Which back ends can an ORMIT™-OpenJava Oracle Forms migration use?

Two: a Java (Spring Boot) back end with a Node.js validation service, or a back end written entirely in Node.js. The 100% Node.js version loads and builds faster and uses less memory. You can switch from one to the other during the project or later, with no rework: the same code is regenerated for the other back end. There is no Java-only option, because the validation rules must run in the same language in the browser and on the server.