NETCONF E. Voit Internet-Draft Cisco Systems Intended status: Standards Track A. Clemm Expires: February 4, 2019 Huawei A. Gonzalez Prieto Microsoft E. Nilsen-Nygaard A. Tripathy Cisco Systems August 3, 2018 Customized Subscriptions to a Publisher's Event Streams draft-ietf-netconf-subscribed-notifications-15 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 February 4, 2019. 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 February 4, 2019 [Page 1] Internet-Draft Subscribed Notifications August 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 . . . . . . . . . . . . . . . . . . . . . . . . . . 6 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 . . . . . . . . . . . . . . . . . . 24 2.7. Subscription State Notifications . . . . . . . . . . . . 25 2.8. Subscription Monitoring . . . . . . . . . . . . . . . . . 30 2.9. Advertisement . . . . . . . . . . . . . . . . . . . . . . 31 3. YANG Data Model Trees . . . . . . . . . . . . . . . . . . . . 31 3.1. Event Streams Container . . . . . . . . . . . . . . . . . 31 3.2. Filters Container . . . . . . . . . . . . . . . . . . . . 32 3.3. Subscriptions Container . . . . . . . . . . . . . . . . . 32 4. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 34 5. Considerations . . . . . . . . . . . . . . . . . . . . . . . 61 5.1. IANA Considerations . . . . . . . . . . . . . . . . . . . 61 5.2. Implementation Considerations . . . . . . . . . . . . . . 62 5.3. Transport Requirements . . . . . . . . . . . . . . . . . 62 5.4. Security Considerations . . . . . . . . . . . . . . . . . 63 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 67 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 67 7.1. Normative References . . . . . . . . . . . . . . . . . . 67 7.2. Informative References . . . . . . . . . . . . . . . . . 69 Appendix A. Example Configured Transport Augmentation . . . . . 70 Appendix B. Changes between revisions . . . . . . . . . . . . . 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 76 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 Voit, et al. Expires February 4, 2019 [Page 2] Internet-Draft Subscribed Notifications August 2018 permissions of each target receiver are understood by the publisher before subscribed event records are marshaled and pushed. The 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 [RFC8342]. 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. Client: defined in [RFC8342]. Configuration: defined in [RFC8342]. Voit, et al. Expires February 4, 2019 [Page 3] Internet-Draft Subscribed Notifications August 2018 Configuration datastore: defined in [RFC8342]. Configured subscription: A subscription installed via configuration into a configuration datastore. Dynamic subscription: A subscription created dynamically by a subscriber via a remote procedure call. 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: A client 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 [RFC8340]. Voit, et al. Expires February 4, 2019 [Page 4] Internet-Draft Subscribed Notifications August 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 a receiver of a configured subscription. 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 February 4, 2019 [Page 5] Internet-Draft Subscribed Notifications August 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 message 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. o unlike [RFC5277], this document enables a single transport session to intermix of notification messages and RPCs for different subscriptions. 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. Voit, et al. Expires February 4, 2019 [Page 6] Internet-Draft Subscribed Notifications August 2018 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. Event records MUST NOT be delivered to a receiver in a different order than they were placed onto an event stream. 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 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 Voit, et al. Expires February 4, 2019 [Page 7] Internet-Draft Subscribed Notifications August 2018 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 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 optional capability of the publisher; support for it is identified via the "qos" feature. Voit, et al. Expires February 4, 2019 [Page 8] Internet-Draft Subscribed Notifications August 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. Start and end states are depicted to reflect subscription creation and deletion events. ......... : start : :.......: | establish-subscription | | .-------modify-subscription--------. v v | .-----------. .-----------. .--------. | receiver |--insufficient CPU, b/w-->| receiver | modify- '| active | | suspended | subscription | |<----CPU, b/w sufficient--| | ---------->'-----------' '-----------' | | 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 the active state. Voit, et al. Expires February 4, 2019 [Page 9] Internet-Draft Subscribed Notifications August 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 when there is insufficient CPU or bandwidth available to service the subscription. This is notified to a subscriber with a "subscription-suspended" state change notification. o A suspended subscription may be modified by the subscriber (for example in an attempt to use fewer resources). Successful modification returns the subscription to an active state. o Even without a "modify-subscription" request, a publisher may return a subscription to the active state should the resource constraints become sufficient again. This is announced to the subscriber via the "subscription-resumed" subscription state change notification. 