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module ietf-subscribed-notifications {
  yang-version 1.1;
  namespace 
    "urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications";

  prefix sn;

  import ietf-yang-types {
    prefix yang;
  }
  import ietf-inet-types {
    prefix inet;
  }
  import ietf-interfaces {
    prefix if;
  }

  organization "IETF";
  contact
    "WG Web:   <http:/tools.ietf.org/wg/netconf/>
     WG List:  <mailto:netconf@ietf.org>
     
     Editor:   Alexander Clemm
               <mailto:ludwig@clemm.org>

     Editor:   Eric Voit
               <mailto:evoit@cisco.com>
               
     Editor:   Alberto Gonzalez Prieto
               <mailto:agonzalezpri@vmware.com>

     Editor:   Einar Nilsen-Nygaard
               <mailto:einarnn@cisco.com>

     Editor:   Ambika Prasad Tripathy
               <mailto:ambtripa@cisco.com>";


  description
    "Contains a conceptual YANG specification for subscribing to events 
    and receiving matching content within notification messages.";
  
  revision 2017-09-22 {
    description
      "Filtering and stream structures updated, replay a feature.";
    reference 
      "draft-ietf-netconf-subscribed-notifications-04";
  }
  
  /*
   * FEATURES
   */
  
  feature json {
    description
      "This feature indicates that JSON encoding of notifications
       is supported.";
  }

  feature configured-subscriptions {
    description
      "This feature indicates that management plane configuration 
       of subscription is supported.";
  }
  
  feature replay {
    description
      "This feature indicates that historical event replay is 
      supported.  With replay, it is possible for past events to be 
      will be streamed in chronological order.";
  }
  
  /* 
   * EXTENSIONS
   */
   
  extension subscription-state-notif {
    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 receive 
       notifications."; 
  }
  
  /*
   * IDENTITIES
   */

  /* Identities for streams */
  identity stream {
    description
      "Base identity to represent a generic stream of event 
       notifications exposed for subscription by a system.";
  }
  
  identity NETCONF {
    base stream;
    description
      "Default NETCONF event stream, containing events based on 
      notifications defined as YANG modules that are supported by the
      system.  As a historical reference, this contains the same set 
      of events in a default RFC-5277 NETCONF stream.";  
  }
  
  identity SYSLOG {
    base stream;
    description
      "A stream of events mirroring the discrete set entries 
      concurrently being placed into a device's local Syslog.";  
  }
  
  identity custom-stream {
    base stream;
    description
      "A supported stream not defined via an identity in this model";
  }
  
  /* Identities for subscription results */
  identity subscription-result {
    description
      "Base identity for RPC responses and State Change Notifications
      providing information on the creation, modification, deletion of 
       subscriptions.";
  }
  
  identity ok {
    base subscription-result;
    description
      "OK - RPC was successful and was performed as requested.";
  }
  
  identity error {
    base subscription-result;
    description
      "Problem with subscription.  Base identity for error return 
      codes for RPCs and State Change Notifications.";
  }

  /* Identities for subscription stream status */
  identity subscription-status {
    description
      "Base identity for the status of a subscription.  This status
      indicates whether a subscriber is actively generating 
      notifications intended for a particular receiver.";
  }
  
  identity active {
    base subscription-status;
    description
      "Status is active and healthy.";
  }
  
  identity inactive {
    base subscription-status;
    description
      "Status is inactive, for example after the stop time, but not
      yet deleted from the configuration.";
  }
  
  identity suspended {
    base subscription-status;
    description
      "The status is suspended, meaning that the publisher is currently
       unable to provide the negotiated updates for the subscription.";
  }
  
  identity in-error {
    base subscription-status;
    description
      "The status is in error or degraded, meaning that stream and/or
      subscription is currently unable to provide the negotiated
      notifications.";
  }

