NETCONF E. Voit
Internet-Draft Cisco Systems
Intended status: Standards Track A. Clemm
Expires: October 18, 2018 Huawei
A. Gonzalez Prieto
VMWare
E. Nilsen-Nygaard
A. Tripathy
Cisco Systems
April 16, 2018
Customized Subscriptions to a Publisher's Event Streams
draft-ietf-netconf-subscribed-notifications-12
Abstract
This document defines a YANG data model and associated mechanisms
enabling subscriber-specific subscriptions to a publisher's event
streams. Applying these elements allows a subscriber to request for
and receive a continuous, custom feed of publisher generated
information.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 18, 2018.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
Voit, et al. Expires October 18, 2018 [Page 1]
Internet-Draft Subscribed Notifications April 2018
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.3. Solution Overview . . . . . . . . . . . . . . . . . . . . 5
1.4. Relationship to RFC-5277 . . . . . . . . . . . . . . . . 6
2. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1. Event Streams . . . . . . . . . . . . . . . . . . . . . . 7
2.2. Event Stream Filters . . . . . . . . . . . . . . . . . . 7
2.3. QoS . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.4. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . 9
2.5. Configured Subscriptions . . . . . . . . . . . . . . . . 16
2.6. Event Record Delivery . . . . . . . . . . . . . . . . . . 22
2.7. Subscription State Notifications . . . . . . . . . . . . 23
2.8. Subscription Monitoring . . . . . . . . . . . . . . . . . 28
2.9. Advertisement . . . . . . . . . . . . . . . . . . . . . . 29
3. YANG Data Model Trees . . . . . . . . . . . . . . . . . . . . 29
3.1. Event Streams Container . . . . . . . . . . . . . . . . . 29
3.2. Filters Container . . . . . . . . . . . . . . . . . . . . 30
3.3. Subscriptions Container . . . . . . . . . . . . . . . . . 30
4. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 32
5. Considerations . . . . . . . . . . . . . . . . . . . . . . . 57
5.1. Implementation Considerations . . . . . . . . . . . . . . 58
5.2. IANA Considerations . . . . . . . . . . . . . . . . . . . 58
5.3. Security Considerations . . . . . . . . . . . . . . . . . 59
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 62
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 62
7.1. Normative References . . . . . . . . . . . . . . . . . . 62
7.2. Informative References . . . . . . . . . . . . . . . . . 63
Appendix A. Changes between revisions . . . . . . . . . . . . . 64
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 68
1. Introduction
This document defines a YANG data model and associated mechanisms
enabling subscriber-specific subscriptions to a publisher's event
streams. Effectively this enables a 'subscribe then publish'
capability where the customized information needs and access
permissions of each target receiver are understood by the publisher
before subscribed event records are marshaled and pushed. The
Voit, et al. Expires October 18, 2018 [Page 2]
Internet-Draft Subscribed Notifications April 2018
receiver then gets a continuous, custom feed of publisher generated
information.
While the functionality defined in this document is transport-
agnostic, transports like NETCONF [RFC6241] or RESTCONF [RFC8040] can
be used to configure or dynamically signal subscriptions, and there
are bindings defined for subscribed event record delivery for NETCONF
within [I-D.draft-ietf-netconf-netconf-event-notifications], and for
HTTP2 or HTTP1.1 within [I-D.draft-ietf-netconf-restconf-notif].
The YANG model in this document conforms to the Network Management
Datastore Architecture defined in
[I-D.draft-ietf-netmod-revised-datastores].
1.1. Motivation
Various limitations in [RFC5277] are discussed in [RFC7923].
Resolving these issues is the primary motivation for this work. Key
capabilities supported by this document include:
o multiple subscriptions on a single transport session
o support for dynamic and configured subscriptions
o modification of an existing subscription in progress
o per-subscription operational counters
o negotiation of subscription parameters (through the use of hints
returned as part of declined subscription requests)
o subscription state change notifications (e.g., publisher driven
suspension, parameter modification)
o independence from transport
1.2. Terminology
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.
Configuration: defined in [I-D.draft-ietf-netmod-revised-datastores].
Configuration datastore: defined in
[I-D.draft-ietf-netmod-revised-datastores].
Voit, et al. Expires October 18, 2018 [Page 3]
Internet-Draft Subscribed Notifications April 2018
Configured subscription: A subscription installed via configuration
into a configuration datastore.
Dynamic subscription: A subscription agreed between subscriber and
publisher created via an "establish-subscription" RPC.
Event: An occurrence of something that may be of interest. Examples
include a configuration change, a fault, a change in status, crossing
a threshold, or an external input to the system.
Event occurrence time: a timestamp matching the time an originating
process identified as when an event happened.
Event record: A set of information detailing an event.
Event stream: A continuous, chronologically ordered set of events
aggregated under some context.
Event stream filter: Evaluation criteria which may be applied against
event records within an event stream. Event records pass the filter
when specified criteria are met.
Notification message: Information intended for a receiver indicating
that one or more event(s) have occurred.
Publisher: An entity responsible for streaming notification messages
per the terms of a subscription.
Receiver: A target to which a publisher pushes subscribed event
records. For dynamic subscriptions, the receiver and subscriber are
the same entity.
Subscriber: An entity able to request and negotiate a contract for
the generation and push of event records from a publisher. For
dynamic subscriptions, the receiver and subscriber are the same
entity.
Subscription: A contract with a publisher, stipulating which
information one or more receivers wish to have pushed from the
publisher without the need for further solicitation.
All YANG tree diagrams used in this document follow the notation
defined in [I-D.ietf-netmod-yang-tree-diagrams].
Voit, et al. Expires October 18, 2018 [Page 4]
Internet-Draft Subscribed Notifications April 2018
1.3. Solution Overview
This document describes a transport agnostic mechanism for
subscribing to and receiving content from an event stream within a
publisher. This mechanism is through the use of a subscription.
Two types of subscriptions are supported:
1. Dynamic subscriptions, where a subscriber initiates a
subscription negotiation with a publisher via an RPC. If the
publisher is able to serve this request, it accepts it, and then
starts pushing notification messages back to the subscriber. If
the publisher is not able to serve it as requested, then an error
response is returned. This response MAY include hints at
subscription parameters that, had they been present, would have
enabled the dynamic subscription request to be accepted.
2. Configured subscriptions, which allow the management of
subscriptions via a configuration so that a publisher can send
notification messages to configured receiver(s). Support for
configured subscriptions is optional, with its availability
advertised via a YANG feature.
Additional characteristics differentiating configured from dynamic
subscriptions include:
o The lifetime of a dynamic subscription is bound by the transport
session used to establish it. For connection-oriented stateful
transports like NETCONF, the loss of the transport session will
result in the immediate termination of any associated dynamic
subscriptions. For connectionless or stateless transports like
HTTP, a lack of receipt acknowledgment of a sequential set of
notification messages and/or keep-alives can be used to trigger a
termination of a dynamic subscription. Contrast this to the
lifetime of a configured subscription. This lifetime is driven by
relevant configuration being present within the publisher's
applied configuration. Being tied to configuration operations
implies configured subscriptions can be configured to persist
across reboots, and implies a configured subscription can persist
even when its publisher is fully disconnected from any network.
o Configured subscriptions can be modified by any configuration
client with write permission on the configuration of the
subscription. Dynamic subscriptions can only be modified via an
RPC request made by the original subscriber, or a change to
configuration data referenced by the subscription.
Voit, et al. Expires October 18, 2018 [Page 5]
Internet-Draft Subscribed Notifications April 2018
Note that there is no mixing-and-matching of dynamic and configured
operations on a single subscription. Specifically, a configured
subscription cannot be modified or deleted using RPCs defined in this
document. Similarly, a subscription established via RPC cannot be
modified through configuration operations. Also note that transport
specific transport drafts based on this specification MUST detail the
life cycles of both dynamic and configured subscriptions.
A publisher MAY terminate a dynamic subscription at any time.
Similarly, it MAY decide to temporarily suspend the sending of
notification messages for any dynamic subscription, or for one or
more receivers of a configured subscription. Such termination or
suspension is driven by internal considerations of the publisher.
1.4. Relationship to RFC-5277
This document is intended to provide a superset of the subscription
capabilities initially defined within [RFC5277]. Especially when
extending an existing [RFC5277] implementation, it is important to
understand what has been reused and what has been replaced. Key
relationships between these two documents include:
o this document defines a transport independent capability,
[RFC5277] is specific to NETCONF.
o the data model in this document is used instead of the data model
in Section 3.4 of [RFC5277] for the new operations.
o the RPC operations in this draft replaces the operation "create-
subscription" defined in [RFC5277], section 4.
o the one way operation of [RFC5277], Section 4 is used.
o the included contents of the "NETCONF" event stream are identical
between this document and [RFC5277].
o a publisher MAY implement both the Notification Management Schema
and RPCs defined in [RFC5277] and this new document concurrently,
in order to support old clients. However the use of both
alternatives on a single transport session is prohibited.
o unlike [RFC5277], this document enables a single transport session
to intermix of notification messages and RPCs for different
subscriptions.
Voit, et al. Expires October 18, 2018 [Page 6]
Internet-Draft Subscribed Notifications April 2018
2. Solution
Per the overview provided in Section 1.3, this section details the
overall context, state machines, and subsystems which may be
assembled to allow the subscription of events from a publisher.
2.1. Event Streams
An event stream is a named entity on a publisher which exposes a
continuously updating set of event records. Each event stream is
available for subscription. It is out of the scope of this document
to identify a) how streams are defined (other than the NETCONF
stream), b) how event records are defined/generated, and c) how event
records are assigned to streams.
There is only one reserved event stream name within this document:
"NETCONF". The "NETCONF" event stream contains all NETCONF XML event
record information supported by the publisher, except for the
subscription state notifications described in Section 2.7. Among
these included NETCONF XML event records are individual YANG 1.1
notifications described in section 7.16 of [RFC7950]. Each of these
YANG 1.1 notifications will be treated as a distinct event record.
Beyond the "NETCONF" stream, implementations MAY define additional
event streams.
As event records are created by a system, they may be assigned to one
or more streams. The event record is distributed to a subscription's
receiver(s) where: (1) a subscription includes the identified stream,
and (2) subscription filtering does not exclude the event record from
that receiver.
Access control permissions may be used to silently exclude event
records from within an event stream for which the receiver has no
read access. As an example of how this might be accomplished, see
[RFC8341] section 3.4.6. Note that per Section 2.7 of this document,
subscription state change notifications are never filtered out.
If no access control permissions are in place for event records on an
event stream, then a receiver MUST be allowed access to all the event
records. If subscriber permissions change during the lifecycle of a
subscription and event stream access is no longer permitted, then the
subscription MUST be terminated.
2.2. Event Stream Filters
This document defines an extensible filtering mechanism. The filter
itself is a boolean test which is placed on the content of an event
record. A 'false' filtering result causes the event message to be
Voit, et al. Expires October 18, 2018 [Page 7]
Internet-Draft Subscribed Notifications April 2018
excluded from delivery to a receiver. A filter never results in
information being stripped from within an event record prior to that
event record being encapsulated within a notification message. The
two optional event stream filtering syntaxes supported are [XPATH]
and subtree [RFC6241].
If no event stream filter is provided within a subscription, all
event records on an event stream are to be sent.
2.3. QoS
This document provide for several QoS parameters. These parameters
indicate the treatment of a subscription relative to other traffic
between publisher and receiver. Included are:
o A "dscp" marking to differentiate prioritization of notification
messages during network transit.
o A "weighting" so that bandwidth proportional to this weighting can
be allocated to this subscription relative to other subscriptions
destined for that receiver.
o a "dependency" upon another subscription.
If the publisher supports the "dscp" feature, then a subscription
with a "dscp" leaf MUST result in a corresponding [RFC2474] DSCP
marking being placed within the IP header of any resulting
notification messages and subscription state change notifications.
