module ietf-yang-push {

    yang-version 1;

    namespace
      "urn:ietf:params:xml:ns:yang:ietf-yang-push";

    prefix yp;

    import ietf-inet-types {
      prefix inet;
    }
    import ietf-yang-types {
      prefix yang;
    }
    import ietf-event-notifications {
      prefix notif-bis;
    }

    organization "IETF";

    contact
      "WG Web:   <http://tools.ietf.org/wg/netconf/>
WG List:  <mailto:netconf@ietf.org>

WG Chair: Mahesh Jethanandani
	  <mailto:mjethanandani@gmail.com>

WG Chair: Mehmet Ersue
	  <mailto:mehmet.ersue@nokia.com>

Editor:   Alexander Clemm
	  <mailto:alex@sympotech.com>

Editor:   Eric Voit
	  <mailto:evoit@cisco.com>

Editor:   Alberto Gonzalez Prieto
	  <mailto:albertgo@cisco.com>

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

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

Editor:   Andy Bierman
	  <mailto:andy@yumaworks.com>

Editor:   Balazs Lengyel
	  <mailto:balazs.lengyel@ericsson.com>";

    description
      "This module contains conceptual YANG specifications
for YANG push.";

    revision "2021-03-01" {
      description
        "Correct datastore-*-string to datastore-*-xml";
    }

    revision "2016-10-28" {
      description
        "Updates to simplify modify-subscription, add anchor-time";
      reference
        "YANG Datastore Push, draft-ietf-netconf-yang-push-04";

    }


    feature on-change {
      description
        "This feature indicates that on-change updates are
supported.";
    }

    identity error-data-not-authorized {
      base notif-bis:error;
      description
        "No read authorization for a requested data node.";
    }

    identity yang-push {
      base notif-bis:stream;
      description
        "A conceptual datastream consisting of all datastore
updates, including operational and configuration data.";
    }

    identity custom-stream {
      base notif-bis:stream;
      description
        "A conceptual datastream for datastore
updates with custom updates as defined by a user.";
    }

    identity http2 {
      base notif-bis:transport;
      description
        "HTTP2 notifications as a transport";
    }

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

    typedef change-type {
      type enumeration {
        enum "create" {
          value 0;
          description
            "A new data node was created";
        }
        enum "delete" {
          value 1;
          description
            "A data node was deleted";
        }
        enum "modify" {
          value 2;
          description
            "The value of a data node has changed";
        }
      }
      description
        "Specifies different types of changes that may occur
to a datastore.";
    }

    grouping update-filter {
      description
        "This groupings defines filters for push updates for a
datastore tree.  The filters define which updates are of
interest in a push update subscription.  Mixing and matching
of multiple filters does not occur at the level of this
grouping. When a push-update subscription is created, the
filter can be a regular subscription filter, or one of the
additional filters that are defined in this grouping.";
      choice update-filter {
        description
          "Define filters regarding which data nodes to include
in push updates";
        case subtree {
          description "Subtree filter.";
          anyxml subtree-filter {
            description
              "Subtree-filter used to specify the data nodes targeted
for subscription within a subtree, or subtrees, of a
conceptual YANG datastore.  Objects matching the filter
criteria will traverse the filter. The syntax follows
the subtree filter syntax specified in RFC 6241,
section 6.";
            reference
              "RFC 6241 section 6";

          }
        }  // case subtree

        case xpath {
          description "XPath filter";
          leaf xpath-filter {
            type yang:xpath1.0;
            description
              "Xpath defining the data items of interest.";
          }
        }  // case xpath
      }  // choice update-filter
    }  // grouping update-filter

    grouping update-policy {
      description
        "This grouping describes the conditions under which an
update will be sent as part of an update stream.";
      choice update-trigger {
        description
          "Defines necessary conditions for sending an event to
the subscriber.";
        case periodic {
          description
            "The agent is requested to notify periodically the
current values of the datastore or the subset
defined by the filter.";
          leaf period {
            type yang:timeticks;
            mandatory true;
            description
              "Duration of time which should occur between periodic
push updates.  Where the anchor of a start-time is
available, the push will include the objects and their
values which exist at an exact multiple of timeticks
aligning to this start-time anchor.";
          }

          leaf anchor-time {
            type yang:date-and-time;
            description
              "Designates a timestamp from which the series of
periodic push updates are computed. The next update
will take place at the next period interval from the
anchor time.  For example, for an anchor time at the
top of a minute and a period interval of a minute,
the next update will be sent at the top of the next
minute.";
          }
        }  // case periodic

