases" format="default"/> describes the firs
t three use
cases in detail. cases in detail.
</t><t> </t>
<t>
There are many and varied use cases where YANG instance data There are many and varied use cases where YANG instance data
could be used. This document does not limit future uses of instance data could be used. This document does not limit future uses of instance data
sets, so specifying how and when to use YANG instance data sets, so specifying how and when to use YANG instance data
is out of scope for this document. It is anticipated that other is out of scope for this document. It is anticipated that other
documents will define specific use cases. Use cases are listed documents will define specific use cases. Use cases are listed
only as examples. only as examples.
</t> </t>
<section title="Terminology" anchor="terminology"> <section anchor="terminology" numbered="true" toc="default">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL <name>Terminology</name>
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", <t>
"MAY", and "OPTIONAL" in this document are to be interpreted as The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQU
described in BCP 14 <xref target="RFC2119"/> IRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
<xref target="RFC8174"/> when, and only when, they NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>
appear in all capitals, as shown here.</t> RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
<t>Instance Data: A collection of instantiated data nodes.</t> "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to
<t>Instance Data Set: A named set of data items annotated with metadata be interpreted as
that can be used as instance data in a YANG data tree.</t> described in BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
<t>Instance Data File: A file containing an instance data set formatted when, and only when, they appear in all capitals, as shown here.
according to the rules described in this document.</t> </t>
<t>Content-schema: A set of YANG modules with their revision, supported <dl>
features, and deviations for which the instance data set contains inst <dt>Instance Data:</dt><dd>A collection of instantiated data nodes.</dd>
ance data.</t> <dt>Instance Data Set:</dt><dd>A named set of data items annotated with
<t>Content defining YANG module: an individual YANG module that is part metadata
of the content-schema.</t> that can be used as instance data in a YANG data tree.</dd>
<t>The term "server" is used as defined in <xref target="RFC8342"/>.</t> <dt>Instance Data File:</dt><dd>A file containing an instance data set f
ormatted
according to the rules described in this document.</dd>
<dt>Content-schema:</dt><dd>A set of YANG modules with their revision, s
upported
features, and deviations for which the instance data set contains inst
ance data.</dd>
<dt>Content-defining YANG Module:</dt><dd>An individual YANG module th
at is part of the content-schema.</dd>
</dl>
<t>The term "server" is used as defined in <xref target="RFC8342" format
="default"/>.</t>
</section> </section>
<section title="Principles"> <section numbered="true" toc="default">
<name>Principles</name>
<t>The following is a list of the basic principles of the instance data format: <t>The following is a list of the basic principles of the instance data format:
<list style="format P%d">
<t>Two standard formats shall be defined based on the XML and
JSON encodings.</t>
<t>Instance data shall reuse existing encoding rules for
YANG defined data.
</t>
<t>Metadata about the instance data set
(<xref target="instance_data_set_metadata"/>) shall be defined.</t
>
<t>A YANG instance data set shall be allowed to contain data
for multiple YANG modules.</t>
<t>Instance data shall be allowed to contain configuration data,
state data, or a mix of the two.</t>
<t>Partial data sets shall be allowed.</t>
<t>The YANG instance data format shall be usable for any data for wh
ich
YANG module(s) are defined and available to the reader, independen
t
of whether the module is implemented by a server.</t>
<t>It shall be possible to report the identity of the datastore with
which the
instance data set is associated.</t>
</list>
</t> </t>
<ol spacing="normal" type="P%d"><li>Two standard formats shall be define
d based on the XML and
JSON encodings.</li>
<li>Instance data shall reuse existing encoding rules for
YANG-defined data.
</li>
<li>Metadata about the instance data set
(<xref target="instance_data_set_metadata" format="default"/>) sha
ll be defined.</li>
<li>A YANG instance data set shall be allowed to contain data
for multiple YANG modules.</li>
<li>Instance data shall be allowed to contain configuration data,
state data, or a mix of the two.</li>
<li>Partial data sets shall be allowed.</li>
<li>The YANG instance data format shall be usable for any data for whi
ch
YANG module(s) are defined and available to the reader, independen
t
of whether the module is implemented by a server.</li>
<li>It shall be possible to report the identity of the datastore with
which the
instance data set is associated.</li>
</ol>
</section> </section>
<section title="Delivery of Instance Data"> <section numbered="true" toc="default">
<name>Delivery of Instance Data</name>
<t>Instance data sets that are produced as <t>Instance data sets that are produced as
a result of some sort of specification or design effort a result of some sort of specification or design effort
may be available without the need for a live may be available without the need for a live
server e.g., via download from the vendor's website, or in any other server, e.g., via download from the vendor's website or in any other
way that product documentation is distributed.</t> way that product documentation is distributed.</t>
<t>Other instance data sets may be read from or produced by the YANG <t>Other instance data sets may be read from or produced by the YANG
server itself e.g., UC5 documenting diagnostic data.</t> server itself, e.g., <xref target="uc5" format="none">UC5</xref> doc
umenting diagnostic data.</t>
</section> </section>
<section title="Data Life cycle"> <section numbered="true" toc="default">
<t> <name>Data Life Cycle</name>
<t>
A YANG instance data set is created at a specific A YANG instance data set is created at a specific
point of time. If the data changes afterwards, the instance data s et point of time. If the data changes afterwards, the instance data s et
will no longer represent the current data, unless it is updated. will no longer represent the current data unless it is updated.
The current values may be The current values may be
retrieved at run-time via NETCONF/RESTCONF or retrieved at runtime via NETCONF/RESTCONF or
received e.g., in YANG-Push notifications. received, e.g., in YANG-Push notifications.
</t> </t>
<t> <t>
Whether the instance data changes and if so, when and how, Whether the instance data changes and, if so, when and how
should be described either in the instance data set's 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.
</t> </t>
</section> </section>
</section> </section>
<section anchor="instance_data_file_format" numbered="true" toc="default">
<section anchor="instance_data_file_format" title="Instance Data File Format <name>Instance Data File Format</name>
">
<t> <t>
A YANG instance data file MUST contain a single instance data set and no A YANG instance data file <bcp14>MUST</bcp14> contain a single instance data set and no
additional data. additional data.
</t> </t>
<t>The format of the instance data set is defined by the <t>The format of the instance data set is defined by the
"ietf-yang-instance-data" YANG module. "ietf-yang-instance-data" YANG module.
It is made up of a header part and content-data. It is made up of a header part and content-data.
The header part carries metadata for the instance data set. The header part carries metadata for the instance data set.
The content-data, defined as an anydata data node, carries The content-data, defined as an anydata data node, carries
the instance data that the user wants to document/provide. the instance data that the user wants to document and/or provide.
The syntax and semantics of content-data is defined by the content-schem The syntax and semantics of content-data are defined by the content-sche
a. ma.
</t> </t>
<t>Two formats are specified based on the XML and JSON YANG encodings. The <t>Two formats are specified based on the XML and JSON YANG encodings. The
file formats are achieved by applying the respective XML and JSON file formats are achieved by applying the respective XML and JSON
encoding rules for the YANG structure included in this document. encoding rules for the YANG structure included in this document.
Later, as other YANG encodings (e.g., CBOR) are defined, further Later, as other YANG encodings (e.g., CBOR) are defined, further
instance data formats may be specified. instance data formats may be specified.
</t> </t>
<t>The content-data part MUST conform to the content-schema, while allowin <t>The content-data part <bcp14>MUST</bcp14> conform to the content-schema
g for the while allowing for the
exceptions listed below. The content-data part SHALL follow the exceptions listed below. The content-data part <bcp14>SHALL</bcp14> foll
encoding rules defined in <xref target="RFC7950"/> for XML and ow the
<xref target="RFC7951"/> for JSON and MUST use UTF-8 character encoding. encoding rules defined in <xref target="RFC7950" format="default"/> for
Content-data MAY include: XML and
<list style="symbols"> <xref target="RFC7951" format="default"/> for JSON and <bcp14>MUST</bcp1
<t>metadata, as defined by <xref target="RFC7952"/>.</t> 4> use UTF-8 character encoding.