For the "weighting" parameter, when concurrently dequeuing
notification messages from multiple subscriptions to a receiver, the
publisher MUST allocate bandwidth to each subscription proportionally
to the weights assigned to those subscriptions. "Weighting" is an is
an optional capability of the publisher; support for it is identified
via the "QoS" feature.
If a subscription has the "dependency" parameter set, then any
buffered notification messages containing event records selected by
the parent subscription MUST be dequeued prior to the notification
messages of the dependent subscription. If notification messages
have dependencies on each other, the notification message queued the
longest MUST go first. If a "dependency" included within an RPC
references a subscription which does not exist or is no longer
accessible to that subscriber, that "dependency" MUST be silently
removed. "Dependency" is an is an optional capability of the
publisher; support for it is identified via the "QoS" feature.
Voit, et al. Expires October 18, 2018 [Page 8]
Internet-Draft Subscribed Notifications April 2018
2.4. Dynamic Subscriptions
Dynamic subscriptions are managed via protocol operations (in the
form of [RFC7950], Section 7.14 RPCs) made against targets located
within the publisher. These RPCs have been designed extensibly so
that they may be augmented for subscription targets beyond event
streams. For examples of such augmentations, see the RPC
augmentations within [I-D.ietf-netconf-yang-push]'s YANG model.
2.4.1. Dynamic Subscription State Model
Below is the publisher's state machine for a dynamic subscription.
Each state is shown in its own box. It is important to note that
such a subscription doesn't exist at the publisher until an
"establish-subscription" RPC is accepted. The mere request by a
subscriber to establish a subscription is insufficient for that
subscription to be externally visible. States that are reflected in
the YANG model appear in upper-case letters; in addition, start and
end states are depicted to reflect subscription creation and deletion
events.
.........
: start :
:.......:
|
establish-subscription
|
| .------modify-subscription-------.
v v |
.-----------. .-----------.
.--------. | receiver |--suspend-subscription->| receiver |
modify- '| ACTIVE | | SUSPENDED |
subscription | |<--resume-subscription--| |
---------->'-----------' '-----------'
| |
delete/kill-subscription delete/kill-
| subscription
v |
......... |
: end :<-------------------------------'
:.......:
Figure 1: Publisher's state for a dynamic subscription
Of interest in this state machine are the following:
o Successful "establish-subscription" or "modify-subscription" RPCs
put the subscription into an active state.
Voit, et al. Expires October 18, 2018 [Page 9]
Internet-Draft Subscribed Notifications April 2018
o Failed "modify-subscription" RPCs will leave the subscription in
its previous state, with no visible change to any streaming
updates.
o A delete or kill RPC will end the subscription, as will the
reaching of a "stop-time".
o A publisher may choose to suspend a subscription, this is notified
to a subscriber with a "subscription-suspended" state change
notification.
o A resume subscription state change is notified to a subscriber
"subscription-resumed". There are no direct external controls
over resuming a subscription other than for a subscriber to
attempt the modification of a subscription in a way which reduces
the resources consumed.
2.4.2. Establishing a Dynamic Subscription
The "establish-subscription" RPC allows a subscriber to request the
creation of a subscription. The transport selected by the subscriber
to reach the publisher MUST be able to support multiple "establish-
subscription" requests made within the same transport session.
The input parameters of the operation are:
o A "stream" name which identifies the targeted event stream against
which the subscription is applied.
o An event stream filter which may reduce the set of event records
pushed.
o Where the transport used by the RPC supports multiple encodings,
an optional "encoding" for the event records pushed. Note: If no
"encoding" is included, the encoding of the RPC MUST be used.
o An optional "stop-time" for the subscription. If no "stop-time"
is present, notification messages will continue to be sent until
the subscription is terminated.
o An optional "start-time" for the subscription. The "start-time"
MUST be in the past and indicates that the subscription is
requesting a replay of previously generated information from the
event stream. For more on replay, see Section 2.4.2.1. Where
there is no "start-time", the subscription starts immediately.
Voit, et al. Expires October 18, 2018 [Page 10]
Internet-Draft Subscribed Notifications April 2018
If the publisher can satisfy the "establish-subscription" request, it
replies with an identifier for the subscription, and then immediately
starts streaming notification messages.
Below is a tree diagram for "establish-subscription". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---x establish-subscription
+---w input
| +---w (target)
| | +--:(stream)
| | +---w (stream-filter)?
| | | +--:(by-reference)
| | | | +---w stream-filter-ref
| | | | stream-filter-ref
| | | +--:(within-subscription)
| | | +---w (filter-spec)?
| | | +--:(stream-subtree-filter)
| | | | +---w stream-subtree-filter? <anydata>
| | | | {subtree}?
| | | +--:(stream-xpath-filter)
| | | +---w stream-xpath-filter?
| | | yang:xpath1.0 {xpath}?
| | +---w stream stream-ref
| | +---w replay-start-time? yang:date-and-time
| | {replay}?
| +---w stop-time? yang:date-and-time
| +---w dscp? inet:dscp {dscp}?
| +---w weighting? uint8 {qos}?
| +---w dependency? subscription-id {qos}?
| +---w encoding? encoding
+--ro output
+--ro identifier subscription-id
+--ro replay-start-time-revision? yang:date-and-time
{replay}?
Figure 2: establish-subscription RPC tree diagram
A publisher MAY reject the "establish-subscription" RPC for many
reasons as described in Section 2.4.6. The contents of the resulting
RPC error response MAY include details on input parameters which if
considered in a subsequent "establish-subscription" RPC, may result
in a successful subscription establishment. Any such hints MUST be
transported within a yang-data "establish-subscription-stream-error-
info" container included within the RPC error response.
Voit, et al. Expires October 18, 2018 [Page 11]
Internet-Draft Subscribed Notifications April 2018
yang-data establish-subscription-stream-error-info
+--ro establish-subscription-stream-error-info
+--ro reason? identityref
+--ro filter-failure-hint? string
Figure 3: establish-subscription RPC yang-data tree diagram
2.4.2.1. Requesting a replay of event records
Replay provides the ability to establish a subscription which is also
capable of passing recently generated event records. In other words,
as the subscription initializes itself, it sends any previously
generated content from within the target event stream which meets the
filter and timeframe criteria. The end of these historical event
records is identified via a "replay-completed" state change
notification. Any event records generated since the subscription
establishment may then follow. All event records will be delivered
in the order they are placed into the stream.
Replay is an optional feature which is dependent on an event stream
supporting some form of logging. This document puts no restrictions
on the size or form of the log, or where it resides within the
publisher.
The inclusion of a "replay-start-time" within an "establish-
subscription" RPC indicates a replay request. If the "replay-start-
time" contains a value that is earlier than what a publisher's
retained history supports, then if the subscription is accepted, the
actual publisher's revised start time MUST be set in the returned
"replay-start-time-revision" object.
A "stop-time" parameter may be included in a replay subscription.
For a replay subscription, the "stop-time" MAY be earlier than the
current time, but MUST be later than the "replay-start-time".
If the time the replay starts is later than the time marked within
any event records retained within the replay buffer, then the
publisher MUST send a "replay-completed" notification immediately
after a successful establish-subscription RPC response.
If an event stream supports replay, the "replay-support" leaf is
present in the "/streams/stream" list entry for the stream. An event
stream that does support replay is not expected to have an unlimited
supply of saved notifications available to accommodate any given
replay request. To assess the timeframe available for replay,
subscribers can read the leafs "replay-log-creation-time" and
"replay-log-aged-time". See Figure 18 for the tree describing these
elements. The actual size of the replay log at any given time is a
Voit, et al. Expires October 18, 2018 [Page 12]
Internet-Draft Subscribed Notifications April 2018
publisher specific matter. Control parameters for the replay log are
outside the scope of this document.
2.4.3. Modifying a Dynamic Subscription
The "modify-subscription" operation permits changing the terms of an
existing dynamic subscription established on that transport session
via "establish-subscription". Dynamic subscriptions can be modified
any number of times. If the publisher accepts the requested
modifications, it acknowledges success to the subscriber, then
immediately starts sending event records based on the new terms.
Subscriptions created by configuration cannot be modified via this
RPC. However configuration may be used to modify objects referenced
by the subscription (such as a referenced filter).
Below is a tree diagram for "modify-subscription". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---x modify-subscription
+---w input
+---w identifier subscription-id
+---w (target)
| +--:(stream)
| +---w (stream-filter)?
| +--:(by-reference)
| | +---w stream-filter-ref
| | stream-filter-ref
| +--:(within-subscription)
| +---w (filter-spec)?
| +--:(stream-subtree-filter)
| | +---w stream-subtree-filter? <anydata>
| | {subtree}?
| +--:(stream-xpath-filter)
| +---w stream-xpath-filter?
| yang:xpath1.0 {xpath}?
+---w stop-time? yang:date-and-time
Figure 4: modify-subscription RPC tree diagram
If the publisher accepts the requested modifications on a currently
suspended subscription, the subscription will immediately be resumed
(i.e., the modified subscription is returned to the ACTIVE state.)
The publisher MAY immediately suspend this newly modified
subscription through the "subscription-suspended" notification before
any event records are sent.
Voit, et al. Expires October 18, 2018 [Page 13]
Internet-Draft Subscribed Notifications April 2018
If the publisher rejects the RPC request, the subscription remains as
prior to the request. That is, the request has no impact whatsoever.
Rejection of the RPC for any reason is indicated by via RPC error as
described in Section 2.4.6. The contents of such a rejected RPC MAY
include hints on inputs which (if considered) may result in a
successfully modified subscription. These hints MUST be transported
within a yang-data "modify-subscription-stream-error-info" container
inserted into the RPC error response.
Below is a tree diagram for "modify-subscription-RPC-yang-data". All
objects contained in this tree are described within the included YANG
model within Section 4.
yang-data modify-subscription-stream-error-info
+--ro modify-subscription-stream-error-info
+--ro reason? identityref
+--ro filter-failure-hint? string
Figure 5: modify-subscription RPC yang-data tree diagram
2.4.4. Deleting a Dynamic Subscription
The "delete-subscription" operation permits canceling an existing
subscription established on that transport session. If the publisher
accepts the request, and the publisher has indicated success, the
publisher MUST NOT send any more notification messages for this
subscription. If the delete request matches a known subscription
established on the same transport session, then it MUST be deleted;
otherwise it MUST be rejected with no changes to the publisher.
Below is a tree diagram for "delete-subscription". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---x delete-subscription
+---w input
+---w identifier subscription-id
Figure 6: delete-subscription RPC tree diagram
Dynamic subscriptions can only be deleted via this RPC using the same
transport session previously used for subscription establishment.
Configured subscriptions cannot be deleted using RPCs.
Voit, et al. Expires October 18, 2018 [Page 14]
Internet-Draft Subscribed Notifications April 2018
2.4.5. Killing a Dynamic Subscription
The "kill-subscription" operation permits an operator to end a
dynamic subscription which is not associated with the transport
session used for the RPC. A publisher MUST terminate any dynamic
subscription identified by RPC request. An operator may find
subscription identifiers which may be used with "kill-subscription"
by searching for the IP address of a receiver within
"subscriptions/subscription/receivers/receiver/address".
Configured subscriptions cannot be killed using this RPC. Instead,
configured subscriptions are deleted as part of regular configuration
operations. Publishers MUST reject any RPC attempt to kill a
configured subscription.
Below is a tree diagram for "kill-subscription". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---x kill-subscription
+---w input
+---w identifier subscription-id
Figure 7: kill-subscription RPC tree diagram
2.4.6. RPC Failures
Whenever an RPC is unsuccessful, the publisher returns relevant
information as part of the RPC error response. Transport level error
processing MUST be done before RPC error processing described in this
section. In all cases, RPC error information returned will use
existing transport layer RPC structures, such as those seen with
NETCONF in [RFC6241] Appendix A, or with RESTCONF in [RFC8040]
Section 7.1. These structures MUST be able to encode subscription
specific errors identified below and defined within this document's
YANG model.
