What technologies should be chosen when writing a mobile application?

Question

PostgreSQL

In general, I need to solve the following problem.
Write a mobile application on Android with a base on postgresql and there must be an Internet connection using a wifi network. It is very multiple.
Be sure to say to use Xamarin for mobile development and the PostgreSQL database. And the essence of the program is the order of products when connected to a wifi network. In this grid there is a server with which the client (phone) communicates, processes and shows what the client ordered and what needs to be brought.
I would like to know what technologies and in which direction to look. How will it be easier and easier to implement this application, where to start? How to write a server? In what language? In general, if you had a need to write such an application, share your experience.

Answer 1

How will it be easier and easier to implement this application, where to start?

Which you know better, including the ability to connect to PostgreSQL.
On the server from the "external" side, I recommend doing a REST API with JSON responses, but before that, be sure to think about what will happen next with these orders, do you need an "admin panel", any other Web interface, this is a very important question, it defines the tools used on the server, because of this, I had to abandon the Slim Framework in favor of Yii2, the first one would seem to be better suited for the REST API and not so cumbersome, but the second one can quickly make both the Web interface and the REST API.