Uber Style Web App

Hello Fellow Ruby Devs,

I'm currently in need of your support. I would like to develop a fast
transaction market place web app like Uber, but with a different theme
on Ruby on Rails. I know Uber was developed using Angular.JS. But, can
you help me define the architecture behind the app in a ruby setting?

What approach should I take and how can I build a concurrency back-end
to support the API?

Thank You