A Serveroften has no direct access to the information that it manages. Variables or services might be in underlying systems where additional effort is required to establish a connection to these systems. The RegisterNodes Servicecan be used by Clientsto register the Nodesthat they know they will access repeatedly (e.g. Write, Call). It allows Serversto set up anything needed so that the access operations will be more efficient. Clientscan expect performance improvements when using registered NodeIds, but the optimization measures are vendor-specific. For Variable Nodes Serversshall concentrate their optimization efforts on the Value Attribute.

RegisteredNodeIdsare only guaranteed to be valid within the current Session. Clientsshall unregister unneeded Ids immediately to free up resources.

RegisterNodesdoes not validate the NodeIdsfrom the request. Serverswill simply copy unknown NodeIdsin the response. Structural NodeIderrors (size violations, invalid id types) will cause the complete Serviceto fail.

For the purpose of Auditing, Serversshall not use the registered NodeIdsbut only the canonical NodeIds which is the value of theNodeId Attribute.