<t>origin metadata, as specified in Content-data <bcp14>MAY</bcp14> include:
<xref target="RFC8526"/> and <xref target="RFC8527"/></t>
<t>implementation specific metadata relevant to individual
data nodes. Unknown metadata MUST be ignored by users of
instance data, allowing it to be used
later for other purposes.</t>
</list>
</t> </t>
<t>An instance data set MAY contain data for any number of <ul spacing="normal">
YANG modules; if needed it MAY carry the complete configuration and stat <li>metadata, as defined by <xref target="RFC7952" format="default"/>.</
e li>
<li>origin metadata, as specified in
<xref target="RFC8526" format="default"/> and <xref target="RFC8527" f
ormat="default"/>.</li>
<li>implementation-specific metadata relevant to individual
data nodes. Unknown metadata <bcp14>MUST</bcp14> be ignored by users
of
instance data, allowing it to be used
later for other purposes.</li>
</ul>
<t>An instance data set <bcp14>MAY</bcp14> contain data for any number of
YANG modules; if needed, it <bcp14>MAY</bcp14> carry the complete config
uration and state
data for a server. data for a server.
Default values should be excluded where they do not provide Default values should be excluded where they do not provide
additional useful data. additional useful data.
</t><t> </t>
<t>
Configuration ("config true") and operational state data ("config false" ) Configuration ("config true") and operational state data ("config false" )
MAY be mixed in the instance data file. <bcp14>MAY</bcp14> be mixed in the instance data file.
</t><t>
Instance data files MAY contain partial data sets. This means "mandatory
",
"min-elements", "require-instance true", "must" and "when" constraints M
AY be violated.
</t> </t>
<t>The name of the instance data file SHOULD be of the form (using ABNF no <t>
tation <xref target="RFC5234"/>): Instance data files <bcp14>MAY</bcp14> contain partial data sets. This m
<figure align="center" anchor="filename" suppress-title="true"> eans "mandatory",
<artwork align="left" name="filename-abnf"> "min-elements", "require-instance true", "must", and "when" constraints
<![CDATA[ instance-data-set-name ["@" ( revision-date / timestamp ) ] <bcp14>MAY</bcp14> be violated.
</t>
<t>The name of the instance data file <bcp14>SHOULD</bcp14> be of the foll
owing form (using ABNF notation <xref target="RFC5234" format="default"/>):
</t>
<sourcecode name="filename-abnf" type="abnf"><![CDATA[
instance-data-set-name ["@" ( revision-date / timestamp ) ]
( ".xml" / ".json" ) ( ".xml" / ".json" )
]]></sourcecode>
E.g., acme-router-modules.xml <t>Examples include:</t>
E.g., acme-router-modules@2018-01-25.xml <artwork><![CDATA[
E.g., acme-router-modules@2018-01-25T15_06_34_3+01_00.json acme-router-modules.xml
]]> acme-router-modules@2018-01-25.xml
</artwork> acme-router-modules@2018-01-25T15_06_34_3+01_00.json
</figure> ]]></artwork>
<t>
If the leaf "name" is present in the instance data header, If the leaf "name" is present in the instance data header,
its value SHOULD be used for the "instance-data-set-name" in the filenam e. its value <bcp14>SHOULD</bcp14> be used for the "instance-data-set-name" in the filename.
If the "revision-date" is present in the filename it MUST conform to If the "revision-date" is present in the filename, it <bcp14>MUST</bcp14 > conform to
the format of the revision-date leaf in the YANG model. the format of the revision-date leaf in the YANG model.
If the "revision-date" is present in both the filename and in the If the "revision-date" is present in both the filename and the
instance data header, the revision date in the file name MUST be instance data header, the revision date in the filename <bcp14>MUST</bcp
14> be
set to the latest revision date inside the instance data set. set to the latest revision date inside the instance data set.
If the "timestamp" is present in the filename it MUST conform to If the "timestamp" is present in the filename, it <bcp14>MUST</bcp14> co nform to
the format of the timestamp leaf in the YANG model except for the format of the timestamp leaf in the YANG model except for
replacing colons as described below. replacing colons as described below.
If the "timestamp" is present both in the filename and in the If the "timestamp" is present in both the filename and the
instance data header, the timestamp in the file name SHOULD be instance data header, the timestamp in the filename <bcp14>SHOULD</bcp14
> be
set to the timestamp inside the instance data set; any colons, set to the timestamp inside the instance data set; any colons,
if present, shall be replaced by underscores. if present, shall be replaced by underscores.
</t> </t>
<t anchor="instance_data_set_metadata">Metadata, information about the <t anchor="instance_data_set_metadata">Metadata, information about the
data set itself MUST be included. Some metadata items are data set itself, <bcp14>MUST</bcp14> be included. Some metadata items are
defined in the YANG module "ietf-yang-instance-data", but other items MAY defined in the YANG module "ietf-yang-instance-data", but other items <bcp
be used.</t><t> 14>MAY</bcp14>
Metadata MUST include: be used.</t>
<list><t><list style="symbols"> <t>
<t>Version of the YANG Instance Data format (if not explicitly present Metadata <bcp14>MUST</bcp14> include:
the default value is used)</t> </t>
</list></t></list> <ul empty="true" spacing="normal">
Metadata SHOULD include: <li>
<list><t><list style="symbols"> <ul spacing="normal">
<t>Name of the data set</t> <li>Version of the YANG instance data format (if not explicitly pres
<t>Content-schema specification (i.e., the "content-schema" node)</t> ent, the default value is used).</li>
<t>Description of the instance data set. The description SHOULD </ul>
contain information whether and how the data can change during </li>
the lifetime of the server </ul>
</t> <t>
<t>An indication whether default values are included. Metadata <bcp14>SHOULD</bcp14> include:
The default handling uses the concepts defined in <xref target="RFC6 </t>
243"/>, <ul empty="true" spacing="normal">
however as only concepts are re-used, users of instance data sets, <li>
do not need to support RFC 6243. <ul spacing="normal">
</t> <li>Name of the data set.</li>
</list></t></list> <li>Content-schema specification (i.e., the "content-schema" node).<
</t> /li>
<section title="Specifying the Content Schema"> <li>Description of the instance data set. The description <bcp14>SHO
ULD</bcp14>
contain information on whether and how the data can change during
the lifetime of the server.
</li>
<li>An indication of whether default values are included.
The default handling uses the concepts defined in <xref target="RFC6
243" format="default"/>;
however, as only concepts are re-used, users of instance data sets
do not need to support <xref target="RFC6243"/>.
</li>
</ul>
</li>
</ul>
<section numbered="true" toc="default">
<name>Specifying the Content Schema</name>
<t>To properly understand and use an instance data set, the user needs t o <t>To properly understand and use an instance data set, the user needs t o
know the content-schema. The content-schema can be either know the content-schema. The content-schema can be specified either in
specified in external documents or within the instance data set. external documents or within the instance data set.
In the latter case one of the following methods MUST be used: In the latter case, one of the following methods <bcp14>MUST</bcp14> b
<list> e used:
<t>Inline method: Include the needed information as part of the </t>
instance data set.</t> <dl spacing="normal">
<t>Simplified-Inline method: Include the needed information as part o <dt>Inline method:</dt><dd>Include the needed information as part of t
f he
the instance data set; short specification, only the module name and instance data set.</dd>
revision-date is used.</t> <dt>Simplified-inline method:</dt><dd>Include the needed information a
<t>URI method: Include a URI that references another YANG instance s part of
the instance data set; only the modules' name and revision-date are
used.</dd>
<dt>URI method:</dt><dd>Include a URI that references another YANG ins
tance
data file. This instance data file will use the same content-schema data file. This instance data file will use the same content-schema
as the referenced YANG instance data file. as the referenced YANG instance data file (if you don't want to repe
(if you don't want to repeat the info again and again)</t> at the info again and again).</dd>
</list> </dl>
Additional methods e.g., a YANG-package based solution may be added la <t>
ter. Additional methods, e.g., a YANG-package-based solution may be added l
ater.