As a result of this mixture, how subscription errors are encoded
within an RPC error response is transport dependent. Following are
valid errors which can occur for each RPC:
Voit, et al. Expires October 18, 2018 [Page 15]
Internet-Draft Subscribed Notifications April 2018
establish-subscription modify-subscription
---------------------- -------------------
dscp-unavailable filter-unsupported
filter-unsupported insufficient-resources
history-unavailable no-such-subscription
insufficient-resources
replay-unsupported
delete-subscription kill-subscription
---------------------- ----------------------
no-such-subscription no-such-subscription
To see a NETCONF based example of an error response from above, see
[I-D.draft-ietf-netconf-netconf-event-notifications], Figure 10.
There is one final set of transport independent RPC error elements
included in the YANG model. These are the following three yang-data
structures for failed event stream subscriptions:
1. "establish-subscription-stream-error-info": This MUST be returned
if an RPC error reason has not been placed elsewhere within the
transport portion of a failed "establish-subscription" RPC
response. This MUST be sent if hints on how to overcome the RPC
error are included.
2. "modify-subscription-stream-error-info": This MUST be returned if
an RPC error reason has not been placed elsewhere within the
transport portion of a failed "modify-subscription" RPC response.
This MUST be sent if hints on how to overcome the RPC error are
included.
3. "delete-subscription-error-info": This MUST be returned if an RPC
error reason has not been placed elsewhere within the transport
portion of a failed "delete-subscription" or "kill-subscription"
RPC response.
2.5. Configured Subscriptions
A configured subscription is a subscription installed via
configuration. Configured subscriptions may be modified by any
configuration client with the proper permissions. Subscriptions can
be modified or terminated via configuration at any point of their
lifetime.
Configured subscriptions have several characteristics distinguishing
them from dynamic subscriptions:
o persistence across publisher reboots,
Voit, et al. Expires October 18, 2018 [Page 16]
Internet-Draft Subscribed Notifications April 2018
o persistence even when transport is unavailable, and
o an ability to send notification messages to more than one receiver
(note that receivers are unaware of the existence of any other
receivers.)
Supporting configured subscriptions is optional and advertised using
the "configured" feature.
In addition to the subscription parameters available to dynamic
subscriptions described in Section 2.4.2, the following additional
parameters are also available to configured subscriptions:
o A "transport" which identifies the transport protocol to use to
connect with all subscription receivers.
o One or more receivers, each with an "address", where each address
is intended as the destination for event records.
o Optional parameters to identify where traffic should egress a
publisher:
* A "source-interface" which identifies the egress interface to
use from the publisher. Publisher support for this is optional
and advertised using the "interface-designation" feature.
* A "source-address" address, which identifies the IP address to
stamp on notification messages destined for the receiver.
* A "source-vrf" which identifies the VRF on which to reach
receivers. This VRF is a network instance as defined within
[I-D.draft-ietf-rtgwg-ni-model]. Publisher support for VRFs is
optional and advertised using the "supports-vrf" feature.
If none of the above parameters are set, notification messages
MUST egress the publisher's default interface.
A tree diagram describing these parameters is shown in Figure 20.
All parameters are described within the YANG model in Section 4.
2.5.1. Configured Subscription State Model
Below is the state machine for a configured subscription on the
publisher. This state machine describes the three states (VALID,
INVALID, and CONCLUDED), as well as the transitions between these
states. Start and end states are depicted to reflect configured
subscription creation and deletion events. The creation or
modification of a configured subscription initiates an evaluation by
Voit, et al. Expires October 18, 2018 [Page 17]
Internet-Draft Subscribed Notifications April 2018
the publisher to determine if the subscription is in VALID or INVALID
states. The publisher uses its own criteria in making this
determination. If in the VALID state, the subscription becomes
operational. See (1) in the diagram below.
.........
: start :-.
:.......: |
create .---modify-----.----------------------------------.
| | | |
V V .-------. ....... .---------.
.----[evaluate]--no--->|INVALID|-delete->: end :<-delete-|CONCLUDED|
| '-------' :.....: '---------'
|-[evaluate]--no-(2). ^ ^ ^
| ^ | | | |
yes | '->unsupportable delete stop-time
| modify (subscription- (subscription- (subscription-
| | terminated*) terminated*) concluded*)
| | | | |
(1) | (3) (4) (5)
| .---------------------------------------------------------------.
'-->| VALID |
'---------------------------------------------------------------'
Legend:
dotted boxes: subscription added or removed via configuration
dashed boxes with uppercase letters: states for a subscription
[evaluate]: decision point on whether the subscription is supportable
(*): resulting subscription state change notification
Figure 8: Publisher state model for a configured subscription
A subscription in the VALID state may move to the INVALID state in
one of two ways. First, it may be modified in a way which fails a
re-evaluation. See (2) in the diagram. Second, the publisher might
determine that the subscription is no longer supportable. This could
be for reasons of an unexpected but sustained increase in an event
stream's event records, degraded CPU capacity, a more complex
referenced filter, or other higher priority subscriptions which have
usurped resources. See (3) in the diagram. No matter the case, a
"subscription-terminated" notification is sent to any receivers in an
ACTIVE or SUSPENDED state. A subscription in the VALID state may
also transition to the CONCLUDED state via (5) if a configured stop
time has been reached. In this case, a "subscription-concluded"
notification is sent to any receivers in ACTIVE or SUSPENDED states.
Finally, a subscription may be deleted by configuration (4).
Voit, et al. Expires October 18, 2018 [Page 18]
Internet-Draft Subscribed Notifications April 2018
When a subscription is in the VALID state, a publisher will attempt
to connect with all configured receivers and deliver notification
messages. Below is the state machine for each receiver of a
configured subscription. This receiver state machine is fully
contained within the state machine of the configured subscription,
and is only relevant when the configured subscription is in the VALID
state.
.-----------------------------------------------------------------.
| VALID |
| .----------. .--------. |
| | receiver |------------------timeout->|receiver| |
| |CONNECTING|<----------------reset--(4)|TIMEOUT | |
| | |<-transport---. '--------' |
| '----------' loss,reset | |
| (1) | | |
| subscription- (3) | |
| started* .--------. | .---------. |
| '----->| | '--------------------(3)| | |
| |receiver|(2)-subscription-suspended*->|receiver | |
| subscription-| ACTIVE | |SUSPENDED| |
| modified* | |<--subscription-resumed*,----| | |
| '---->'--------' subscription-modified* '---------' |
'-----------------------------------------------------------------'
Legend:
dashed boxes which include the word 'receiver' show the possible
states for an individual receiver of a VALID configured subscription.
* indicates a state change notification
Figure 9: Receiver state for a configured subscription on a Publisher
When a configured subscription first moves to the VALID state, the
"state" leaf of each receiver is initialized to "CONNECTING". If
transport connectivity is not available to any receiver, a transport
session is established (e.g., through [RFC8071]). Individual
receivers are moved to the ACTIVE state when a "subscription-started"
state change notification is successfully passed to that receiver
(1). Event records are only sent to ACTIVE receivers. Configured
receivers remain ACTIVE if both transport connectivity can be
verified to the receiver, and event records are not being dropped due
to a publisher buffer overflow. The result is that a receiver will
remain ACTIVE on the publisher as long as events aren't being lost,
or the receiver cannot be reached. However if there is buffer
overflow, or the publisher cannot generate notification messages for
a receiver, the receiver MUST be moved to SUSPENDED (2). In
addition, a configured subscription's receiver MUST be moved to
CONNECTING if transport connectivity cannot be achieved, or if the
Voit, et al. Expires October 18, 2018 [Page 19]
Internet-Draft Subscribed Notifications April 2018
receiver is reset via the "reset" action (3), (4). For more on
reset, see Section 2.5.5.
A configured subscription's receiver MUST be moved to the SUSPENDED
state if there is transport connectivity between the publisher and
receiver, but notification messages are not able to be generated for
that receiver. A configured subscription receiver MUST be returned
to the ACTIVE state from the SUSPENDED state when notification
messages are again being generated and a receiver has successfully
been sent a "subscription-resumed" or "subscription-modified"
notification.
Modification of a configured subscription is possible at any time. A
"subscription-modified" state change notification will be sent to all
active receivers, immediately followed by notification messages
conforming to the new parameters. Suspended receivers will also be
informed of the modification. However this notification will await
the end of the suspension for that receiver.
The mechanisms described above are mirrored in the RPCs and
notifications within the document. It should be noted that these
RPCs and notifications have been designed to be extensible and allow
subscriptions into targets other than event streams. For instance,
the YANG module defined in Section 5 of [I-D.ietf-netconf-yang-push]
augments "/sn:modify-subscription/sn:input/sn:target".
2.5.2. Creating a Configured Subscription
Configured subscriptions are established using configuration
operations against the top-level "subscriptions" subtree.
Because there is no explicit association with an existing transport
session, configuration operations require additional parameters
beyond those of dynamic subscriptions to indicate receivers, and
possibly whether the notification messages need to come from a
specific egress interface on the publisher.
After a subscription is successfully established, the publisher
immediately sends a "subscription-started" state change notification
to each receiver. It is quite possible that upon configuration,
reboot, or even steady-state operations, a transport session may not
be currently available to the receiver. In this case, when there is
something to transport for an active subscription, transport specific
call-home operations will be used to establish the connection. When
transport connectivity is available, notification messages may then
be pushed.
Voit, et al. Expires October 18, 2018 [Page 20]
Internet-Draft Subscribed Notifications April 2018
With active configured subscriptions, it is allowable to buffer event
records even after a "subscription-started" has been sent. However
if events are lost (rather than just delayed) due to replay buffer
overflow, a new "subscription-started" must be sent. This new
"subscription-started" indicates an event record discontinuity.
To see an example of subscription creation using configuration
operations over NETCONF, see Appendix A of
[I-D.draft-ietf-netconf-netconf-event-notifications].
Note that is possible to configure replay on a configured
subscription. This capability is to allow a configured subscription
to exist on a system so that event records generated during boot can
be buffered and pushed as soon as the transport session is
established.
2.5.3. Modifying a Configured Subscription
Configured subscriptions can be modified using configuration
operations against the top-level "subscriptions" subtree.
If the modification involves adding receivers, added receivers are
placed in the CONNECTING state. If a receiver is removed, the state
change notification "subscription-terminated" is sent to that
receiver if that receiver is ACTIVE or SUSPENDED.
If the modification involves changing the policies for the
subscription, the publisher sends to currently active receivers a
"subscription-modified" notification. For any suspended receivers, a
"subscription-modified" notification will be delayed until the
receiver is resumed. (Note: in this case, the "subscription-
modified" notification informs the receiver that the subscription has
been resumed, so no additional "subscription-resumed" need be sent.
Also note that if multiple modifications have occurred during the
suspension, only the latest one need be sent to the receiver.)
2.5.4. Deleting a Configured Subscription
Subscriptions can be deleted through configuration against the top-
level "subscriptions" subtree.
Immediately after a subscription is successfully deleted, the
publisher sends to all receivers of that subscription a state change
notification stating the subscription has ended (i.e., "subscription-
terminated").
Voit, et al. Expires October 18, 2018 [Page 21]
Internet-Draft Subscribed Notifications April 2018
2.5.5. Resetting a Configured Receiver
It is possible that a configured subscription to a receiver needs to
be reset. This is accomplished via the "reset" action within the
YANG model at "/subscriptions/subscription/receivers/receiver/reset".
This re-initialization may be useful in cases where a publisher has
timed out trying to reach a receiver. When such a reset occurs, a
transport session will be initiated if necessary, and a new
"subscription-started" notification will be sent. This action does
not have any effect on transport connectivity if the needed
connectivity already exists.
2.5.6. Replay for a Configured Subscription
It is possible to place a start time on a configured subscription.
This enables streaming of logged information immediately after
restart.