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 Voit, et al. Expires February 4, 2019 [Page 10] Internet-Draft Subscribed Notifications August 2018 event stream. For more on replay, see Section 2.4.2.1. Where there is no "start-time", the subscription starts immediately. 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? | | | | {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 Voit, et al. Expires February 4, 2019 [Page 11] Internet-Draft Subscribed Notifications August 2018 transported within a yang-data "establish-subscription-stream-error- info" container included within the RPC error response. 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. For a particular subscription, 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, where it resides within the publisher, or when event record entries in the log are purged. 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 Voit, et al. Expires February 4, 2019 [Page 12] Internet-Draft Subscribed Notifications August 2018 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 YANG tree, and Section 4 for the YANG model describing these elements. The actual size of the replay log at any given time is a 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. 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? | | {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.) Voit, et al. Expires February 4, 2019 [Page 13] Internet-Draft Subscribed Notifications August 2018 The publisher MAY immediately suspend this newly modified subscription through the "subscription-suspended" notification before any event records are sent. 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. 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 February 4, 2019 [Page 14] Internet-Draft Subscribed Notifications August 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. 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 February 4, 2019 [Page 15] Internet-Draft Subscribed Notifications August 2018 establish-subscription modify-subscription ---------------------- ------------------- dscp-unavailable filter-unsupported encoding-unsupported insufficient-resources filter-unsupported no-such-subscription history-unavailable 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. Multiple configured subscriptions MUST be supportable over a single transport session. Configured subscriptions have several characteristics distinguishing them from dynamic subscriptions: Voit, et al. Expires February 4, 2019 [Page 16] Internet-Draft Subscribed Notifications August 2018 o persistence across publisher reboots, 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.) On the publisher, supporting configured subscriptions is optional and advertised using the "configured" feature. On a receiver of a configured subscription, support for dynamic subscriptions is optional except where replaying missed event records is required. 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 intended as the destination for event records. Note that each individual receiver is identifiable by its "name". Via this "name", publisher transport parameters must be defined in order to establish and maintain a transport connection with a receiver. This transport specific reference can come in several forms, including the augmentation of leafrefs to an actual transport instance. Such augmentations must be defined in transport specific specifications building upon this document. 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. Voit, et al. Expires February 4, 2019 [Page 17] Internet-Draft Subscribed Notifications August 2018 A tree diagram describing these parameters is shown in Figure 20 within Section 3.3. 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 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: 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 Voit, et al. Expires February 4, 2019 [Page 18] Internet-Draft Subscribed Notifications August 2018 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). When a subscription is in the valid state, a publisher will attempt to connect with all receivers of a configured subscription 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--(c)|timeout | | | | |<-transport '--------' | | '----------' loss,reset------------------------------. | | (a) | | | | subscription- (b) (b) | | started* .--------. .---------. | | '----->| |(d)-insufficient CPU,------->| | | | |receiver| buffer overflow |receiver | | | subscription-| active | |suspended| | | modified* | |<----CPU, b/w sufficient,-(e)| | | | '---->'--------' 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 and there are any notification messages to deliver, a transport session is established (e.g., through [RFC8071]). Individual receivers are Voit, et al. Expires February 4, 2019 [Page 19] Internet-Draft Subscribed Notifications August 2018 moved to the active state when a "subscription-started" state change notification is successfully passed to that receiver (a). Event records are only sent to active receivers. Receivers of a configured subscription 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. In addition, a configured subscription's receiver MUST be moved to connecting if transport connectivity cannot be achieved, or if the receiver is reset via the "reset" action (b), (c). 