</t> </t>
<t>Note, the specified content-schema only indicates the set of <t>Note that the specified content-schema only indicates 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 server supporting a Sometimes instance data may be used for a server supporting a
different YANG module set (e.g., for the "Preloading default different YANG module set (e.g., for the "Preloading default
configuration data" use-case, UC2 in <xref target="intro"/>, the insta nce configuration data" use case, <xref target="uc2" format="none">UC2</xr ef> in <xref target="intro" format="default"/>, the instance
data set may not be updated every time the YANG modules on the data set may not be updated every time the YANG modules on the
server are updated). server are updated).
Whether an instance data set originally defined using a specific Whether an instance data set originally defined using a specific
content-schema is usable with a different other schema content-schema is usable with another schema
depends on many factors including the amount of differences and the depends on many factors, including the number of differences and the
compatibility between the original and the compatibility between the original and the
other schema, considering modules, revisions, features, other schema when considering modules, revisions, features,
deviations, the scope of the instance data, etc. deviations, the scope of the instance data, etc.
</t> </t>
<section title="Inline Method"> <section numbered="true" toc="default">
<t>The inline-yang-library anydata data node carries instance data (co <name>Inline Method</name>
nforming to <t>The "inline-yang-library" anydata data node carries instance data (
ietf-yang-library@2019-01-04) <xref target="RFC8525"/> that specifie conforming to
s the content "ietf-yang-library@2019-01-04") <xref target="RFC8525" format="defau
defining YANG modules including revision, lt"/> that specifies the content-defining YANG modules, including revision,
supported features, deviations and any relevant additional data. supported features, deviations, and any additional relevant data.
An example of the "inline" method is provided in <xref target="acme- An example of the inline method is provided in <xref target="acme-ro
router-modules-example"/>. uter-modules-example" format="default"/>.
</t> </t>
</section> </section>
<section title="Simplified-Inline Method"> <section numbered="true" toc="default">
<t>The instance data set contains a list of content defining YANG <name>Simplified-Inline Method</name>
modules including the revision date for each. <t>The instance data set contains a list of content-defining YANG
modules, including the revision date for each.
Usage of this method implies that the modules are Usage of this method implies that the modules are
used without any deviations and with all features used without any deviations and with all features
supported. YANG modules that are only required to satisfy supported. YANG modules that are only required to satisfy
import-only dependencies MAY be excluded from the leaf-list. import-only dependencies <bcp14>MAY</bcp14> be excluded from the le
If they are excluded then the consumer of the instance data af-list.
If they are excluded, then the consumer of the instance data
set has to apply the YANG language rules to resolve the imports. set has to apply the YANG language rules to resolve the imports.
An example of the "simplified-inline" method is provided in <xref t arget="read-only-acm-rules-example"/>. An example of the simplified-inline method is provided in <xref tar get="read-only-acm-rules-example" format="default"/>.
</t> </t>
</section> </section>
<section title="URI Method"> <section numbered="true" toc="default">
<t>The "same-schema-as-file" leaf SHALL contain a URI that references <name>URI Method</name>
another YANG <t>The "same-schema-as-file" leaf <bcp14>SHALL</bcp14> contain a URI t
hat 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
content-schema as the referenced file. content-schema as the referenced file.
</t><t> </t>
The referenced instance data file MAY have no content-data if it is <t>
The referenced instance data file <bcp14>MAY</bcp14> have no content
-data if it is
used solely for specifying the content-schema. used solely for specifying the content-schema.
</t><t> </t>
If a referenced instance data file is unavailable, content-schema <t>
If a referenced instance data file is unavailable, the content-schem
a
is unknown. is unknown.
</t><t> </t>
<t>
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 content-schema in each instance data overhead of specifying the content-schema in each instance data
file: E.g., In UC6, when the system creates a diagnostic file file -- for example, in <xref target="uc6" format="none">UC6</xref>,
every minute to document the state of the server. when the system creates a diagnostic file every minute to document the state of
</t> the server.
<t>An example of the "URI" method is provided in <xref target="acme-rout </t>
er-netconf-diagnostics-example"/>.</t> <t>An example of the URI method is provided in <xref target="acme-rout
er-netconf-diagnostics-example" format="default"/>.</t>
</section> </section>
</section> </section>
<section title="Examples" anchor="examples"> <section anchor="examples" numbered="true" toc="default">
<section title="Documentation of server capabilities" anchor="acme-route <name>Examples</name>
r-modules-example"> <section anchor="acme-router-modules-example" numbered="true" toc="defau
<t>The example file acme-router-modules@2021-09-16.xml reflects UC1 in lt">
<xref target="intro"/>. <name>Documentation of Server Capabilities</name>
<t>The example file acme-router-modules@2022-01-20.xml reflects <xref
target="uc1" format="none">UC1</xref> in <xref target="intro" format="default"/>
.
It provides a list of supported YANG modules and NETCONF capabilitie s for a server. It provides a list of supported YANG modules and NETCONF capabilitie s for a server.
It uses the "inline" method to specify the content-schema.</t> It uses the inline method to specify the content-schema.</t>
<t>The example uses artwork folding <xref target="RFC8792"/>.</t> <t>The example uses artwork folding <xref target="RFC8792" format="def
<figure align="center" anchor="acme-router-modules"> ault"/>.</t>
<artwork align="left" name="acme-router-modules@2021-09-16.xml"> <figure anchor="acme-router-modules">
<![CDATA[========== NOTE: '\' line wrapping per RFC 8792 =========== <sourcecode name="acme-router-modules@2022-01-20.xml" type="xml"><![
CDATA[
========== NOTE: '\' line wrapping per RFC 8792 ===========
<?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>
<content-schema> <content-schema>
<inline-yang-library> <inline-yang-library>
<modules-state \ <modules-state \
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"> xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library">
<module> <module>
skipping to change at line 354 skipping to change at line 385
</module> </module>
</modules-state> </modules-state>
</inline-yang-library> </inline-yang-library>
</content-schema> </content-schema>
<revision> <revision>
<date>2020-10-23</date> <date>2020-10-23</date>
<description>Initial version</description> <description>Initial version</description>
</revision> </revision>
<description>Defines the minimal set of modules that any \ <description>Defines the minimal set of modules that any \
acme-router will contain. This minimal set will \ acme-router will contain. This minimal set will \
only change when a new SW release is \ only change when a new software release is \
introduced.</description> introduced.</description>
<contact>info@acme.example.com</contact> <contact>info@acme.example.com</contact>
<content-data> <content-data>
<modules-state \ <modules-state \
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"> xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library">
<module> <module>
<name>ietf-yang-library</name> <name>ietf-yang-library</name>
<revision>2019-01-04</revision> <revision>2019-01-04</revision>
<namespace>\ <namespace>\
urn:ietf:params:xml:ns:yang:ietf-yang-library\ urn:ietf:params:xml:ns:yang:ietf-yang-library\
</namespace> </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>
<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-netconf-monitoring</name> <name>ietf-netconf-monitoring</name>
skipping to change at line 414 skipping to change at line 445
<netconf-state \ <netconf-state \
xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring"> xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring">
<capabilities> <capabilities>
<capability>\ <capability>\
urn:ietf:params:netconf:capability:validate:1.1\ urn:ietf:params:netconf:capability:validate:1.1\
</capability> </capability>
</capabilities> </capabilities>
</netconf-state> </netconf-state>
</content-data> </content-data>
</instance-data-set> </instance-data-set>
]]></artwork> ]]></sourcecode>
</figure> </figure>
</section> </section>
<section title="Preloading default configuration data" anchor="read-onl <section anchor="read-only-acm-rules-example" numbered="true" toc="defau
y-acm-rules-example"> lt">
<t>The example file read-only-acm-rules@2021-09-16.xml reflects UC2 in <name>Preloading Default Configuration Data</name>
<xref target="intro"/>. <t>The example file read-only-acm-rules@2022-01-20.xml reflects <xref
target="uc2" format="none">UC2</xref> in <xref target="intro" format="default"/>
.