When any such configured subscription receivers become ACTIVE,
buffered event records (if any) will be sent immediately after the
"subscription-started" notification. The leading event record sent
will be the first event record subsequent to the latest of four
different times: the "replay-log-creation-time", "replay-log-aged-
time", "replay-start-time", or the most recent publisher boot time.
All other replay functionality remains the same as with dynamic
subscriptions as described in Section 2.4.2.1.
2.6. Event Record Delivery
Whether dynamic or configured, once a subscription has been set up,
the publisher streams event records via notification messages per the
terms of the subscription. For dynamic subscriptions, notification
messages are sent over the session used to establish the
subscription. For configured subscriptions, notification messages
are sent over the connections specified by the transport and each
configured receiver. In all cases, a single transport session MUST
be capable of supporting the intermixing of RPCs and notifications
from different subscriptions.
A notification message is sent to a receiver when an event record is
not blocked by either the specified filter criteria or receiver
permissions. This notification message MUST be encoded in a
<notification> message as defined within [RFC5277], Section 4. And
per [RFC5277]'s "eventTime" object definition, the "eventTime" is
populated with the event occurrence time.
Voit, et al. Expires October 18, 2018 [Page 22]
Internet-Draft Subscribed Notifications April 2018
The following example within [RFC7950] section 7.16.3 is an example
of a compliant message:
<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0">
<eventTime>2007-09-01T10:00:00Z</eventTime>
<link-failure xmlns="http://acme.example.com/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>
Figure 10: subscribed notification message
When a dynamic subscription has been started or modified, with
"establish-subscription" or "modify-subscription" respectively, event
records matching the newly applied filter criteria MUST NOT be sent
until after the RPC reply has been sent.
When a configured subscription has been started or modified, event
records matching the newly applied filter criteria MUST NOT be sent
until after the "subscription-started" or "subscription-modified"
notifications has been sent, respectively.
2.7. Subscription State Notifications
In addition to sending event records to receivers, a publisher MUST
also send subscription state notifications when events related to
subscription management have occurred.
Subscription state notifications are unlike other notifications in
that they are never included in any stream. Instead, they are
inserted (as defined in this section) within the sequence of
notification messages sent to a particular receiver. Subscription
state notifications cannot be filtered out, they cannot be stored in
replay buffers, and they are delivered only to impacted receivers of
a subscription. The identification of subscription state
notifications is easy to separate from other notification messages
through the use of the YANG extension "subscription-state-notif".
This extension tags a notification as a subscription state
notification.
The complete set of subscription state notifications is described in
the following subsections.
Voit, et al. Expires October 18, 2018 [Page 23]
Internet-Draft Subscribed Notifications April 2018
2.7.1. subscription-started
This notification indicates that a configured subscription has
started, and event records may be sent. Included in this state
change notification are all the parameters of the subscription,
except for the receiver(s) addressing information and origin
information indicating where notification messages will egress the
publisher. Note that if a referenced filter from the "filters"
container has been used within the subscription, the notification
still provides the contents of that referenced filter under the
"within-subscription" subtree.
Note that for dynamic subscriptions, no "subscription-started"
notifications are ever sent.
Below is a tree diagram for "subscription-started". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---n subscription-started {configured}?
+--ro identifier subscription-id
+--ro (target)
| +--:(stream)
| +--ro (stream-filter)?
| | +--:(by-reference)
| | | +--ro stream-filter-ref stream-filter-ref
| | +--:(within-subscription)
| | +--ro (filter-spec)?
| | +--:(stream-subtree-filter)
| | | +--ro stream-subtree-filter? <anydata>
| | | {subtree}?
| | +--:(stream-xpath-filter)
| | +--ro stream-xpath-filter? yang:xpath1.0
| | {xpath}?
| +--ro stream stream-ref
| +--ro replay-start-time? yang:date-and-time
| {replay}?
+--ro stop-time? yang:date-and-time
+--ro dscp? inet:dscp {dscp}?
+--ro weighting? uint8 {qos}?
+--ro dependency? subscription-id {qos}?
+--ro transport transport {configured}?
+--ro encoding? encoding
+--ro purpose? string {configured}?
Figure 11: subscription-started notification tree diagram
Voit, et al. Expires October 18, 2018 [Page 24]
Internet-Draft Subscribed Notifications April 2018
2.7.2. subscription-modified
This notification indicates that a subscription has been modified by
configuration operations. It is delivered directly after the last
event records processed using the previous subscription parameters,
and before any event records processed after the modification.
Below is a tree diagram for "subscription-modified". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---n subscription-modified
+--ro identifier subscription-id
+--ro (target)
| +--:(stream)
| +--ro (stream-filter)?
| | +--:(by-reference)
| | | +--ro stream-filter-ref stream-filter-ref
| | +--:(within-subscription)
| | +--ro (filter-spec)?
| | +--:(stream-subtree-filter)
| | | +--ro stream-subtree-filter? <anydata>
| | | {subtree}?
| | +--:(stream-xpath-filter)
| | +--ro stream-xpath-filter? yang:xpath1.0
| | {xpath}?
| +--ro stream stream-ref
| +--ro replay-start-time? yang:date-and-time
| {replay}?
+--ro stop-time? yang:date-and-time
+--ro dscp? inet:dscp {dscp}?
+--ro weighting? uint8 {qos}?
+--ro dependency? subscription-id {qos}?
+--ro transport transport {configured}?
+--ro encoding? encoding
+--ro purpose? string {configured}?
Figure 12: subscription-modified notification tree diagram
A publisher most often sends this notification directly after the
modification of any configuration parameters impacting a configured
subscription. But it may also be sent at two other times:
1. Where a configured subscription has been modified during the
suspension of a receiver, the notification will be delayed until
the receiver's suspension is lifted. In this situation, the
notification indicates that the subscription has been both
modified and resumed.
Voit, et al. Expires October 18, 2018 [Page 25]
Internet-Draft Subscribed Notifications April 2018
2. While this state change will most commonly be used with
configured subscriptions, with dynamic subscriptions, there is
also one time this notification will be sent. A "subscription-
modified" state change notification MUST be sent if the contents
of the filter identified by the subscription's "stream-filter-
ref" leaf has changed.
2.7.3. subscription-terminated
This notification indicates that no further event records for this
subscription should be expected from the publisher. A publisher may
terminate the sending event records to a receiver for the following
reasons:
1. Configuration which removes a configured subscription, or a
"kill-subscription" RPC which ends a dynamic subscription. These
are identified via the reason "no-such-subscription".
2. A referenced filter is no longer accessible. This is identified
by "filter-unavailable".
3. The event stream referenced by a subscription is no longer
accessible by the receiver. This is identified by "stream-
unavailable".
4. A suspended subscription has exceeded some timeout. This is
identified by "suspension-timeout".
Each of the reasons above correspond one-to-one with a "reason"
identityref specified within the YANG model.
Below is a tree diagram for "subscription-terminated". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---n subscription-terminated
+--ro identifier subscription-id
+--ro reason identityref
Figure 13: subscription-terminated notification tree diagram
Note: this state change notification MUST be sent to a dynamic
subscription's receiver when the subscription ends unexpectedly. The
cases when this might happen are when a "kill-subscription" RPC is
successful, or when some other event not including the reaching the
subscription's "stop-time" results in a publisher choosing to end the
subscription.
Voit, et al. Expires October 18, 2018 [Page 26]
Internet-Draft Subscribed Notifications April 2018
2.7.4. subscription-suspended
This notification indicates that a publisher has suspended the
sending of event records to a receiver, and also indicates the
possible loss of events. Suspension happens when capacity
constraints stop a publisher from serving a valid subscription. The
two conditions where is this possible are:
1. "insufficient-resources" when a publisher is unable to produce
the requested event stream of notification messages, and
2. "unsupportable-volume" when the bandwidth needed to get generated
notification messages to a receiver exceeds a threshold.
These conditions are encoded within the "reason" object. No further
notification will be sent until the subscription resumes or is
terminated.
Below is a tree diagram for "subscription-suspended". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---n subscription-suspended
+--ro identifier subscription-id
+--ro reason identityref
Figure 14: subscription-suspended notification tree diagram
2.7.5. subscription-resumed
This notification indicates that a previously suspended subscription
has been resumed under the unmodified terms previously in place.
Subscribed event records generated after the issuance of this state
change notification may now be sent.
Below is the tree diagram for "subscription-resumed". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---n subscription-resumed
+--ro identifier subscription-id
Figure 15: subscription-resumed notification tree diagram
Voit, et al. Expires October 18, 2018 [Page 27]
Internet-Draft Subscribed Notifications April 2018
2.7.6. subscription-completed
This notification indicates that a configured subscription, which
includes a "stop-time", has successfully finished passing event
records upon the reaching of that time.
Below is a tree diagram for "subscription-completed". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---n subscription-completed
+--ro identifier subscription-id
Figure 16: subscription-completed notification tree diagram
2.7.7. replay-completed
This notification indicates that all of the event records prior to
the current time have been passed to a receiver. It is sent before
any notification message containing an event record with a timestamp
later than (1) the "stop-time" or (2) the subscription's start time.
If a subscription contains no "stop-time", or has a "stop-time" that
has not been reached, then after the "replay-completed" notification
has been sent, additional event records will be sent in sequence as
they arise naturally on the publisher.
Below is a tree diagram for "replay-completed". All objects
contained in this tree are described within the included YANG model
within Section 4.
+---n replay-completed
+--ro identifier subscription-id
Figure 17: replay-completed notification tree diagram
2.8. Subscription Monitoring
In the operational datastore, the container "subscriptions" maintains
the state of all dynamic subscriptions, as well as all configured
subscriptions. Using datastore retrieval operations, or subscribing
to the "subscriptions" container [I-D.ietf-netconf-yang-push] allows
the state of subscriptions and their connectivity to receivers to be
monitored.
Each subscription in the operational datastore is represented as a
list element. Included in this list are event counters for each
receiver, the state of each receiver, as well as the subscription
Voit, et al. Expires October 18, 2018 [Page 28]
Internet-Draft Subscribed Notifications April 2018
parameters currently in effect. The appearance of the leaf
"configured-subscription-state" indicates that a particular
subscription came into being via configuration. This leaf also
indicates if current state of that subscription is VALID, INVALID,
and CONCLUDED.
To understand the flow of event records within a subscription, there
are two counters available for each configured and dynamic receiver.
The first counter is "pushed-notifications" which shows the quantity
of events actually identified for sending to a receiver. The second
counter is "excluded-notifications" which shows event records not
sent to receiver. "excluded-notifications" shows the combined
results of both access control and per-subscription filtering. For
configured subscriptions, counters are reset whenever the
subscription is evaluated to VALID (see (1) in Figure 8).
Dynamic subscriptions are removed from the operational datastore once
they expire (reaching stop-time) or when they are terminated. While
many subscription objects are shown as configurable, dynamic
subscriptions are only included within the operational datastore and
as a result are not configurable.
2.9. Advertisement
Publishers supporting this document MUST indicate support of the YANG
model "ietf-subscribed-notifications" within the YANG library of the
publisher. In addition support for optional features "encode-xml",
"encode-json", "configured" "supports-vrf", "qos", "xpath",
"subtree", "interface-designation", "dscp", and "replay" MUST be
indicated if supported.
3. YANG Data Model Trees
This section contains tree diagrams for nodes defined in Section 4.
For tree diagrams of state change notifications, see Section 2.7. Or
for the tree diagrams for the RPCs, see Section 2.4.
3.1. Event Streams Container
A publisher maintains a list of available event streams as
operational data. This list contains both standardized and vendor-
specific event streams. This enables subscribers to discover what
streams a publisher supports.
Voit, et al. Expires October 18, 2018 [Page 29]
Internet-Draft Subscribed Notifications April 2018
+--ro streams
+--ro stream* [name]
+--ro name string
+--ro description string
+--ro replay-support? empty {replay}?
+--ro replay-log-creation-time yang:date-and-time {replay}?
+--ro replay-log-aged-time? yang:date-and-time {replay}?
