1. From Java...to Rails
Nick Sieger
@nicksieger

2. Are you happy with
your development pace
?

3. ?
How do you get to a place
where it’s better?

5. Introduce
Language

6. Replace JSF with
*Anything*

7. throw away

8. Built environment
long-running projects
with legacy codebases

9. Sagrada Família,
Barcelona, Spain

10. passion
facade
nativity
facade
scaffolded interior

11. Ryugyong Hotel,
2004 North Korea 2011

12. seismic retrofit

13. Szkieletor,
Kraków, Poland

14. Metaphor Use Ruby, JRuby, and Rails to...
Sagrada • Build new facade faster
Familia • Scaffolding during refactoring
Ryugyong
• Revive a project with a new face
Hotel
Seismic • Reinforce business rules with a DSL
retrofit • Harden security
Szkieletor • Find novel uses for abandoned code

15. Metaphor Use Ruby, JRuby, and Rails to...
Sagrada • Build new facade faster
Familia • Scaffolding during refactoring
Ryugyong
• Revive a project with a new face
Hotel
Seismic • Reinforce business rules with a DSL
retrofit • Harden security
Szkieletor • Find novel uses for abandoned code

16. Metaphor Use Ruby, JRuby, and Rails to...
Sagrada • Build new facade faster
Familia • Scaffolding during refactoring
Ryugyong
• Revive a project with a new face
Hotel
Seismic • Reinforce business rules with a DSL
retrofit • Harden security
Szkieletor • Find novel uses for abandoned code

17. Metaphor Use Ruby, JRuby, and Rails to...
Sagrada • Build new facade faster
Familia • Scaffolding during refactoring
Ryugyong
• Revive a project with a new face
Hotel
Seismic • Reinforce business rules with a DSL
retrofit • Harden security
Szkieletor • Find novel uses for abandoned code

18. Metaphor Use Ruby, JRuby, and Rails to...
Sagrada • Build new facade faster
Familia • Scaffolding during refactoring
Ryugyong
• Revive a project with a new face
Hotel
Seismic • Reinforce business rules with a DSL
retrofit • Harden security
Szkieletor • Find novel uses for abandoned code

19. Biological evolution
new replaces old over time

20. Strangler Fig

23. github.com/nicksieger/refactoring-to-rails

24. Before we begin...

25. Test Plan
Don’t leave home without it

26. gembundler.com

27. Bundler
source :rubygems
group :test do
gem 'rspec-rails'
gem 'cucumber-rails'
gem 'capybara'
end

29. Feature: Owners
Scenario: Add New Owner
Given I am on the new owner page
When I fill in the following:
| First name | Dan |
| Last name | Wood |
| Address | 123 Main St |
| City | Anywhere |
| Telephone | 5555555 |
And I press "Add Owner"
Then I should see "Owner Information" within "h2"
And I should see "Dan Wood"

32. Foot in the door
Sneaking Ruby in

33. JRuby-Rack
org.jruby.rack:jruby-rack

34. Servlet
Java Ruby
/* /rack/*
App

35. <listener>
<listener-class>
org.jruby.rack.RackServletContextListener
</listener-class>
</listener>
<servlet>
<servlet-name>rack</servlet-name>
<servlet-class>org.jruby.rack.RackServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>rack</servlet-name>
<url-pattern>/rack/*</url-pattern>
</servlet-mapping>

36. # WEB-INF/config.ru
require 'sinatra'
if development?
require 'sinatra/reloader'
use Rack::ShowExceptions
end
require 'app'
set :run, false
run Sinatra::Application

37. # app.rb
get '/rack/' do
'<h1>Sinatra</h1>'
end

38. REST
Not just APIs...

39. URIs + HREFs
Architecture of the Web

40. <a href="/vets.xml">View as XML</a>

41. <a href="/rack/vets.xml">View as XML</a>

42. In JSPs
<jruby-rack:rails path="/rack/vets" params="layout=none"/>

43. Red Green Refactor
Continuous improvement

45. Interceptor pattern
Partial strangulation

46. Filter
/owners Java/
/ /vets /owners /1/pets Spring
App

47. Filter
/ /vets Ruby
/owners Java/
/ /vets /owners /1/pets Spring
App

48. SpringPetclinic::Application.routes.draw do
root :to => "welcome#index"
resources :vets
end

49. Rails Java
Request
response response
/ 200 OK (N/A)
404 Not
/owners 200 OK
Found

50. Re-use views
JSP-in-ERB

51. <%= request.render '/WEB-INF/jsp/header.jsp' %>
<%= yield %>
<%= request.render '/WEB-INF/jsp/footer.jsp' %>

