The document discusses the integration of Ruby with Java using JRuby, highlighting its advantages and challenges. It covers topics such as invoking Java libraries in Ruby, handling impedance mismatches between Ruby and Java syntax, and practical applications like system provisioning with Puppet and Chef. Additionally, it emphasizes Ruby's role as a 'glue' language for connecting various codebases and its capabilities for handling database interactions through ORMs like Active Record and Sequel.

1. The Enterprise Strikes Back
The Ruby Trilogy: Part III

2. The Enterprise Strikes Back
The Ruby Trilogy: Part III

3. Burke Libbey Stefan Penner
@burkelibbey @stefanpenner

4. Burke Libbey Stefan Penner
@burkelibbey @stefanpenner

5. Burke Libbey Stefan Penner
@burkelibbey @stefanpenner

6. Overview
• Ruby on the JVM (20m)
• Ruby as Glue (20m)
• Testing Java with RSpec (10m)
• Cloud City (15m)

7. Ruby Java
+ Productive + Not Scary
- Scary - Less productive

8. Ruby in Java
+ Not Scary
+ Productive

9. http://jruby.org

10. • Full ruby implementation on the JVM
• Access to both ruby and Java libraries
• Can be deployed to existing Java
infrastructure

11. The many flavours of ruby
• MRI (and YARV)
• JRuby
• IronRuby
• MacRuby
• Rubinius
• ...and several more...

12. java.lang.System.out.println("Hello World")

13. The Magic Sauce
require 'java'
(contains up to 30% midichlorians)

14. Calling Java from ruby
f = javax.swing.JFrame.new
f.getContentPane.add(javax.swing.JLabel.new("Hello World"))
close_operation = javax.swing.JFrame::EXIT_ON_CLOSE
f.setDefaultCloseOperation(close_operation)
f.pack
f.setVisible(true)

15. Impedance Mismatch
f = javax.swing.JFrame.new
f.getContentPane.add(javax.swing.JLabel.new("Hello World"))
close_operation = javax.swing.JFrame::EXIT_ON_CLOSE
f.setDefaultCloseOperation(close_operation)
f.pack
f.setVisible(true)
Let’s break this down.

16. Impedance Mismatch
“Getters” and “Setters” are non-idiomatic in ruby.
f = javax.swing.JFrame.new
f.getContentPane.add(javax.swing.JLabel.new("Hello World"))
getContentPane
close_operation = javax.swing.JFrame::EXIT_ON_CLOSE
f.setDefaultCloseOperation(close_operation)
f.pack
f.setVisible(true)
snake_case is generally preferred to CamelCase

17. Impedance Mismatch
JavaBean properties can be accessed like this:
f = javax.swing.JFrame.new
f.content_pane.add(javax.swing.JLabel.new("Hello World"))
close_operation = javax.swing.JFrame::EXIT_ON_CLOSE
f.setDefaultCloseOperation(close_operation)
f.pack
f.setVisible(true)
“get” disappears, CamelCase changes to snake_case

18. Impedance Mismatch
“set” is replaced by “=”
f = javax.swing.JFrame.new
f.content_pane.add(javax.swing.JLabel.new("Hello World"))
close_operation = javax.swing.JFrame::EXIT_ON_CLOSE
f.default_close_operation = close_operation
f.pack
f.visible = true
“setDefaultCloseOperation(x)”
becomes
“default_close_operation = x”

19. Ugliness Abounds
f = javax.swing.
javax.swing.JFrame.new
f.content_pane.add(javax.swing.JLabel.new("Hello World"))
javax.swing.
close_operation = javax.swing.
javax.swing.JFrame::EXIT_ON_CLOSE
f.default_close_operation = close_operation
f.pack
f.visible = true
Namespaces everywhere!

20. Ugliness Abounds
java_import 'javax.swing.JFrame'
java_import 'javax.swing.JLabel'
f = JFrame.new
f.content_pane.add(JLabel.new("Hello World"))
JLabel.new
close_operation = JFrame::EXIT_ON_CLOSE
f.default_close_operation = close_operation
f.pack
f.visible = true
java_import adds classes to a ruby context

21. 100% Rubified™
java_import 'javax.swing.JFrame'
java_import 'javax.swing.JLabel'
JFrame.new.tap do |f|
f.content_pane.add JLabel.new("Hello World")
f.default_close_operation = JFrame::EXIT_ON_CLOSE
f.pack
f.visible = true
end

