RailsConf Europe 2006 Presentation by myself and Romek Szczesniak. Ranges from Ruby pcap and roll-your-own WEBrick application servers to Why's brilliant Camping framework. Some technical ability required.

1. Camping: Going off
the Rails with Ruby
Adventures in creative coding
for people who should know better

2. The weasel words
This presentation contains code
That code is probably broken
If that bothers you - fix it
That’s called a learning experience

3. Who are these lunatics?
Eleanor McHugh
eleanor@games-with-brains.com
She does real-time systems
Romek Szczesniak
romek@spikyblackcat.co.uk
He does security

4. Alright, but what are
they doing here?
Ruby
Pcap & BitStruct
WEBrick
Camping
but no Rails...

5. No Rails?
That’s right, we don’t use Rails
But we do use Ruby
And we do write web applications
So how is that possible?

6. Camping!!!
That’s right, we use Camping
It’s by Why The Lucky Stiff
It’s cool
It’s really cool
It’s so damn cool you’d have to be mad
not to use it!!!

7. It’s this simple!
%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(quot;markaby.#{m}(*args,&blk)quot;);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 (quot;POSTquot;==e['REQUEST_METHOD'])and %r|Amultipart
/form-data.*boundary=quot;?([^quot;;,]+)quot;?|n.match(e['CONTENT_TYPE']);return r(500,
quot;No multipart/form-data supported.quot;)else;@input=C.qs_parse(e['REQUEST_METHOD'
]==quot;POSTquot;?r.read(e['CONTENT_LENGTH'].to_i):e['QUERY_STRING']);end;@body=
method(m.downcase).call(*a);@headers[quot;Set-Cookiequot;]=@cookies.marshal_dump.map{
|k,v|quot;#{k}=#{C.escape(v)}; path=/quot;if v != cook[k]}.compact;self;end;def to_s
quot;Status: #{@status}n#{{'Content-Type'=>'text/html'}.merge(@headers).map{|k,v|
v.to_a.map{|v2|quot;#{k}: #{v2}quot;}}.flatten.join(quot;nquot;)}nn#{@body}quot;;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(quot;#{C} Problem!quot;)+h2(quot;#{p} not foundquot;)
});end end;class ServerError<R;def get(k,m,e);r(500,markaby.div{h1 quot;#{C} Prob
lem!quot;;h2 quot;#{k}.#{m}quot;;h3 quot;#{e.class} #{e.message}:quot;;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,$~[1..-1] if (k.urls rescue quot;/#{c.downcase}quot;).find {|x|path=~/^#{x}
/?$/}};[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 quot;/#{ENV['PATH_INFO']}quot;.
gsub(%r!/+!,'/');m=ENV['REQUEST_METHOD']||quot;GETquot;;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,quot;GETquot;,[k,m,e]);end;end;end
module Views; include Controllers; include Helpers end;end

8. Why?
For fun
For profit
For the satisfaction of knowing exactly
how your application works
For the look on your boss’s face when he
reads the documentation

9. Earlier...
But let’s not get ahead of ourselves
First we want to take you on a journey
A journey back in time
A journey back to...

10. January 3rd 2006
Location: The Secret Basement Lair tm of
Captain IP and The DNS avengers
Their task: to launch a new Top Level
Domain which DOESN’T RESOLVE
MACHINE ADDRESSES?!?!?!
Their resources? Hands to wave with
and hit keyboards with!

11. Ruby to the Rescue
It’s easy to learn
It’s quick to code in
It’s pleasing to the eye
It’s fun!

12. You keep saying that
Yes!!!
Fun makes for better coders
Better coders write good code
Good code stands the test of time
If coding isn’t fun YOU’RE USING THE
WRONG TOOLS!!!!