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 failing to be delivered due to publisher buffer overflow, or notification messages are not able to be generated for that receiver due to insufficient CPU (d). This is indicated to the receiver by the "subscription-suspended" state change notification. A configured subscription receiver MUST be returned to the active state from the suspended state when notification messages are able to be generated, bandwidth is sufficient to handle the notification messages, and a receiver has successfully been sent a "subscription- resumed" or "subscription-modified" state change notification (e). The choice as to which of these two state change notifications is sent is determined by whether the subscription was modified during the period of suspension. 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 (e). 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. Voit, et al. Expires February 4, 2019 [Page 20] Internet-Draft Subscribed Notifications August 2018 Because there is no explicit association with an existing transport session, configuration operations MUST include additional parameters beyond those of dynamic subscriptions to indicate each receiver, how to contact that receiver, and possibly whether the notification messages need to come from a specific egress interface on the publisher. Some of these parameters MUST be configured via transport specific augmentations to this specification." 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. 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 and following 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 Voit, et al. Expires February 4, 2019 [Page 21] Internet-Draft Subscribed Notifications August 2018 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"). 2.5.5. Resetting a Configured Subscription 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 do replay on a configured subscription. This is supported via the configuration of the "configured-replay" object on the subscription. The setting of this object enables the streaming of the buffered events for the subscribed stream. All buffered event which have been retained since the last publisher restart will be sent. Replay of events records created since restart is useful. It allows event records generated before transport connectivity establishment to be passed to a receiver. Setting the restart time as the earliest configured replay time precludes possibility of resending of event records logged prior to publisher restart. It also ensures the same records will be sent to each configured receiver, regardless of the speed of transport connectivity establishment to each receiver. Finally, establishing restart as the earliest potential time for event records to be included within notification messages, a well- understood timeframe for replay is defined. Voit, et al. Expires February 4, 2019 [Page 22] Internet-Draft Subscribed Notifications August 2018 As a result, when any configured subscription receivers become active, buffered event records 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 three different times: the "replay-log-creation-time", "replay-log-aged- time", or the most recent publisher boot time. The "replay-log- creation-time" and "replay-log-aged-time" are discussed in Section 2.4.2.1. The most recent publisher boot time ensures that duplicate event records are not replayed from a previous time the publisher was booted. It is quite possible that a receiver might want to retrieve event records from a stream prior to the latest boot. If such records exist where there is a configured replay, the publisher MUST send the time of the event record immediately preceding the "replay-start- time" within the "replay-previous-event-time" leaf. Through the existence of the "replay-previous-event-time", the receiver will know that earlier events prior to reboot exist. In addition, if the subscriber was previously receiving event records with the same subscription id, the receiver can determine if there was a timegap where records generated on the publisher were not successully received. And with this information, the receiver may choose to dynamically subscribe to retrieve any event records placed into the stream before the most recent boot time. All other replay functionality remains the same as with dynamic subscriptions as described in Section 2.4.2.1. 2.5.7. Transport Connectivity for a Configured Subscription This specification is transport independent. However supporting a configured subscription will often require the establishment of transport connectivity. And the parameters used for this transport connectivity establishment happen to be transport specific. As a result, the YANG model defined within Section 4 is not able to directly define these transport parameters. It is necessary to support the connection establishment process. To support this function, the YANG model does include a node where transport specific parameters may be augmented into the model. This node is the choice "transport" located under "/subscriptions/subscription/receivers/receiver". By augmenting YANG case entries under this node, system developers are able to incorporate the YANG objects necessary to support the transport connectivity establishment process. Any implementation of this specification where the optional feature "configured" is supported MUST augment the YANG model with at least Voit, et al. Expires February 4, 2019 [Page 23] Internet-Draft Subscribed Notifications August 2018 one transport specific YANG case under the choice "transport". For more information and an example on how this might be accomplished see Appendix A. 