Experimental Physics and
Industrial Control System

Correct.

Well, in a way, yes, nah, almost.

The database is the database. CA (client) to database mapping is handled by link support calling into the CA client library. Database to PVA mapping is done inside QSRV.

Do you mean PVA to CA when writing through that IOC? That works when the QSRV mapping is done in the right way (which is not always trivial).

Or another IOC that maps a device speaking PVA into a flat CA control system namespace? Don't really know.

That kind of mapping can be done in QSRV, where you can basically create a structure by pointing leaves to record fields in the database.

Again: you're mapping the elements of a PVA structure that QSRV serves up to fields of records in the EPICS database. CA is not involved on this end.

The fact that records can use CA to connect to other IOCs (or other devices running a CA server) is unrelated.

Your clients connect to a normal EPICS IOC using PVA, and you're effectively using CA as a field bus below the IOC, conceptually similar to Modbus, SCPI, EtherCAT, OPC UA, ...

Cheers,
~Ralph