Internet-Draft | YANG-Push Notification Envelope | October 2024 |
Huang Feng, et al. | Expires 22 April 2025 | [Page] |
This document defines a new extensible notification structure, defined in YANG, for use in YANG-Push Notification messages enabling any YANG compatible encodings such as XML, JSON or CBOR.¶
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YANG-Push [RFC8639] allows publishers to send notifications to a data collection. The YANG-Push receiver decodes the message and optionally validates the header and the content before forwarding to the next process.¶
The notification container from YANG-Push is currently based on the XML model from NETCONF Event Notifications [RFC5277]. This model has the drawback that only a single mandatory "eventTime" leaf is defined and does offer a way to extend this header with new metadata. Additionally, this XML model is only valid for XML-based environments. When messages are encoded in other YANG encodings, such as JSON [RFC7951] or CBOR [RFC9254], validators cannot use YANG to validate the message schema.¶
YANG data consumer receiving notifications require additional metadata to understand the full context of the received message. For example, in addition to the timestamp of when the event was encoded, it is also important to know the hostname which sourced the message, and have sequence numbers in generated messages so that lost notification messages can be detected. This additional metadata is also helpful to correlate the data with other sources of Network Telemetry [RFC9232] information.¶
For such reasons, this document proposes the following:¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
The terms "subscriber", "publisher", and "receiver" are used as defined in [RFC8639].¶
The terms "client" is used as defined in [RFC6241] for NETCONF and [RFC8040] for RESTCONF.¶
The terms "implementation-time information" and "runtime information" are used as defined in [RFC9196].¶
This section shows the relationship to [RFC5277], [RFC8639], [RFC7951] and [RFC9254].¶
[RFC5277] defines a mechanism for NETCONF nodes to send notifications to a collector. These are the key relationships between the current document and [RFC5277]:¶
Subscribed Notifications [RFC8639] defines a mechanism on top of [RFC5277] to stream notifications from the NETCONF node. These are the key relationships between the current document and [RFC8639]:¶
[RFC7950] defines how YANG data is encoded in XML. These are the key relationship points between the current document and [RFC7950]:¶
[RFC7951] defines how YANG data is encoded using JSON. These are the key relationship points between the current document and [RFC7951]:¶
[RFC9254] defines how YANG data is encoded using CBOR. These are the key relationship points between the current document and [RFC9254]:¶
Section 4.2.10 of [RFC7950] defines the encoding of YANG notifications. A notification is created by defining a 'notification' statement in the YANG module. When a NETCONF server sends this notification, it is composed of two parts: a header containing metadata which encapsulates the content and the content defined by the 'notification' statement.¶
In YANG 1.1 [RFC7950], the notification header is based on the model defined in [RFC5277] which contains a single metadata 'eventTime' leaf. An example extracted from [RFC7950] is shown in the following XML:¶
<notification xmlns="urn:ietf:params:netconf:capability:notification:1.0"> <eventTime>2007-09-01T10:00:00Z</eventTime> <link-failure xmlns="urn:example:system"> <if-name>so-1/2/3.0</if-name> <if-admin-status>up</if-admin-status> <if-oper-status>down</if-oper-status> </link-failure> </notification>¶
This document defines a new notification header and enables extending it with new metadata. The notification header defined in the following sections is to be used in YANG-Push [RFC8641] environments and can be implemented with NETCONF [RFC6241] and RESTCONF [RFC8040].¶
Section 3.1 defines how a client enables the header defined in this document. Section 3.2 extends the model from [RFC9196] to enable clients to discover the capability of using the new notification header for both implementation-time information and runtime information. Lastly, Section 3.3.2 defines the new notification header and how it is encoded using XML, JSON and CBOR.¶
The use of the notification envelope defined in this document can be enabled during the configuration of a YANG-Push subscription. This document augments the "ietf-subscribed-notification" model [RFC8639] to support the configuration of "notification-envelope".¶
module: ietf-notification-container augment /sn:subscriptions/sn:subscription: +--rw enable-notification-envelope? boolean {notification-envelope}? +--rw metadata augment /sn:establish-subscription/sn:input: +---w enable-notification-envelope? boolean {notification-envelope}? +---w metadata augment /sn:modify-subscription/sn:input: +---w enable-notification-envelope? boolean {notification-envelope}? +---w metadata¶
When the node 'enable-notification-envelope' is set to true, the notifications published by a YANG-Push publisher MUST use the header defined in Section 3.3.1. If any metadata is enabled during the configuration of the subscription, the metadata nodes MUST be present in the header.¶
