Self Describing Data Object Tags

Self Describing Data Object Tags Huawei

101 Software Avenue, Yuhua District Nanjing Jiangsu 210012 China bill.wu@huawei.com

Cisco

De Kleetlaan 6a b1 Diegem 1831 Belgium bclaise@cisco.com

China Mobile

32 Xuanwumen West St, Xicheng District Beijing 10053 liupengyjy@chinamobile.com

China Mobile

32 Xuanwumen West St, Xicheng District Beijing 10053 duzongpeng@chinamobile.com

Orange

Rennes 35000 France mohamed.boucadair@orange.com

OPS Area NETMOD Working Group This document defines a method to tag data objects associated with operation and management data in YANG Modules. This YANG data object tagging method can be used to classify data objects from different YANG modules and identify characteristics data. It also can provide input, instruction, indication to selection filter and filter queries of operational state on a server during a "pub/sub" service for YANG datastore updates. When the state of all subscriptions of a particular Subscriber to be fetched is huge, the amount of data to be streamed out to the destination can be greatly reduced and only targeted to the characteristics data. These data object tags may be registered as well as assigned during the module definition; assigned by implementations; or dynamically defined and set by users.

As described in [I.D-ietf-netmod-module-tags], the use of tags for classification and organization is fairly ubiquitous not only within IETF protocols, but in the internet itself (e.g., "#hashtags"). A module tag defined in [I.D-ietf-netmod-module-tags] is a string associated only with a module name at module level. At the time of writing this document (2020), there are many data models that have been specified or are being specified by various different SDOs and Open Souce community. They cover many of the networking protocols and techniques. However data objects defined by these technology specific data models might represent a portion of fault, configuration, accounting, performance, security management categories information at different locations in various different ways, lack consistent classification criteria and representation for a specific service, feature or data source. This document defines self-describing data object tags and associates them with data objects within YANG module, which Provide dictionary meaning for specific targeted data objects; Indicate relationship between data objects within the same YANG module or from different YANG modules; Identify key performance metric data objects and the absolute XPath expression identifying the element path to the node; The self describing data object tags can be used by the client to classify data objects from different YANG modules and identify characteristics data. In addition, it can provide input, instruction, indication to selection filter and filter queries of configuration or operational state on a server based on these data object tags, .e.g., return specific object type of operational state related to system-management. NETCONF clients can discover data objects with self describing data object tags supported by a NETCONF server via <get-schema> operation. The self describing data object tag capability can also be advertised via Capability Notification Model [I-D.netconf-notification-capabilities] by the NETCONF server or some place where offline document are kept. These data object tags may be registered as well as assigned during the module definition; assigned by implementations; or dynamically defined and set by users. This document defines a YANG module [RFC7950] which augments module tag model and provides a list of data object entries to allow for adding or removing of self describing tags as well as viewing the set of self describing tags associated with specific data objects within YANG modules. This document defines an extension statement to be used to indicate self describing tags that SHOULD be added by the module implementation automatically (i.e., outside of configuration). This document also defines an IANA registry for tag prefixes as well as a set of globally assigned tags. provides guidelines for authors of YANG data models. The YANG data model in this document conforms to the Network Management Datastore Architecture defined in [RFC8342].

Among data object tags, the opm (object, property, metric) tags can be used to tackle massive data objects collection and only capture YANG data objects associated with performance metrics data modelled with YANG (See ).

