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rtfm!
https://ru.wikipedia.org/wiki/Model-View-Controller
https://commons.wikimedia.org/wiki/File:MVC-Process.png?uselang=ru
http://stackoverflow.com/questions/2832017/what-is-the-difference-between-loose-coupling-and-tight-coupling-in-object-orien
http://habrahabr.ru/post/206684/


model SHOULD NOT know anything about controllers and so on