22. Method Rubification™
• In general, CamelCase Java methods
can optionally be transliterated to snake
case.

23. Uniform Access Principle
All services offered by a
module should be available
through a uniform notation,
which does not betray whether
they are implemented through
storage or through
computation.
- Bertrand Meyer

24. Two Rules
• Everything's an Object
• Objects expose Methods and Only Methods

26. Method Rubification™
Java System.currentTimeMillis()
Ruby System.current_time_millis

27. Seriously though, not
actually trademarked.
Method Rubification™
Java person.getName()
Ruby person.name

28. Someone should
get on that.
Method Rubification™
Java person.setAge(42)
Ruby person.age = 42

29. Method Rubification™
FALSE! TRUE!
Java person.isJedi()
Ruby person.jedi?

30. Is ruby an acceptable
Java? (http://bit.ly/pfNluA)
• Most Java code can literally be written
as ruby with few high-level changes.
• A more relaxed type system and syntax
often has productivity benefits.

31. Exhibit A
// interfaces = HashMap{ label => NetworkInterface }
Java Collection c = interfaces.values();
Iterator itr = c.iterator();
while(itr.hasNext()) {
NetworkInterface interface = itr.next();
if (interface.isLoopback()) {
return interface.getDisplayName();
}
}
VS.
# interfaces = {label => NetworkInterface}
Ruby interfaces.values.find(&:loopback?).display_name

32. Exhibit A
// interfaces = HashMap{ label => NetworkInterface }
Java Collection c = interfaces.values();
Iterator itr = c.iterator();
while(itr.hasNext()) {
NetworkInterface interface = itr.next();
if (interface.isLoopback()) {
return interface.getDisplayName();
}
}
VS.
# interfaces = {label => NetworkInterface}
Ruby interfaces.values.find(&:loopback?).display_name
1 2 345 67
Only 7 characters of syntactic support!

33. “Are you suggesting I write
all my Java in ruby?!”
• Not really...
• JRuby is much slower than Java
(doesn’t matter as often as you’d think)
• Ruby’s added expressiveness makes it
easier to shoot yourself in the foot.
(or, in fact, to lazily clone an infinite number of your feet every
planck length between your gun and your target)

34. “Are you suggesting I write
all my Java in ruby?!”
• ...but maybe sometimes.
• One possibility:
• Encode high-level logic in expressive
and concise ruby code
• Supporting code in fast, safe Java
• Mix and match as appropriate

35. Ruby as Glue
• Ruby is great for:
• wiring existing codebases together
• other miscellaneous tasks

36. Perl The original
“Swiss Army Knife”

37. Perl Pretty much mean
the same thing.
• “glue”
• “duct tape”
• “swiss army knife”

38. Perl Ruby

39. Subcategories of “Glue”
• Wiring stuff together
• Sysadmin tasks

40. Wiring stuff together
• There’s a lot we could cover here, but:

41. Nokogiri
• An extremely user-friendly XML library
• fast! (wraps libxml2)

42. Nokogiri
require 'open-uri'
require 'nokogiri'
html = open("http://slashdot.org").read
doc = Nokogiri::XML(html)
(doc/".story a").each do |link|
puts "#{link.text} (#{link.attr('href')})"
end
# Britain's Broadband Censors: a Bunch of Students (//yro.slashdot...
# ...

43. Don’t do this.
(Nokogiri::XML(open("http://slashdot.org").read)/".story a").each{|a|puts
"#{a.text} (#{a.attr("href")})"}

44. Sysadmin with Ruby
• Nice system APIs
(quite similar to perl’s)
• System provisioning libraries/DSLs

45. Provisioning systems
• Puppet
• Chef
• Vagrant

46. Puppet
• Describe system, and puppet sets it up
• Nontrivial, but the general idea is:
• I want mysql
• I want nginx < 0.8
• I want this cron job: “....”
• Go.
http://puppetlabs.com/

47. Puppet
class postgres-server {
package { postgresql-server:
ensure => latest
}
group { postgres: gid => 26 }
user { postgres:
comment => "PostgreSQL Server",
uid => 26,
gid => 26,
home => "/var/lib/pgsql",
shell => "/bin/bash"
}
service { postgresql:
running => true,
pattern => "/usr/bin/postmaster",
require => package["postgresql-server"]
}
}

48. Puppet
• Fantastic for defining a reproducible
production environment

49. Chef
• Same idea as puppet
• Somewhat less powerful
• Slightly more approachable to most
ruby developers
http://www.opscode.com/chef/

