.. _glossary:

OPC UA Glossary
===============

.. glossary::

  Address Space
    collection of information that an OPC UA Server makes visible to its Clients

  Attribute
    data element of :term:`Node` which can be read and written by a Client

  BrowseName
    attribute of :term:`Node` contains its human-readable name

  Communication Stack
    layered set of software modules between the application and the hardware that provides various
    functions to encode, encrypt and format a Message for sending, and to decode, decrypt and unpack
    a Message that was received

  Endpoint
    physical address available on a network that allows Clients to access one
    or more :term:`Service`\ s provided by a Server

  Discovery
    mechanism which allows OPC UA Clients to find OPC UA Servers on the network

  DiscoveryUrl
    a URL for a network :term:`Endpoint` that provides the information required
    to connect to a Server

  Information Model
    organizational framework that defines, characterizes and relates information
    resources of a given system or set of systems.

  Method
    callable software function that is a component of an :term:`Object`

  Node
    fundamental component of an :term:`Address Space`

  Object
    :term:`Node` that represents a physical or abstract element of a system

  ObjectType
    :term:`Node` that represents the type definition for an :term:`Object`

  Reference
    explicit relationship (a named pointer) from one :term:`Node` to another

  Secure Channel
    a long-term logical connection between a single client and a single server on
    :term:`Communication Stack`'s level

  Service
    client-callable operation in an OPC UA Server

  Session
    a long-term logical connection between a single client and a single server
    on OPC UA application level

  Variable
    :term:`Node` that contains a value