A plugin that responds to an action

yo. creating first plugin.
Is it not possible to create a plugin that defines controller actions?

module Foo def on_callback render_text 'foo', :layout => false end end ActionController::Base.send(:include, Foo) . . . http://url:3000/controller/on_callback "ActionController::UnknownAction (No action responded to on_callback):"

but the following will work:

def ApplicationController < ActionController::Base
include Foo
end
.
.
.
http://url:3000/controller/on_callback
‘foo’

I found the answer to my question here
http://www.robbyonrails.com/xml/atom/article/22486/feed.xml

see “un-hiding actions” at bottom of page.