  /* Identities for subscription errors */

  identity internal-error {
    base error;
    description
      "Error within publisher prohibits operation.";
  }
  
  identity suspension-timeout {
    base error;
    description
     "Termination of previously suspended subscription. The publisher 
      has eliminated the subscription as it exceeded a time limit for
      suspension.";
  }
  
  identity stream-unavailable {
    base error;
    description
     "Stream does not exist or is not available to the receiver.";
  }
  
  identity encoding-unavailable {
    base error;
    description
     "Encoding not supported";
  }
  
  identity replay-unsupported {
    base error;
    description
     "Replay cannot be performed for this subscription. The publisher 
     does not provide the requested historic information via replay.";
  }
  
  identity history-unavailable {
    base error;
    description
     "Replay request too far into the past. The publisher does store
      historic information for all parts of requested subscription, but
      not back to the requested timestamp.";
  }
  
  identity filter-unavailable {
    base error;
    description
     "Referenced filter does not exist";
  }
  
  identity filter-type-unsupported {
    base error;
    description
     "Publisher does not support filters constructed using this
     filtering technology syntax.";
  }
  
  identity filter-unsupported {
    base error;
    description
     "Failure can be from a syntax error, or a syntax too complex to be 
     processed by the platform. The supplemental info should include 
     the invalid part of the filter.";
  }
  
  identity namespace-unavailable {
    base error;
    description
     "Referenced namespace doesn't exist or is unavailable  
      to the receiver.";
  }
  
  identity no-such-subscription {
    base error;
    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 acceptable subscription which has been
      statically configured.";
  }
  
  identity error-insufficient-resources {
    base error;
    description
      "The server has insufficient resources to support the
       subscription as requested by an RPC.";
  }
  
  identity unsupportable-volume {
    base error;
    description
      "The publisher cannot support the volume of information intended
      to be sent for an existing subscription.";
  }
  
  identity error-no-such-option {
    base error;
    description
      "A requested parameter setting is not supported.";
  }

  /* Identities for encodings */
  identity encodings {
    description
      "Base identity to represent data encodings";
  }
  
  identity encode-xml {
    base encodings;
    description
      "Encode data using XML";
  }
  
  identity encode-json {
    base encodings;
    description
      "Encode data using JSON";
  }

  /* Identities for transports */
  identity transport {
    description
      "An identity that represents a transport protocol for event 
       notifications";
  }
  
  identity netconf {
    base transport;
    description
      "Netconf notifications as a transport.";
  }
  
  identity http2 {
    base transport;
    description
      "HTTP2 notifications as a transport";
  }
  
  /*
   * TYPEDEFs
   */

  typedef subscription-id {
    type uint32;
    description
      "A type for subscription identifiers.";
  }

  typedef filter-id {
    type uint32;
    description
      "A type to identify filters which can be associated with a 
       subscription.";
  }

  typedef subscription-result {
    type identityref {
      base subscription-result;
    }
    description
      "The result of a subscription operation";
  }

  typedef subscription-errors {
    type identityref {
      base error;
    }
    description
      "The reason for the failure of an RPC request or the sending  
       of a subscription suspension or termination notification";
  }  
  
  typedef encoding {
    type identityref {
      base encodings;
    }
    description
      "Specifies a data encoding, e.g. for a data subscription.";
  }
  
  typedef subscription-status {
    type identityref {
      base subscription-status;
    }
    description
      "Specifies the status of a subscription.";
  }
  
  typedef transport-protocol {
    type identityref {
      base transport;
    }
    description
      "Specifies transport protocol used to send notifications to a
       receiver.";
  }

  typedef egressing-from {
    type enumeration {
      enum "interface-originated" {
        description
          "Notifications will be sent from a specific interface on a 
           publisher";
      }
      enum "address-originated" {
        description
          "Notifications will be sent from a specific address on a 
           publisher";
      }
    }
    description
      "Specifies from where notifications will be sourced when 
       being sent by the publisher.";
  }

  typedef stream {
    type identityref {
      base stream;
    }
    description
      "Specifies a system-provided datastream.";
  }

  typedef event-filter-ref {
    type leafref {
      path "/sn:filters/sn:event-filter/sn:identifier";
    }
    description
      "This type is used to reference an event filter.";
  }

