Spider, a Web spidering library for Ruby. It handles the robots.txt, scraping, collecting, and looping so that you can just handle the data.

== Examples

=== Crawl the Web, loading each page in turn, until you run out of memory

require 'spider' Spider.start_at('http://mike-burns.com/') {}

=== To handle erroneous responses

require 'spider' Spider.start_at('http://mike-burns.com/') do |s| s.on :failure do |a_url, resp, prior_url| puts "URL failed: #{a_url}" puts " linked from #{prior_url}" end end

=== Or handle successful responses

require 'spider' Spider.start_at('http://mike-burns.com/') do |s| s.on :success do |a_url, resp, prior_url| puts "#{a_url}: #{resp.code}" puts resp.body puts end end

=== Limit to just one domain

require 'spider' Spider.start_at('http://mike-burns.com/') do |s| s.add_url_check do |a_url| a_url =~ %r{^http://mike-burns.com.*} end end

=== Pass headers to some requests

require 'spider' Spider.start_at('http://mike-burns.com/') do |s| s.setup do |a_url| if a_url =~ %r{^http://.wikipedia.} headers['User-Agent'] = "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" end end end

=== Use memcached to track cycles

require 'spider' require 'spider/included_in_memcached' SERVERS = ['10.0.10.2:11211','10.0.10.3:11211','10.0.10.4:11211'] Spider.start_at('http://mike-burns.com/') do |s| s.check_already_seen_with IncludedInMemcached.new(SERVERS) end

=== Track cycles with a custom object

require 'spider' class ExpireLinks < Hash def <<(v) self[v] = Time.now end def include?(v) self[v].kind_of?(Time) && (self[v] + 86400) >= Time.now end end

Spider.start_at('http://mike-burns.com/') do |s| s.check_already_seen_with ExpireLinks.new end

=== Store nodes to visit with Amazon SQS

require 'spider' require 'spider/next_urls_in_sqs' Spider.start_at('http://mike-burns.com') do |s| s.store_next_urls_with NextUrlsInSQS.new(AWS_ACCESS_KEY, AWS_SECRET_ACCESS_KEY) end

==== Store nodes to visit with a custom object

require 'spider' class MyArray < Array def pop super end

def push(a_msg) super(a_msg) end end

Spider.start_at('http://mike-burns.com') do |s| s.store_next_urls_with MyArray.new end

=== Create a URL graph

require 'spider' nodes = {} Spider.start_at('http://mike-burns.com/') do |s| s.add_url_check {|a_url| a_url =~ %r{^http://mike-burns.com.*} }

s.on(:every) do |a_url, resp, prior_url| nodes[prior_url] ||= [] nodes[prior_url] << a_url end end

=== Use a proxy

require 'net/http_configuration' require 'spider' http_conf = Net::HTTP::Configuration.new(:proxy_host => '7proxies.org', :proxy_port => 8881)
http_conf.apply do Spider.start_at('http://img.4chan.org/b/') do |s| s.on(:success) do |a_url, resp, prior_url| File.open(a_url.gsub('/',':'),'w') do |f| f.write(resp.body) end end end end

== Author

John Ewart john@unixninjas.org

John Nagro john.nagro@gmail.com

Mike Burns http://mike-burns.com mike@mike-burns.com (original author)

Many thanks to: Matt Horan Henri Cook Sander van der Vliet John Buckley Brian Campbell

With `robot_rules' from James Edward Gray II via http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/177589