What architecture does an ORMIT™-OpenJava Oracle Forms migration produce?

There are three tiers. The browser runs a React or Angular application, which talks only to a REST API back end. That back end is written in Java (Spring Boot) or entirely in Node.js (see the back ends), and it reads and writes the Oracle database. Before each save, the form's validation rules run again on the server, in Node.js. The database and its PL/SQL stay as they are.