To a Client the transparent Redundant Server Set appears as if it is just a single Server and the Client has no Failoveractions to perform. All Serversin the Redundant Server Sethave an identical ServerUriand an identical EndpointUrl.

Figure 26shows a typical transparent Redundancysetup.


Figure 26– Transparent Redundancy setup example

For transparent Redundancy, OPC UA provides data structures to allow Clientsto identify which Serversare in the Redundant Server Set, the ServiceLevelof each Server, and which Server is currently responsible for the Client Session. This information is specified in TransparentRedundancyType ObjectTypedefined in OPC 10000-5. Since the ServerUriis identical for all Serversin the Redundant Server Set, the Serversare identified with a ServerIdcontained in the information provided in the TransparentRedundancyType Object.

In transparent Redundancy, a Clientis not able to control which physical Serverit actually connects to. Failoveris controlled by the Redundant Server Setand a Clientis also not able to actively Failoverto another Serverin the Redundant Server Set.