/----\ /Object\ +-------------+ Tag +---------------+------------------+ | \- +-/ | | | +---------V--------+ have | | | | YANG Data Node <----------+-----+ | | | /Data Object 1 | | | | | +--A-------------A-+ | | | | |have |have | | | | | | | | | +-V-----------+-----+ +-+------------V+ +-+------------V+ | YANG Data Node | | YANG Data Node| | YANG Data Node| | /Data Object 2 | | /Data Object 3| | /Data Object 4| +---A------ --- ----+ +-A----------- -+ +-A----------- -+ | | | | /-+-\ /-+-\ /-+--\ Metric \ Metric \ Property | Tag | | Tag | \ Tag / \-^-/ \-^-/ \----/ | | | /----\ | | /Metric\ | +----| Group +----| \ Tag / \- --/ In , object can contain other objects called subobjects. Both object and subobjects can be modeled as YANG data nodes [RFC7950]. Object can be one of container, leaf-list and list. subobject tagged with property tag is a leaf node. subobject tagged with metric tag can be one of container, leaf-list, list, leaf node. A data Object contains one single object tag, or one single object tag and one single property tag, or one single object tag and one single metric tag. A data Object also can contain one single Metric Group tag and/or one single multi-source tag. The use of opm tags would be to help filter discrete categories of YANG data objects scattered across the same or different YANG modules supported by a device and capture all network performance data or all property data in the single view of the truth (see ). In , tunnel-svc data object is a container node in the tunnel-pm module and can be seen as the root object for property tagged subobjects (e.g., tunnel-svc/create-time) and metric tagged subobjects (e.g.,tunnel-svc/avg-latency). Name, create-time, modified-time are property tagged subobjects under tunnel-svc container. Avg-latency,packet -loss are metric tagged subobjects under tunnel-svc container node. Take tunnel-svc data object and tunnel-svc/name data object as an example, tunnel-svc data object has one single object tag (i.e., ietf:object) while tunnel-svc/name data object has one object tag (ietf:object) and one property subobject tag (i.e., ietf:property). In addition, not all metric subobjects need to be tagged, e.g., only specific category (e.g., loss related) metric subobjects need to be tagged with metric-group tag which can further reduce amount data to be fetched.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

- Object Property Metric

All data object tags SHOULD begin with a prefix indicating who owns their definition. An IANA registry () is used to support registering data object tag prefixes. Currently 3 prefixes are defined. No further structure is imposed by this document on the value following the registered prefix, and the value can contain any YANG type 'string' characters except carriage-returns, newlines and tabs. Therefore, designers, implementers, and users are free to add or not add any structure they may require to their own tag values.

An IETF tag is a data object tag that has the prefix "ietf:". All IETF data object tags are registered with IANA in a registry defined later in this document ().

A vendor tag is a tag that has the prefix "vendor:". These tags are defined by the vendor that implements the module, and are not registered; however, it is RECOMMENDED that the vendor include extra identification in the tag to avoid collisions such as using the enterprise or organization name following the "vendor:" prefix (e.g., vendor:vendor-defined-classifier).

A user tag is any tag that has the prefix "user:". These tags are defined by the user/administrator and are not meant to be registered. Users are not required to use the "user:" prefix; however, doing so is RECOMMENDED as it helps avoid prefix collisions.

Any tag not starting with the prefix "ietf:", "vendor:" or "user:" is reserved for future use. These tag values are not invalid, but simply reserved in the context of specifications (e.g., RFCs).

Tags can become associated with a data object within YANG module in a number of ways. Tags may be defined and associated at the module design time, at implementation time without the need of live server, or via user administrative control . As the main consumer of data object tags are users, users may also remove any tag from a live server, no matter how the tag became associated with a data object within a YANG module.

A data object definition MAY indicate a set of data object tags to be added by the module implementer. These design time tags are indicated using a set of extension statements which include: Classify management and operation data into object, property subobject and metric subobject three categories. Object can contain other objects called subobjects. Property and metric objects are both subobjects belonging to specific object. Both object and subobjects can be modeled as data nodes [RFC7950]. Object can be one of container, leaf-list and list. Property subobject is a leaf node. Metric subobject can be one of container, leaf-list, list, leaf. Object contains zero or many property subobjects, zero or many metric subobjects. See opm-tag example in and . Provide meric subobjects classification (e.g., loss, jitter, delay) within the YANG module. Identify multi-source aggregation type (e.g., aggregated, non-aggregated) related to metric subobject. 'aggregated' multi-source aggregation type allows a large number of measurements on metric subobjects from different sources of the same type (e.g.,line card, each subinterface of aggregated Ethernet interface) being combined into aggregated statistics and report as one metric subobject. 'non-aggregated' multi-source aggregation type allows measurement from each source of the same type (e.g.,line card, each subinterface of aggregated Ethernet interface) be reported separately. Among these extension statements, the metric-group, multi-source-tag extension statements are context information related and can be used to correlate data object from the different modules. If the data node is defined in an IETF standards track document, the data object tags MUST be IETF Tags (2.1). Thus, new data object can drive the addition of new IETF tags to the IANA registry defined in , and the IANA registry can serve as a check against duplication.

