RE: File Observation

Observing file changes isn’t really a Vaadin-specific question - see
Stackoverflow for some answers

In a Vaadin application, you probably need to do observing in a background thread, which require special consideration, as Vaadin UIs are normally only updated on client-server requests. You can use either
to communicate UI changes to the browser. There’s also thread-safety issues; to communicate with UIs that show the file contents, you need to use the access() method to lock the session during access.