any real world example in RSA with ORDS in oracle

Question

I'm using ORDS. I'm going to use RAS(real application security) or VPD to control authorization. I read oracle RAS documentation and I didn't catch how to use it with ORDS(without apex). and this is true for using VPD, I created user in ords.war but I can't find this user in database and it's just create in ORDS layer, I don't know how to find out which user connected to DB for applying VPD policies. my question is how to define application users and connect with them ORDS and get response from ORDS.

For example:
I have a schema that is rest enabled and authorization is required, now for access it's endpoints I saw some videos that add users with ords.war file and login with it and get data, but that's not my problem I want to add some application users (principals in RAS) and set roles to them and apply row level securities. I hope it's be clear.

I'm appreciate in advance.