It provides a default rule set for a read-only operator role. It provides a default rule set for a read-only operator role.
It uses the "simplified-inline" method for specifying the content-sc It uses the simplified-inline method for specifying the content-sche
hema.</t> ma.</t>
<figure align="center" anchor="read-only-acm-rules"> <figure anchor="read-only-acm-rules">
<artwork align="left" name="read-only-acm-rules@2021-09-16.xml"> <sourcecode name="read-only-acm-rules@2022-01-20.xml" type="xml"><![
<![CDATA[========== NOTE: '\' line wrapping per RFC 8792 =========== CDATA[
========== NOTE: '\' line wrapping per RFC 8792 ===========
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<instance-data-set <instance-data-set
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-instance-data"> xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-instance-data">
<name>read-only-acm-rules</name> <name>read-only-acm-rules</name>
<content-schema> <content-schema>
<module>ietf-netconf-acm@2018-02-14</module> <module>ietf-netconf-acm@2018-02-14</module>
</content-schema> </content-schema>
<revision> <revision>
<date>2018-07-04</date> <date>2018-07-04</date>
<description>Initial version</description> <description>Initial version</description>
</revision> </revision>
<description>Default access control rules for a read-only \ <description>Default access control rules for a read-only \
role. This set of rules will only change when a new \ role. This set of rules will only change when a new \
SW release is introduced.</description> software release is introduced.</description>
<content-data> <content-data>
<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>
<access-operation>read</access-operation> <access-operation>read</access-operation>
<action>permit</action> <action>permit</action>
</rule> </rule>
</rule-list> </rule-list>
</nacm> </nacm>
</content-data> </content-data>
</instance-data-set> </instance-data-set>
]]></artwork> ]]></sourcecode>
</figure> </figure>
</section> </section>
<section title="Storing diagnostics data" anchor="acme-router-netconf-d <section anchor="acme-router-netconf-diagnostics-example" numbered="true
iagnostics-example"> " toc="default">
<name>Storing Diagnostics Data</name>
<t>The example file acme-router-netconf-diagnostics@2018-01-25T17_00_3 8Z.json <t>The example file acme-router-netconf-diagnostics@2018-01-25T17_00_3 8Z.json
reflects UC5 in <xref target="intro"/>. reflects <xref target="uc5" format="none">UC5</xref> in <xref target
An instance data set is produced by the server every 15 minutes that ="intro" format="default"/>.
contains An instance data set that contains
statistics about the NETCONF server. As a new set is produced period statistics about the NETCONF server is produced by the server every
ically many times a day a revision-date 15 minutes. As a new set is produced periodically many times a day, a revision-d
would be useless; instead a timestamp is included.</t> ate
<figure align="center" anchor="acme-router-netconf-diagnostics"> would be useless; instead, a timestamp is included.</t>
<artwork align="left" name="acme-router-netconf-diagnostics@2018-01-25 <figure anchor="acme-router-netconf-diagnostics">
T17_00_38Z.json"> <sourcecode name="acme-router-netconf-diagnostics@2018-01-25T17_00_3
<![CDATA[========== NOTE: '\' line wrapping per RFC 8792 =========== 8Z.json" type=""><![CDATA[
========== NOTE: '\' line wrapping per RFC 8792 ===========
{ {
"ietf-yang-instance-data:instance-data-set": { "ietf-yang-instance-data:instance-data-set": {
"name": "acme-router-netconf-diagnostics", "name": "acme-router-netconf-diagnostics",
"content-schema": { "content-schema": {
"same-schema-as-file": "file:///acme-diagnostics-schema.json" "same-schema-as-file": "file:///acme-diagnostics-schema.json"
}, },
"timestamp": "2018-01-25T17:00:38Z", "timestamp": "2018-01-25T17:00:38Z",
"description": ["NETCONF statistics, \ "description": ["NETCONF statistics, \
The data may change at any time."], The data may change at any time."],
skipping to change at line 495 skipping to change at line 528
"dropped-sessions ": "87", "dropped-sessions ": "87",
"in-rpcs ": "8711", "in-rpcs ": "8711",
"in-bad-rpcs ": "408", "in-bad-rpcs ": "408",
"out-rpc-errors ": "408", "out-rpc-errors ": "408",
"out-notifications": "39007" "out-notifications": "39007"
} }
} }
} }
} }
} }
]]></artwork> ]]></sourcecode>
</figure> </figure>
</section> </section>
</section>
</section> </section>
</section> <section anchor="instance_data_yam" numbered="true" toc="default">
<section anchor="instance_data_yam" title="YANG Instance Data Model"> <name>YANG Instance Data Model</name>
<section title="Tree Diagram"> <section numbered="true" toc="default">
<name>Tree Diagram</name>
<t> <t>
The following tree diagram <xref target="RFC8340"/> The following tree diagram <xref target="RFC8340" format="default"/>
provides an overview of the data model. provides an overview of the data model.
</t> </t>
<t> <sourcecode name="" type="yangtree"><![CDATA[
<figure>
<artwork><![CDATA[
module: ietf-yang-instance-data module: ietf-yang-instance-data
structure instance-data-set: structure instance-data-set:
+-- name? string +--name? string
+-- format-version? string +--format-version? string
+-- includes-defaults? enumeration +--includes-defaults? enumeration
+-- content-schema +--content-schema
| +-- (content-schema-spec)? | +--(content-schema-spec)?
| +--:(simplified-inline) | +--:(simplified-inline)
| | +-- module* module-with-revision-date | | +--module* module-with-revision-date
| +--:(inline) | +--:(inline)
| | +-- inline-yang-library <anydata> | | +--inline-yang-library <anydata>
| +--:(uri) | +--:(uri)
| +-- same-schema-as-file? inet:uri | +--same-schema-as-file? inet:uri
+-- description* string +--description* string
+-- contact? string +--contact? string
+-- organization? string +--organization? string
+-- datastore? ds:datastore-ref +--datastore? ds:datastore-ref
+-- revision* [date] +--revision* [date]
| +-- date string | +--date string
| +-- description? string | +--description? string
+-- timestamp? yang:date-and-time +--timestamp? yang:date-and-time
+-- content-data? <anydata> +--content-data? <anydata>
]]></artwork> ]]></sourcecode>
</figure>
</t>
</section> </section>
<section title="YANG Model" anchor="yang-model"> <section anchor="yang-model" numbered="true" toc="default">
<t> <name>YANG Model</name>
This YANG module imports typedefs from <xref target="RFC6991"/>, <t>
<xref target="RFC6243"/>, This YANG module imports typedefs from <xref target="RFC6991" forma
identities from <xref target="RFC8342"/> and t="default"/>,
the "structure" extension from <xref target="RFC8791"/>. <xref target="RFC6243" format="default"/>,
It also references <xref target="RFC8525"/>. identities from <xref target="RFC8342" format="default"/>, and
</t><t> the "structure" extension from <xref target="RFC8791" format="defau
<figure> lt"/>.
<artwork align="left" name="ietf-yang-instance-data@2021-09-16 It also references <xref target="RFC8525" format="default"/>.