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 receiver of a configured subscription. 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 message as defined within [RFC5277], Section 4. And per [RFC5277]'s "eventTime" object definition, the "eventTime" is populated with the event occurrence time. The following example within [RFC7950] section 7.16.3 is an example of a compliant message: 2007-09-01T10:00:00Z so-1/2/3.0 up down 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. Voit, et al. Expires February 4, 2019 [Page 24] Internet-Draft Subscribed Notifications August 2018 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. 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) transport connection 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. Voit, et al. Expires February 4, 2019 [Page 25] Internet-Draft Subscribed Notifications August 2018 +---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? | | | {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 replay-previous-event-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 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. Voit, et al. Expires February 4, 2019 [Page 26] Internet-Draft Subscribed Notifications August 2018 +---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? | | | {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. 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. Voit, et al. Expires February 4, 2019 [Page 27] Internet-Draft Subscribed Notifications August 2018 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. 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 Voit, et al. Expires February 4, 2019 [Page 28] Internet-Draft Subscribed Notifications August 2018 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 2.7.6. subscription-completed This notification indicates that a subscription that includes a "stop-time" has successfully finished passing event records upon the reaching of that time. Voit, et al. Expires February 4, 2019 [Page 29] Internet-Draft Subscribed Notifications August 2018 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 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. Voit, et al. Expires February 4, 2019 [Page 30] Internet-Draft Subscribed Notifications August 2018 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 "count-sent" which shows the quantity of events actually identified for sending to a receiver. The second counter is "count-excluded" which shows event records not sent to receiver. "count-excluded" 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. +--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 Voit, et al. Expires February 4, 2019 [Page 31] Internet-Draft Subscribed Notifications August 2018 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? {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) | +--rw (stream-filter)? | | +--:(by-reference) | | | +--rw stream-filter-ref | | | stream-filter-ref | | +--:(within-subscription) | | +--rw (filter-spec)? | | +--:(stream-subtree-filter) | | | +--rw stream-subtree-filter? | | | {subtree}? Voit, et al. Expires February 4, 2019 [Page 32] Internet-Draft Subscribed Notifications August 2018 | | +--:(stream-xpath-filter) | | +--rw stream-xpath-filter? yang:xpath1.0 | | {xpath}? | +--rw stream stream-ref | +--ro replay-start-time? | | yang:date-and-time {replay}? | +--rw configured-replay? empty | {configured,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 +--ro count-sent? yang:zero-based-counter64 +--ro count-excluded? yang:zero-based-counter64 +--ro state enumeration +---x reset {configured}? | +--ro output | +--ro time yang:date-and-time +--rw (transport) {configured}? Figure 20: Subscriptions tree diagram Voit, et al. Expires February 4, 2019 [Page 33] Internet-Draft Subscribed Notifications August 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 This module imports typedefs from [RFC6991], [RFC8343], and [RFC8040], and it references [I-D.draft-ietf-rtgwg-ni-model], [XPATH], [RFC6241], [RFC7540], [RFC7951] and [RFC7950]. [ note to the RFC Editor - please replace XXXX within this YANG model with the number of this document, and XXXY with the number of [I-D.draft-ietf-rtgwg-ni-model] ] [ note to the RFC Editor - please replace the two dates within the YANG module with the date of publication ] file "ietf-subscribed-notifications@2018-08-03.