13. The console jockeys
let’s write a menu driven calculator
output: puts(), print()
input: gets(), termios library
old-fashioned and unattractive
termios is fiddly

14. A simple calculator
#!/usr/bin/env ruby -w
require 'termios'
$total = 0
$menu_entries = [['+', quot;Addquot;], ['-', quot;Subtractquot;], ['*', quot;Multiplyquot;], ['/', quot;Dividequot;], ['c', 'Clear'], ['q',quot;Quitquot;]]
$commands = $entries.inject([]) { | commands, entry |
commands << entry[0]
}
$captions = $entries.inject([]) { | captions, entry |
captions << entry[1]
}
loop do
puts quot;nSimple Calculatornquot;
entries.each { | entry |
puts quot;#{entry[0]}. #{entry[1]}nquot;
}
t = Termios.tcgetattr(STDIN)
t.lflag &= ~Termios::ICANON
Termios.tcsetattr(STDIN,0,t)
begin
action = STDIN.getc.chr
end until $commands.member?(action)
exit() if action == $commands.last
action = $commands.index(action)
puts quot;n#{$captions[action]}nnquot;
case action
when 0
:
$total += gets()
when 1
:
$total -= gets()
when 2
:
$total *= gets()
when 3
:
$total /= gets()
when 4
:
$total = 0
end
puts quot;Total = #{$total}quot;
end

15. A Ruby packet reader
The 7 layer IP model

16. What the heck?
We’re exploring the UDP layer
We want to look at UDP and DNS traffic
Our first implementation is console-
based, so hold on to your hats...

17. UDP header in Ruby
udpip.rb
require 'bit-struct' class DNSQueryHeader < BitStruct
unsigned
:dns_id,
16,
quot;IDquot;
class IP < BitStruct
unsigned
:dns_qr,
1,
quot;QRquot;
unsigned
:ip_v,
4,
quot;Versionquot;
unsigned
:dns_opcode,
4,
quot;OpCodequot;
unsigned
:ip_hl,
4,
quot;Header lengthquot;
unsigned
:dns_aa,
1,
quot;AAquot;
unsigned
:ip_tos,
8,
quot;TOSquot;
unsigned
:dns_tc,
1,
quot;TCquot;
unsigned
:ip_len,
16,
quot;Lengthquot;
unsigned
:dns_rd,
1,
quot;RDquot;
unsigned
:ip_id,
16,
quot;IDquot;
unsigned
:dns_ra,
1,
quot;RAquot;
unsigned
:ip_off,
16,
quot;Frag offsetquot;
unsigned
:dns_z,
3,
quot;Zquot;
unsigned
:ip_ttl,
8,
quot;TTLquot;
unsigned
:dns_rcode,
4,
quot;RCODEquot;
unsigned
:ip_p,
8,
quot;Protocolquot;
unsigned
:dns_qdcount,
16,
quot;QDCountquot;
unsigned
:ip_sum,
16,
quot;Checksumquot;
unsigned
:dns_ancount,
16,
quot;ANCountquot;
octets
:ip_src,
32,
quot;Source addrquot;
unsigned
:dns_arcount,
16,
quot;ARCountquot;
octets
:ip_dst,
32,
quot;Dest addrquot;
rest
:data,
quot;Dataquot;
rest
:body,
quot;Body of messagequot; end
note
quot;rest is application defined message bodyquot;
initial_value.ip_v = 4 class Time
initial_value.ip_hl = 5
# tcpdump style format
end
def to_s
sprintf
quot;%0.2d:%0.2d:%0.2d.%0.6dquot;, hour, min, sec, tv_usec
class UDP < BitStruct
end
unsigned
:udp_srcport,
16,
quot;Source Portquot; end
unsigned
:udp_dstport,
16,
quot;Dest Portquot;
unsigned
:udp_len,
16,
quot;UDP Lengthquot;
unsigned
:udp_chksum,
16,
quot;UDP Checksumquot;
rest
:body,
quot;Body of messagequot;
note
quot;rest is application defined message bodyquot;
end

18. Capturing UDP packets
tcpdump.rb
#!/usr/local/bin/ruby
require 'pcaplet'
include Pcap
require 'udpip'
DIVIDER = quot;-quot; * 50
def print_details(section)
puts DIVIDER, section, DIVIDER
end
pcaplet = Pcaplet.new('-s 1500')
pcaplet.each_packet { |pkt|
if pkt.udp?
puts quot;Packet: #{pkt.time} #{pkt}quot;
if (pkt.sport == 53)
udp = UDP.new
udp.udp_srcport = pkt.sport
udp.udp_dstport = pkt.dport
udp.udp_len = pkt.udp_len
udp.udp_chksum = pkt.udp_sum
udp.body = pkt.udp_data
print_details udp.inspect_detailed
# look for DNS request only
dns = DNSQueryHeader.new(pkt.udp_data)
bytearray = Array.new
udp.body.each_byte { |c|
bytearray.concat(c.to_s.to_a)
print c.to_s(16), ' '
}
print_details dns.inspect_detailed
end
end
}
pcaplet.close