An implementation MAY include additional tags associated with data object within a YANG module. These tags SHOULD be IETF Tags (i.e., registered) or vendor specific tags.

Data object tags of any kind, with or without a prefix, can be assigned and removed by the user from a live server using normal configuration mechanisms. In order to remove a data object tag from the operational datastore, the user adds a matching "masked-tag" entry for a given data object within the ietf-data-object-tags Module.

The tree associated with the "ietf-data-object-tags" module follows. The meaning of the symbols can be found in [RFC8340].

module: ietf-data-object-tags augment /tags:module-tags/tags:module: +--rw data-object-tags +--rw data-object* [object-name] +--rw object-name nacm:node-instance-identifier +--rw tag* tags:tag +--rw masked-tag* tags:tag

<CODE BEGINS> file "ietf-data-object-tags@2019-05-03.yang" module ietf-data-object-tags { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-data-object-tags"; prefix ntags; import ietf-netconf-acm { prefix nacm; } import ietf-module-tags { prefix tags; } organization "IETF NetMod Working Group (NetMod)"; contact "WG Web: <https://tools.ietf.org/wg/netmod/> WG List: <mailto:netmod@ietf.org> Editor: Qin Wu <mailto:bill.wu@huawei.com> Editor: Benoit Claise <mailto:bclaise@cisco.com> Editor: Peng Liu <mailto:liupengyjy@chinamobile.com> Editor: Zongpeng Du <mailto:duzongpeng@chinamobile.com> Editor: Mohamed Boucadair <mailto:mohamed.boucadair@orange.com>"; description "This module describes a mechanism associating self-describing tags with YANG data object within YANG modules. Tags may be IANA assigned or privately defined. Copyright (c) 2020 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://tools.ietf.org/html/rfcXXXX); see the RFC itself for full legal notices."; revision 2019-05-03 { description "Initial revision."; reference "RFC XXXX: Self Describing Data Object Tags"; } extension opm-tag { argument tag; description "The argument 'tag' is of type 'tag'. This extension statement is used by module authors to indicate the opm tags that SHOULD be added automatically by the system. Opm Tag is used to classify operation and management data into object, property subobject, and metric subobject three categories. Object can contain other objects called subobjects. Property and metric objects are both subobjects belonging to specific object. Both object and subobjects can be modeled as data nodes. Object can be one of container, leaf-list and list. Property subobject is a leaf node. Metric subobject can be one of container, leaf-list, list, leaf. Object contains zero or many property subobjects, zero or many metric subobjects. As such the origin of the value for the pre-defined tags should be set to 'system'[RFC8342]."; } extension metric-group { argument tag; description "The argument 'tag' is of type 'tag'.The metric-group can be used to provide metric subobject classification (e.g., loss, jitter, packet loss) within the YANG module."; } extension multi-source-tag { argument tag; description "The argument 'tag' is of type 'tag'.The multi-source-tag can be used to identify multi-source aggregation type (e.g., aggregated, non-aggregated) related to metric subobject. 'aggregated' multi-source aggregation type allows a large number of measurements on metric subobjects from different sources of the same type (e.g.,line card, each subinterface of aggregated Ethernet interface) being combined into aggregated statistics and report as one metric subobject value. 'non-aggregated' multi-source aggregation type allows measurement from each source of the same type (e.g.,line card, each subinterface of aggregated Ethernet interface) be reported separately."; } augment "/tags:module-tags/tags:module" { description "Augment the Module Tags module with data object tag attributes"; container data-object-tags { description "Contains the list of data objects and their associated data object tags"; list data-object { key "object-name"; description "A list of data objects and their associated data object tags"; leaf object-name { type nacm:node-instance-identifier; mandatory true; description "The YANG data object name."; } leaf-list tag { type tags:tag; description "Tags associated with the data object within the YANG module. See the IANA 'YANG Data Object Tag Prefixes' registry for reserved prefixes and the IANA'IETF YANG Data Object Tags' registry for IETF tags. The 'operational' state [RFC8342] view of this list is constructed using the following steps: 1) System tags (i.e., tags of 'system' origin) are added. 2) User configured tags (i.e., tags of 'intended' origin) are added. 3) Any tag that is equal to a masked-tag is removed."; } leaf-list masked-tag { type tags:tag; description "The list of tags that should not be associated with the data object within the YANG module. The user can remove (mask) tags from the operational state datastore [RFC8342] by adding them to this list. It is not an error to add tags to this list that are not associated with the data object within YANG module, but they have no operational effect."; } } } } } <CODE ENDS>

This section updates [RFC8407].