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 8343: A YANG Data Model for Interface Management"; } import ietf-network-instance { prefix ni; reference "draft-ietf-rtgwg-ni-model-12: YANG Model for Network Instances"; } import ietf-restconf { prefix rc; reference "RFC 8040: RESTCONF Protocol"; } import ietf-yang-types { prefix yang; reference Voit, et al. Expires February 4, 2019 [Page 34] Internet-Draft Subscribed Notifications August 2018 "RFC 6991: Common YANG Data Types"; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: WG List: Author: Alexander Clemm Author: Eric Voit Author: Alberto Gonzalez Prieto Author: Einar Nilsen-Nygaard Author: Ambika Prasad Tripathy "; description "Contains a YANG specification for subscribing to event records and receiving matching content within notification messages. Copyright (c) 2018 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2018-08-03 { description "Initial version"; reference "RFC XXXX: Customized Subscriptions to a Publisher's Event Streams"; } /* * FEATURES Voit, et al. Expires February 4, 2019 [Page 35] Internet-Draft Subscribed Notifications August 2018 */ 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 "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 Voit, et al. Expires February 4, 2019 [Page 36] Internet-Draft Subscribed Notifications August 2018 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 "RFC XXXY, Section 6."; } feature xpath { description "This feature indicates support for xpath filtering."; reference "http://www.w3.org/TR/1999/REC-xpath-19991116"; } /* * 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. This statement is not for use outside of this YANG module."; } /* * 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' Voit, et al. Expires February 4, 2019 [Page 37] Internet-Draft Subscribed Notifications August 2018 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 '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 encoding-unsupported { base establish-subscription-error; description "Unable to encode notification messages in the desired format."; } 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."; Voit, et al. Expires February 4, 2019 [Page 38] Internet-Draft Subscribed Notifications August 2018 } 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."; } 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."; Voit, et al. Expires February 4, 2019 [Page 39] Internet-Draft Subscribed Notifications August 2018 } 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."; } 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; Voit, et al. Expires February 4, 2019 [Page 40] Internet-Draft Subscribed Notifications August 2018 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."; } 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."; } Voit, et al. Expires February 4, 2019 [Page 41] Internet-Draft Subscribed Notifications August 2018 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 "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 Voit, et al. Expires February 4, 2019 [Page 42] Internet-Draft Subscribed Notifications August 2018 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. 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"; Voit, et al. Expires February 4, 2019 [Page 43] Internet-Draft Subscribed Notifications August 2018 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 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 Voit, et al. Expires February 4, 2019 [Page 44] Internet-Draft Subscribed Notifications August 2018 "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, 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 { Voit, et al. Expires February 4, 2019 [Page 45] Internet-Draft Subscribed Notifications August 2018 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; config false; description "Used to trigger the replay feature for a dynamic subscription, with event records being selected needing to be at or after the 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."; 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 'not(../transport) or derived-from(../transport, "sn:configurable-encoding")'; Voit, et al. Expires February 4, 2019 [Page 46] Internet-Draft Subscribed Notifications August 2018 type encoding; description "The type of encoding for notification messages. For a dynamic subscription, if not included as part of an establish- subscription RPC, the encoding will be populated with the encoding used by that RPC. For a configured subscription, if not explicitly configured the encoding with be the default encoding for an underlying transport."; } 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 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; Voit, et al. Expires February 4, 2019 [Page 47] Internet-Draft Subscribed Notifications August 2018 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; description "Information describing where and/or why a provided filter was unsupportable for a subscription."; } } } rpc modify-subscription { Voit, et al. Expires February 4, 2019 [Page 48] Internet-Draft Subscribed Notifications August 2018 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."; } leaf filter-failure-hint { type string; description "Information describing where and/or why a provided filter was unsupportable for a subscription."; } } Voit, et al. Expires February 4, 2019 [Page 49] Internet-Draft Subscribed Notifications August 2018 } 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 'establish-subscription' can be deleted via this RPC."; } } } rc:yang-data delete-subscription-error-info { container delete-subscription-error-info { description Voit, et al. Expires February 4, 2019 [Page 50] Internet-Draft Subscribed Notifications August 2018 "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"; 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 