message.rb

class Message
  extend ActiveModel::Naming
  include ActiveModel::Serializers::Xml
  include ActiveModel::Serializers::JSON
  
  def self.for_subscriber(subscriber_id)
    # nasty!
    5.times.collect { Message.new }  
  end
  
  def attributes
    {'id' => id, 'content' => content}
  end
  
  def content
    Faker::Lorem.sentences(1 + rand(4)).join(" ")
  end
end

subscriber_messages_controller.rb

class SubscriberMessagesController < ApplicationController
  respond_to :json, :xml
  
  def index
    respond_with Message.for_subscriber(params[:subscriber_id])
  end
end