.yang"><![CDATA[ </t>
<CODE BEGINS> file "ietf-yang-instance-data@2021-09-16.yang" <sourcecode name="ietf-yang-instance-data@2022-01-20.yang" type="yang" m
// RFC Ed.: replace the date above if the module gets changed in arkers="true"><![CDATA[
//any way during reviews or RFC editor process and remove this note
module ietf-yang-instance-data { module ietf-yang-instance-data {
yang-version 1.1; yang-version 1.1;
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;
import ietf-yang-structure-ext { import ietf-yang-structure-ext {
prefix sx; prefix sx;
reference reference
"YANG Data Structure Extensions: "RFC 8791: YANG Data Structure Extensions";
draft-ietf-netmod-yang-data-ext-05";
} }
import ietf-datastores { import ietf-datastores {
prefix ds; prefix ds;
reference reference
"RFC 8342: Network Management Datastore Architecture (NMDA)"; "RFC 8342: Network Management Datastore Architecture (NMDA)";
} }
import ietf-inet-types { import ietf-inet-types {
prefix inet; prefix inet;
reference reference
"RFC 6991: Common YANG Data Types"; "RFC 6991: Common YANG Data Types";
skipping to change at line 604 skipping to change at line 629
"The module defines the structure and content of YANG "The module defines the structure and content of YANG
instance data sets. instance data sets.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document 'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document
are to be interpreted as described in BCP 14 (RFC 2119) are to be interpreted as described in BCP 14 (RFC 2119)
(RFC 8174) when, and only when, they appear in all (RFC 8174) when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
Copyright (c) 2021 IETF Trust and the persons identified as Copyright (c) 2022 IETF Trust and the persons identified as
authors of the code. All rights reserved. authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License to the license terms contained in, the Revised BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions set forth in Section 4.c of the IETF Trust's
Relating to IETF Documents Legal Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info). (https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see This version of this YANG module is part of RFC 9195
the RFC itself for full legal notices."; (https://www.rfc-editor.org/info/rfc9195); see the RFC itself
// RFC Ed.: replace XXXX with RFC number and remove this note for full legal notices.";
revision 2021-09-16 { revision 2022-01-20 {
// RFC Ed.: replace the date above if the module gets changed in
// anyway during reviews or RFC editor process and remove
//this note
description description
"Initial revision."; "Initial revision.";
reference reference
"RFC XXXX: YANG Instance Data Format"; "RFC 9195: YANG Instance Data File Format";
// RFC Ed.: replace XXXX with RFC number and remove this note
} }
typedef module-with-revision-date { typedef module-with-revision-date {
type string { type string {
pattern '[a-zA-Z_][a-zA-Z0-9\-_.]*' pattern '[a-zA-Z_][a-zA-Z0-9\-_.]*'
+ '(@\d{4}-(1[0-2]|0[1-9])-(0[1-9]|[1|2][0-9]|3[0-1]))?'; + '(@\d{4}-(1[0-2]|0[1-9])-(0[1-9]|[1|2][0-9]|3[0-1]))?';
pattern '.|..|[^xX].*|.[^mM].*|..[^lL].*'; pattern '.|..|[^xX].*|.[^mM].*|..[^lL].*';
} }
description description
"A type defining a module name and an optional revision "A type defining a module name and an optional revision
date, e.g. ietf-yang-library@2019-01-04"; date, e.g., ietf-yang-library@2019-01-04.";
} }
sx:structure "instance-data-set" { sx:structure instance-data-set {
description description
"A data structure to define a format for YANG instance "A data structure to define a format for YANG instance
data. The majority of the YANG nodes provide meta-data data. The majority of the YANG nodes provides metadata
about the instance data; the instance data itself is about the instance data; the instance data itself is
contained only in the 'content-data' node."; contained only in the 'content-data' node.";
leaf name { leaf name {
type string; type string;
description description
"An arbitrary name for the YANG instance data set. This "An arbitrary name for the YANG instance data set. This
value is primarily used for descriptive purposes. However, value is primarily used for descriptive purposes. However,
when the instance data set is saved to a file, then the when the instance data set is saved to a file, then the
filename MUST encode the name's value, per Section 2 filename MUST encode the name's value per Section 2
of RFC XXXX."; of RFC 9195.";
// RFC Ed.: replace XXXX with RFC number and remove this note
} }
leaf format-version { leaf format-version {
type string { type string {
pattern '\d{4}-(1[0-2]|0[1-9])-(0[1-9]|[1|2][0-9]|3[0-1])'; pattern '\d{4}-(1[0-2]|0[1-9])-(0[1-9]|[1|2][0-9]|3[0-1])';
} }
default "2021-09-16"; default "2022-01-20";
// RFC Ed.: replace the date above if the module gets changed
// in anyway during reviews or RFC editor process and remove
// this note
description description
"The 'revision' of the 'ietf-yang-instance-data' module "The 'revision' of the 'ietf-yang-instance-data' module
used to encode this 'instance-data-set'."; used to encode this 'instance-data-set'.";
} }
leaf includes-defaults { leaf includes-defaults {
type ncwd:with-defaults-mode; type ncwd:with-defaults-mode;
default report-all; default "report-all";
description " description
Indicates how data nodes with default values are "Indicates how data nodes with default values are
represented for all data nodes contained in the represented for all data nodes contained in the
instance-data-set. instance-data-set.
It uses the same definitions as per section 3 of RFC 6243, It uses the same definitions as per Section 3 of RFC 6243
but applied in the context of an instance data file rather but applied in the context of an instance data file rather
than a NETCONF request using the <with-defaults> than a NETCONF request using the <with-defaults>
parameter. parameter.
For JSON files, the encoding of the 'report-all-tagged' For JSON files, the encoding of the 'report-all-tagged'
option is as defined in section 4.8.9 of RFC 8040."; option is as defined in Section 4.8.9 of RFC 8040.";
reference "With-defaults Capability for NETCONF, RFC 6243."; reference
"RFC 6243: With-defaults Capability for NETCONF";
} }
container content-schema { container content-schema {
description description
"The content schema (i.e., YANG modules) used to create "The content schema (i.e., YANG modules) used to create
the instance data set. the instance data set.
If not present the user needs to obtain the information If not present, the user needs to obtain the information
through external documents."; through external documents.";
choice content-schema-spec { choice content-schema-spec {
description description
"Specification of the content-schema."; "Specification of the content-schema.";
case simplified-inline { case simplified-inline {
leaf-list module { leaf-list module {
type module-with-revision-date; type module-with-revision-date;
min-elements 1; min-elements 1;
description description
"The list of content defining YANG modules. "The list of content-defining YANG modules.
The value SHALL start with the module name. The value SHALL start with the module name.
If the module contains a revision statement the If the module contains a revision statement, the
revision date SHALL be included in the leaf-list revision date SHALL be included in the leaf-list
entry. entry, e.g., ietf-yang-library@2019-01-04.
E.g., ietf-yang-library@2019-01-04
Usage of this leaf-list implies the modules are Usage of this leaf-list implies the modules are
used without any deviations and with all features used without any deviations and with all features
supported. Multiple revisions of the same module supported. Multiple revisions of the same module
MUST NOT be specified."; MUST NOT be specified.";
} }
} }
case inline { case inline {
anydata inline-yang-library { anydata inline-yang-library {
mandatory true; mandatory true;
description description
"Instance data corresponding to the "Instance data corresponding to the
ietf-yang-library@2019-01-04 defining ietf-yang-library@2019-01-04 defining
the set of content defining YANG modules for the set of content-defining YANG modules for
this instance-data-set."; this instance-data-set.";
} }
} }
case uri { case uri {
leaf same-schema-as-file { leaf same-schema-as-file {
type inet:uri; type inet:uri;
description description
"A reference to another YANG instance data file. "A reference to another YANG instance data file.
This instance data file uses the same This instance data file uses the same
content schema as the referenced file. content schema as the referenced file.
Referenced files using the 'inline' or the Referenced files using the 'inline' or the
'simplified-inline' methods MUST be supported. 'simplified-inline' methods MUST be supported.
Referenced files using the 'URI Method' MAY be Referenced files using the 'URI method' MAY be
supported. supported.