19. A live UDP packet

20. A live DNS packet

21. Can we have that on
Windows?
A GUI? You gotta be joking!!
Why do you think we use Macs?
How about we just turn it into a web
application instead?
Sure, we can do that with Ruby
[What have we let ourselves in for...]

22. The NDA kicks in
Here’s where we hit the brick wall on
what we can talk about
You might imagine a DNS-sniffing web
application, but we couldn’t possibly
comment
So lets get down to some web app basics
And yes, we will be kicking it old-skool...

23. Introducing WEBrick
WEBrick is an HTTP ser ver library
It’s part of the Ruby 1.8 release
It can ser ve static documents
It can ser ve HTTPS using Ruby/OpenSSL
It can ser ve arbitrary code blocks
It can ser ve ser vlets

24. Static content
A standard HTTP ser ver
#!/usr/local/bin/ruby
require 'webrick'
server = WEBrick::HTTPServer.new(:Port => 8080, :DocumentRoot => Dir::pwd + quot;/htdocsquot;)
# mount personal directory, generating directory indexes
server.mount(quot;/~eleanorquot;, WEBrick::HTTPServlet::FileHandler, quot;/Users/eleanor/Sitesquot;, true)
# catch keyboard interrupt signal to terminate server
trap(quot;INTquot;){ server.shutdown }
server.start
An HTTPS ser ver
#!/usr/local/bin/ruby
# This requires Ruby/OpenSSL
require 'webrick'
require 'webrick/https'
certificate_name = [ [quot;Cquot;,quot;UKquot;], [quot;Oquot;,quot;games-with-brains.orgquot;], [quot;CNquot;, quot;WWWquot;] ]
server = WEBrick::HTTPServer.new(
:DocumentRoot = Dir::pwd + quot;/htdocsquot;, :SSLEnable = true,
:SSLVerifyClient = ::OpenSSL::SSL::VERIFY_NONE, :SSLCertName = certificate_name )
trap(quot;INTquot;){ s.shutdown }
s.start

25. Ser vlets
A Ruby code block
#!/usr/local/bin/ruby
require 'webrick'
server = WEBrick::GenericServer.new()
trap(quot;INTquot;){ server.shutdown }
server.start{|socket|
socket.puts(quot;This is a code blockrquot;)
}
A WEBrick ser vlet
#!/usr/local/bin/ruby
require 'webrick'
server = WEBrick::HTTPServer.new()
trap(quot;INTquot;){ server.shutdown }
def generate_response(response)
response.body = quot;HTMLhello, world./HTMLquot;
response['Content-Type'] = quot;text/htmlquot;
end
class HelloServlet WEBrick::HTTPServlet::AbstractServlet
def do_GET(request, response)
generate_response(response)
end
end
server.mount_proc(quot;/hello/simplequot;){ | request, response |
generate_response(response)
}
server.mount(quot;/hello/advancedquot;, HelloServlet)
server.start

26. It’s that simple?
Yes, it’s that simple
Of course these are trivial examples...
...so let’s build an application ser ver

27. An application ser ver
Still wondering when we get to the
really good stuff?
Soon, we promise
But first to show you how NOT to do it!