A module MAY indicate, using data object tag extension statements, a set of data object tags that are to be automatically associated with data object within the module (i.e., not added through configuration).

module example-module-A { //... import ietf-data-node-tags { prefix ntags; } container top { ntags:opm-tag "ietf:object"; list X { leaf foo { ntags:opm-tag "ietf:property"; } } container Y { leaf bar { ntags:opm-tag "ietf:metric"; } } } // ... } The module writer can use existing standard data object tags, or use new data object tags defined in the data object definition, as appropriate. For IETF standardized modules, new data object tags MUST be assigned in the IANA registry defined below, see Section .

IANA is asked to create a new registry "YANG Data Object Tag Prefixes" grouped under a new "Protocol" category named "YANG Data Object Tag Prefixes". This registry allocates tag prefixes. All YANG Data Object Tags SHOULD begin with one of the prefixes in this registry. Prefix entries in this registry should be short strings consisting of lowercase ASCII alpha-numeric characters and a final ":" character. The allocation policy for this registry is Specification Required [RFC8126]. The Reference and Assignee values should be sufficient to identify and contact the organization that has been allocated the prefix. The initial values for this registry are as follows.

IANA is asked to create 3 new registries "IETF OPM Tags","IETF Metric Group Tags","IETF Multiple Source Tags" grouped under a new "Protocol" category. These 3 registries should be included below "YANG Data Object Tag Prefixes" when listed on the same page. 3 registries allocate tags that have the registered prefix "ietf:". New values should be well considered and not achievable through a combination of already existing IETF tags. The allocation policy for these three registries is IETF Review [RFC8126]. The initial values for these three registries are as follows.

This document registers a URI in the "IETF XML Registry" [RFC3688]. Following the format in [RFC3688], the following registration has been made:

URI: urn:ietf:params:xml:ns:yang:ietf-data-object-tags Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace.

This document registers one YANG module in the "YANG Module Names" registry [RFC6020]. Following the format in [RFC6020], the following registration has been made:

name: ietf-data-object-tags namespace: urn:ietf:params:xml:ns:yang:ietf-data-object-tags prefix: ntags reference: RFC XXXX (RFC Ed.: replace XXX with actual RFC number and remove this note.)

The YANG module defined in this memo is designed to be accessed via the NETCONF protocol [RFC6241]. The lowest NETCONF layer is the secure transport layer and the mandatory-to-implement secure transport is SSH [RFC6242]. This document adds the ability to associate data object tag meta-data with data object within the YANG modules. This document does not define any actions based on these associations, and none are yet defined, and therefore it does not by itself introduce any new security considerations. Users of the data object tag meta-data may define various actions to be taken based on the data object tag meta-data. These actions and their definitions are outside the scope of this document. Users will need to consider the security implications of any actions they choose to define.

The authors would like to thank Ran Tao for his major contributions to the initial modeling and use cases. The authors would also like to acknowledge the comments and suggestions received from Juergen Schoenwaelder, Andy Bierman, Lou Berger,Jaehoon Paul Jeong, Wei Wang, Yuan Zhang, Ander Liu, Peng Liu, YingZhen Qu, Boyuan Yan.

Liang Geng China Mobile 32 Xuanwumen West St, Xicheng District Beijing 10053 Email: gengliang@chinamobile.com

The following is a fictional NETCONF example result from a query of the data object tags list. For the sake of brevity only a few module and associated data object results are imagined.