50. Chef
package "sudo" do
action :upgrade
end
template "/etc/sudoers" do
source "sudoers.erb"
mode 0440
owner "root"
group "root"
variables(
:sudoers_groups => node['authorization']['sudo']['groups'],
:sudoers_users => node['authorization']['sudo']['users'],
:passwordless => node['authorization']['sudo']['passwordless']
)
end

51. Puppet Chef
Configuration Language custom ruby
Targeted at production production
“Powerfulness” Lots Mostly lots
Verdict Good Different
Written in ruby ruby

52. Vagrant
• Uses puppet and/or chef
• End product is a virtual machine for
development use
• Consistent system for all developers, per
project

53. Vagrant
• If you use puppet or chef, vagrant lets
you test production locally

54. Suggestions
• As a non-ruby-dev:
• Use puppet
• Consider vagrant

55. Suggestions
• As a ruby developer:
• Consider chef and puppet, use
whichever suits your taste and needs
• Consider vagrant

56. Databases

57. In the Real World,

58. In the Real World,
We have Data

59. In the Real World,
We have Data
Which lives in Databases

60. Databases Are Always
simple

61. All our data is
ALWAYS
in the same DBMS

62. Reality Check

63. Luckily
We have
ODBC + JDBC

64. Luckily
We have
ODBC + JDBC
+
Ruby

65. Ruby Gives you Options
• Active Record
• Sequel
• DataMapper
• more

66. Active Record
Design pattern coined by Martin Fowler in
“Patterns of enterprise application
architecture”.
Also, Ruby on Rails’s default ORM.
• Lots of Power
• Lots of Opinion
• Might fight with you (for non-standard uses)
https://github.com/rails/rails/tree/master/activerecord

67. Active Record Syntax (Raw)
require 'active_record'
ActiveRecord::Base.establish_connection({
:adapter => 'mysql',
:database => 'test_database',
:username => 'tester',
:password => 'test22'
})
connection = ActiveRecord::Base.connection
connection.tables
> ['users', 'products', 'ducks', 'oranges']
users = []
connection.execute('SELECT * FROM users').each_hash do |user|
users << user
end
users
> .... array of users, each user as a hash.
users.first
> { :id => 1, :username => 'stefan', :password => 'is_super_secure' }

68. Active Record Syntax (ORM)
require 'active_record'
ActiveRecord::Base.establish_connection({
:adapter => 'mysql',
:database => 'test_database',
:username => 'tester',
:password => 'test22'
})
# class <camel_case_singular_table_name> < ActiveRecord::Base
class User < ActiveRecord::Base
# if the table's name does not fit convention, it can be manually overridden.
# table_name :users_table
end
User.first
> #<User id: 2, :name => 'stefan', :password => 'is_super_secure' >
User.find(2)
> #<User id: 2, :name => 'stefan', :password => 'is_super_secure' >
User.where(:name => 'stefan')
> #<User id: 2, :name => 'stefan', :password => 'is_super_secure' >

69. Active Record Syntax (AREL)
User.first
> #<User id: 2, :name => 'stefan', :password => 'is_super_secure' >
User.find(2)
> #<User id: 2, :name => 'stefan', :password => 'is_super_secure' >
User.where(:name => 'stefan')
> #<User id: 2, :name => 'stefan', :password => 'is_super_secure' >
User.where(:name => 'stefan').order('id ASC')
> #<User id: 2, :name => 'stefan', :password => 'is_super_secure' >

70. Sequel
Elegant Full featured database toolkit for ruby.
• Supports a ton of DBMS’s
• DSL
• ORM
http://sequel.rubyforge.org/
Supports
- ADO, Amalgalite, DataObjects, DB2, DBI, DO, Firebird, ibmdb, Informix,
JDBC, MySQL, Mysql2, ODBC, OpenBase, Oracle, PostgreSQL, SQLite3,
Swift, and tinytds

71. require "sequel"
Sequel Example
# connect to an in-memory database
DB = Sequel.sqlite
# create an items table
DB.create_table :items do
primary_key :id
String :name
Float :price
end
# create a dataset from the items table
items = DB[:items]
# populate the table
items.insert(:name => 'abc', :price => rand * 100)
items.insert(:name => 'def', :price => rand * 100)
items.insert(:name => 'ghi', :price => rand * 100)
# print out the number of records
puts "Item count: #{items.count}"
# print out the average price
puts "The average price is: #{items.avg(:price)}"