Figure 18: Stream Container tree diagram
Above is a tree diagram for the streams container. All objects
contained in this tree are described within the included YANG model
within Section 4.
3.2. Filters Container
The "filters" container maintains a list of all subscription filters
that persist outside the life-cycle of a single subscription. This
enables pre-defined filters which may be referenced by more than one
subscription.
+--rw filters
+--rw stream-filter* [identifier]
+--rw identifier filter-id
+--rw (filter-spec)?
+--:(stream-subtree-filter)
| +--rw stream-subtree-filter? <anydata> {subtree}?
+--:(stream-xpath-filter)
+--rw stream-xpath-filter? yang:xpath1.0 {xpath}?
Figure 19: Filter Container tree diagram
Above is a tree diagram for the filters container. All objects
contained in this tree are described within the included YANG model
within Section 4.
3.3. Subscriptions Container
The "subscriptions" container maintains a list of all subscriptions
on a publisher, both configured and dynamic. It can be used to
retrieve information about the subscriptions which a publisher is
serving.
+--rw subscriptions
+--rw subscription* [identifier]
+--rw identifier subscription-id
+--rw (target)
| +--:(stream)
Voit, et al. Expires October 18, 2018 [Page 30]
Internet-Draft Subscribed Notifications April 2018
| +--rw (stream-filter)?
| | +--:(by-reference)
| | | +--rw stream-filter-ref
| | | stream-filter-ref
| | +--:(within-subscription)
| | +--rw (filter-spec)?
| | +--:(stream-subtree-filter)
| | | +--rw stream-subtree-filter?
| | | <anydata> {subtree}?
| | +--:(stream-xpath-filter)
| | +--rw stream-xpath-filter?
| | yang:xpath1.0 {xpath}?
| +--rw stream stream-ref
| +--rw replay-start-time?
| yang:date-and-time {replay}?
+--rw stop-time? yang:date-and-time
+--rw dscp? inet:dscp {dscp}?
+--rw weighting? uint8 {qos}?
+--rw dependency? subscription-id
| {qos}?
+--rw transport transport
| {configured}?
+--rw encoding? encoding
+--rw purpose? string {configured}?
+--rw (notification-message-origin)? {configured}?
| +--:(interface-originated)
| | +--rw source-interface?
| | if:interface-ref {interface-designation}?
| +--:(address-originated)
| +--rw source-vrf?
| | -> /ni:network-instances/network-instance/name
| | {supports-vrf}?
| +--rw source-address?
| inet:ip-address-no-zone
+--ro configured-subscription-state? enumeration
| {configured}?
+--rw receivers
+--rw receiver* [name]
+--rw name string
+--rw address? inet:host
+--ro pushed-notifications? yang:counter64
+--ro excluded-notifications? yang:counter64
+--ro state enumeration
+---x reset {configured}?
+--ro output
+--ro time yang:date-and-time
Figure 20: Subscriptions tree diagram
Voit, et al. Expires October 18, 2018 [Page 31]
Internet-Draft Subscribed Notifications April 2018
Above is a tree diagram for the subscriptions container. All objects
contained in this tree are described within the included YANG model
within Section 4.
4. Data Model
<CODE BEGINS> file "ietf-subscribed-notifications@2018-04-12.yang"
module ietf-subscribed-notifications {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications";
prefix sn;
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types";
}
import ietf-interfaces {
prefix if;
reference
"RFC 7223: A YANG Data Model for Interface Management";
}
import ietf-network-instance {
prefix ni;
reference
"draft-ietf-rtgwg-ni-model-11: YANG Model for Network Instances";
}
import ietf-restconf {
prefix rc;
reference
"RFC 8040 - RESTCONF Protocol";
}
import ietf-yang-types {
prefix yang;
reference
"RFC 6991: Common YANG Data Types";
}
organization "IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http:/tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Author: Alexander Clemm
<mailto:ludwig@clemm.org>
Voit, et al. Expires October 18, 2018 [Page 32]
Internet-Draft Subscribed Notifications April 2018
Author: Eric Voit
<mailto:evoit@cisco.com>
Author: Alberto Gonzalez Prieto
<mailto:agonzalezpri@vmware.com>
Author: Einar Nilsen-Nygaard
<mailto:einarnn@cisco.com>
Author: Ambika Prasad Tripathy
<mailto:ambtripa@cisco.com>";
description
"Contains a YANG specification for subscribing to event records
and receiving matching content within notification messages.";
revision 2018-04-12 {
description
"Initial version";
reference
"RFC XXXX: Customized Subscriptions to a Publisher's Event Streams";
}
/*
* FEATURES
*/
feature configured {
description
"This feature indicates that configuration of subscription is
supported.";
}
feature dscp {
description
"This feature indicates a publisher supports the placement of
suggested prioritization levels for network transport within
notification messages.";
}
feature encode-json {
description
"This feature indicates that JSON encoding of notification
messages is supported.";
}
feature encode-xml {
description
Voit, et al. Expires October 18, 2018 [Page 33]
Internet-Draft Subscribed Notifications April 2018
"This feature indicates that XML encoding of notification
messages is supported.";
}
feature interface-designation {
description
"This feature indicates a publisher supports sourcing all receiver
interactions for a configured subscription from a single
designated egress interface.";
}
feature qos {
description
"This feature indicates a publisher supports absolute dependencies
of one subscription's traffic over another, as well as weighted
bandwidth sharing between subscriptions. Both of these are
Quality of Service (QoS) features which allow differentiated
treatment of notification messages between a publisher and a
specific receiver.";
}
feature replay {
description
"This feature indicates that historical event record replay is
supported. With replay, it is possible for past event records to
be streamed in chronological order.";
}
feature subtree {
description
"This feature indicates support for YANG subtree filtering.";
reference "RFC 6241, Section 6.";
}
feature supports-vrf {
description
"This feature indicates a publisher supports VRF configuration
for configured subscriptions. VRF support for dynamic
subscriptions does not require this feature.";
reference "draft-ietf-rtgwg-ni-model";
}
feature xpath {
description
"This feature indicates support for xpath filtering.";
reference "http://www.w3.org/TR/1999/REC-xpath-19991116";
}
Voit, et al. Expires October 18, 2018 [Page 34]
Internet-Draft Subscribed Notifications April 2018
/*
* EXTENSIONS
*/
extension subscription-state-notification {
description
"This statement applies only to notifications. It indicates that
the notification is a subscription state notification. Therefore
it does not participate in a regular event stream and does not
need to be specifically subscribed to in order to be received.
This statement can only occur as a substatement to the YANG
'notification' statement.";
}
/*
* IDENTITIES
*/
/* Identities for RPC and Notification errors */
identity delete-subscription-error {
description
"Problem found while attempting to fulfill either a
'delete-subscription' RPC request or a 'kill-subscription'
RPC request.";
}
identity establish-subscription-error {
description
"Problem found while attempting to fulfill an
'establish-subscription' RPC request.";
}
identity modify-subscription-error {
description
"Problem found while attempting to fulfill a
'modify-subscription' RPC request.";
}
identity subscription-suspended-reason {
description
"Problem condition communicated to a receiver as part of a
'subscription-terminated' notification.";
}
identity subscription-terminated-reason {
description
"Problem condition communicated to a receiver as part of a
Voit, et al. Expires October 18, 2018 [Page 35]
Internet-Draft Subscribed Notifications April 2018
'subscription-terminated' notification.";
}
identity dscp-unavailable {
base establish-subscription-error;
if-feature "dscp";
description
"The publisher is unable mark notification messages with a
prioritization information in a way which will be respected during
network transit.";
}
identity filter-unavailable {
base subscription-terminated-reason;
description
"Referenced filter does not exist. This means a receiver is
referencing a filter which doesn't exist, or to which they do not
have access permissions.";
}
identity filter-unsupported {
base establish-subscription-error;
base modify-subscription-error;
description
"Cannot parse syntax within the filter. This failure can be from
a syntax error, or a syntax too complex to be processed by the
publisher.";
}
identity history-unavailable {
base establish-subscription-error;
if-feature "replay";
description
"Replay request too far into the past. This means the publisher
does store historic information for the requested stream, but
not back to the requested timestamp.";
}
identity insufficient-resources {
base establish-subscription-error;
base modify-subscription-error;
base subscription-suspended-reason;
description
"The publisher has insufficient resources to support the
requested subscription. An example might be that allocated CPU
is too limited to generate the desired set of notification
messages.";
}
Voit, et al. Expires October 18, 2018 [Page 36]
Internet-Draft Subscribed Notifications April 2018
identity no-such-subscription {
base modify-subscription-error;
base delete-subscription-error;
base subscription-terminated-reason;
description
"Referenced subscription doesn't exist. This may be as a result of
a non-existent subscription ID, an ID which belongs to another
subscriber, or an ID for configured subscription.";
}
identity replay-unsupported {
base establish-subscription-error;
if-feature "replay";
description
"Replay cannot be performed for this subscription. This means the
publisher will not provide the requested historic information from
the event stream via replay to this receiver.";
}
identity stream-unavailable {
base subscription-terminated-reason;
description
"Not a subscribable stream. This means the referenced event stream
is not available for subscription by the receiver.";
}
identity suspension-timeout {
base subscription-terminated-reason;
description
"Termination of previously suspended subscription. The publisher
has eliminated the subscription as it exceeded a time limit for
suspension.";
}
identity unsupportable-volume {
base subscription-suspended-reason;
description
"The publisher does not have the network bandwidth needed to get
the volume of generated information intended for a receiver.";
}
/* Identities for encodings */
identity configurable-encoding {
description
"If a transport identity derives from this identity, it means
that it supports configurable encodings.";
}
Voit, et al. Expires October 18, 2018 [Page 37]
Internet-Draft Subscribed Notifications April 2018
identity encoding {
description
"Base identity to represent data encodings";
}
identity encode-xml {
base encoding;
if-feature "encode-xml";
description
"Encode data using XML as described in RFC 7950";
reference
"RFC 7950 - The YANG 1.1 Data Modeling Language";
}
identity encode-json {
base encoding;
if-feature "encode-json";
description
"Encode data using JSON as described in RFC 7951";
reference
"RFC 7951 - JSON Encoding of Data Modeled with YANG";
}
/* Identities for transports */
identity transport {
description
"An identity that represents the underlying mechanism for
passing notification messages.";
}
identity inline-address {
description
"A transport identity can derive from this identity in order to
allow inline definition of the host address in the
'receiver' list";
}
/*
* TYPEDEFs
*/
typedef encoding {
type identityref {
base encoding;
}
description
"Specifies a data encoding, e.g. for a data subscription.";
}
Voit, et al. Expires October 18, 2018 [Page 38]
Internet-Draft Subscribed Notifications April 2018
typedef filter-id {
type string;
description
"A type to identify filters which can be associated with a
subscription.";
}
typedef stream-filter-ref {
type leafref {
path "/sn:filters/sn:stream-filter/sn:identifier";
}
description
"This type is used to reference an event stream filter.";
}
typedef stream-ref {
type leafref {
path "/sn:streams/sn:stream/sn:name";
}
description
"This type is used to reference a system-provided stream.";
}
typedef subscription-id {
type uint32;
description
"A type for subscription identifiers.";
}
typedef transport {
type identityref {
base transport;
}
description
"Specifies transport used to send notification messages to a
receiver.";
}
/*
* GROUPINGS
*/
grouping stream-filter-elements {
description
"This grouping defines the base for filters applied to event
streams.";
choice filter-spec {
description
Voit, et al. Expires October 18, 2018 [Page 39]
Internet-Draft Subscribed Notifications April 2018
"The content filter specification for this request.";
anydata stream-subtree-filter {
if-feature "subtree";
description
"Event stream evaluation criteria encoded in the syntax of a
subtree filter as defined in RFC 6241, Section 6.
The subtree filter is applied to the representation of
individual, delineated event records as contained within the
event stream. For example, if the notification message
contains an instance of a notification defined in YANG, then
the top-level element is the name of the YANG notification.
