Ruby xml validator

validate_xml.rb

# -*- coding: utf-8 -*-
class RssFeedValidator < ActiveModel::EachValidator
  def validates_each(record, attribute, value)
    feed = Curl::Easy.new(url) do|curl|
      curl.on_success validate_xml(feed, record, attribute)
      curl.on_failure record.errors[attribute] << "remote host not avalible." 
    end    
  end

  def validate_xml(feed, record, attribute)
    begin
      XML::Document.string(feed)
    rescue REXML::ParseException => e
      record.errors[attribute] << "is not valid xml.  #{e.continued_exception}"
    end    
  end
end