Lets say i have user A and user B.
in my database i have a table called clients and every client is mapped to A or B.
if user A log in i want to load his data to a grid of clients , and if i refresh my page the user logs out
how i can store the logged in users to spring context holder? or vaadin?
If you’re using Spring, then SessionRegistry might help you do that. Otherwise, you might have to implement it manually by listening for events when users log in and log out.
There’s nothing like this enabled by default for security reasons - even a small mistake anywhere in the application might have serious consequences if data about all sessions is readily available.
Is vadin has its own methods to handle that without using the spring security?
im lost 
Nope (at least not based on my understanding of what you try to acheive)
Alright, thanks anyway i will try to solve it