A client can discover the support of 'notification-envelope' model through the capabilities model defined in [RFC9196]. This documents extends the 'ietf-notification-capabilities' model with a container that includes:¶
The YANG model defined in Section 5 augments the 'ietf-notification-capabilities' model with the leaf and container listed above.¶
augment /sysc:system-capabilities/notc:subscription-capabilities: +--ro notification-metadata +--ro notification-envelope? boolean {notification-envelope}? +--ro metadata¶
This model can be retrieved via a NETCONF <get> RPC.¶
This section defines how YANG notifications are structured when the notification envelope is enabled on a YANG-Push subscription. The following sections define how this model is encoded in XML, JSON and CBOR.¶
When a YANG-Push publisher uses the notification model defined in this document, the notification is structured as follows:¶
The following YANG tree [RFC8340] illustrates the notification envelope containing the mandatory metadata 'event-time'. See Section 3.4 for more detail on the optional metadata.¶
notifications: +---n envelope +--ro event-time yang:date-and-time +--ro notification-contents? <anydata>¶
The YANG notification can be encoded using XML [W3C.REC-xml-20001006][RFC7951], JSON [RFC7951] and CBOR [RFC9254].¶
A YANG notification encoded in XML is structured as a root "envelope" container. The namespace of this container is the namespace defined in the YANG module "ietf-yp-notification":¶
urn:ietf:params:xml:ns:netconf:notification:2.0¶
Two mandatory child nodes within the "envelope" container are expected, representing the event time and the notification payload. The "event-time" node is defined within the same XML namespace as the "envelope" container. The "event-time" node MUST be compliant with [RFC3339]. Other metadata defined within the YANG module defined in Section 5 MUST use the same XML namespace. See Section 3.4 for more details.¶
When other metadata is enabled through configuration, the supplementary nodes are encoded at the same level of the mandatory "event-time" node and use the XML namespace defined in the YANG module.¶
The content of the notification that is defined by the 'notification' statement is encoded in the "notification-contents" node. The name and namespace of this payload element are determined by the YANG module containing the 'notification' statement representing the notification message.¶
The following example shows a "push-update" notification defined in the YANG module of YANG-Push [RFC8641] encoded in XML:¶
A YANG notification encoded in JSON is structured as a root "envelope" container. The namespace of this container is the name of the YANG module "ietf-yp-notification" defined in Section 5.¶
Two mandatory child nodes within the "ietf-notification:envelope" container are expected, representing the event time and the notification payload. The "event-time" node is defined within the same namespace as the "ietf-yp-notification:envelope" container and is compliant with [RFC3339]. Other metadata defined within the YANG module defined in Section 5 MUST use the same namespace "ietf-yp-notification".¶
When other metadata is enabled through configuration, the supplementary nodes are encoded at the same level of the mandatory 'event-time' node and use the YANG module name as its namespace. See Section 3.4 for more details.¶
The content of the notification that is defined by the 'notification' statement is encoded in the "notification-contents" node. The name and namespace of this payload element are determined by the YANG module containing the 'notification' statement representing the notification message.¶
The following example shows a "push-update" notification defined in the YANG module of YANG-Push [RFC8641] encoded in JSON:¶
YANG notifications can be encoded in CBOR using Names or SIDs in keys.¶
Notifications encoded using names is similar to JSON encoding as defined in Section 3.3 of [RFC9254]. The key of the element can be the name of the element itself or be namespace-qualified. In the latter case, the namespace of the notification container uses the YANG module name "ietf-yp-notification" defined in Section 5.¶
Notification encoded using YANG-SIDs replaces the names of the keys of the CBOR encoded message for a 63 bit unsigned integer. In this case, the keys of the encoded data use the SID value as defined in Section 3.2 of [RFC9254]. A SID allocation process is needed beforehand following [I-D.ietf-core-sid].¶
In the notification, two mandatory child nodes within the "ietf-yp-notification:envelope" container are expected, representing the event time and the notification payload. The "event-time" node is defined within the same namespace as the "ietf-yp-notification:envelope" container and is compliant with [RFC3339].¶
When other metadata is enabled through configuration, the supplementary nodes are encoded at the same level of the mandatory "event-time" node and use the YANG module name as its namespace when they are encoded as names. When they are encoded using YANG SIDs, a SID value assigned to the metadata node is used. See Section 3.4 for more details.¶
