Ruby on Rails

Here is how the concept of Model, View, Controller (MVC) fits into rails.

1. ActiveRecord is the Model. Business logic is here
2. ActionView is the View. HTML and XML goes here
3. ActionController is the Controller. The routing requests and their processing goes in here
4. ActiveResource: Support for RESTful APIs.
5. Active Support: JSON glue/helpers, All extensions to Ruby base classes and other "stuff"

I need to get more definition on items 3, 4 and 5.