In OPC UA 1.04 we defined add/remove methods at each level of the PubSub configuration hierarchy to add and remove individual items or sub-trees. There was no way to modify existing items and combine this with other changes to the tree in an atomic operation.

In OPC UA 1.05, we add configuration via the PubSubConfiguration object with file transfer of a delta configuration and the ability to apply all changes in an atomic operation, including the option not to apply the changes if errors occur.

This feature was developed in conjunction with the OPC UA FX working group, which had similar requirements. The OPC UA FX EstablishConnections and the PubSubConfiguration object with CloseAndUpdate use the same basic functionality to apply PubSub configuration changes as a delta configuration in one atomic operation.

Now we have a new and complete mechanism that completely replaces the partial OPC UA 1.04 configuration option with individual methods.

It would make sense to mark the optional methods as deprecated in a future release.