72. Sequel ORM
require "sequel"
# connect to an in-memory database
DB = Sequel.sqlite
# create an items table
DB.create_table :items do
primary_key :id
String :name
Float :price
end
# create a dataset from the items table
class Item < Sequel::Model(:items)
# associations
# validations
end
# populate the table
Item.create(:name => 'abc', :price => rand * 100)
Item.create(:name => 'def', :price => rand * 100)
Item.create(:name => 'ghi', :price => rand * 100)
# print out the number of records
puts "Item count: #{Item.count}"
# print out the average price
puts "The average price is: #{Item.avg(:price)}"

73. Sequel ORM
+
jRuby
ready out of the box

74. Sequel ORM
+
IRONRuby
apparently works?

75. Case Study (Access)
• Access (top 2 solutions)
• Solution 1 (Cross Platform)
• jRuby
• JDBC
• HXTT’s driver (www.hxtt.com)
• Sequel
• Solution 2 (Windows Only)
• Ruby
• ADO via WIN32OLE
• Sequel

76. Case Study (Access)

77. Case Study (Access)
1. Download jRuby
http://jruby.org/

78. Case Study (Access)
1. Download jRuby
http://jruby.org/
2. Install Sequel
gem install Sequel

79. Case Study (Access)
1. Download jRuby
http://jruby.org/
2. Install Sequel
gem install Sequel
3. Download JDBC Access Driver
http://www.hxtt.com/access.html

80. Case Study (Access)
require 'rubygems'
require 'sequel'
require 'sequel/adapters/jdbc'
require 'sequel/jdbc_hxtt_adapter'
require '../Support/Access_JDBC40.jar'
root = File.expand_path "../../", __FILE__
path_to_db = root + "/Support/AccessThemeDemo.mdb"
DB = Sequel.connect("jdbc:access:////#{path_to_db}")
puts DB.tables
class Notes < Sequel::Model(:Notes)
end
class ThemeImages < Sequel::Model(:tbl_ThemeImages)
end
class Users < Sequel::Model(:tbl_Users)
end

81. ba-da-bing

82. But our new app
and our old database
have different
system requirements.

83. We Want Isolation

84. _
-Need
We Want Isolation

85. Power by.. Sinatra
Web DSL
get '/pictures' do
['picture1','picture2','picture2']
end
post '/pictures' {}
put '/pictures/:id' {}
delete '/pictures/:id' {}
used at linkedIn
http://engineering.linkedin.com/44/linkedin-app-end-end-jruby-frontier-and-voldemort

86. sooo... big deal?

87. RestServer
• any jdbc database into a restful json
service
• https://github.com/stefanpenner/restserver

88. Portability/Bundling
• Warbler
http://github.com/nicksieger/warbler
• single jar/war file
• compiled (if needed)

89. it’s an app!

90. Putting it all together (p1)
ScreenShotr
download:
https://github.com/stefanpenner/screenshotr/zipball/master
git@github.com:stefanpenner/screenshotr

91. Sorry, contrived
example!

92. anyways...

93. Java Gives Us
• Portability
Ruby Gives Us
• Happiness

94. ScreenShotr
Normally Annoying re: Portability
• screen capture
• GUI
but thx jRuby

95. Lets Shoot some Screens
require 'java'
java_import 'java.awt.Robot'
java_import 'java.awt.Toolkit'
java_import 'java.awt.Rectangle'
java_import 'java.awt.Image'
java_import 'java.awt.image.BufferedImage'
java_import 'javax.imageio.ImageIO'
screenRect = Rectangle.new(Toolkit.default_toolkit.getScreenSize())
capture = Robot.new.createScreenCapture(screenRect)
ImageIO.write(capture,'jpg',java.io.File.new('some_tmp_file.jpg'))

96. Hold UP

97. Hold UP
java_import ?

98. Hold UP
java_import ?
why not require?

99. Hold UP
java_import ?
why not require?
requiring classes just makes them discoverable later.

100. Hold UP
java_import ?
why not require?
requiring classes just makes them discoverable later.
why not import?

101. Hold UP
java_import ?
why not require?
requiring classes just makes them discoverable later.
why not import?
Rake defines import

102. Hold UP
java_import ?
why not require?
requiring classes just makes them discoverable later.
why not import?
Rake defines import
weird...

103. And fill some clipboards
require 'java'
java_import 'java.awt.Toolkit'
java_import 'javax.imageio.ImageIO'
ss = StringSelection.new(public_url)
Toolkit.getDefaultToolkit().getSystemClipboard().setContents(ss, nil)

104. upload to server
gem install rest-client
require 'rubygems'
require 'rest-client'
RestClient.post('http://../resource',
:file => File.new('path/to/file'))

105. upload to server
gem install rest-client
require 'rubygems'
require 'rest-client'
RestClient.post('http://../resource',
:file => File.new('path/to/file'))

106. <Insert Segue Here>

107. ...and Vice Versa
• We’ve done a lot of calling Java from ruby.
• The reverse is possible as well.