The content of the notification that is defined by the 'notification' statement is encoded in the "notification-contents" node. The name and namespace of this payload element are determined by the YANG module containing the 'notification' statement representing the notification message. Similarly, SIDs can be used as keys if they are well allocated.¶
Figure 3 shows a "push-update" notification defined in the YANG module of YANG-Push [RFC8641] encoded in CBOR using names as keys. The example uses the CBOR diagnostic notation as defined in section 3.1 of [RFC9254]:¶
And Figure 4 shows the same notifcation encoded using SIDs:¶
This section described two optional YANG notification header extensions which are enabled by default when the notification envelope is enabled. When the envelope is enabled using the "enable-notification-envelope" node, the publisher includes by default the "hostname" and "sequence-number" defined in the following sections. The client discovers the support of these two extension headers with the mechanism defined in Section 3.2.¶
This document defines the following metadata as shown in the following YANG tree [RFC8340]. See the following sections for more details.¶
notifications: +---n envelope +--ro event-time yang:date-and-time +--ro hostname? inet:host | {notification-hostname-sequence-number}? +--ro sequence-number? yang:counter32 | {notification-hostname-sequence-number}? +--ro notification-contents? <anydata>¶
When YANG-Push notification messages are forwarded from a receiver to another system, such as a message broker or a time series database, the transport context is lost since it is not part of the metadata of the notification container. Therefore, the downstream system is unable to associate the message to the publishing process (the exporting network node), nor able to detect message loss or reordering.¶
To correlate network data among different Network Telemetry planes as described in Section 3.1 of [RFC9232] or among different YANG-Push subscription types as defined in Section 3.1 of [RFC8641], a reference to the node streaming the data is needed. This is essential for understanding the timely relationship among these different planes and YANG-Push subscription types.¶
Today, network operators work around this impediment by preserving the transport source IP address and sequence numbers of the publishing process. However, this implies encoding this information in the YANG-Push notification messages which impacts the semantic readability of the message in the downstream system.¶
On top of that, the transport source IP address might not represent the management IP address by which the YANG-Push publisher should be known. In other terms, the source-host [RFC6470], which is the "Address of the remote host for the session" might not be the management IP address.¶
To overcome these issues, this document proposes a notification container extension with a hostname and a sequence number. This allows the downstream system to not only be able to identify from which network node, subscription, and time the message was published but also, the order of the published messages.¶
Figure 5 provides an example of a JSON encoded, [RFC8259], "push-update" notification message with hostname and sequence-number as extension.¶
TBD: explain co-existence with RFC5277¶
This YANG module extends "ietf-subscribed-notifications" [RFC8641] and "ietf-notification-capabilities" [RFC9196] as shown in the following YANG tree [RFC8340]:¶
module: ietf-yp-notification augment /sn:subscriptions/sn:subscription: +--rw enable-notification-envelope? boolean | {notification-envelope}? +--rw metadata +--rw hostname-sequence-number? boolean {notification-hostname-sequence-number}? augment /sn:establish-subscription/sn:input: +---w enable-notification-envelope? boolean | {notification-envelope}? +---w metadata +---w hostname-sequence-number? boolean {notification-hostname-sequence-number}? augment /sn:modify-subscription/sn:input: +---w enable-notification-envelope? boolean | {notification-envelope}? +---w metadata +---w hostname-sequence-number? boolean {notification-hostname-sequence-number}? augment /sysc:system-capabilities/notc:subscription-capabilities: +--ro notification-metadata +--ro notification-envelope? boolean | {notification-envelope}? +--ro metadata +--ro hostname-sequence-number? boolean {notification-hostname-sequence-number}? notifications: +---n envelope +--ro event-time yang:date-and-time +--ro hostname? inet:host | {notification-hostname-sequence-number}? +--ro sequence-number? yang:counter32 | {notification-hostname-sequence-number}? +--ro notification-contents? <anydata>¶
The YANG module augments the module "ietf-subscribed-notifications" [RFC8641] and uses "ietf-yang-types" module [RFC6991].¶
