Explain about frontend and backend?

Question

ExtJS/Sencha

Hello! The question may seem stupid to someone, but ...
I want to write a web interface for my Internet gateway in the style of Kerio Control. I take ExtJS, I make tabs, controls. And then what? How is the relationship between frontend and backend done? how to make a backend, in the form of separate scripts or as a service? Who has a similar experience, tell me.
I googled about creating web applications, but only django and ruby-with-rails come up in requests.

Answer 1

How is the relationship between frontend and backend done?

According to the HTTP protocol, as a transport + communication protocol (API) client-server specifically for your needs. The last one you do yourself.
)) books are written about this in N volumes, do you really think that you will get a complete answer in the form of a short commentary?
Seriously, at least indicate the language in which you are going to write the backing.

Answer 2

I may not write to the cashier - but there is cms Drupal