28. Wrap the request
A basic request context
class RequestContext
attr_reader
:request, :response, :servlets, :creation_time
def initialize(request, response)
@request, @response, = request, response
@creation_time = Time.now()
end
def page_not_found
@response.status = WEBrick::HTTPStatus::NotFound.new()
end
def response_page(page)
@response['Content-Type'] = page.content_type
@response.body = CGI::pretty(page.to_str())
end
def (item)
@response.body CGI::pretty(item)
end
end

29. Ser ve the pages
The application ser ver
IP_ADDRESS_PATTERN = /^d{1,3}.d{1,3}.d{1,3}.d{1,3}/
class ApplicationServer
attr_reader
:web_server, :server_address, :servlets, :pages
def initialize(parameters = {})
@server_address = parameters[:my_address] or raise “Please supply a server address”
raise “Invalid IP address for server” unless IP_ADDRESS_PATTERN.match(@server_address)
@web_server = WEBrick::HTTPServer.new({:BindAddress = @server_address})
@servlets = {}
@pages = {}
end
def start
trap(quot;INTquot;) { @web_server.shutdown }
@web_server.start
end
def register_page(path, page)
@pages[path] = page
@web_server.mount_proc(path) { | request, response |
context = RequestContext.new(request, response)
@pages[request.path] ? context.response_page(@pages[request.path]) : context.page_not_found()
}
end
def register_method(path, handler)
@servlets[path] = self.method(handler).to_proc
@web_server.mount_proc(path) {
| request, response |
context = RequestContext.new(request, response)
@servlets[request.path] ? (context @servlets[request.path].call(context).to_str()) : context.page_not_found()
}
end
end

30. Write the application
Revisiting “hello, world”
#!/usr/local/bin/ruby
require 'appserver.rb'
class SimpleServer ApplicationServer
def initialize(parameters = {})
super
register_page(quot;/hello/simplequot;, quot;HTMLHello, world/HTMLquot;)
register_method(quot;/hello/advancedquot;, :hello_world)
end
def hello_world(context)
quot;HTMLHello, world/HTMLquot;
end
end
begin
SimpleServer.new({:my_address = ARGV.shift()}).start()
rescue RuntimeError = e
$stderr.puts quot;Usage:
simpleserver
host-addressquot;
$stderr.puts quot;
address must be provided in dotted-quad format (i.e. xxx.xxx.xxx.xxx)quot;
end

31. What have we done?!?
On the surface this is elegant
But underneath it sucks
There’s no support for HTML
Only methods can be used as ser vlets
We’re tied to WEBrick - which is slow

32. The road to perdition
So we added an HTML 4 library
And a ser ver pages container
And ActiveRecord
We meta’d the code to death
But it still lacked va-va-voom...

33. The case for Rails
So perhaps we should have just used
Rails in the first place
We’d be another of those “Rails saved
my career” success stories!
Hindsight’s always 20/20
But we’re old-school coders and it’s far
too user friendly for our comfort

34. The pressure against
Working at a very low level
Simple code required
Can Rails talk nicely to low-level code?
Strong management resistance - too
high a learning cur ve?

35. So why Camping?
Camping is beauty incarnate
It’s less than 4K of code
It uses Markaby and ActiveRecord
It runs on JRuby!!!
Oh, and it’s great fun to abuse...

36. Gratuitous diagram
How Why? The Lucky Stiff teaches it
lifted from
http://redhanded.hobix.com/bits/campingAMicroframework.html

37. Markaby
An XHTML Domain Specific Language
Allows you to embed XHTML code in
Ruby code without building a complex
object hierarchy
Can be used with Rails

38. But that’s so simple!
Markaby embedded in Ruby
require 'markaby'
page = Markaby::Builder.new
page.xhtml_strict do
head { title quot;Camping Presentationquot; }
body do
h1.page_heading quot;Camping: Going off the Rails with Rubyquot;
ul.page_index do
li.page_index { a “introduction”, :href = ‘#introduction’ }
li.page_index { a “the presentation”, :href = ‘/presentation’ }
li.page_index { a “comments”, :href = ‘#comments’ }
end
div.introduction! { “Everything will be alright!!!” }
div.comments! { “Have your say” }
end
end
puts page.to_s
?xml version=quot;1.0quot; encoding=quot;UTF-8quot;?
!DOCTYPE html PUBLIC quot;-//W3C//DTD XHTML 1.0 Strict//ENquot; quot;DTD/xhtml1-strict.dtdquot;
html lang=quot;enquot; xml:lang=quot;enquot; xmlns=quot;http://www.w3.org/1999/xhtmlquot;
head
meta content=quot;text/html; charset=utf-8quot; http-equiv=quot;Content-Typequot;/
titleCamping Presentation/title
/head
body
h1 class=quot;page_headingquot;Camping: Going off the Rails with Ruby/h1
ul class=quot;page_indexquot;
li class=quot;page_indexquot;a href=quot;#introductionquot;introduction/a/li
Creates this
li class=quot;page_indexquot;a href=quot;/presentationquot;the presentation/a/li
li class=quot;page_indexquot;a href=quot;#commentsquot;comments/a/li
/ul
div id=quot;introductionquot;Just breathe deeply.../div
div id=quot;commentsquot;Have your say/div
/body
/html

