How to move from Zend_Auth to Symfony, and use session in Symfony



I am trying to moving from Pimcore 4 to PImcore 5.
We are using Zend_Auth and Website_AuthAdapter to authenticate user and create session on our website.

I read the “Authenticate against Pimcore Objects” in the dev doc, but I still don’t understand on how to use it like Zend_Auth.

Another thing is the Symfony Session.
I know how to create session and read them on the fly.
$authSession = new Zend_Session_Namespace(‘Zend_Auth’);
$authSession->UIDs[‘somthing’] = array(“page” => 1, “mode” => 1);

I also read the “working with Sessions” in dev doc. It seems I will have to define all session namespace before hand in the SeesionCartConfigurator. Am I understand it right?
How I define and access session namespace on the fly like Zend_Session?

Thank you.