A Full Web Service with HTTP caching in 7 lines(slightlynew.blogspot.com)

     %w[rubygems active_record markaby metaid ostruct].each {|lib| require lib}
 module Camping;C=self;module Models;end;Models::Base=ActiveRecord::Base
 module Helpers;def R c,*args;p=/\(.+?\)/;args.inject(c.urls.detect{|x|x.
 scan(p).size==args.size}.dup){|str,a|str.gsub(p,(a.method(a.class.primary_key
 )[]rescue a).to_s)};end;def / p;File.join(@root,p) end;end;module Controllers
 module Base;include Helpers;attr_accessor :input,:cookies,:headers,:body,
 :status,:root;def method_missing(m,*args,&blk);str=m==:render ? markaview(
 *args,&blk):eval("markaby.#{m}(*args,&blk)");str=markaview(:layout){str
 }rescue nil;r(200,str.to_s);end;def r(s,b,h={});@status=s;@headers.merge!(h)
 @body=b;end;def redirect(c,*args);c=R(c,*args)if c.respond_to?:urls;r(302,'',
 'Location'=>self/c);end;def service(r,e,m,a);@status,@headers,@root=200,{},e[
 'SCRIPT_NAME'];@cookies=C.cookie_parse(e['HTTP_COOKIE']||e['COOKIE']);cook=
 @cookies.marshal_dump.dup;if ("POST"==e['REQUEST_METHOD'])and %r|\Amultipart\
 /form-data.*boundary=\"?([^\";,]+)\"?|n.match(e['CONTENT_TYPE']);return r(500,
 "No multipart/form-data supported.")else;@input=C.qs_parse(e['REQUEST_METHOD'
 ]=="POST"?r.read(e['CONTENT_LENGTH'].to_i):e['QUERY_STRING']);end;@body=
 method(m.downcase).call(*a);@headers["Set-Cookie"][email protected]_dump.map{
 |k,v|"#{k}=#{C.escape(v)}; path=/"if v != cook[k]}.compact;self;end;def to_s
 "Status: #{@status}\n#{{'Content-Type'=>'text/html'}.merge(@headers).map{|k,v|
 v.to_a.map{|v2|"#{k}: #{v2}"}}.flatten.join("\n")}\n\n#{@body}";end;def \
 markaby;Class.new(Markaby::Builder){@root=@root;include Views;def tag!(*g,&b)
 [:href,:action].each{|a|(g.last[a]=self./(g.last[a]))rescue 0};super end}.new(
 instance_variables.map{|iv|[iv[1..-1].intern,instance_variable_get(iv)]},{})
 end;def markaview(m,*args,&blk);markaby.instance_eval{Views.instance_method(m
 ).bind(self).call(*args, &blk);self}.to_s;end;end;class R;include Base end
 class NotFound<R;def get(p);r(404,div{h1("#{C} Problem!")+h2("#{p} not found")
 });end end;class ServerError<R;def get(k,m,e);r(500,markaby.div{h1 "#{C} Prob\
 lem!";h2 "#{k}.#{m}";h3 "#{e.class} #{e.message}:";ul{e.backtrace.each{|bt|li(
 bt)}}})end end;class<<self;def R(*urls);Class.new(R){meta_def(:inherited){|c|
 c.meta_def(:urls){urls}}};end;def D(path);constants.each{|c|k=const_get(c)
 return k,$~[1..-1] if (k.urls rescue "/#{c.downcase}").find {|x|path=~/^#{x}\
 \/?$/}};[NotFound,[path]];end end end;class<<self;def escape(s);s.to_s.gsub(
 /([^ a-zA-Z0-9_.-]+)/n){'%'+$1.unpack('H2'*$1.size).join('%').upcase}.tr(' ',
 '+') end;def unescape(s);s.tr('+', ' ').gsub(/((?:%[0-9a-fA-F]{2})+)/n){[$1.
 delete('%')].pack('H*')} end;def qs_parse(qs,d='&;');OpenStruct.new((qs||'').
 split(/[#{d}] */n).inject({}){|hsh,p|k,v=p.split('=',2).map{|v|unescape(v)}
 hsh[k]=v unless v.empty?;hsh}) end;def cookie_parse(s);c=qs_parse(s,';,') end
 def run(r=$stdin,w=$stdout);w<<begin;k,a=Controllers.D "/#{ENV['PATH_INFO']}".
 gsub(%r!/+!,'/');m=ENV['REQUEST_METHOD']||"GET";k.class_eval{include C
 include Controllers::Base;include Models};o=k.new;o.service(r,ENV,m,a);rescue\
 =>e;Controllers::ServerError.new.service(r,ENV,"GET",[k,m,e]);end;end;end
 module Views; include Controllers; include Helpers end;end