39. ActiveRecord
An Object-Relational Mapper
Implements the Active Record pattern
Supports many popular databases
A key component of Rails

40. ORMtastic
Using Active Record
require 'rubygems'
require_gem ‘activerecord’
ActiveRecord::Base.establish_connection(:adapter = “sqlite3”, :host = “localhost”, :database = “test.db”)
class User ActiveRecord::Base
end
user = User.new()
user.id = “ellie”
user.name = “Eleanor McHugh”
user.password = “somerandomtext”
user.save
user = User.find(“ellie”)
user.destroy()

41. Totally RAD
Camping builds small applications
Why’s guideline? One file per application
If that’s how you prefer it...

42. A simple example
Basic setup
#!/usr/bin/env ruby
$:.unshift File.dirname(__FILE__) + quot;/../../libquot;
require 'camping'
require 'camping/session'
Camping.goes :Jotter
module Blog
include Camping::Session
end
Load the camping libraries
Define a namespace for the application
Include session support (if required)

43. The data model
Defining the data model
module Jotter::Models
class Note Base; end
class Database V 1.0
def self.up
create_table :jotter_notes, :force = true do |t|
t.column :id,
:integer,
:null = false
t.column :created_at,
:interger,
:null = false
t.column :title,
:string,
:limit = 255
t.column :body,
:text
end
end
def self.down
drop_table :jotter_notes
end
end
end
def Jotter.create
Jotter::Models.create_schema
end
We mark our database as version 1.0
A create method builds the database

44. The controllers
Adding controllers
module Jotter::Controllers
class Static R '/static/(.+)'
MIME_TYPES = {'.css' = 'text/css', '.js' = 'text/javascript', '.jpg' = 'image/jpeg'}
PATH = __FILE__[/(.*)//, 1]
def get(path)
@headers['Content-Type'] = MIME_TYPES[path[/.w+$/, 0]] || quot;text/plainquot;
@headers['X-Sendfile'] = quot;#{PATH}/static/#{path}quot;
end
end
class Index R '/'
def get
@notes = Note.find :all
render :index
end
end
class View R '/view/(d+)'
def get note_id
@note = Note.find post_id
render :view
end
end
class Add R ‘/add/’
def get
@note = Note.new
render :add
end
def post
note = Note.create :title = input.post_title, :body = input.post_body
redirect View, post
end
end

45. The controllers
Adding controllers
class Edit R '/edit/(d+)', '/edit'
def get note_id
@note = Note.find note_id
render :edit
end
def post
@note = Note.find input.note_id
@note.update_attributes :title = input.post_title, :body = input.post_body
redirect View, @note
end
end
class Delete R '/delete/(d+)'
def get note_id
@note = Note.find note_id
@note.destroy
redirect Index
end
end
end
Respond to HTTP GET and POST requests
Perform database operations

46. The views
Application views
module Jotter::Views
def layout
xhtml_strict do
head do
title 'blog'
link :rel = 'stylesheet', :type = 'text/css', :href = '/static/styles.css', :media = 'screen'
end
body do
h1.header { a 'jotter', :href = R(Index) }
div.body do
self yield
end
end
end
end
def index
@notes.empty? (p 'No posts found.') : (ol.row! { _list_notes(@notes) })
p { a 'new note', :href = R(Add) }
end
def edit
_form(@note, :action = R(Edit))
end
def view
h1 @note.title
h2 @note.created_at
p @note.body
p do
[
a(quot;Viewquot;, :href = R(View, @note)),
a(quot;Editquot;, :href = R(Edit, @note)),
a(quot;Deletequot;, :href = R(View, @note))
].join quot; | quot;
end
end