Voit, et al. Expires February 4, 2019 [Page 51] Internet-Draft Subscribed Notifications August 2018 "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; description "This references the affected subscription."; } } notification subscription-started { sn:subscription-state-notification; if-feature "configured"; Voit, et al. Expires February 4, 2019 [Page 52] Internet-Draft Subscribed Notifications August 2018 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', 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."; } augment "target/stream" { description "This augmentation adds additional parameters specific to a subscription-started notification."; leaf replay-previous-event-time { when "../replay-start-time"; if-feature "replay"; type yang:date-and-time; description "If there is at least one event in the replay buffer prior to 'replay-start-time', this gives the time of the event generated immediately prior to the 'replay-start-time'. If a receiver previously received event records for this configured subscription, it can compare this time to the last event record previously received. If the two are not the same (perhaps due to a reboot), then a dynamic replay can be initiated to acquire any missing event records."; } } } Voit, et al. Expires February 4, 2019 [Page 53] Internet-Draft Subscribed Notifications August 2018 } 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 { 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 ."; } } Voit, et al. Expires February 4, 2019 [Page 54] Internet-Draft Subscribed Notifications August 2018 /* * DATA NODES */ container streams { config false; description "This container contains information on the built-in streams provided by the publisher."; list stream { key "name"; 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 { Voit, et al. Expires February 4, 2019 [Page 55] Internet-Draft Subscribed Notifications August 2018 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."; } } } 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' Voit, et al. Expires February 4, 2019 [Page 56] Internet-Draft Subscribed Notifications August 2018 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, 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."; } augment "target/stream" { description "Enables objects to added to a configured stream subscription"; leaf configured-replay { if-feature "configured"; if-feature "replay"; type empty; description "The presence of this leaf indicates that replay for the configured subscription should start at the earliest time in the event log, or at the publisher boot time, which ever is later."; } } } 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."; } Voit, et al. Expires February 4, 2019 [Page 57] Internet-Draft Subscribed Notifications August 2018 } 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"; 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 Voit, et al. Expires February 4, 2019 [Page 58] Internet-Draft Subscribed Notifications August 2018 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, transport specific network parameters (or a leafref to those parameters) may augmentated to a specific receiver within this list."; leaf name { type string; description "Identifies a unique receiver for a subscription."; } leaf count-sent { type yang:zero-based-counter64; config false; description "The number of event records sent to the receiver. The count is initialized when a dynamic subscription is established, or when a configured subscription transitions to the valid state."; } leaf count-excluded { type yang:zero-based-counter64; config false; description "The number of event records explicitly removed either via an event stream filter or an access control filter so that they are not passed to a receiver. This count is set to zero each time 'count-sent' is initialized."; } leaf state { type enumeration { enum active { value 1; description "Receiver is currently being sent any applicable notification messages for the subscription."; } enum suspended { Voit, et al. Expires February 4, 2019 [Page 59] Internet-Draft Subscribed Notifications August 2018 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'."; } 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; Voit, et al. Expires February 4, 2019 [Page 60] Internet-Draft Subscribed Notifications August 2018 description "Time a publisher returned the receiver to a 'connecting' state."; } } } choice transport { if-feature "configured"; mandatory true; description "Defines the transport-specific configuration data for the value of the leaf 'transport' specified under '/subscriptions/subsription'. Individual transport specifications MUST augment this choice with YANG case statements. Each transport specific case augmentation enables the inclusion to transport parameters such as the IP address, port, and security credentials. It is these parameters which are used as necessary for making a secure transport connection to the receiver."; } } } } } } 5. Considerations 5.1. 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 February 4, 2019 [Page 61] Internet-Draft Subscribed Notifications August 2018 5.2. 