Server which is currently sourcing information
Note 1 to entry: In OPC UA redundant systems, an Active Server is the Server that a Client is using as the source of data.
permitted range for value changes that will not trigger a data change Notification
Note 1 to entry: Deadband can be applied as a filter when subscribing to Variables and is used to keep noisy signals from updating the Client unnecessarily. This document defines AbsoluteDeadband as a common filter. OPC 10000-8 defines an additional Deadband filter.
Endpoint that allows Clients access to Discovery Services without security
Note 1 to entry: A DiscoveryEndpoint allows access to Discovery Services without a Session and without message security.
physical address available on a network that allows Clients to access one or more Services provided by a Server
Note 1 to entry: Each Server may have multiple Endpoints. Each Endpoint includes a HostName.
public-private key pair generated for each execution of a key establishment process.
Note 1 to entry: EphemeralKeys are necessary when using ECC based SecurityPolicies.
Server that is not operational.
Note 1 to entry: In OPC UA redundant system, a Failed Server is a Server that is unavailable or is not able to serve data.
act of switching the source or target of information.
Note 1 to entry: In OPC UA redundant systems, a Failover is the act of a Client switching away from a failed or degraded Server to another Server in the redundant set (Server failover). In some cases a Client may have no knowledge of a Failover action occurring (transparent redundancy). A Client failover is the act of an alternate Client replacing an existing failed or degraded Client connection to a Server.
Server that acts as an intermediary for one or more Servers
Note 1 to entry: Gateway Servers may be deployed to limit external access, provide protocol conversion or to provide features that the underlying Servers do not support.
unique identifier for a machine on a network
Note 1 to entry: This identifier is unique within a local network; however, it may also be globally unique. The identifier can be an IP address.
presence of duplicate components enabling the continued operation after a failure of an OPC UA component
Note 1 to entry: This may apply to Servers, Clients or networks.
two or more Servers that are redundant with each other
Note 1 to entry: A Redundant Server Set is a group of Servers that are configured to provide Redundancy. These Servers have requirements related to the address space and provide Failovers.
identifier for a cryptographic key set
Note 1 to entry: All SecurityTokens belong to a security context. For OPC UA the security context is the SecureChannel.
ApplicationUri for a Server
digital certificate for a software product that can be installed on several hosts to describe the capabilities of the software product
Note 1 to entry: Different installations of one software product could have the same software certificate. Software certificates are not relevant for security. They are used to identify a software product and its supported features. SoftwareCertificates are described in 6.4.