<ns0:data xmlns:ns0="urn:ietf:params:xml:ns:netconf:base:1.0"> <t:module-tags xmlns:t="urn:ietf:params:xml:ns:yang:ietf-module-tags"> <t:module> <t:name>ietf-interfaces</t:name> <s:data-object-tags xmlns:s="urn:ietf:params:xml:ns:yang:ietf-data-object-tags"> <s:data-object> <s:object-name>/if:interfaces/if:interface</s:object-name> <s:tag>ietf:object</s:tag> </s:data-object> <s:data-object> <s:object-name>/if:interfaces/if:interface/if:last-change</s:object-name> <s:tag>ietf:property</s:tag> </s:data-object> <s:data-object> <s:object-name> /if:interfaces/if:interface/if:statistics/if:in-errors </s:object-name> <s:tag>ietf:metric</s:tag> </s:data-object> </s:data-object-tags> </t:module> <t:module> <t:name>ietf-ip</t:name> <s:data-object-tags xmlns:s="urn:ietf:params:xml:ns:yang:ietf-data-object-tags"> <s:data-object> <s:object-name>/if:interfaces/if:interface/ip:ipv4</s:object-name> <s:tag>ietf:object</s:tag> </s:data-object> <s:data-object> <s:object-name>/if:interfaces/if:interface/ip:ipv4/ip:enable</s:object-name> <s:tag>ietf:property</s:tag> </s:data-object> <s:data-object> <s:object-name>/if:interfaces/if:interface/ip:ipv4/ip:mtu</s:object-name> <s:tag>ietf:metric</s:tag> </s:data-object> </s:data-object-tags> </t:module> </t:module-tags> </ns0:data>

As per [RFC8407] the following is a non-NMDA module to support viewing the operational state for non-NMDA compliant servers.

<CODE BEGINS> file "ietf-data-object-tags-state@2019-05-03.yang" module ietf-data-object-tags-state { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-data-object-tags-state"; prefix ntags-s; import ietf-netconf-acm { prefix nacm; } import ietf-module-tags { prefix tags; } organization "IETF NetMod Working Group (NetMod)"; contact "WG Web: <https://tools.ietf.org/wg/netmod/> WG List: <mailto:netmod@ietf.org> Editor: Qin Wu <mailto:bill.wu@huawei.com> Editor: Benoit Claise <mailto:bclaise@cisco.com> Editor: Peng Liu <mailto:liupengyjy@chinamobile.com> Editor: Zongpeng Du <mailto:duzongpeng@chinamobile.com>"; description "This module describes a mechanism associating self-describing tags with YANG data object within YANG modules. Tags may be IANA assigned or privately defined. Copyright (c) 2020 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://tools.ietf.org/html/rfcXXXX); see the RFC itself for full legal notices."; revision 2019-05-03 { description "Initial revision."; reference "RFC XXXX: Self Describing Data Object Tags"; } extension opm-tag { argument tag; description "The argument 'tag' is of type 'tag'. This extension statement is used by module authors to indicate the opm tags that SHOULD be added automatically by the system. Opm Tag is used to classify operation and management data into object, property subobject, and metric subobject three categories. Object can contain other objects called subobjects. Property and metric objects are both subobjects belonging to specific object. Both object and subobjects can be modeled as data nodes. Object can be one of container, leaf-list and list. Property subobject is a leaf node. Metric subobject can be one of container, leaf-list, list, leaf. Object contains zero or many property subobjects, zero or many metric subobjects. As such the origin of the value for the pre-defined tags should be set to 'system'[RFC8342]."; } extension metric-group { argument tag; description "The argument 'tag' is of type 'tag'.The metric-group can be used to provide metric subobject classification (e.g., loss, jitter, packet loss)within the YANG module."; } extension multi-source-tag { argument tag; description "The argument 'tag' is of type 'tag'.The multi-source-tag can be used to identify multi-source aggregation type (e.g., aggregated, non-aggregated) related to metric subobject. 'aggregated' multi-source aggregation type allows a large number of measurements on metric subobjects from different sources of the same type (e.g.,line card, each subinterface of aggregated Ethernet interface) being combined into aggregated statistics and report as one metric subobject value. 'non-aggregated' multi-source aggregation type allows measurement from each source of the same type (e.g.,line card, each subinterface of aggregated Ethernet interface) be reported separately."; } augment "/tags:module-tags/tags:module" { description "Augment the Module Tags module with data object tag attributes."; container data-object-tags { config false; status deprecated; description "Contains the list of data objects and their associated self describing tags."; list data-object { key "object-name"; status deprecated; description "A list of data objects and their associated self describing tags."; leaf object-name { type nacm:node-instance-identifier; mandatory true; status deprecated; description "The YANG data object name."; } leaf-list tag { type tags:tag; status deprecated; description "Tags associated with the data object within the YANG module. See the IANA 'YANG Data Object Tag Prefixes' registry for reserved prefixes and the IANA'IETF YANG Data Object Tags' registry for IETF tags. The 'operational' state [RFC8342] view of this list is constructed using the following steps: 1) System tags (i.e., tags of 'system' origin) are added. 2) User configured tags (i.e., tags of 'intended' origin) are added. 3) Any tag that is equal to a masked-tag is removed."; } leaf-list masked-tag { type tags:tag; status deprecated; description "The list of tags that should not be associated with the data object within the YANG module. The user can remove (mask) tags from the operational state datastore [RFC8342] by adding them to this list. It is not an error to add tags to this list that are not associated with the data object within YANG module, but they have no operational effect."; } } } } } <CODE ENDS>