<CODE BEGINS> file "ietf-yp-notification@2024-10-18.yang" module ietf-yp-notification { yang-version 1.1; namespace "urn:ietf:params:xml:ns:netconf:notification:2.0"; prefix inotenv; import ietf-yang-types { prefix yang; reference "RFC 6991: Common YANG Data Types"; } import ietf-inet-types { prefix inet; reference "RFC 6991: Common YANG Data Types"; } import ietf-subscribed-notifications { prefix sn; reference "RFC 8639: Subscription to YANG Notifications"; } import ietf-system-capabilities { prefix sysc; reference "RFC 9196: YANG Modules Describing Capabilities for Systems and Datastore Update Notifications"; } import ietf-notification-capabilities { prefix notc; reference "RFC 9196: YANG Modules Describing Capabilities for Systems and Datastore Update Notifications"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: <https://datatracker.ietf.org/group/netconf/> WG List: <mailto:netconf@ietf.org> Authors: Alex Huang Feng <mailto:alex.huang-feng@insa-lyon.fr> Pierre Francois <mailto:pierre.francois@insa-lyon.fr> Thomas Graf <mailto:thomas.graf@swisscom.com> Benoit Claise <mailto:benoit.claise@huawei.com>"; description "Defines a notification header for Subscribed Notifications [RFC8639] and YANG-Push [RFC8641]. When this notification header is enabled through configuration, the root container of the notification is encoded as defined in RFCXXX. This module can be used to validate XML encoded notifications [RFC7950], JSON encoded messages [RFC7951] and CBOR encoded messages [RFC9254]. Refer to Section Y of RFC XXXX for more details. Copyright (c) 2024 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices."; revision 2024-10-18 { description "First revision"; reference "RFC XXXX: YANG-Push Notification Envelope"; } grouping notif-env-configuration { description "This grouping defines the configuration switches for enabling the notification-envelope defined in RFC XXXX and the different supported metadata."; leaf enable-notification-envelope { type boolean; default false; description "Enables YANG-Push to use the notification-envelope defined in RFC XXXX."; } container metadata { description "Container for configuring optional metadata."; } } grouping notif-env-capabilities { description "This grouping defines the capabilities for the notification-envelope defined in RFC XXXX and the different supported metadata."; leaf notification-envelope { type boolean; default false; description "Supports YANG-Push to use the notification-envelope defined in RFC XXXX."; } container metadata { description "Container with the supported optional metadata by the YANG-Push publisher."; leaf hostname-sequence-number { type boolean; default false; description "Supports hostname and sequence-number in the YANG-Push notifications as defined in the YANG-Push notification-envelope in RFC XXXX."; } } } notification envelope { leaf event-time { type yang:date-and-time; mandatory true; description "The date and time the event was generated by the event source. This parameter is of type dateTime and compliant to [RFC3339]."; } leaf hostname { type inet:host; description "The hostname of the network node according to [RFC1213]. This value is usually configured on the node by the administrator to uniquely identify the node in the network."; } leaf sequence-number { type yang:counter32; description "Unique sequence number as described in [RFC9187] for each published message."; } anydata notification-contents { description "This contains the values defined by the 'notification' statement unchanged."; } } // Subscription container augment "/sn:subscriptions/sn:subscription" { description "This augmentation adds the configuration switches for enabling the notification envelope and metadatas."; uses notif-env-configuration; } // Subscription RPCs augment "/sn:establish-subscription/sn:input" { description "This augmentation adds the configuration switches for enabling the notification envelope and other metadatas during the 'establish-subscription' RPC."; uses notif-env-configuration; } augment "/sn:modify-subscription/sn:input" { description "This augmentation adds the configuration switches for enabling the notification envelope and other metadatas during the 'establish-subscription' RPC."; uses notif-env-configuration; } // YANG-Push Capabilities extension augment "/sysc:system-capabilities/notc:subscription-capabilities" { description "Extension to the subscription-capabilities model to enable clients to learn whether the publisher supports the notification-envelope"; container notification-metadata { description "Adds the notification metadata capabilities to subscription capabilities."; uses notif-env-capabilities; } } } <CODE ENDS>¶
This document describes the URI used for the IETF XML Registry and registers a new YANG module name.¶
IANA is requested to add this document as a reference in the following URI in the IETF XML Registry [RFC3688].¶
URI: urn:ietf:params:xml:ns:netconf:notification:2.0 Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace. Reference: RFC-to-be¶
This document registers the following YANG module in the YANG Module Names Registry [RFC6020], within the "YANG Parameters" registry:¶
name: ietf-yp-notification namespace: urn:ietf:params:xml:ns:netconf:notification:2.0 prefix: inotenv reference: RFC-to-be¶
IANA is requested to register a new ".sid" file in the "IETF YANG SID Registry" [I-D.ietf-core-sid]:¶
SID range entry point: TBD SID range size: 50 YANG module name: ietf-yp-notification reference: RFC-to-be¶
A ".sid" file is proposed in Appendix A.¶
The authors would like to thank Per Anderson, Andy Bierman, Carsten Bormann, Mohamed Boucadair, Tom Petch, Jason Sterne, Kent Watsen and Rob Wilton for their review and valuable comments.¶
Note to the RFC-Editor: Please remove this section before publishing.¶
For CBOR encoding using YANG-SIDs identifiers, a ".sid" file is requested to IANA in Section 7.3.¶