OPC UA Part 1 - Overview and Concepts 1.02 Specification(11)

OPC UA Specification Part1 OverView and Concepts

Release 1.02 3 OPC Unified Architecture, Part 1

3.1.11 EventNotifier

A special Attribute of a Node that signifies that a Client may subscribe to that particular Node to receive Notifications of Event occurrences.

3.1.12 Information Model

An organizational framework that defines, characterizes and relates information resources of a given system or set of systems. The core address space model supports the representation of Information Models in the AddressSpace. See Part 5 for a description of the base OPC UA Information Model.

3.1.13 Message

The data unit conveyed between Client and Server that represents a specific Service request or response.

3.1.14 Method

A callable software function that is a component of an Object.

3.1.15 MonitoredItem

A Client-defined entity in the Server used to monitor Attributes or EventNotifiers for new values or Event occurrences and generate Notifications for them.

3.1.16 Node

The fundamental component of an AddressSpace.

3.1.17 NodeClass

The class of a Node in an AddressSpace. NodeClasses define the metadata for the components of the OPC UA Object Model. They also define constructs, such as Views, that are used to organize the AddressSpace.

3.1.18 Notification

The generic term for data that announces the detection of an Event or of a changed Attribute value. Notifications are sent in NotificationMessages.

3.1.19 NotificationMessage

A Message published from a Subscription that contains one or more Notifications.

3.1.20 Object

A Node that represents a physical or abstract element of a system. Objects are modelled using the OPC UA Object Model. Systems, subsystems and devices are examples of Objects. An Object may be defined as an instance of an ObjectType.

3.1.21 Object Instance

A synonym for Object. Not all Objects are defined by ObjectTypes.