The following subsections provides targeted data object collection example which helps reduce amount of data to be fetched. The subscription "id" values of 22 used below is just an example. In production, the actual values of "id" might not be small integers.

+-----------+ +-----------+ | Subscriber| | Publisher | +------+----+ +-----+-----+ | | | | |Telemery data Tagging Advertisement | (data object name, opm-tag = metric) |<---------------------------------| | | | establish-subscription | |--------------------------------->| | | | | | RPC Reply: OK, id = 22 | |<---------------------------------| | | | | | Notification Message (for 22) | | <--------------------------------| | | | | The publisher advertises telemetry data object capability to the subscriber to instruct the receiver to subscribe tagged data object (e.g., performance metric data object) using standard subscribed notification mechanism [RFC8639]. The following XML example [W3C.REC-xml-20081126] illustrates the advertisment of the list of available target objects using YANG instance file format [I-D.ietf-netmod-yang-instance-file-format]:

<?xml version="1.0" encoding="UTF-8"?> <instance-data-set xmlns=\ "urn:ietf:params:xml:ns:yang:ietf-yang-instance-data"> <name>acme-router-notification-capabilities</name> <content-schema> <module>ietf-system-capabilities@2020-03-23</module> <module>ietf-notification-capabilities@2020-03-23</module> <module>ietf-data-export-capabilities@2020-03-23</module> </content-schema>  <description>Defines the notification capabilities of an acme-router. The router only has running, and operational datastores. Every change can be reported on-change from running, but only config=true nodes and some config=false data from operational. Statistics are not reported based on timer based trigger and counter threshold based trigger. </description> <content-data> <system-capabilities \ xmlns="urn:ietf:params:xml:ns:yang:ietf-system-capabilities" \ xmlns:inc=\ "urn:ietf:params:xml:ns:yang:ietf-notification-capabilities" \ xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores"> <datastore-capabilities> <datastore>ds:operational</datastore> <per-node-capabilities> <node-selector>\ /if:interfaces/if:interface/if:statistics/if:in-errors\ </node-selector> <sec:self-describing-capabilities> <sec:opm-tag>metric</sec:opm-tag> <sec:metric-group>loss</sec:metric-group> </sec:self-describing-capabilities> </per-node-capabilities> </datastore-capabilities> </system-capabilities> </content-data> </instance-data-set> With telemetry data tagging information carried in the Telemetry data Tagging Advertisement, the subscriber identifies targeted data object and associated data path to the datastore node and sends a standard establish-subscription RPC [RFC8639] to subscribe tagged data objects that are interests to the client application from the publisher.

<netconf:rpc message-id="101" xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0"> <establish-subscription xmlns="urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications" xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push"> <yp:datastore xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores"> ds:operational </yp:datastore> <yp:datastore-xpath-filter xmlns:ex="https://example.com/sample-data/1.0"> /if:interfaces/if:interface/if:statistics/if:in-errors </yp:datastore-xpath-filter> <yp:periodic> <yp:period>500</yp:period> </yp:periodic> </establish-subscription> </netconf:rpc> The publisher returns specific object type of operational state (e.g., in-errors statistics data) subscribed by the client.

v00 - v01 Merge self describing data object tag use case section into introduction section as a subsection; Add one glossary section; Clarify the relation between data object, object tag, property tag and metric tag in Self Describing Data Object Tags Use Case section; Add update to RFC8407 in the front page.