If the subtree filter returns a non-empty node set, the filter
matches the event record, and the event record is included in
the notification message sent to the receivers.";
reference "RFC 6241, Section 6.";
}
leaf stream-xpath-filter {
if-feature "xpath";
type yang:xpath1.0;
description
"Event stream evaluation criteria encoded in the syntax of
an XPath 1.0 expression.
The XPath expression is evaluated on the representation of
individual, delineated event records as contained within
the event stream. For example, if the notification message
contains an instance of a notification defined in YANG,
then the top-level element is the name of the YANG
notification, and the root node has this top-level element
as the only child.
The result of the XPath expression is converted to a
boolean value using the standard XPath 1.0 rules. If the
boolean value is 'true', the filter matches the event record,
and the event record is included in the notification message
sent to the receivers.
The expression is evaluated in the following XPath context:
o The set of namespace declarations are those in scope on
the 'stream-xpath-filter' leaf element.
o The set of variable bindings is empty.
o The function library is the core function library, and
the XPath functions defined in section 10 in RFC 7950.
Voit, et al. Expires October 18, 2018 [Page 40]
Internet-Draft Subscribed Notifications April 2018
o The context node is the root node.";
reference
"http://www.w3.org/TR/1999/REC-xpath-19991116
RFC 7950, Section 10.";
}
}
}
grouping update-qos {
description
"This grouping describes Quality of Service information
concerning a subscription. This information is passed to lower
layers for transport prioritization and treatment";
leaf dscp {
if-feature "dscp";
type inet:dscp;
default "0";
description
"The desired network transport priority level. This is the
priority set on notification messages encapsulating the results
of the subscription. This transport priority is shared for all
receivers of a given subscription.";
}
leaf weighting {
if-feature "qos";
type uint8 {
range "0 .. 255";
}
description
"Relative weighting for a subscription. Allows an underlying
transport layer perform informed load balance allocations
between various subscriptions";
reference
"RFC-7540, section 5.3.2";
}
leaf dependency {
if-feature "qos";
type subscription-id;
description
"Provides the 'subscription-id' of a parent subscription which
has absolute precedence should that parent have push updates
ready to egress the publisher. In other words, there should be
no streaming of objects from the current subscription if
the parent has something ready to push.
If a dependency is asserted via configuration or via RPC, but
the referenced 'subscription-id' does not exist, the dependency
Voit, et al. Expires October 18, 2018 [Page 41]
Internet-Draft Subscribed Notifications April 2018
is silently discarded. If a referenced subscription is deleted
this dependency is removed.";
reference
"RFC-7540, section 5.3.1";
}
}
grouping subscription-policy-modifiable {
description
"This grouping describes all objects which may be changed
in a subscription.";
choice target {
mandatory true;
description
"Identifies the source of information against which a
subscription is being applied, as well as specifics on the
subset of information desired from that source.";
case stream {
choice stream-filter {
description
"An event stream filter can be applied to a subscription.
That filter will come either referenced from a global list,
or be provided within the subscription itself.";
case by-reference {
description
"Apply a filter that has been configured separately.";
leaf stream-filter-ref {
type stream-filter-ref;
mandatory true;
description
"References an existing stream filter which is to
be applied to an event stream for the subscription.";
}
}
case within-subscription {
description
"Local definition allows a filter to have the same
lifecycle as the subscription.";
uses stream-filter-elements;
}
}
}
}
leaf stop-time {
type yang:date-and-time;
description
"Identifies a time after which notification messages for a
subscription should not be sent. If 'stop-time' is not present,
Voit, et al. Expires October 18, 2018 [Page 42]
Internet-Draft Subscribed Notifications April 2018
the notification messages will continue until the subscription
is terminated. If 'replay-start-time' exists, 'stop-time' must
be for a subsequent time. If 'replay-start-time' doesn't exist,
'stop-time' when established must be for a future time.";
}
}
grouping subscription-policy-dynamic {
description
"This grouping describes the only information concerning a
subscription which can be passed over the RPCs defined in this
model.";
uses subscription-policy-modifiable {
augment target/stream {
description
"Adds additional objects which can be modified by RPC.";
leaf stream {
type stream-ref {
require-instance false;
}
mandatory true;
description
"Indicates the event stream to be considered for
this subscription.";
}
leaf replay-start-time {
if-feature "replay";
type yang:date-and-time;
description
"Used to trigger the replay feature and indicate that the
replay should start at the time specified. If
'replay-start-time' is not present, this is not a replay
subscription and event record push should start immediately.
It is never valid to specify start times that are later than
or equal to the current time.";
}
}
}
uses update-qos;
}
grouping subscription-policy {
description
"This grouping describes the full set of policy information
concerning both dynamic and configured subscriptions, with the
exclusion of both receivers and networking information specific to
the publisher such as what interface should be used to transmit
notification messages.";
Voit, et al. Expires October 18, 2018 [Page 43]
Internet-Draft Subscribed Notifications April 2018
uses subscription-policy-dynamic;
leaf transport {
if-feature "configured";
type transport;
mandatory true;
description
"This leaf specifies the transport used to deliver
messages destined to all receivers of a subscription.";
}
leaf encoding {
when 'derived-from(../transport, "sn:configurable-encoding")';
type encoding;
description
"The type of encoding for the subscribed data. If not
included as part of the RPC, the encoding MUST be set by the
publisher to be the encoding used by this RPC.";
}
leaf purpose {
if-feature "configured";
type string;
description
"Open text allowing a configuring entity to embed the
originator or other specifics of this subscription.";
}
}
/*
* RPCs
*/
rpc establish-subscription {
description
"This RPC allows a subscriber to create (and possibly negotiate)
a subscription on its own behalf. If successful, the
subscription remains in effect for the duration of the
subscriber's association with the publisher, or until the
subscription is terminated. In case an error occurs, or the
publisher cannot meet the terms of a subscription, an RPC error
is returned, the subscription is not created. In that case, the
RPC reply's 'error-info' MAY include suggested parameter settings
that would have a higher likelihood of succeeding in a subsequent
'establish-subscription' request.";
input {
uses subscription-policy-dynamic;
leaf encoding {
type encoding;
description
"The type of encoding for the subscribed data. If not
Voit, et al. Expires October 18, 2018 [Page 44]
Internet-Draft Subscribed Notifications April 2018
included as part of the RPC, the encoding MUST be set by the
publisher to be the encoding used by this RPC.";
}
}
output {
leaf identifier {
type subscription-id;
mandatory true;
description
"Identifier used for this subscription.";
}
leaf replay-start-time-revision {
if-feature "replay";
type yang:date-and-time;
description
"If a replay has been requested, this represents the
earliest time covered by the event buffer for the requested
stream. The value of this object is the
'replay-log-aged-time' if it exists. Otherwise it is the
'replay-log-creation-time'. All buffered event records
after this time will be replayed to a receiver. This
object will only be sent if the starting time has been
revised to be later than the time requested by the
subscriber.";
}
}
}
rc:yang-data establish-subscription-stream-error-info {
container establish-subscription-stream-error-info {
description
"If any 'establish-subscription' RPC parameters are
unsupportable against the event stream, a subscription is not
created and the RPC error response MUST indicate the reason
why the subscription failed to be created. This yang-data MAY be
inserted as structured data within a subscription's RPC error
response to indicate the failure reason. This yang-data MUST be
inserted if hints are to be provided back to the subscriber.";
leaf reason {
type identityref {
base establish-subscription-error;
}
description
"Indicates the reason why the subscription has failed to
be created to a targeted stream.";
}
leaf filter-failure-hint {
type string;
Voit, et al. Expires October 18, 2018 [Page 45]
Internet-Draft Subscribed Notifications April 2018
description
"Information describing where and/or why a provided filter
was unsupportable for a subscription.";
}
}
}
rpc modify-subscription {
description
"This RPC allows a subscriber to modify a dynamic subscription's
parameters. If successful, the changed subscription
parameters remain in effect for the duration of the subscription,
until the subscription is again modified, or until the
subscription is terminated. In case of an error or an inability
to meet the modified parameters, the subscription is not modified
and the original subscription parameters remain in effect.
In that case, the RPC error MAY include 'error-info' suggested
parameter hints that would have a high likelihood of succeeding
in a subsequent 'modify-subscription' request. A successful
'modify-subscription' will return a suspended subscription to an
'ACTIVE' state.";
input {
leaf identifier {
type subscription-id;
mandatory true;
description
"Identifier to use for this subscription.";
}
uses subscription-policy-modifiable;
}
}
rc:yang-data modify-subscription-stream-error-info {
container modify-subscription-stream-error-info {
description
"This yang-data MAY be provided as part of a subscription's RPC
error response when there is a failure of a
'modify-subscription' RPC which has been made against a
stream. This yang-data MUST be used if hints are to be
provided back to the subscriber.";
leaf reason {
type identityref {
base modify-subscription-error;
}
description
"Information in a 'modify-subscription' RPC error response
which indicates the reason why the subscription to an event
stream has failed to be modified.";
Voit, et al. Expires October 18, 2018 [Page 46]
Internet-Draft Subscribed Notifications April 2018
}
leaf filter-failure-hint {
type string;
description
"Information describing where and/or why a provided filter
was unsupportable for a subscription.";
}
}
}
rpc delete-subscription {
description
"This RPC allows a subscriber to delete a subscription that
was previously created from by that same subscriber using the
'establish-subscription' RPC.
If an error occurs, the server replies with an 'rpc-error' where
the 'error-info' field MAY contain an
'delete-subscription-error-info' structure.";
input {
leaf identifier {
type subscription-id;
mandatory true;
description
"Identifier of the subscription that is to be deleted.
Only subscriptions that were created using
'establish-subscription' from the same origin as this RPC
can be deleted via this RPC.";
}
}
}
rpc kill-subscription {
description
"This RPC allows an operator to delete a dynamic subscription
without restrictions on the originating subscriber or underlying
transport session.
If an error occurs, the server replies with an 'rpc-error' where
the 'error-info' field MAY contain an
'delete-subscription-error-info' structure.";
input {
leaf identifier {
type subscription-id;
mandatory true;
description
"Identifier of the subscription that is to be deleted. Only
subscriptions that were created using
Voit, et al. Expires October 18, 2018 [Page 47]
Internet-Draft Subscribed Notifications April 2018
'establish-subscription' can be deleted via this RPC.";
}
}
}
rc:yang-data delete-subscription-error-info {
container delete-subscription-error-info {
description
"If a 'delete-subscription' RPC or a 'kill-subscription' RPC
fails, the subscription is not deleted and the RPC error
response MUST indicate the reason for this failure. This
yang-data MAY be inserted as structured data within a
subscription's RPC error response to indicate the failure
reason.";
leaf reason {
type identityref {
base delete-subscription-error;
}
mandatory true;
description
"Indicates the reason why the subscription has failed to be
deleted.";
}
}
}
/*
* NOTIFICATIONS
*/
notification replay-completed {
sn:subscription-state-notification;
if-feature "replay";
description
"This notification is sent to indicate that all of the replay
notifications have been sent. It must not be sent for any other
reason.";
leaf identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
}
notification subscription-completed {
sn:subscription-state-notification;
if-feature "configured";
Voit, et al. Expires October 18, 2018 [Page 48]
Internet-Draft Subscribed Notifications April 2018
description
"This notification is sent to indicate that a subscription has
finished passing event records, as the 'stop-time' has been
reached.";
leaf identifier {
type subscription-id;
mandatory true;
description
"This references the gracefully completed subscription.";
}
}
notification subscription-modified {
sn:subscription-state-notification;
description
"This notification indicates that a subscription has been
modified. Notification messages sent from this point on will
conform to the modified terms of the subscription. For
completeness, this state change notification includes both
modified and non-modified aspects of a subscription.";
leaf identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
uses subscription-policy {
refine "target/stream/stream-filter/within-subscription" {
description
"Filter applied to the subscription. If the
'stream-filter-ref' is populated, the filter within the
subscription came from the 'filters' container. Otherwise it
is populated in-line as part of the subscription.";
}
}
}
notification subscription-resumed {
sn:subscription-state-notification;
description
"This notification indicates that a subscription that had
previously been suspended has resumed. Notifications will once
again be sent. In addition, a 'subscription-resumed' indicates
that no modification of parameters has occurred since the last
time event records have been sent.";
leaf identifier {
type subscription-id;
mandatory true;
Voit, et al. Expires October 18, 2018 [Page 49]
Internet-Draft Subscribed Notifications April 2018
description
"This references the affected subscription.";
}
}
notification subscription-started {
sn:subscription-state-notification;
if-feature "configured";
description
"This notification indicates that a subscription has started and
notifications are beginning to be sent. This notification shall
only be sent to receivers of a subscription; it does not
constitute a general-purpose notification.";
leaf identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
uses subscription-policy {
refine "target/stream/replay-start-time" {
description
"Indicates the time that a replay using for the streaming of
buffered event records. This will be populated with the most
recent of the following: 'replay-log-creation-time',
'replay-log-aged-time', 'replay-start-time', or the most
recent publisher boot time.";
}
refine "target/stream/stream-filter/within-subscription" {
description
"Filter applied to the subscription. If the
'stream-filter-ref' is populated, the filter within the
subscription came from the 'filters' container. Otherwise it
is populated in-line as part of the subscription.";
}
}
}
notification subscription-suspended {
sn:subscription-state-notification;
description
"This notification indicates that a suspension of the
subscription by the publisher has occurred. No further
notifications will be sent until the subscription resumes.