  /*
   * GROUPINGS
   */
   
  grouping event-filter-elements {
    description
      "This grouping defines the base for filters for notification 
       events.";
    choice filter-spec {
      description
        "The content filter specification for this request.";
      anydata subtree-filter {
        description
          "Event stream evaluation criteria encoded in a syntax of a
           supported type of an RFC 6241, Section 6 filter.  When 
		   applied against an event stream and there is a non-empty or 
           positive result, the event is passed along.";
        reference "RFC 6241, Section 6.";
      }
      leaf xpath-filter {
        type yang:xpath1.0;
        description
          "Event stream evaluation criteria encoded in a syntax of xpath
		  1.0  When applied against an event stream and there is a 
		  non-empty or positive result, the event is passed along.";
		reference "http://www.w3.org/TR/1999/REC-xpath-19991116";
      }
    }
  } 
   
  grouping subscription-policy-modifiable {
    description
      "This grouping describes all objects which may be changed
      in a subscription via an RPC.";  
    choice target {
      mandatory true;
      description
        "A filter must be applied against some source of information.
        This identifies the target for the filter.";
      case stream {
        choice event-filter {
          description
            "A filter can be applied to a subscription.  And 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 event-filter-ref {
              type event-filter-ref;
              mandatory true;
              description
                "References an existing filter which is to be applied to 
                the subscription.";
            }
          }
          case within-subscription {
            description
              "Local definition allows a filter to have the same   
              lifecycle as the subscription.";
            uses event-filter-elements;
          }
        }
      }
    }
    leaf stop-time {
      type yang:date-and-time;
      description
        "Identifies a time after which notification events should not
        be sent.  If stop-time is not present, the notifications will 
        continue until the subscription is terminated.  If 
        replay-start-time exists, stop-time must for a subsequent time.  
        If replay-start-time doesn't exist, stop-time must for a future 
        time.";
    }
  }
  
  grouping subscription-policy {
    description
      "This grouping describes information concerning a subscription.";
    leaf encoding {
      type encoding;
      default "encode-xml";
      description
        "The type of encoding for the subscribed data. Default is XML";
    }       
    uses subscription-policy-modifiable {
      augment target/stream {
        description
          "Adds additional objects which must be set just by RPC.";
        leaf stream {
          type stream;
          mandatory true;
          description
            "Indicates a stream of events against which to apply
            an event filter.";
        }
        leaf replay-start-time {
          if-feature "replay";
          type yang:date-and-time;
          description
            "Used to trigger the replay feature and indicate that the 
            replay should start at the time specified.  If 
            replay-start-time is not present, this is not a replay 
            subscription and event pushes should start immediately.  It 
            is never valid to specify start times that are later than 
            or equal to the current time.";
        }  
      }
    } 
  }
  
  
  grouping notification-origin-info {
    description
      "Defines the sender source from which notifications for a 
       configured subscription are sent.";
    choice notification-origin {
      description
        "Identifies the egress interface on the Publisher from which
         notifications will or are being sent.";
      case interface-originated {
        description
          "When the push source is out of an interface on the 
           Publisher established via static configuration.";
        leaf source-interface {
          type if:interface-ref;
          description
            "References the interface for notifications.";
        }
      }
      case address-originated {
        description
          "When the push source is out of an IP address on the 
           Publisher established via static configuration.";
        leaf source-vrf {
          type string;
          description
            "Network instance name for the VRF.  This could also have
            been a leafref to draft-ietf-rtgwg-ni-model, but that model 
            is not complete, and might not be implemented on a box.";
        }
        leaf source-address {
          type inet:ip-address-no-zone;
          description
            "The source address for the notifications.  If a source VRF
            exists, but this object doesn't, a default address for the
            VRF can be used.";
        }
      }
    }
  }

  grouping receiver-info {
    description
      "Defines where and how to get notifications for a configured 
      subscriptions to one or more targeted recipient.  This includes 
      specifying the destination addressing as well as a transport 
      protocol acceptable to the receiver.";
    container receivers {
      description
        "Set of receivers in a subscription.";
      list receiver {
        key "address port";
        min-elements 1;
        description
          "A single host or multipoint address intended as a target
           for the notifications for a subscription.";
        leaf address {
          type inet:host;
          description
            "Specifies the address for the traffic to reach a remote 
            host. One of the following must be specified: an ipv4 
            address, an ipv6 address, or a host name.";
        }
        leaf port {
          type inet:port-number;
          description
            "This leaf specifies the port number to use for messages
             destined for a receiver.";
        }
        leaf protocol {
          type transport-protocol;
          default "netconf";
          description
            "This leaf specifies the transport protocol used
             to deliver messages destined for the receiver.  Each 
             protocol may use the address and port information 
             differently as applicable.";
        }
      }
    }
  }

