Mendix app connection with existing code

I am fully unfamiliar to Mendix and wondering about possible ways to connect (or extend) Mendix app to the existing code written in NodeJS. Assuming some data have to be passed, for example, with REST API between Mendix app and existing code.  Is there some tutorial or workshop on this topic with the best way to start? Is there a support for other languages, besides Java on the backend side? Are there any example of Java backends, somewhere in templates or other sources?      
1 answers
  1. On this is the most logical one to check: Btw publish any entity (table) is rightclicking the entity, create your service and you’re done. Then see what you have published on https://<your_apps_url>/rest-doc/
  2. No, the Mendix backend is Java.
  3. No, there are none because Mendix backend is proprietary code.

There are also options to create React-widgets that allow you to connect via frontend.