Yes, since we updated to the client library 2.x only .live layers are supported for live sync through Nucleus.
To generate a .live file with the samples, you can run the HelloWorld sample with a -l (“dash L”) flag, this will make helloworld.live which can then be “watched” using this OmniUsdaWatcher.
Another note, I would like to improve OmniUsdaWatcher to output .usd files that are repeatedly saved to disk or Nucleus, but I would fear that it would lead people to believe that they were seeing “live” changes, when in fact it’s just a reloading of the entire file.
Is it okay that I open the live stage file(root.live) in ‘.live/helloworld.live/test.live’ folder for listening change/update events during live session ?
Absolutely! I made this app for this very purpose. When we develop Connectors that make live changes it’s important that they use the USD API to make the proper structural changes to a composed stage. Watching the .live layer like this ensures that the correct things are happening. Actually, the primUtils.h utility was created to help apps do the right things in context of a multilayered stage in a live setting.