  grouping error-identifier {
    description
      "A code passed back within an RPC response to describe why the RFC
       has failed, or within a state change notification to describe why
       the change has occurred.";
    leaf error-id {
      type subscription-errors;
      mandatory true;
      description
        "Identifies the subscription error condition.";
    }
  }
    
  grouping hints {
    description
      "Objects passed back within an RPC response to describe why the 
       RFC has failed, or within a state change notification to 
       describe why the change has occurred.";
    leaf filter-failure { 
      type string;
      description
        "Information describing where and/or why a provided filter was
        unsupportable for a subscription.";
    }
  }
  
  grouping subscription-response-with-hints {
    description
      "Defines the output for the establish-subscription and
       modify-subscription RPCs.";
    leaf subscription-result {
      type subscription-result;
      mandatory true;
      description
        "Indicates whether subscription is operational, or if a problem
         was encountered.";
    }
    choice result {
      description
        "Depending on the subscription result, different data is 
         returned.";
      case no-success {
        description
          "This case applies when a subscription request was not
           successful and no subscription was created (or modified) as a
           result.  In this case, information MAY be returned that
           indicates suggested parameter settings that would have a 
           high likelihood of succeeding in a subsequent establish-
           subscription or modify-subscription request.";
        uses hints;
      }
    }
  }
  
  /*
   * 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 (as indicated by 
       subscription-result) is returned, the subscription is not 
       created.  In that case, the RPC reply MAY include suggested
       parameter settings that would have a higher likelihood of 
       succeeding in a subsequent establish-subscription request.";
    input {
      uses subscription-policy;
    }
    output {
      uses subscription-response-with-hints  {
        augment "result" {
          description
            "Allows information to be passed back as part of a
             successful subscription establishment.";
          case success {
            description
              "This case is used when the subscription request was
               successful.";
            leaf identifier {
              type subscription-id;
              mandatory true;
              description
                "Identifier used for this subscription.";
            }
          }
        }
        augment "result/no-success" {
          description
            "Contains establish RPC specific objects which can be 
             returned as hints for future attempts.";
          leaf replay-start-time-hint {
            type yang:date-and-time;
            description
              "If a replay has been requested, but the requested replay
                 time cannot be honored, this may provide a hint at an
               alternate time which may be supportable.";
          }
        }
      }
    }
  }
  
  rpc modify-subscription {
    description
      "This RPC allows a subscriber to modify a subscription that was
       previously created using establish-subscription.  If successful,
       the changed subscription remains in effect for the duration of 
       the subscriber's association with the publisher, or until the
       subscription is again modified or terminated.  In case an error 
       is returned (as indicated by subscription-result), the 
       subscription is not modified and the original subscription
       parameters remain in effect.  In that case, the rpc error 
       response MAY include suggested parameter hints that would have 
       a high likelihood of succeeding in a subsequent 
       modify-subscription request.";
    input {
      leaf identifier {
        type subscription-id;
        description
          "Identifier to use for this subscription.";
      }
      uses subscription-policy-modifiable;
    }
    output {
      uses subscription-response-with-hints;
    }
  }
  
  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.";
    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.";
      }
    }
    output {
      leaf subscription-result {
        type subscription-result;
        mandatory true;
        description
          "Indicates whether subscription has been deleted, or if a 
          problem was encountered.";
      }
    }
  }
  
  rpc kill-subscription {
    description
      "This RPC allows an operator to delete a dynamic subscription 
      without restrictions on the originating subscriber or underlying 
      transport session.";
    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.";
      }
    }
    output {
      leaf subscription-result {
        type subscription-result;
        mandatory true;
        description
          "Indicates whether subscription has been killed, or if a 
           problem was encountered.";
      }
    }
  }
  
