AggregatingServers can be used to collect information from multiple underlying Servers and add additional functionality to the information and/or source the information for higher-level applications, offloading the underlying Servers. The Information Model that is defined in this document can be aggregated. This clause provides some explanation regarding the aggregation of AutomationComponents and ConnectionManagers.
The AutomationComponent(s) can be reflected in a higher-level Server. This reflection can include Assets and FunctionalEntities, but it is expected that the communication model (between FunctionalEntities) will only exist in the actual Servers, not in the AggregatingServer. Any actions performed against the AutomationComponent in the AggregatingServer are expected to be passed down and performed on the actual Server, including any method calls. Also, only the status/configuration information from a ConnectionEndpoint would be mirrored. ControlGroup information may be displayed in an AggregatingServer. Still, all data just reflects data from the underlying Servers, so changes to values would only occur in the underlying Server and could only be made if no locks are in place. Any writes or Method calls made against an AutomationComponent on an AggregatingServer would need to be applied against the AutomationComponent in the underlying Server. The value in the AggregatingServer would only be updated due to mirroring the change in the underlying Server. The value would not be directly updated in the AggregatingServer.
An AggregatingServer may add functionality, such as the generation of Alarms or historization. It may also be the source of data for higher-level applications such as HMIs or advanced control applications. Multiple AutomationComponents from multiple Servers could be included under a single AggregatingServer.
An AggregatingServer may expose a ConnectionManager, but only one well-known ConnectionManager is allowed on a Server. This single ConnectionManager may reflect the ConnectionConfigurationSets from underlying Servers. It may directly execute any commands it receives or pass the commands down to the underlying Servers.