47. The views
Application views
def _list_notes(notes)
@notes.each do | note |
li do
ul do
li { a note.title, :href = R(View, note) }
li note.created_at
li { a quot;Editquot;, :href = R(Edit, note) }
li { a quot;Deletequot;, :href = R(Delete, note) }
end
end
end
end
def _form(note, opts)
form({:method = 'post'}.merge(opts)) do
label 'Title', :for = 'note_title'; br
input :name = 'note_title', :type = 'text', :value = note.title; br
label 'Body', :for = 'note_body'; br
textarea note.body, :name = 'note_body'; br
input :type = 'hidden', :name = 'note_id', :value = note.id
input :type = 'submit'
end
end
Views incorporate Markaby for XHTML
Have access to controller data

48. The post-amble
A basic CGI post-amble
if __FILE__ == $0
Jotter::Models::Base.establish_connection :adapter = 'sqlite3', :database = 'notes.db'
Jotter::Models::Base.logger = Logger.new('camping.log')
Jotter.create if Jotter.respond_to? :create
puts Jotter.run
end
A Mongrel post-amble
if __FILE__ == $0
Jotter::Models::Base.establish_connection :adapter = 'sqlite3', :database = 'notes.db'
Jotter::Models::Base.logger = Logger.new('camping.log')
Jotter::Models::Base.threaded_connections = false
Jotter.create if Jotter.respond_to? :create
server = Mongrel::Camping::start(“0.0.0.0”, 3000, “/jotter”, Jotter)
puts “Jotter application running at http://localhost:3000/jotter”
server.run.join
end
Allows an application to self-execute
Can be customised to suit your platform

49. The style-sheet
A simple style sheet
body {
font-family: Utopia, Georga, serif;
}
h1.header {
background-color: #fef;
margin: 0;
padding: 10px;
}
div.body {
padding: 10px;
}
#row ul {
list-style: none;
margin: 0;
padding: 0;
padding-top: 4px;
}
#row li {
display: inline;
}
#row a:link, #row a:visited {
padding: 3px 10px 2px 10px;
color: #FFFFFF;
background-color: #B51032;
text-decoration: none;
border: 1px solid #711515;
}

50. Larger applications
One application per file is a nice idea
But what about large applications?
Each can be broken down into discrete
micro-applications
Each micro-application has its own file
and mount points

51. Sharing a database
Camping apps keep their database
tables in separate namespaces
Larger applications will want to share
state bet ween micro-applications
We could do some ActiveRecord voodoo
Or we could cheat... guess which?

52. Camping in the wilds
Installing a database in the framework
require 'rubygems'
require_gem 'camping', '=1.4'
require 'camping/session'
module Camping
module Models
def self.schema(block)
@@schema = block if block_given?
@@schema
end
class User Base
validates_uniqueness_of :name, :scope = :id
validates_presence_of :password
end
end
def self.create
Camping::Models::Session.create_schema
ActiveRecord::Schema.define(Models.schema)
end
Models.schema do
unless Models::User.table_exists?
create_table :users, :force = true do
|t|
t.column :id,
:integer,
:null = false
t.column :created_on,
:integer,
:null = false
t.column :name,
:string,
:null = false
t.column :password,
:string,
:null = false
t.column :comment,
:string,
:null = false
end
execute quot;INSERT INTO users (created_on, name, password, comment) VALUES ('#{Time.now}', 'admin', 'admin', 'system administrator')quot;
end
end
end

53. Camping ser ver
The camping ser ver ties together a
series of web applications
A simple implementation ships with the
framework

54. The ser ver rules
Monitor a directory
load/reload all camping apps that
appear in it or a subdirectory
Mount apps according to the filenames
(i.e. jotter.rb mounts as /jotter)
Run create method on app startup
Support the X-Sendfile header

55. Summing up
Web applications are useful outside the
usual web app environment
Cross platform is easy when you only
need an XHTML browser
These tasks need a light weight design
Camping is a good way to solve them
And as you can see, Ruby rocks!!!

56. Where to next?
http://code.whytheluckystiff.net/camping/wiki
http://www.goto.info.waseda.ac.jp/~fukusima/ruby/pcap-e.html
http://raa.ruby-lang.org/project/bit-struct/
http://raa.ruby-lang.org/project/ruby-termios/