BASE_URL/component/controller/method/arg/s

And the paths:

/back/components/controllers/controller.php

/back/components/models/model.php

/back/components/views/view.php

Example request: https://borjaabad.com/back/login

/back/login/controllers/indexController.php

/back/login/models/usuarioModel.php

/back/login/views/index/login.phhtml

Note: in the previous example, the view is nested one directory deeper, in a directory named after the controller that invokes it.
If the component controller does not exist, the method is looked up in indexController:

/back/component/controller/method/arg/s

This allows:

/back/login/index/validar/arg/s

To become:

/back/login/validar/arg/s