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. For configured replay subscriptions, the receiver is protected from duplicated events being pushed after a publisher is rebooted. However it is possible that a receiver might want to acquire event records which failed to be delivered just prior to the reboot. Delivering these event records be accomplished by leveraging the "eventTime" from the last event record received prior to the receipt of a "subscription-started" state change notification. With this "eventTime" and the "replay-start-time" from the "subscription- started" notification, an independent dynamic subscription can be established which retrieves any event records which may have been generated but not sent to the receiver. 5.3. Transport Requirements This section provides requirements for any subscribed notification transport supporting the solution presented in this document. For both configured and dynamic subscriptions the publisher MUST authenticate a receiver via some transport level mechanism before sending any event records for which they are authorized to see. In addition, the receiver MUST authenticate the publisher at the Voit, et al. Expires February 4, 2019 [Page 62] Internet-Draft Subscribed Notifications August 2018 transport level. The result is mutual authentication between the two. 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. A specific transport specification built upon this document may or may not choose to require the use of the same logical channel for the RPCs and the event records. However the event records and the subscription state notifications MUST be sent on the same transport session to ensure the properly ordered delivery. Additional transport requirements will be dictated by the choice of transport used with a subscription. For an example of such requirements with NETCONF transport, see [I-D.draft-ietf-netconf-netconf-event-notifications]. 5.4. 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. 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. 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. When a receiver of a configured subscription gets a new "subscription-started" message for a known subscription where it is already consuming events, the receiver SHOULD retrieve any event Voit, et al. Expires February 4, 2019 [Page 63] Internet-Draft Subscribed Notifications August 2018 records generated since the last event record was received. This can be accomplish by establishing a separate dynamic replay subscription with the same filtering criteria with the publisher", assuming the publisher supports the "replay" feature. For dynamic subscriptions, implementations need to protect against malicious or buggy subscribers which may send a large number "establish-subscription" requests, thereby using up system resources. To cover this possibility operators SHOULD monitor for such cases and, if discovered,take remedial action to limit the resources used, such as suspending or terminating a subset of the subscriptions or, if the underlying transport is session based, terminate the underlying transport session. 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 where there is a specific 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 "configured-replay": can be used to send a large number of event records to a 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 "identifier": can overwrite an existing subscription, perhaps one configured by another entity. Voit, et al. Expires February 4, 2019 [Page 64] Internet-Draft Subscribed Notifications August 2018 o "name": adding a new key entry can be used to attempt to send traffic to an unwilling receiver. 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 "transport": this YANG choice node can be augmented with transport parameters which could then send the subscribed information to an undesired receiver". 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. Voit, et al. Expires February 4, 2019 [Page 65] Internet-Draft Subscribed Notifications August 2018 o "replay-support": if access control is not properly configured, can expose logs to those who should have no access. Container: "/subscriptions" o "count-excluded": 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 February 4, 2019 [Page 66] Internet-Draft Subscribed Notifications August 2018 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-rtgwg-ni-model] Berger, L., Hopps, C., and A. Lindem, "YANG Network Instances", draft-ietf-rtgwg-ni-model-12 (work in progress), March 2018. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [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, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008, . [RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . Voit, et al. Expires February 4, 2019 [Page 67] Internet-Draft Subscribed Notifications August 2018 [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, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, . [RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, . [XPATH] Clark, J. and S. DeRose, "XML Path Language (XPath) Version 1.0", November 1999, . Voit, et al. Expires February 4, 2019 [Page 68] Internet-Draft Subscribed Notifications August 2018 7.2. Informative References [I-D.draft-ietf-netconf-netconf-client-server] Watsen, K. and G. Wu, "NETCONF Client and Server Models", draft-ietf-netconf-netconf-client-server-06 (work in progress), June 2018. [I-D.draft-ietf-netconf-netconf-event-notifications] Clemm, Alexander., Voit, Eric., Gonzalez Prieto, Alberto., Nilsen-Nygaard, E., and A. Tripathy, "NETCONF