An alternative approach, taking the ownership of the instance into account, is to provide Methods to add or remove Nodes on the parent where the new Node is to be added or removed.

This is a more intuitive approach for client users as they directly experience where the new Node is added or an existing one can be removed, and from a server developer’s perspective fits better to the place where the functionality would be implemented.

Examples of this approach can be found in the PubSub configuration of OPC 10000-14. For example, the PubSubConnectionType allows you to add a WriterGroup with the AddWriteGroup Method or a ReaderGroup with a AddReaderGroup Method, and to delete them with the RemoveGroup Method. Those added groups become direct children of instances of the PubSubConnectionType. See Figure 8 for a graphical representation, taken from OPC 10000-14. A Server may have several instances of those, and the Object on which the Method is called, gives the context where an instance is added or removed.

Figure 8 – Example of Methods at the place the instance is located (taken from OPC 10000-14)