108. ...and Vice Versa
import org.jruby.embed.InvokeFailedException;
import org.jruby.embed.ScriptingContainer;
// ...
ScriptingContainer container = new ScriptingContainer();
container.runScriptlet("puts "That's no Moon"");
http://en.wikipedia.org/wiki/Jruby

109. Testing Java with Ruby
“i find your lack of
tests disturbing.”

110. Testing Java with Ruby
• JtestR is wonderful
• Includes most of ruby’s leading
testing libraries
• supports ant and maven
• easy to add to a project
• takes advantage of jruby/java bridge

111. JtestR Installation
• Download jarfile from jtestr.codehaus.org
• Add to classpath
• Add a task to maven/ant
• Create tests in ./test or ./spec
• Run task

112. Example!
import java.util.HashMap
describe "An empty", HashMap do
before :each do
@hash_map = HashMap.new
end
it "accepts new entries" do
@hash_map.put "foo", "bar"
@hash_map.get("foo").should == "bar"
end
it "returns a keyset iterator that throws an exception on next" do
proc do
@hash_map.key_set.iterator.next
end.should raise_error(java.util.NoSuchElementException)
end
end

113. “i saw a city
in the clouds”

114. MYTH: Ruby can’t scale.

115. FACT: Ruby scales like a BOSS

116. FACT: Ruby scales like a BOSS
(because it has to)

117. Fog
• “The Ruby Cloud Services Library”
• Lets you upload to S3, provision
instances in EC2, set DNS records in
DNSimple...
• ...and much more.

118. Fog
“
• Chewbacca-approved.
whargarblbgarblgr-
”
garblgragh

119. Fog
“
• Chewbacca-approved. (chewbaccaproved?)
whargarblbgarblgr-
garblgragh ”

120. 2.5 imperial tons of
providers

121. ( )eh.
2.5 imperial tons of
H
providers

146. Sinatra Example
#config.ru
require './lib/screen_shotr/server'
run ScreenShotr::Server.new

147. require 'sinatra'
require 'fog'
require 'digest/sha1'

148. module ScreenShotr
class Server < Sinatra::Base
def storage
#@storage ||= Fog::Storage.new({
# :provider => 'AWS',
# :aws_access_key_id => ACCESS_KEY_ID,
# :aws_secret_access_key => SECRET_ACCESS_KEY})
@storage ||= Fog::Storage.new({
:local_root => '~/fog',
:provider => 'Local'
})
def directory
storage.directories.find("data").first or
storage.directories.create(:key => 'data' )
end
# snip ....

149. get '/' do
"hello, world!"
end

150. post '/picture/create' do
file = params[:file]
data = file[:tempfile]
#super secure filename
filename = file[:filename]
key = Digest::SHA1.hexdigest("super random seed"+Time.now.to_s)
key << '.jpg'
file = directory.files.create(
:body => data.read,
:key => key
)
file.public_url or "http://0.0.0.0:9292/picture/#{key}"
end

151. get '/picture/:key' do
file = directory.files.get(params[:key])
send_file file.send(:path)
end

152. rackup

153. and...

155. Fog Storage:
Kind of cool.

156. Fog Compute:
Wicked cool.

167. Heroku
Classic Stack (run rack/rails)
Cedar Stack (run “anything”)

168. Heroku
Classic Stack (run rack/rails)
$ heroku create
Created sushi.herokuapp.com | git@heroku.com:sushi.git
$ git push heroku master
-----> Heroku receiving push
-----> Rails app detected
-----> Compiled slug size is 8.0MB
-----> Launching... done, v1
http://sushi.herokuapp.com deployed to Heroku

169. Heroku
Cedar Stack (run “anything”)
$ cat Procfile
web: bundle exec rails server -p $PORT
worker: bundle exec rake resque:work QUEUE=*
urgentworker: bundle exec rake resque:work QUEUE=urgent
clock: bundle exec clockwork clock.rb
$ heroku scale web=4 worker=2 urgentworker=1 clock=1
Scaling processes... done
“Officially Everything”:
Ruby, Node.js,Clojure, Java, Python, and Scala

170. “help me ruby...
you’re my only hope!”

171. “good... the force is
strong with you.
Thanks!
a powerful rubyist you
will become.”