support for event notifications", May 2018, . [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", May 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", May 2018, . [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/RFC7540, May 2015, . [RFC7923] Voit, E., Clemm, A., and A. Gonzalez Prieto, "Requirements for Subscription to YANG Datastores", RFC 7923, DOI 10.17487/RFC7923, June 2016, . [RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home", RFC 8071, DOI 10.17487/RFC8071, February 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . Voit, et al. Expires February 4, 2019 [Page 69] Internet-Draft Subscribed Notifications August 2018 Appendix A. Example Configured Transport Augmentation This appendix provides a non-normative example of how the YANG model defined in Section 4 may be enhanced to incorporate the configuration parameters needed to support the transport connectivity process. In this example, NETCONF transport connectivity is explored. Other transports may be supported via a similar YANG model. For more on the overall need, see Section 2.5.7. Within the YANG model defined below are two main elements. First is a transport identity "netconf". This transport identity allows a configuration agent to define NETCONF as the selected type of transport for s subscription. Second is a YANG case augmentation "netconf" which is made to the "/subscriptions/subscription/receivers/receiver/transport" choice node of Section 4. Within this augmentation are the necessary transport configuration parameters. In this case the parameters consist of a leafref to the ietf-netconf-client.yang model of [I-D.draft-ietf-netconf-netconf-client-server]. This leafref itself allows referencing to the actual parameters which would be used to establish the transport connection. file "ietf-netconf-subscribed-notifications@2018-08-03.yang" module ietf-netconf-subscribed-notifications { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-subscribed-notifications"; prefix nsn; import ietf-subscribed-notifications { prefix sn; } import ietf-netconf-client { prefix ncc; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: WG List: "; description "Defines NETCONF as a supported transport for subscribed event notifications."; revision 2018-08-03 { Voit, et al. Expires February 4, 2019 [Page 70] Internet-Draft Subscribed Notifications August 2018 description "Initial version"; reference "RFC XXXX: Customized Subscriptions to a Publisher's Event Streams"; } identity netconf { base sn:transport; base sn:inline-address; description "NETCONF is used as a configured subscription transport for notification messages and state change notifications."; reference "RFC-6241: Network Configuration Protocol (NETCONF)"; } augment "/sn:subscriptions/sn:subscription/sn:receivers/sn:receiver" + "/sn:transport" { when 'derived-from(../../../../transport, "nsn:netconf")'; description "This augmentation allows NETCONF specific parameters to be exposed for a receiver."; case "netconf" { description "This case allows NETCONF specific parameters to be exposed for a receiver."; leaf netconf-endpoint { type leafref { path "/ncc:netconf-client/ncc:initiate/ncc:netconf-server" + "/ncc:endpoints/ncc:endpoint/ncc:name"; } mandatory true; description "Remote client which need to initiate the NETCONF transport if an existing NETCONF session from that client is not available."; } } } } Figure 21: Example Transport Augmentation for NETCONF Voit, et al. Expires February 4, 2019 [Page 71] Internet-Draft Subscribed Notifications August 2018 Appendix B. Changes between revisions (To be removed by RFC editor prior to publication) v14 - v15 o Text tweaks. o Mandatory empty case "transport" added for transport parameters. This includes a new section and an appendix explaining it. v13 - v14 o Removed the 'address' leaf. o Replay is now of type 'empty' for configured. v12 - v13 o Tweaks from Kent's comments o Referenced in YANG model updated per Tom Petch's comments o Added leaf replay-previous-event-time o Renamed the event counters, downshifted the subscription states v11 - v12 o Tweaks from Kent's, Tim's, and Martin'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 Voit, et al. Expires February 4, 2019 [Page 72] Internet-Draft Subscribed Notifications August 2018 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 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 Voit, et al. Expires February 4, 2019 [Page 73] Internet-Draft Subscribed Notifications August 2018 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 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. Voit, et al. Expires February 4, 2019 [Page 74] Internet-Draft Subscribed Notifications August 2018 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. 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. Voit, et al. Expires February 4, 2019 [Page 75] Internet-Draft Subscribed Notifications August 2018 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 Alexander Clemm Huawei Email: ludwig@clemm.org Alberto Gonzalez Prieto Microsoft Email: alberto.gonzalez@microsoft.com Einar Nilsen-Nygaard Cisco Systems Email: einarnn@cisco.com Voit, et al. Expires February 4, 2019 [Page 76] Internet-Draft Subscribed Notifications August 2018 Ambika Prasad Tripathy Cisco Systems Email: ambtripa@cisco.com Voit, et al. Expires February 4, 2019 [Page 77]