osem/app/controllers/api/v1/rooms_controller.rb

module Api
  module V1
    class RoomsController < Api::BaseController
      respond_to :json

      def index
        if params[:conference_id].blank?
          rooms = Room.all
        else
          conference = Conference.find_by_guid(params[:conference_id])
          rooms = conference.rooms
        end
        respond_with rooms
      end
    end
  end
end