The controller handles incoming requests and puts any data the client needs into a component called a model. When the controller's work is done, the model is passed to a view component for rendering.

I'm interested to hear discussion on patterns for multi-tier applications having a central (in-house, internal network) datadatabase, but multiple UI clients across multiple platforms (HTML5, Android, ...

You have a Contoller class called Adminstration that only admins should use. There's about a dozen Action methods in the Controller class and they all should only be accessed by users in the Admin or ...