@PreserveOnRefresh - Purpose and need?

Question

I have a doubt regarding the purpose of @PreserveOnRefresh annotation. What is the purpose of this particular annotation and what are the scenarios in which it has to be use

Answer 1

When the enduser does press F5 (or click Refresh) in the web browser, then the behaviours is:

With @PreserveOnRefresh -> Use the same session, just refresh the UI from the server state

Without @PreserveOnRefresh -> Vaadin is creating a new session for the user and the user is shown the "first" page of your application

So usually the @PreserveOnRefresh is the intended behaviour, otherwise the user is logged out when he clicks on refresh