How to design a module for Bitrix?

Question

1C-Bitrix

Hello, I need to design a module for Bitrix that would accept a request, for example: placing an order, etc. and gave the result. The result is received and returned via JSON. What do you think is the best way to build a system? I have controller classes and command classes and I want to make a parser class that accepts an input request and performs checks and validations and provides methods to retrieve data. How justified is this?