The URL schemes 'file://' and 'https://' MUST The URL schemes 'file://' and 'https://' MUST
be supported, other schemes MAY also be be supported; other schemes MAY also be
supported."; supported.";
} }
} }
} }
} }
leaf-list description { leaf-list description {
type string; type string;
description description
"Description of the instance data set."; "Description of the instance data set.";
} }
skipping to change at line 767 skipping to change at line 783
type string; type string;
description description
"Organization responsible for the instance "Organization responsible for the instance
data set."; data set.";
} }
leaf datastore { leaf datastore {
type ds:datastore-ref; type ds:datastore-ref;
description description
"The identity of the datastore with which the "The identity of the datastore with which the
instance data set is associated, e.g., the datastore from instance data set is associated, e.g., the datastore from
where the data was read or the datastore into which the data where the data was read, the datastore into which the data
may be loaded or the datastore which is being documented. may be loaded, or the datastore that is being documented.
If a single specific datastore cannot be specified, the If a single specific datastore cannot be specified, the
leaf MUST be absent. leaf MUST be absent.
If this leaf is absent, then the datastore to which the If this leaf is absent, then the datastore to which the
instance data belongs is unspecified."; instance data belongs is unspecified.";
} }
list revision { list revision {
key "date"; key "date";
description description
"Instance data sets that are produced as "Instance data sets that are produced as
a result of some sort of specification or design effort a result of some sort of specification or design effort
SHOULD have at least one revision entry. For every SHOULD have at least one revision entry. For every
published editorial change, a new unique revision SHOULD published editorial change, a new unique revision SHOULD
be added in front of the revisions sequence so that all be added in front of the revisions sequence so that all
revisions are in reverse chronological order. revisions are in reverse chronological order.
In case of instance data sets that are read from In cases of instance data sets that are read from
or produced by a server or otherwise subject to or produced by a server or otherwise subject to
frequent updates or changes, revision frequent updates or changes, revision
SHOULD NOT be present"; SHOULD NOT be present.";
leaf date { leaf date {
type string { type string {
pattern '\d{4}-(1[0-2]|0[1-9])-(0[1-9]|[1|2][0-9]|3[0-1])'; pattern '\d{4}-(1[0-2]|0[1-9])-(0[1-9]|[1|2][0-9]|3[0-1])';
} }
description description
"Specifies the date the instance data set "Specifies the date the instance data set
was last modified. Formatted as YYYY-MM-DD"; was last modified. Formatted as YYYY-MM-DD.";
} }
leaf description { leaf description {
type string; type string;
description description
"Description of this revision of the instance data set."; "Description of this revision of the instance data set.";
} }
} }
leaf timestamp { leaf timestamp {
type yang:date-and-time; type yang:date-and-time;
description description
"The date and time when the instance data set "The date and time when the instance data set
was last modified. was last modified.
In case of instance data sets that are read from or In cases of instance data sets that are read from or
produced by a server or otherwise subject to frequent produced by a server or otherwise subject to frequent
updates or changes, timestamp SHOULD be present. updates or changes, the timestamp SHOULD be present.
If both a revision list entry and timestamp are present If both a revision list entry and timestamp are present,
the timestamp SHOULD contain the same date as the the timestamp SHOULD contain the same date as the
latest revision statement."; latest revision statement.";
} }
anydata content-data { anydata content-data {
description description
"Contains the real instance data. "Contains the real instance data.
The data MUST conform to the relevant YANG modules The data MUST conform to the relevant YANG modules
specified either in the content-schema or in some other specified either in the content-schema or in some other
implementation specific manner."; implementation-specific manner.";
} }
} }
} }
<CODE ENDS> ]]></sourcecode>
]]></artwork>
</figure>
</t>
</section> </section>
</section> </section>
<section anchor="security" numbered="true" toc="default">
<section anchor="security" title="Security Considerations"> <name>Security Considerations</name>
<t>The YANG module defined in this document only defines a wrapper structu re <t>The YANG module defined in this document only defines a wrapper structu re
specifying a format and a metadata header for YANG specifying a format and a metadata header for YANG
instance data defined by the content-schema. Because of this instance data defined by the content-schema. Because of this,
the security considerations template for YANG models in the security considerations template for YANG models in
section 3.7.1 in <xref target="RFC8407"/> is not followed. <xref target="RFC8407" sectionFormat="of" section="3.7.1"/> is not follo wed.
The instance data is designed to be accessed as a stored file or The instance data is designed to be accessed as a stored file or
over any file access method or protocol. over any file access method or protocol.
</t> </t>
<t>The document does not specify any method to influence the <t>The document does not specify any method to influence the
behavior of a server.</t> behavior of a server.</t>
<t> <t>
The header part is usually not security sensitive, however sensitive The header part is usually not security sensitive; however, sensitive
information may be included, in which case it needs to be handled secure information may be included, in which case it needs to be handled secure
ly ly,
as mentioned below. Information to consider includes: as mentioned below. Information to consider includes:
<list style="symbol">
<t>If the URI method is used for specification of the content-schema a
nd
the URI includes a userinfo subcomponent</t>
<t>Any description text</t>
</list>
</t> </t>
<ul spacing="normal">
<li>If the URI method is used for specification of the content-schema an
d
the URI includes a userinfo subcomponent</li>
<li>Any description text</li>
</ul>
<t>The content part may contain sensitive data. <t>The content part may contain sensitive data.
The security sensitivity of this data is completely dependent on The security sensitivity of this data is completely dependent on
the content-schema. the content-schema.
Depending on the nature of the instance data, instance data Depending on the nature of the instance data, instance data
files MAY need to be handled securely. files <bcp14>MAY</bcp14> need to be handled securely.
The same kind of handling should be applied to this file at-rest and The same kind of handling should be applied to this file at rest and
in-transit that would be needed for the result of a read operation in transit that would be needed for the result of a read operation
returning the same data. These in-transit protection mechanisms will returning the same data. These in-transit protection mechanisms will
also mitigate integrity issues when transporting the file. also mitigate integrity issues when transporting the file.
</t> </t>
<t>Instance data files should be protected against modification or <t>Instance data files should be protected against modification or
unauthorized access using normal file handling mechanisms. unauthorized access using normal file-handling mechanisms.
Care should be taken, when copying the original files or When copying the original files or providing file access for
providing file access for additional users, not to reveal additional users, care should be taken not to reveal information
information unintentionally. unintentionally.
</t> </t>
<t>If the URI method is used for specification of the content-schema, <t>If the URI method is used for specification of the content-schema,
there is a risk that the config schema section in the referenced YANG there is a risk that the config schema section in the referenced YANG
instance data file may be altered maliciously or even as part of its nor mal instance data file may be altered maliciously or even as part of its nor mal
handling. In this case the content-schema might differ from the one handling. In this case, the content-schema might differ from the one
expected. Protecting the integrity and stability of the referenced expected. Protecting the integrity and stability of the referenced
file should be ensured. file should be ensured.
