Simple RSS Feed in Sinatra

main.rb

require 'sinatra'
require 'data_mapper'
require 'builder'

class ExitStatusOne < Sinatra::Base
  get '/rss' do
    @post = Post.all :order => :id.desc
    builder :rss
  end 
end

rss.builder

xml.instruct! :xml, :version => '1.0'
xml.rss :version => "2.0" do
  xml.channel do
    xml.title "Title of Feed"
    xml.description "Description of Site"
    xml.link "web-site-url.com"

    @post.each do |feed|
      xml.item do
        xml.title feed.title
        xml.link "web-site-url.com/path/to/rss/feed/#{feed.id}"
        xml.description feed.summary
        xml.pubDate feed.created_at
        xml.guid "web-site-url.com/path/to/rss/feed/#{feed.id}"
      end 
    end 
  end 
end