  /*
   * NOTIFICATIONS
   */

  notification replay-completed {
    sn:subscription-state-notif;
    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-notif;
    description
      "This notification is sent to indicate that a subscription has
       finished passing events.";
    leaf identifier {
      type subscription-id;
      mandatory true;
      description
        "This references the gracefully completed subscription.";
    }
  }

  notification subscription-started {
    sn:subscription-state-notif;
    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;
  }
  
  notification subscription-resumed {
    sn:subscription-state-notif;
    description
      "This notification indicates that a subscription that had
       previously been suspended has resumed. Notifications will once
       again be sent.";
    leaf identifier {
      type subscription-id;
      mandatory true;
      description
        "This references the affected subscription.";
    }
  }
  
  notification subscription-modified {
    sn:subscription-state-notif;
    description
      "This notification indicates that a subscription has been 
       modified.  Notifications sent from this point on will conform to
       the modified terms of the subscription.  For completeness, this 
       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;
  }
  
  notification subscription-terminated {
    sn:subscription-state-notif;
    description
      "This notification indicates that a subscription has been
       terminated.";
    leaf identifier {
      type subscription-id;
      mandatory true;
      description
        "This references the affected subscription.";
    }
    uses error-identifier;
    uses hints;
  }

  notification subscription-suspended {
    sn:subscription-state-notif;
    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.";
    }
    uses error-identifier;
    uses hints;
  }

  /*
   * DATA NODES
   */

  container streams {
    config false;
    description
      "This container contains information on the built-in streams 
      provided by the publisher.";
    list stream {
      key "stream";
      description
        "Identifies the built-in streams that are supported by the
         publisher.";
      leaf stream {
        type stream;
        description
          "A handle for a sequential set of events, each of which 
           is characterized by its own domain and semantics.
           In case configurable custom streams are supported,
           as indicated by the custom-stream identity, the configuration
           of those custom streams is provided separately.";
      }
      leaf description {
        type string;
        mandatory true;
        description
          "A description of the event stream, including such information 
           as the type of events that are sent over this stream.";
      }
      leaf replay-support {
        type empty;
        description
          "Indicates that event replay is available on this stream.";
      }
      leaf replay-log-creation-time {
        type yang:date-and-time;
        description
          "The timestamp of the creation of the log used to support the 
          replay function on this stream. Note that this might be 
          earlier then the earliest available notification in the log.  
          This object is updated if the log resets for some reason.  
          This object MUST be present if replay is supported.";
      }
      leaf replay-log-aged-time {
        type yang:date-and-time;
        description
          "The timestamp of the last notification aged out of the log. 
          This object MUST be present if replay is supported and any 
          notifications 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 event-filter {
      key "identifier";
      description
        "A list of pre-positioned filters that can be applied to
         event subscriptions.";
      leaf identifier {
        type filter-id;
        description
          "An identifier to differentiate between filters.";
      }
      uses event-filter-elements;
    }
  }
  
  container subscription-config {
    if-feature "configured-subscriptions";
    description
      "Contains the list of subscriptions that are configured,
       as opposed to established via RPC or other means.";
    list subscription {
      key "identifier";
      description
        "Content of a subscription.";
      leaf identifier {
        type subscription-id;
        description
          "Identifier to use for this subscription.";
      }
      uses subscription-policy;
      uses receiver-info;
      uses notification-origin-info;
    }
  }
  container subscriptions {
    config false;
    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
        "Content of a subscription. Subscriptions can be created using 
         a control channel or RPC, or be established through 
         configuration.";
      leaf identifier {
        type subscription-id;
        description
          "Identifier of a subscription; unique within a publisher";
      }
      leaf configured-subscription {
       if-feature "configured-subscriptions";
       type empty;
       description
         "The presence of this leaf indicates that the subscription
          originated from configuration, not through a control channel 
          or RPC.";
      }
      uses subscription-policy;
      uses notification-origin-info {
        if-feature "configured-subscriptions";
      }
      uses receiver-info {
        augment receivers/receiver {
          description
            "include operational data for receivers.";
          leaf pushed-notifications {
            type yang:counter64;
            description
              "Operational data which provides the number of update
               notifications pushed to a receiver.";
            } 
          leaf excluded-notifications {
            type yang:counter64;
            description
              "Operational data which provides the number of events
               from a stream explicitly removed via filtering so that 
               they are not sent to a receiver.";
            }
          leaf status {
            type subscription-status;
            mandatory true;
            description
              "The status of the subscription.";
          }            
        }
      }
    }
  }
}