async_request_of_doom.rb

require 'pp'

require 'rubygems'
require 'eventmachine'
require 'dnsruby'

require '/Users/djensen/Source/Ruby/em-http-request/lib/em-http'

res = Dnsruby::Resolver.new # use system defaults
Dnsruby::Resolver.use_eventmachine
Dnsruby::Resolver.start_eventmachine_loop(false)

# Will timeout
uri_of_doom = URI.parse "http://jan.kneschke.de/feed/atom.xml"

# Needs host header set
#uri_of_doom = URI.parse "http://gregmankiw.blogspot.com/feeds/posts/default"

EventMachine.run {
  uri = uri_of_doom.clone
  p "lookup #{uri.host}"
  df = res.send_async Dnsruby::Message.new(uri.host)
  df.callback {|msg|
    ip = msg.answer.find { |rr| rr.type == "A"}.rdata.to_s
    uri.host = ip

    req = EventMachine::HttpRequest.new(uri.to_s)
    p req
    http = req.get :head => {:host => uri_of_doom.host}
    http.callback {
      p http.response_header.status
      p http.response_header
      puts http.response
      p "\n"
      EventMachine.stop
    }

  }
  df.errback {|msg, err|
    print "Sorry - can't resolve #{uri_of_doom}. Error = #{err}n"
    EventMachine.stop
  }
  
}