This notification shall only be sent to receivers of a
subscription; it does not constitute a general-purpose
notification.";
leaf identifier {
Voit, et al. Expires October 18, 2018 [Page 50]
Internet-Draft Subscribed Notifications April 2018
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
leaf reason {
type identityref {
base subscription-suspended-reason;
}
mandatory true;
description
"Identifies the condition which resulted in the suspension.";
}
}
notification subscription-terminated {
sn:subscription-state-notification;
description
"This notification indicates that a subscription has been
terminated.";
leaf identifier {
type subscription-id;
mandatory true;
description
"This references the affected subscription.";
}
leaf reason {
type identityref {
base subscription-terminated-reason;
}
mandatory true;
description
"Identifies the condition which resulted in the termination .";
}
}
/*
* DATA NODES
*/
container streams {
config false;
description
"This container contains information on the built-in streams
provided by the publisher.";
list stream {
key "name";
Voit, et al. Expires October 18, 2018 [Page 51]
Internet-Draft Subscribed Notifications April 2018
description
"Identifies the built-in event streams that are supported by the
publisher.";
leaf name {
type string;
description
"A handle for a system-provided event stream made up of a
sequential set of event records, each of which is
characterized by its own domain and semantics.";
}
leaf description {
type string;
mandatory true;
description
"A description of the event stream, including such information
as the type of event records that are available within this
event stream.";
}
leaf replay-support {
if-feature "replay";
type empty;
description
"Indicates that event record replay is available on this
stream.";
}
leaf replay-log-creation-time {
when "../replay-support";
if-feature "replay";
type yang:date-and-time;
mandatory true;
description
"The timestamp of the creation of the log used to support the
replay function on this stream. This time might be earlier
than the earliest available information contained in the log.
This object is updated if the log resets for some reason.";
}
leaf replay-log-aged-time {
if-feature "replay";
type yang:date-and-time;
description
"The timestamp associated with last event record which has
been aged out of the log. This timestamp identifies how far
back into history this replay log extends, if it doesn't
extend back to the 'replay-log-creation-time'. This object
MUST be present if replay is supported and any event records
have been aged out of the log.";
}
}
Voit, et al. Expires October 18, 2018 [Page 52]
Internet-Draft Subscribed Notifications April 2018
}
container filters {
description
"This container contains a list of configurable filters
that can be applied to subscriptions. This facilitates
the reuse of complex filters once defined.";
list stream-filter {
key "identifier";
description
"A list of pre-configured filters that can be applied to
subscriptions.";
leaf identifier {
type filter-id;
description
"An identifier to differentiate between filters.";
}
uses stream-filter-elements;
}
}
container subscriptions {
description
"Contains the list of currently active subscriptions, i.e.
subscriptions that are currently in effect, used for subscription
management and monitoring purposes. This includes subscriptions
that have been setup via RPC primitives as well as subscriptions
that have been established via configuration.";
list subscription {
key "identifier";
description
"The identity and specific parameters of a subscription.
Subscriptions within this list can be created using a control
channel or RPC, or be established through configuration.
If configuration operations or the 'kill-subscription' RPC are
used to delete a subscription, a 'subscription-terminated'
message is sent to any ACTIVE or SUSPENDED receivers.";
leaf identifier {
type subscription-id;
description
"Identifier of a subscription; unique within a publisher";
}
uses subscription-policy {
refine "target/stream/stream" {
description
"Indicates the event stream to be considered for this
subscription. If an event stream has been removed,
Voit, et al. Expires October 18, 2018 [Page 53]
Internet-Draft Subscribed Notifications April 2018
and no longer can be referenced by an active subscription,
send a 'subscription-terminated' notification with
'stream-unavailable' as the reason. If a configured
subscription refers to a non-existent stream, move that
subscription to the 'INVALID' state.";
}
}
choice notification-message-origin {
if-feature "configured";
description
"Identifies the egress interface on the publisher from which
notification messages are to be sent.";
case interface-originated {
description
"When notification messages to egress a specific, designated
interface on the publisher.";
leaf source-interface {
if-feature "interface-designation";
type if:interface-ref;
description
"References the interface for notification messages.";
}
}
case address-originated {
description
"When notification messages are to depart from a publisher
using specific originating address and/or routing context
information.";
leaf source-vrf {
if-feature "supports-vrf";
type leafref {
path "/ni:network-instances/ni:network-instance/ni:name";
}
description
"VRF from which notification messages should egress a
publisher.";
}
leaf source-address {
type inet:ip-address-no-zone;
description
"The source address for the notification messages. If a
source VRF exists, but this object doesn't, a publisher's
default address for that VRF must be used.";
}
}
}
leaf configured-subscription-state {
if-feature "configured";
Voit, et al. Expires October 18, 2018 [Page 54]
Internet-Draft Subscribed Notifications April 2018
type enumeration {
enum VALID {
value 1;
description
"Connection is active and healthy.";
}
enum INVALID {
value 2;
description
"The subscription as a whole is unsupportable with its
current parameters.";
}
enum CONCLUDED {
value 3;
description
"A subscription is inactive as it has hit a stop time,
but not yet been removed from configuration.";
}
}
config false;
description
"The presence of this leaf indicates that the subscription
originated from configuration, not through a control channel
or RPC. The value indicates the system established state
of the subscription.";
}
container receivers {
description
"Set of receivers in a subscription.";
list receiver {
key "name";
min-elements 1;
description
"A host intended as a recipient for the notification
messages of a subscription. For configured subscriptions
the 'address' may identify a receiver. Additional ways of
specifying configured receivers may be added through an
augmentation to the objects within this list.";
leaf name {
type string;
description
"Identifies a unique receiver for a subscription.";
}
leaf address {
when
'derived-from(../../../transport, "sn:inline-address")';
type inet:host;
description
Voit, et al. Expires October 18, 2018 [Page 55]
Internet-Draft Subscribed Notifications April 2018
"Specifies the address for the traffic to reach a remote
host using the subscription's transport. One of the
following must be specified: an ipv4 address, an ipv6
address, or a host name.";
}
leaf pushed-notifications {
type yang:counter64;
config false;
description
"Operational data which provides the number of update
notification messages pushed to a receiver.";
}
leaf excluded-notifications {
type yang:counter64;
config false;
description
"Operational data which provides the number of event
records from an event stream explicitly removed either
via an event stream filter or an access control filter so
that they are not passed to a receiver.";
}
leaf state {
type enumeration {
enum ACTIVE {
value 1;
description
"Receiver is currently being sent any applicable
notification messages for the subscription.";
}
enum SUSPENDED {
value 2;
description
"Receiver state is 'SUSPENDED', so the publisher
is currently unable to provide notification messages
for the subscription.";
}
enum CONNECTING {
value 3;
if-feature "configured";
description
"A subscription has been configured, but a
'subscription-started' state change notification needs
to be successfully received before notification
messages are sent.
If the 'reset' action is invoked for a receiver of an
active configured subscription, the state must be
moved to 'CONNECTING'.";
Voit, et al. Expires October 18, 2018 [Page 56]
Internet-Draft Subscribed Notifications April 2018
}
enum TIMEOUT {
value 4;
if-feature "configured";
description
"A subscription has failed in sending a subscription
started state change to the receiver.
Additional attempts at connection attempts are not
currently being made.";
}
}
config false;
mandatory true;
description
"Specifies the state of a subscription from the
perspective of a particular receiver. With this info it
is possible to determine whether a subscriber is currently
generating notification messages intended for that
receiver.";
}
action reset {
if-feature "configured";
description
"Allows the reset of this configured subscription receiver
to the 'CONNECTING' state. This enables the
connection process to be re-initiated.";
output {
leaf time {
type yang:date-and-time;
mandatory true;
description
"Time a publisher returned the receiver to a
'CONNECTING' state.";
}
}
}
}
}
}
}
}
<CODE ENDS>
5. Considerations
Voit, et al. Expires October 18, 2018 [Page 57]
Internet-Draft Subscribed Notifications April 2018
5.1. Implementation Considerations
To support deployments including both configured and dynamic
subscriptions, it is recommended to split subscription identifiers
into static and dynamic halves. That way it eliminates the
possibility of collisions if the configured subscriptions attempt to
set a subscription-id which might have already been dynamically
allocated. A best practice is to use lower half the "identifier"
object's integer space when that "identifier" is assigned by an
external entity (such as with a configured subscription). This
leaves the upper half of subscription identifiers available to be
dynamically assigned by the publisher.
If a subscription is unable to marshal a series of filtered event
records into transmittable notification messages, the receiver should
be suspended with the reason "unsupportable-volume".
For configured subscriptions, operations are against the set of
receivers using the subscription identifier as a handle for that set.
But for streaming updates, state change notifications are local to a
receiver. In this specification it is the case that receivers get no
information from the publisher about the existence of other
receivers. But if a network operator wants to let the receivers
correlate results, it is useful to use the subscription identifier
across the receivers to allow that correlation.
5.2. IANA Considerations
This document registers the following namespace URI in the "IETF XML
Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
This document registers the following YANG module in the "YANG Module
Names" registry [RFC6020]:
Name: ietf-subscribed-notifications
Namespace: urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications
Prefix: sn
Reference: draft-ietf-netconf-ietf-subscribed-notifications-11.txt
(RFC form)
Voit, et al. Expires October 18, 2018 [Page 58]
Internet-Draft Subscribed Notifications April 2018
5.3. Security Considerations
The YANG module specified in this document defines a schema for data
that is designed to be accessed via network management transports
such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF
layer is the secure transport layer, and the mandatory-to-implement
secure transport is Secure Shell (SSH) [RFC6242]. The lowest
RESTCONF layer is HTTPS, and the mandatory-to-implement secure
transport is TLS [RFC5246].
The NETCONF Access Control Model (NACM) [RFC8341] provides the means
to restrict access for particular NETCONF or RESTCONF users to a
preconfigured subset of all available NETCONF or RESTCONF operations
and content.
There are a number of data nodes defined in this YANG module that are
writable/creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., edit-config)
to these data nodes without proper protection can have a negative
effect on network operations. These are the subtrees and data nodes
and their sensitivity/vulnerability:
Container: "/filters"
o "stream-subtree-filter": updating a filter could increase the
computational complexity of all referencing subscriptions.
o "stream-xpath-filter": updating a filter could increase the
computational complexity of all referencing subscriptions.
