OPC UA Specification Part1 OverView and Concepts
OPC Unified Architecture, Part 1 4 Release 1.02
3.1.22 ObjectType
A Node that represents the type definition for an Object.
3.1.23 Profile
A specific set of capabilities, defined in Part 7, to which a Server may claim conformance. Each Server may claim conformance to more than one Profile.
3.1.24 Program
An executable Object that, when invoked, immediately returns a response to indicate that execution has started, and then returns intermediate and final results through Subscriptions identified by the Client during invocation.
3.1.25 Reference
An explicit relationship (a named pointer) from one Node to another. The Node that contains the Reference is the source Node, and the referenced Node is the target Node. All References are defined by ReferenceTypes.
3.1.26 ReferenceType
A Node that represents the type definition of a Reference. The ReferenceType specifies the semantics of a Reference. The name of a ReferenceType identifies how source Nodes are related to target Nodes and generally reflects an operation between the two, such as “A Contains B”.
3.1.27 RootNode
The beginning or top Node of a hierarchy. The RootNode of the OPC UA AddressSpace is defined in Part 5.
3.1.28 Server
A software application that implements and exposes the Services specified in this set of specifications.
3.1.29 Service
A Client-callable operation in an OPC UA Server.Services are defined in Part 4. A Service is similar to a method call in a programming language or an operation in a Web services WSDL contract.
3.1.30 Service Set
A group of related Services.
3.1.31 Session
A logical long-running connection between a Client and a Server. A Session maintains state information between Service calls from the Client to the Server.
3.1.32 Subscription
A Client-defined endpoint in the Server, used to return Notifications to the Client. Generic term that describes a set of Nodes selected by the Client(1) that the Server periodically monitors for the