</t> </t>
</section> </section>
<section anchor="iana" title="IANA Considerations"> <section anchor="iana" numbered="true" toc="default">
<name>IANA Considerations</name>
<t>This document registers one URI and one YANG module.</t> <t>This document registers one URI and one YANG module.</t>
<section title="URI Registration"> <section numbered="true" toc="default">
<t>This document registers one URI in the <xref target="RFC3688"> <name>URI Registration</name>
IETF XML registry </xref>. Following the format in RFC 3688, the <t>This document registers the following URI in the <xref target="RFC368
following registration is requested to be made:</t> 8" format="default">
<t><figure><artwork> "IETF XML Registry"</xref>:</t>
URI: urn:ietf:params:xml:ns:yang:ietf-yang-instance-data <dl spacing="compact">
Registrant Contact: The IESG. <dt>URI:</dt><dd>urn:ietf:params:xml:ns:yang:ietf-yang-instance-data</dd>
XML: N/A, the requested URI is an XML namespace. <dt>Registrant Contact:</dt><dd>The IESG.</dd>
</artwork></figure></t> <dt>XML:</dt><dd>N/A, the requested URI is an XML namespace.</dd>
</dl>
</section> </section>
<section title="YANG Module Name Registration"> <section numbered="true" toc="default">
<t>This document registers one YANG module in the YANG Module Names <name>YANG Module Name Registration</name>
registry <xref target="RFC6020"/>. Following the format in [RFC6020], <t>This document registers the following YANG module in the "YANG Module
the following registrations are requested: Names"
</t> registry <xref target="RFC6020" format="default"/>:</t>
<t><figure><artwork> <dl spacing="compact">
name: ietf-yang-instance-data <dt>Name:</dt><dd>ietf-yang-instance-data</dd>
namespace: urn:ietf:params:xml:ns:yang:ietf-yang-instance-data <dt>Namespace:</dt><dd>urn:ietf:params:xml:ns:yang:ietf-yang-instance-data</dd>
prefix: yid <dt>Prefix:</dt><dd>yid</dd>
reference: RFC XXXX <dt>Reference:</dt><dd>RFC 9195</dd>
// RFC Ed.: replace XXXX with RFC number and remove this note </dl>
</artwork></figure></t>
</section> </section>
</section> </section>
<section title="Acknowledgments">
<t>For their valuable comments, discussions, and feedback, we wish to
acknowledge Andy Bierman, Juergen Schoenwaelder, Rob Wilton, Joe Clarke,
Kent Watsen,
Martin Bjorklund, Ladislav Lhotka, Qin Wu and other members of the Netmo
d WG.</t>
</section>
</middle> </middle>
<?rfc needLines="20"?>
<back> <back>
<references title="Normative References"> <references>
<?rfc include='reference.RFC.7950'?> <name>References</name>
<?rfc include='reference.RFC.7951'?> <references>
<?rfc include='reference.RFC.7952'?> <name>Normative References</name>
<?rfc include='reference.RFC.8526'?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include='reference.RFC.8527'?> FC.7950.xml"/>
<?rfc include='reference.RFC.6243'?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include="reference.RFC.8342"?> FC.7951.xml"/>
<?rfc include='reference.RFC.2119'?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include='reference.RFC.8174'?> FC.7952.xml"/>
<?rfc include='reference.RFC.6991'?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include='reference.RFC.8525'?> FC.8526.xml"/>
<?rfc include='reference.RFC.8791'?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include='reference.RFC.6020'?> FC.8527.xml"/>
<?rfc include='reference.RFC.5234'?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
</references> FC.6243.xml"/>
<references title="Informative References"> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include='reference.RFC.8641'?> FC.8342.xml"/>
<?rfc include='reference.RFC.8632'?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include='reference.RFC.3688'?> FC.2119.xml"/>
<?rfc include="reference.RFC.8340"?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include="reference.RFC.8407"?> FC.8174.xml"/>
<?rfc include='reference.RFC.8792'?> <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
<?rfc include='reference.RFC.8808'?> FC.6991.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8525.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8791.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.6020.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.5234.xml"/>
</references>
<references>
<name>Informative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8641.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8632.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.3688.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8340.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8407.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8792.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8808.xml"/>
</references>
</references> </references>
<?rfc needLines="100"?> <section numbered="true" toc="default">
<name>Backwards Compatibility</name>
<section title="Changes between revisions"> <t>The concept of "backwards compatibility" and what changes are backwards
<t>RFC Ed.: Remove section "Changes between revisions"</t> compatible are not defined for instance data sets as they are highly
<t>v20 - v21
<list style="symbols">
<t>Minor updates for IESG comments</t>
<t>Added ABNF as a normative reference for the filename's definition.<
/t>
<t>Enhanced security considerations</t>
<t>Added data change information to the description of the examples.</
t>
</list>
</t>
<t>v19 - v20
<list style="symbols">
<t>Minor updates for IESG comments</t>
</list>
</t>
<t>v18 - v19
<list style="symbols">
<t>Updated leaf includes-defaults </t>
</list>
</t>
<t>v17 - v18
<list style="symbols">
<t>Added the report-all-tagged mode to the leaf includes-defaults</t>
</list>
</t>
<t>v16 - v17
<list style="symbols">
<t>Removed default statement from includes-default</t>
</list>
</t>
<t>v15 - v16
<list style="symbols">
<t>Editorial changes</t>
</list>
</t>
<t>v14 - v15
<list style="symbols">
<t>Removed reference to revision-label</t>
<t>For the inline method made the usage of
ietf-yang-library@2019-01-04 mandatory.
Simplified the case "inline" in the YANG module.</t>
<t>Removed the "inline-module" leaf as it does not carry
useful information anymore.</t>
<t>Removed YANG feature</t>
</list>
</t>
<t>v13 - v14
<list style="symbols">
<t>Added leaf includes-defaults</t>
<t>Many small changes based on AD review</t>
</list>
</t>
<t>v09 - v13
<list style="symbols">
<t>Editorial updates</t>
</list>
</t>
<t>v08 - v09
<list style="symbols">
<t>Removed statement "the format will be similar to the response of a
NETCONF get operation"</t>
<t>Introduced artwork folding in the examples</t>
</list>
</t>
<t>v07 - v08
<list style="symbols">
<t>Moved compatibility into appendix</t>
<t>Renamed yid-version to format-version.
Changed format to date of the YANG module</t>
<t>Made support of ietf-yang-library mandatory if
inline-content-schema is supported</t>
<t>Many small changes based on WGLC</t>
</list>
</t>
<t>v06 - v07
<list style="symbols">
<t>Updated terminology, use-cases</t>
<t>Many small changes based on WGLC</t>
</list>
</t>
<t>v05 - v06
<list style="symbols">
<t>Modified module name format, removed .yin or .yang extension</t>
<t>Removed pattern for module and inline-module. The
usage of revision-label should also be allowed.
</t>
</list>
</t>
<t>v04 - v05
<list style="symbols">
<t>Updated according to YANG-Doctor review</t>
<t>Updated security considerations</t>
<t>Added a wrapping container for the schema, and renamed the data
nodes in the inline and uri cases.
</t>
<t>Allowed .yin for simplified-inline schema naming.
Made date optional if it is unavailable in the YANG module.</t>
<t>Added a mandatory yid-version to the header metadata to allow
later updates of the module.</t>
</list>
</t>
<t>v03 - v04
<list style="symbols">
<t>removed entity-tag and last-modified timestamp</t>
<t>Added simplified-inline method of content-schema specification</t>
</list>
</t>
<t>v02 - v03
<list style="symbols">
<t>target renamed to "content-schema" and "content defining YANG
module(s)"</t>
<t>Made name of instance data set optional</t>
<t>Updated according to draft-ietf-netmod-yang-data-ext-03</t>
<t>Clarified that entity-tag and last-modified timestamp are encoded
as metadata. While they contain useful data, the HTTP-header based
encoding from Restconf is not suitable.</t>
</list>
</t>
<t>v01 - v02
<list style="symbols">
<t>Removed design time from terminology</t>
<t>Defined the format of the content-data part by referencing various
RFCs and drafts instead of the result of the get-data and get operatio
ns.</t>
<t>Changed target-ptr to a choice</t>
<t>Inline target-ptr may include augmenting modules and alternatives t
o ietf-yang-library</t>
<t>Moved list of target modules into a separate &lt;target-modules> el
ement.</t>
<t>Added backwards compatibility considerations</t>
</list>
</t>
<t>v00 - v01
<list style="symbols">
<t>Added the target-ptr metadata with 3 methods</t>
<t>Added timestamp metadata</t>
<t>Removed usage of dedicated .yid file extension</t>
<t>Added list of use cases</t>
<t>Added list of principles</t>
<t>Updated examples</t>
<t>Moved detailed use case descriptions to appendix</t>
</list>
</t>
</section>
<section title="Backwards Compatibility">
<t>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 content-schema. dependent on the specific use case and the content-schema.
</t><t> </t>
<t>
In case of "instance data sets" that are the result of design or specifica tion In case of "instance data sets" that are the result of design or specifica tion
activity, some changes that may be good to avoid are listed below. activity, some changes that may be good to avoid are listed below.
