What is the best way to create a backend for applications?

Question

Programming

I write apps for desktop and mobile devices. For desktop it's C++/C#, for mobile it's Java.
The question is: how best to do the backend?
REST or using sockets? What is the best language to write in? What is more productive? What DBMS to use?

Answer 1

This weekend, the data is any base, any protocol. Need more details for recommendation

Answer 2

Advise YaPy and the type of backend. What would you use in such a task?

I would do it on naked JS and naked PHP, don’t go to the grandmother (naked) (naked).
It will work with reinforced concrete, as a bonus you will get a huge experience.
Sockets then pour to taste.