Hello.
This part in current QuickOPC version (2022.1 as of today) is based on OPC UA specification version 1.04. The features you are referring to are from version 1.05.01.
The configuration access is read-only in this QuickOPC version. It simply uses OPC UA Read-s and Browse-s to obtain the pieces of information from the various node in the PubSub configuration model.
There is a special case: We have a provision for a FileType node present in servers based on Unified Automation SDK which contains the whole configuration. When available, we read the whole file at once, and then provide the information from memory, which is faster. (this feature can be turned off).
This is based on approach that Unified Automation has implemented in their own way in their SDKs originally. OPC UA specification 1.05.01 came out later, and is quite similar but slightly different (for start, the name of the FileType node is different), so we do not support it yet. Some future QuickOPC version will support 1.05.01 too.
The IUAReadOnlyPubSubConfiguration is a higher-level API, which makes it easier to "consume" the PubSub configuration in the client code. Of course you can always write a lower-level code and work with the PubSub objects in the usual way. The upcoming QuickOPC version 2022.2 will bring in the 1.05.01 data types, which means that types like PubSubConfiguration2DataType will be returned as .NET SDK structures,
Feel free to ask if something is not clear.
Best regards