</t><t> </t>
<t>
YANG uses the concept of managed entities identified by key YANG uses the concept of managed entities identified by key
values; if the connection between the represented entity and the key values; if the connection between the represented entity and the key
value is not preserved during an update, this may lead to the following pr oblems. value is not preserved during an update, this may lead to the following pr oblems.
<list style="symbols"> </t>
<t>If the key value of a list entry that represents the same <ul spacing="normal">
<li>If the key value of a list entry that represents the same
managed entity as before is changed, the user may mistakenly managed entity as before is changed, the user may mistakenly
identify the list entry as new.</t> identify the list entry as new.</li>
<t>If the meaning of a list entry is changed, but the key values <li>If the meaning of a list entry is changed but the key values
are not (e.g., redefining an alarm-type but not changing its are not (e.g., redefining an alarm-type but not changing its
alarm-type-id) the change may not be noticed.</t> alarm-type-id), the change may not be noticed.</li>
<t>If the key value of a previously removed list entry is reused <li>If the key value of a previously removed list entry is reused
for a different entity, the change may be misinterpreted as for a different entity, the change may be misinterpreted as
reintroducing the previous entity.</t> reintroducing the previous entity.</li>
</list> </ul>
</t>
</section> </section>
<section anchor="detailed_use_cases" numbered="true" toc="default">
<section title="Detailed Use Cases" anchor="detailed_use_cases"> <name>Detailed Use Cases</name>
<t>This section is non-normative.</t> <t>This section is non-normative.</t>
<section title="Use Case 1: Early Documentation of Server Capabilities"> <section numbered="true" toc="default">
<t> A server has a number of server-capabilities that are defined <name>Use Case 1: Early Documentation of Server Capabilities</name>
<t> A server has a number of server capabilities that are defined
in YANG modules and can be retrieved from the server in YANG modules and can be retrieved from the server
using protocols like NETCONF or RESTCONF. Server capabilities include: using protocols like NETCONF or RESTCONF. Server capabilities include:
<list style="symbols"> </t>
<t> data defined in "ietf-yang-library": YANG modules, submodules, <ul spacing="normal">
<li> data defined in "ietf-yang-library": YANG modules, submodules,
features, deviations, schema-mounts, and datastores features, deviations, schema-mounts, and datastores
supported (<xref target="RFC8525"/>)</t> supported (<xref target="RFC8525" format="default"/>).</li>
<t>alarms supported (<xref target="RFC8632"/>)</t> <li>alarms supported (<xref target="RFC8632" format="default"/>).</li>
<t>data nodes and subtrees that support or do not support on-change <li>data nodes and subtrees that support or do not support on-change
notifications (<xref target="RFC8641"/>)</t> notifications (<xref target="RFC8641" format="default"/>).</li>
<t>netconf-capabilities in ietf-netconf-monitoring.</t> <li>netconf-capabilities in ietf-netconf-monitoring.</li>
</list> </ul>
<t>
While it is good practice to allow a client to query these capabilitie s While it is good practice to allow a client to query these capabilitie s
from the live server, that is often not possible. from the live server, that is often not possible.
</t> </t>
<t> <t>
Often when a network node is released, an associated NMS Often when a network node is released, an associated Network Managemen
(network management system) is also released with it. The NMS depends t System (NMS)
on the capabilities of the server. is also released with it. The NMS depends on the capabilities of the s
erver.
During NMS implementation, information about server capabilities is ne eded. During NMS implementation, information about server capabilities is ne eded.
If the information is unavailable early in some offline If the information is unavailable early in some offline
document, but only as instance data from the live network node, the NM document but only as instance data from the live network node, the NMS
S implementation will be implementation will be
delayed, because it has to wait until the network node is ready. Also delayed because it has to wait until the network node is ready. Also,
assuming assuming
that all NMS implementors will have a correctly configured network nod that all NMS implementors will have correctly configured network nodes
es from which data can be retrieved is a very expensive proposition. (An
from which data can be retrieved, is a very expensive proposition. (An NMS may handle dozens
NMS may handle dozens
of node types.) of node types.)
</t> </t>
<t> <t>
Network operators often build their own home-grown NMS systems that Network operators often build their own homegrown NMS systems that
need to be integrated with a vendor's network node. The operator need to be integrated with a vendor's network node. The operator
needs to know the network node's server capabilities in order to do needs to know the network node's server capabilities in order to do
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 Operations, Admin istration, and Maintenance (OAM) feature set
documented as the server's capabilities. documented as the server's capabilities.
</t> </t>
<t> <t>
Beside NMS implementors, system integrators and many others also need the same Beside NMS implementors, system integrators and many others also need the same
information early. Examples could be model driven testing, generating information early. Examples could be model-driven testing, generating
documentation, etc. documentation, etc.
</t> </t>
<t> <t>
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 the addition or removal of hardware. Th ey are upgrade or due to licensing or the addition or removal of hardware. Th ey are
usually defined by a vendor at design time, before the product is rele ased. usually defined by a vendor at design time, before the product is rele ased.
It is feasible and advantageous to define/document them early
e.g., in a YANG instance data File. It is feasible and advantageous to define and document them early,
e.g., in a YANG instance data file.
</t> </t>
<t>It is anticipated that a separate IETF document will define in <t>It is anticipated that a separate IETF document will define in
detail how and which set of server capabilities should be documented. detail how and which set of server capabilities should be documented.
</t> </t>
</section> </section>
<section title="Use Case 2: Preloading Data"> <section numbered="true" toc="default">
<name>Use Case 2: Preloading Data</name>
<t> <t>
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, often a simple default configuration will by the operator. However, a simple default configuration often will
be sufficient. be sufficient.
</t><t> </t>
<t>
One example is access control groups/roles and related rules. One example is access control groups/roles and related rules.
While a sophisticated operator may define dozens of different groups, While a sophisticated operator may define dozens of different groups,
often a basic (read-only operator, read-write system administrator, often a basic (read-only operator, read-write system administrator,
security-administrator) triplet will be enough. security-administrator) triplet will be enough.
Vendors will often provide such default configuration data to make Vendors will often provide such default configuration data to make
device configuration easier for an operator. device configuration easier for an operator.
</t> <t> </t>
<t>
The device vendor may define a set of default groups (/nacm:nacm/group s) and rules The device vendor may define a set of default groups (/nacm:nacm/group s) and rules
for these groups to access specific parts of the common models (/nacm: nacm/rule-list/rule). for these groups to access specific parts of the common models (/nacm: nacm/rule-list/rule).
</t> </t>
<t> <t>
YANG instance data files can be used to document and/or preload the YANG instance data files can be used to document and/or preload the
default configuration. default configuration.
</t> </t>
</section> </section>
<section title="Use Case 3: Documenting Factory Default Settings"> <section numbered="true" toc="default">
<name>Use Case 3: Documenting Factory Default Settings</name>
<t> <t>
Nearly every server has a factory default configuration. If the Nearly every server has a factory default configuration. If the
system is really badly misconfigured or if the current configuration system is really badly misconfigured or if the current configuration
is to be abandoned, the system can be reset to the default factory is to be abandoned, the system can be reset to the default factory
configuration. configuration.
</t><t> </t>
<t>
YANG instance data can be used to document the factory default YANG instance data can be used to document the factory default
configuration. See <xref target="RFC8808"></xref>. configuration. See <xref target="RFC8808" format="default"/>.
</t> </t>
</section> </section>
</section> </section>
<section numbered="false" toc="default">
<name>Acknowledgments</name>
<t>For their valuable comments, discussions, and feedback, we wish to
acknowledge <contact fullname="Andy Bierman"/>, <contact fullname="Juerg
en Schoenwaelder"/>, <contact fullname="Rob Wilton"/>, <contact fullname="Joe C
larke"/>, <contact fullname="Kent Watsen"/>, <contact fullname="Martin Bjork
lund"/>, <contact fullname="Ladislav Lhotka"/>, <contact fullname="Qin Wu"/>, an
d other members of the Netmod Working Group.</t>
</section>
</back> </back>
</rfc> </rfc>
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