        case on-change {
          if-feature on-change;
          description
            "The agent is requested to notify changes in
values in the datastore or a subset of it defined
by a filter.";
          leaf no-synch-on-start {
            type empty;
            description
              "This leaf acts as a flag that determines behavior at the
start of the subscription.  When present,
synchronization of state at the beginning of the
subscription is outside the scope of the subscription.
Only updates about changes that are observed from the
start time, i.e. only push-change-update notifications
are sent.
When absent (default behavior), in order to facilitate
a receiver's synchronization, a full update is sent
when the subscription starts using a push-update
notification, just like in the case of a periodic
subscription.  After that, push-change-update
notifications only are sent unless the Publisher chooses
to resynch the subscription again.";
          }

          leaf dampening-period {
            type yang:timeticks;
            mandatory true;
            description
              "Minimum amount of time that needs to have
passed since the last time an update was
provided.";
          }

          leaf-list excluded-change {
            type change-type;
            description
              "Use to restrict which changes trigger an update.
For example, if modify is excluded, only creation and
deletion of objects is reported.";
          }
        }  // case on-change
      }  // choice update-trigger
    }  // grouping update-policy

    grouping subscription-qos {
      description
        "This grouping describes Quality of Service information
concerning a subscription.  This information is passed to lower
layers for transport priortization and treatment";
      leaf dscp {
        if-feature notif-bis:configured-subscriptions;
        type inet:dscp;
        default "0";
        description
          "The push update's IP packet transport priority.
This is made visible across network hops to receiver.
The transport priority is shared for all receivers of
a given subscription.";
      }

      leaf subscription-priority {
        type uint8;
        description
          "Relative priority for a subscription.   Allows an
underlying transport layer perform informed load
balance allocations between various subscriptions";
      }

      leaf subscription-dependency {
        type string;
        description
          "Provides the Subscription ID of a parent subscription
without which this subscription should not exist. In
other words, there is no reason to stream these objects
if another subscription is missing.";
      }
    }  // grouping subscription-qos

    augment /notif-bis:establish-subscription/notif-bis:input {
      description
        "Define additional subscription parameters that apply
specifically to push updates";
      uses update-policy;

      uses subscription-qos;
    }

    augment /notif-bis:establish-subscription/notif-bis:input/notif-bis:filter-type {
      description
        "Add push filters to selection of filter types.";
      case update-filter {
        description
          "Additional filter options for push subscription.";
        uses update-filter;
      }  // case update-filter
    }

    augment /notif-bis:establish-subscription/notif-bis:output {
      description
        "Allow to return additional subscription parameters that apply
specifically to push updates.";
      uses update-policy;

      uses subscription-qos;
    }

    augment /notif-bis:establish-subscription/notif-bis:output/notif-bis:result/notif-bis:no-success/notif-bis:filter-type {
      description
        "Add push filters to selection of filter types.";
      case update-filter {
        description
          "Additional filter options for push subscription.";
        uses update-filter;
      }  // case update-filter
    }

    augment /notif-bis:modify-subscription/notif-bis:input {
      description
        "Define additional subscription parameters that apply
specifically to push updates.";
      uses update-policy;
    }

    augment /notif-bis:modify-subscription/notif-bis:input/notif-bis:filter-type {
      description
        "Add push filters to selection of filter types.";
      case update-filter {
        description
          "Additional filter options for push subscription.";
        uses update-filter;
      }  // case update-filter
    }

    augment /notif-bis:modify-subscription/notif-bis:output {
      description
        "Allow to retun additional subscription parameters that apply
specifically to push updates.";
      uses update-policy;

      uses subscription-qos;
    }

    augment /notif-bis:modify-subscription/notif-bis:output/notif-bis:result/notif-bis:no-success/notif-bis:filter-type {
      description
        "Add push filters to selection of filter types.";
      case update-filter {
        description
          "Additional filter options for push subscription.";
        uses update-filter;
      }  // case update-filter
    }

    notification push-update {
      description
        "This notification contains a push update, containing
data subscribed to via a subscription.
This notification is sent for periodic updates, for a
periodic subscription.  It can also be used for
synchronization updates of an on-change subscription.
This notification shall only be sent to receivers
of a subscription; it does not constitute a general-purpose
notification.";
      leaf subscription-id {
        type notif-bis:subscription-id;
        mandatory true;
        description
          "This references the subscription because of which the
notification is sent.";
      }

      leaf time-of-update {
        type yang:date-and-time;
        description
          "This leaf contains the time of the update.";
      }

