Terminology

Term	Definition
Configured Subscription	A static Subscription which persists across reboots.
Data Node	An instance of management information in a datastore.
Data Node Filter	A Filter which removes Update Records from an Update Notification as per policy within the Subscription.
Data Node Security Filter	A Filter which removes Update Records from an Update Notification as per the permissions of the Receiver.
Data Node Update	A data item containing the current value/property of a Data Node at the time the Data Node Update was created.
Dynamic Subscription	A Subscription negotiated between Subscriber and Publisher via create, establish, modify, and delete RPC control plane signaling messages.
Datastore	A conceptual store of instantiated information, with individual data items represented by Data Nodes which are arranged in hierarchical manner.
Event	An occurrence of something that may be of interest. (e.g., a configuration change, a fault, a change in status, crossing a threshold, status of a flow, or an external input to the system.)
Event Notification	A set of information intended for a Receiver indicating that one or more Event(s) have occurred. Details of the Event(s) may be included within the Notification.
Event Stream	A continuous, ordered set of Events grouped under an explicit criteria.
Filter	Match criteria which may be applied against an Event Stream.
Notification	The communication of an occurrence, perhaps triggered by the occurrence of an Event.
Publisher	An entity responsible for streaming Event Notifications per the terms of a Subscription.
Receiver	A target to which a Publisher pushes Event Notifications. For Dynamic Subscriptions, the Receiver and Subscriber will often be the same entity.
Subscriber	An entity able to request and negotiate a contract for the receipt of Event Notifications from a Publisher
Subscription	A contract between a Subscriber and a Publisher stipulating which information the Receiver wishes to have pushed from the Publisher without the need for further solicitation.
Subscription Policy	A policy that specifies under what circumstances to create an Event Notification.
Update Notification	An Event Notification including those Data Node Update(s) to be pushed in order to meet the obligations of a single Subscription. All included Data Node Updates must reflect the state of a Datastore at a snapshot in time.
Update Record	A representation of a Data Node Update as a data record. An Update Record can be included as part of an Update Stream. It can also be logged for retrieval. In general, an Update Record will include the value/property of a Data Node. It may also include information about the type of Data Node Update, i.e. whether the data node was modified/updated, or newly created, or deleted.
Update Record Filter	A Filter which selects Update Notifications of interest per the policy of a Subscription.
Update Stream	A conceptual Event Stream that streams the contents of an entire Datastore continuously and perpetually.
Update Trigger	A trigger, as specified by a Subscription Policy, that determines when a Data Node Update is to be communicated. (e.g., a change trigger, invoked when the value of a Data Node changes or a data node is created or deleted, or a time trigger, invoked after the laps of a periodic time interval.)