Periodic Publication for yang-push With periodic subscriptions, the first push-update with the subscribed information is sent immediately; but it can be delayed if the device is busy or due to network congestion. Updates are then sent at the expiry of the configured periodic timer. For example, if the period is configured as 10 minutes, the first update is sent immediately after the subscription is created and every 10 minutes thereafter. The period is time, in centiseconds (1/100 of a second), between periodic push updates. A period of 1000 will result in getting updates to the subscribed information every 10 seconds. The minimum period that can be configured is 100, or one second.
There is no default value. This value must be explicitly set in the RPC for dynamic subscriptions and in the configuration for configured subscriptions. Periodic updates contain a full copy of the subscribed data element or table for all supported transport protocols. When subscribing for empty data using a periodic subscription, empty update notifications are sent at the requested period. If data comes into existence, its values at the next period are sent as a normal update notification. On-Change Publication for yang-push When creating an on-change subscription, the dampening period must be set to 0 to indicate that there is no dampening period; no other value is supported.
With on-change subscriptions, the first push update is the entire set of subscribed to data (the initial sychronization as defined in the IETF documents). This is not controllable. Subsequent updates are sent when the data changes, and consist of only the changed data. However, the minimum data resolution for a change is a row. So, if an on-change subscription is to a leaf within a row, if any item in that row changes, an update notification is sent. The exact contents of the update notification depend on the transport protocol. In addition, on-change subscriptions are not hierarchical.
That is, when subscribing to a container that has child containers, changes in the child container are not seen by the subscription. Subscriptions for data that does not currently exist are permitted and run as normal subscriptions. The initial synchronization update notification is empty and there are no further updates until data is available. XPath expressions must specify a single object. That object can be a container, a leaf, a leaf list or a list. The yang-notif-native Stream The yang-notif-native stream is any YANG notification in the publisher where the underlying source of events for the notification uses Cisco IOS XE native technology.
This stream also supports an XPath filter that specifies which notifications are of interest. Update notifications for this stream are sent only when events that the notifications are for occur. Since this stream supports only on-change subscriptions, the dampening interval must be specified with a value of 0. XPath Filter for yang-notif-native The dataset within the yang-notif-native stream to be subscribed to is specified by the use of an XPath filter. The following guideline applies to the XPath expression: • XPath expressions must specify an entire YANG notification; attribute filtering is not supported. • The union operator (|) is not supported.
Model-Driven Telemetry Periodic Publication for yang-push Model-Driven Telemetry 39