      leaf updates-not-sent {
        type empty;
        description
          "This is a flag which indicates that not all data nodes
subscribed to are included included with this
update.  In other words, the publisher has failed to
fulfill its full subscription obligations.
This may lead to intermittent loss of synchronization
of data at the client.  Synchronization at the client
can occur when the next push-update is received.";
      }

      anyxml datastore-contents-xml {
        description
          "This contains the updated data.  It constitutes a snapshot
at the time-of-update of the set of data that has been
subscribed to.  The format and syntax of the data
corresponds to the format and syntax of data that would be
returned in a corresponding get operation with the same
filter parameters applied.";
      }
    }  // notification push-update

    notification push-change-update {
      if-feature on-change;
      description
        "This notification contains an on-change push update.
This notification shall only be sent to the receivers
of a subscription; it does not constitute a general-purpose
notification.";
      leaf subscription-id {
        type notif-bis:subscription-id;
        mandatory true;
        description
          "This references the subscription because of which the
notification is sent.";
      }

      leaf time-of-update {
        type yang:date-and-time;
        description
          "This leaf contains the time of the update, i.e. the
time at which the change was observed.";
      }

      leaf updates-not-sent {
        type empty;
        description
          "This is a flag which indicates that not all changes which
have occured since the last update are included with this
update.  In other words, the publisher has failed to
fulfill its full subscription obligations, for example in
cases where it was not able to keep up with a change burst.
To facilitate synchronization, a publisher MAY subsequently
send a push-update containing a full snapshot of subscribed
data. Such a push-update might also be triggered by a
subscriber requesting an on-demand synchronization.";
      }

      anyxml datastore-changes-xml {
        description
          "This contains datastore contents that has changed
since the previous update, per the terms of the
subscription.  Changes are encoded analogous to
the syntax of a corresponding yang-patch operation,
i.e. a yang-patch operation applied to the YANG datastore
implied by the previous update to result in the current
state (and assuming yang-patch could also be applied to
operational data).";
      }
    }  // notification push-change-update

    augment /notif-bis:subscription-started {
      description
        "This augmentation adds push subscription parameters
to the notification that a subscription has
started and data updates are beginning to be sent.
This notification shall only be sent to receivers
of a subscription; it does not constitute a general-purpose
notification.";
      uses update-policy;

      uses subscription-qos;
    }

    augment /notif-bis:subscription-started/notif-bis:filter-type {
      description
        "This augmentation allows to include additional update filters
options to be included as part of the notification that a
subscription has started.";
      case update-filter {
        description
          "Additional filter options for push subscription.";
        uses update-filter;
      }  // case update-filter
    }

    augment /notif-bis:subscription-modified {
      description
        "This augmentation adds push subscription parameters
to the notification that a subscription has
been modified.

This notification shall only be sent to receivers
of a subscription; it does not constitute a general-purpose
notification.";
      uses update-policy;

      uses subscription-qos;
    }

    augment /notif-bis:subscription-modified/notif-bis:filter-type {
      description
        "This augmentation allows to include additional update
filters options to be included as part of the notification
that a subscription has been modified.";
      case update-filter {
        description
          "Additional filter options for push subscription.";
        uses update-filter;
      }  // case update-filter
    }

    augment /notif-bis:filters/notif-bis:filter/notif-bis:filter-type {
      description
        "This container adds additional update filter options
to the list of configurable filters
that can be applied to subscriptions.  This facilitates
the reuse of complex filters once defined.";
      case update-filter {
        uses update-filter;
      }  // case update-filter
    }

    augment /notif-bis:subscription-config/notif-bis:subscription {
      description
        "Contains the list of subscriptions that are configured,
as opposed to established via RPC or other means.";
      uses update-policy;

      uses subscription-qos;
    }

    augment /notif-bis:subscription-config/notif-bis:subscription/notif-bis:filter-type {
      description
        "Add push filters to selection of filter types.";
      case update-filter {
        uses update-filter;
      }  // case update-filter
    }

    augment /notif-bis:subscriptions/notif-bis:subscription {
      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, e.g. establish-subscription, delete-subscription,
and modify-subscription, as well as subscriptions that
have been established via configuration.";
      uses update-policy;

      uses subscription-qos;
    }

    augment /notif-bis:subscriptions/notif-bis:subscription/notif-bis:filter-type {
      description
        "Add push filters to selection of filter types.";
      case update-filter {
        description
          "Additional filter options for push subscription.";
        uses update-filter;
      }  // case update-filter
    }
  }  // module ietf-yang-push