Container: "/subscriptions"
The following considerations are only relevant for configuration
operations made upon configured subscriptions:
o "address": can be used to attempt to send traffic to an unwilling
receiver.
o "dependency": can be used to force important traffic to be queued
behind less important updates.
o "dscp": if unvalidated, can result in the sending of traffic with
a higher priority marking than warranted.
o "encoding": may be possible to set to a value which a receiver is
unable to interpret.
Voit, et al. Expires October 18, 2018 [Page 59]
Internet-Draft Subscribed Notifications April 2018
o "identifier": can overwrite an existing subscription, perhaps one
configured by another entity.
o "replay-start-time": can be used to push very large logs, wasting
resources.
o "source-address": the configured address might not be able to
reach a desired receiver.
o "source-interface": the configured interface might not be able to
reach a desired receiver.
o "source-vrf": can place a subscription into a virtual network
where receivers are not entitled to view the subscribed content.
o "stop-time": could be used to terminate content at an inopportune
time.
o "stream": could set a subscription to an event stream containing
no content permitted for the targeted receivers.
o "stream-filter-ref": could be set to a filter which is irrelevant
to the event stream.
o "stream-subtree-filter": a complex filter can increase the
computational resources for this subscription.
o "stream-xpath-filter": a complex filter can increase the
computational resources for this subscription.
o "weighting": placing a large weight can overwhelm the dequeuing of
other subscriptions.
Some of the readable data nodes in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus
important to control read access (e.g., via get, get-config, or
notification) to these data nodes. These are the subtrees and data
nodes and their sensitivity/vulnerability:
Container: "/streams"
o "name": if access control is not properly configured, can expose
system internals to those who should have no access to this
information.
o "replay-support": if access control is not properly configured,
can expose logs to those who should have no access.
Voit, et al. Expires October 18, 2018 [Page 60]
Internet-Draft Subscribed Notifications April 2018
Container: "/subscriptions"
o "excluded-notifications": leaf can provide information about
filtered event records. A network operator should have
permissions to know about such filtering.
o "subscription": different operational teams might have a desire to
set varying subsets of subscriptions. Access control should be
designed to permit read access to just the allowed set.
Some of the RPC operations in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus
important to control access to these operations. These are the
operations and their sensitivity/vulnerability:
RPC: all
o If a malicious or buggy subscriber sends an unexpectedly large
number of RPCs, the result might be an excessive use of system
resources on the publisher just to determine that these
subscriptions should be declined. In such a situation,
subscription interactions MAY be terminated by terminating the
transport session.
RPC: "delete-subscription"
o No special considerations.
RPC: "establish-subscription"
o Subscriptions could overload a publisher's resources. For this
reason, publishers MUST ensure that they have sufficient resources
to fulfill this request or otherwise reject the request.
RPC: "kill-subscription"
o The "kill-subscription" RPC MUST be secured so that only
connections with administrative rights are able to invoke this
RPC.
RPC: "modify-subscription"
o Subscriptions could overload a publisher's resources. For this
reason, publishers MUST ensure that they have sufficient resources
to fulfill this request or otherwise reject the request.
Voit, et al. Expires October 18, 2018 [Page 61]
Internet-Draft Subscribed Notifications April 2018
For both configured and dynamic subscriptions the publisher MUST
authenticate and authorize a receiver via some transport level
mechanism before sending any updates.
A secure transport is highly recommended and the publisher MUST
ensure that the receiver has sufficient authorization to perform the
function they are requesting against the specific subset of content
involved.
With configured subscriptions, one or more publishers could be used
to overwhelm a receiver. Notification messages SHOULD NOT be sent to
any receiver which does not support this specification. Receivers
that do not want notification messages need only terminate or refuse
any transport sessions from the publisher.
One subscription identifier can be used for two or more receivers of
the same configured subscription. But due to the possibility of
different access control permissions per receiver, it cannot be
assumed that each receiver is getting identical updates.
6. Acknowledgments
For their valuable comments, discussions, and feedback, we wish to
acknowledge Andy Bierman, Tim Jenkins, Martin Bjorklund, Kent Watsen,
Balazs Lengyel, Robert Wilton, Sharon Chisholm, Hector Trevino, Susan
Hares, Michael Scharf, and Guangying Zheng.
7. References
7.1. Normative References
[I-D.draft-ietf-netmod-revised-datastores]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore
Architecture", draft-ietf-netmod-revised-datastores-10
(work in progress), February 2018.
[I-D.draft-ietf-rtgwg-ni-model]
Berger, L., Hopps, C., and A. Lindem, "YANG Network
Instances", draft-ietf-rtgwg-ni-model-06 (work in
progress), January 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
Voit, et al. Expires October 18, 2018 [Page 62]
Internet-Draft Subscribed Notifications April 2018
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998,
<https://www.rfc-editor.org/info/rfc2474>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event
Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008,
<https://www.rfc-editor.org/info/rfc5277>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[XPATH] Clark, J. and S. DeRose, "XML Path Language (XPath)
Version 1.0", November 1999,
<http://www.w3.org/TR/1999/REC-xpath-19991116>.
7.2. Informative References
[I-D.draft-ietf-netconf-netconf-event-notifications]
Clemm, Alexander., Voit, Eric., Gonzalez Prieto, Alberto.,
Nilsen-Nygaard, E., Tripathy, A., Chisholm, S., and H.
Trevino, "NETCONF support for event notifications",
October 2017, <https://datatracker.ietf.org/doc/
draft-ietf-netconf-netconf-event-notifications/>.
[I-D.draft-ietf-netconf-restconf-notif]
Voit, Eric., Clemm, Alexander., Tripathy, A., Nilsen-
Nygaard, E., and Alberto. Gonzalez Prieto, "Restconf and
HTTP transport for event notifications", January 2018,
<https://datatracker.ietf.org/doc/
draft-ietf-netconf-restconf-notif/>.
Voit, et al. Expires October 18, 2018 [Page 63]
Internet-Draft Subscribed Notifications April 2018
[I-D.ietf-netconf-yang-push]
Clemm, Alexander., Voit, Eric., Gonzalez Prieto, Alberto.,
Tripathy, A., Nilsen-Nygaard, E., Bierman, A., and B.
Lengyel, "YANG Datastore Subscription", December 2017,
<https://datatracker.ietf.org/doc/
draft-ietf-netconf-yang-push/>.
[I-D.ietf-netmod-yang-tree-diagrams]
Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft-
ietf-netmod-yang-tree-diagrams-06 (work in progress),
February 2018.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[RFC7923] Voit, E., Clemm, A., and A. Gonzalez Prieto, "Requirements
for Subscription to YANG Datastores", RFC 7923,
DOI 10.17487/RFC7923, June 2016,
<https://www.rfc-editor.org/info/rfc7923>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
RFC 8071, DOI 10.17487/RFC8071, February 2017,
<https://www.rfc-editor.org/info/rfc8071>.
Appendix A. Changes between revisions
(To be removed by RFC editor prior to publication)
v11 - v12
Voit, et al. Expires October 18, 2018 [Page 64]
Internet-Draft Subscribed Notifications April 2018
o Tweaks from Kent's comments
o Clarified dscp text, and made its own feature
o YANG model tweaks alphabetizing, features.
v10 - v11
o access control filtering of events in streams included to match
RFC5277 behavior
o security considerations updated based on YANG template.
o dependency QoS made non-normative on HTTP2 QoS
o tree diagrams referenced for each figure using them
o reference numbers placed into state machine figures
o broke configured replay into its own section
o many tweaks updates based on LC and YANG doctor reviews
o trees and YANG model reconciled were deltas existed
o new feature for interface originated.
o dscp removed from the qos feature
o YANG model updated in a way which collapses groups only used once
so that they are part of the 'subscriptions' container.
o alternative encodings only allowed for transports which support
them.
v09 - v10
o Typos and tweaks
v08 - v09
o NMDA model supported. Non NMDA version at https://github.com/
netconf-wg/rfc5277bis/
o Error mechanism revamped to match to embedded implementations.
o Explicitly identified error codes relevant to each RPC/
Notification
Voit, et al. Expires October 18, 2018 [Page 65]
Internet-Draft Subscribed Notifications April 2018
v07 - v08
o Split YANG trees to separate document subsections.
o Clarified configured state machine based on Balazs comments, and
moved it into the configured subscription subsections.
o Normative reference to Network Instance model for VRF
o One transport for all receivers of configured subscriptions.
o QoS section moved in from yang-push
v06 - v07
o Clarification on state machine for configured subscriptions.
v05 - v06
o Made changes proposed by Martin, Kent, and others on the list.
Most significant of these are stream returned to string (with the
SYSLOG identity removed), intro section on 5277 relationship, an
identity set moved to an enumeration, clean up of definitions/
terminology, state machine proposed for configured subscriptions
with a clean-up of subscription state options.
o JSON and XML become features. Also Xpath and subtree filtering
become features
o Terminology updates with event records, and refinement of filters
to just event stream filters.
o Encoding refined in establish-subscription so it takes the RPC's
encoding as the default.
o Namespaces in examples fixed.
v04 - v05
o Returned to the explicit filter subtyping of v00
o stream object changed to 'name' from 'stream'
o Cleaned up examples
o Clarified that JSON support needs notification-messages draft.
v03 - v04
Voit, et al. Expires October 18, 2018 [Page 66]
Internet-Draft Subscribed Notifications April 2018
o Moved back to the use of RFC5277 one-way notifications and
encodings.
v03 - v04
o Replay updated
v02 - v03
o RPCs and Notification support is identified by the Notification
2.0 capability.
o Updates to filtering identities and text
o New error type for unsupportable volume of updates
o Text tweaks.
v01 - v02
o Subscription status moved under receiver.
v00 - v01
o Security considerations updated
o Intro rewrite, as well as scattered text changes
o Added Appendix A, to help match this to related drafts in progress
o Updated filtering definitions, and filter types in yang file, and
moved to identities for filter types
o Added Syslog as an event stream
o HTTP2 moved in from YANG-Push as a transport option
o Replay made an optional feature for events. Won't apply to
datastores
o Enabled notification timestamp to have different formats.
o Two error codes added.
v01 5277bis - v00 subscribed notifications
o Kill subscription RPC added.
Voit, et al. Expires October 18, 2018 [Page 67]
Internet-Draft Subscribed Notifications April 2018
o Renamed from 5277bis to Subscribed Notifications.
o Changed the notification capabilities version from 1.1 to 2.0.
o Extracted create-subscription and other elements of RFC5277.
o Error conditions added, and made specific in return codes.
o Simplified yang model structure for removal of 'basic' grouping.
o Added a grouping for items which cannot be statically configured.
o Operational counters per receiver.
o Subscription-id and filter-id renamed to identifier
o Section for replay added. Replay now cannot be configured.
o Control plane notification renamed to subscription state
notification
o Source address: Source-vrf changed to string, default address
option added
o In yang model: 'info' changed to 'policy'
o Scattered text clarifications
v00 - v01 of 5277bis
o YANG Model changes. New groupings for subscription info to allow
restriction of what is changeable via RPC. Removed notifications
for adding and removing receivers of configured subscriptions.
o Expanded/renamed definitions from event server to publisher, and
client to subscriber as applicable. Updated the definitions to
include and expand on RFC 5277.
o Removal of redundancy with other drafts
o Many other clean-ups of wording and terminology
Authors' Addresses
Eric Voit
Cisco Systems
Email: evoit@cisco.com
Voit, et al. Expires October 18, 2018 [Page 68]
Internet-Draft Subscribed Notifications April 2018
Alexander Clemm
Huawei
Email: ludwig@clemm.org
Alberto Gonzalez Prieto
VMWare
Email: agonzalezpri@vmware.com
Einar Nilsen-Nygaard
Cisco Systems
Email: einarnn@cisco.com
Ambika Prasad Tripathy
Cisco Systems
Email: ambtripa@cisco.com
Voit, et al. Expires October 18, 2018 [Page 69]