52. Re-use models
Hibernate + ActiveModel

53. # app/models/owner.rb
java_import org.springframework.samples.petclinic.Owner

54. # app/models/owner.rb
java_import org.springframework.samples.petclinic.Owner
class Owner
extend ActiveModel::Naming
include ActiveModel::Validations
include ActiveModel::Conversion
end

55. # app/models/owner.rb
java_import org.springframework.samples.petclinic.Owner
class Owner
extend ActiveModel::Naming
include ActiveModel::Validations
include ActiveModel::Conversion
validates_presence_of :first_name, :last_name,
:address, :city, :telephone
validates_format_of :telephone, :with => /[-0-9.+ ]+/,
:message => "..."
end

56. <%# app/views/owner/_form.html.erb %>
<%= form_for @owner do |f| %>
<%= f.label :first_name %>
<br/>
<%= f.text_field :first_name %>
<%= f.label :last_name %>
<br/>
<%= f.text_field :last_name %>
<%# ... %>
<% end -%>

57. <%# app/views/owner/_form.html.erb %>
<%= form_for @owner do |f| %>
@owner
<%= f.label :first_name %>
<br/>
<%= f.text_field :first_name %>
<%= f.label :last_name %>
<br/>
<%= f.text_field :last_name %>
<%# ... %>
<% end -%>

58. Rails takes over
Final strangulation

59. $ rails new petclinic --skip-active-record

60. $ mvn org.jruby.plugins:jruby-rake-plugin:classpath

61. # config/initializers/classpath.rb
module Maven
extend self
CLASSPATH = [
"#{BASEDIR}/target/classes",
"#{ENV['HOME']}/.m2/.../org.springframework.core-3.0.0.RELEASE.jar",
# lots of jars here...
]
def set_classpath
require 'java'
CLASSPATH.each {|p| $CLASSPATH << p }
end
end

62. Maven.set_classpath
module Spring
SPRING_XML_CONFIG_FILES = [
'classpath:applicationContext.xml'
].to_java :string # creates a String[]
CONTEXT = ClassPathXmlApplicationContext.new(
SPRING_XML_CONFIG_FILES)
end

63. Warbler
INSTALL gem install warbler

64. # config/warble.rb
Warbler::Config.new do |config|
require 'config/initializers/classpath'
config.java_libs += Maven.jar_files
config.java_classes = FileList["target/classes/**/*"]
end

65. $ warble executable war
Creating refactoring-to-rails.war
$ java -jar refactoring-to-rails.war

66. Hollow out the tree

67. JRuby T-Shirts!
Stop by booth #5605

68. Party Tue 6:30pm
http://ey.io/oeuot1

69. ➡ Script Bowl
Nic Williams
Wed 8:30 AM–Hilton Grand Ballroom B
➡ Accelerate Your Business and Aim for the
Cloud with Java and JRuby
Jacob Lehrbaum, Mike Piech
Wed 3:00 PM–Parc 55 Embarcadero
➡ Real World JRuby
Charles Nutter, Thomas Enebo
Wed 4:30 PM–Parc 55 Market Street

71. Images
http://www.flickr.com/photos/john_mcclumpha/4138419594/
http://www.flickr.com/photos/phil_shirley/4500893932/
http://www.flickr.com/photos/y_i/2330044065/
http://www.flickr.com/photos/herzogbr/462383777/
http://en.wikipedia.org/wiki/File:Sagrada_Familia_01.jpg
http://www.flickr.com/photos/koocheekoo/38407225/
http://www.flickr.com/photos/27649557@N07/5000528445/
http://www.flickr.com/photos/gpaumier/446059442/
http://www.flickr.com/photos/ilm/12831049/
http://upload.wikimedia.org/wikipedia/commons/9/95/Ryugyong_hotel_01.jpg
http://upload.wikimedia.org/wikipedia/commons/7/78/
Ryugyeong_Hotel_on_February_2011.jpg
http://en.wikipedia.org/wiki/File:ExteiorShearTruss.jpg
http://en.wikipedia.org/wiki/File:ExtReenfDetail.jpg
http://en.wikipedia.org/wiki/File:Szkieleteor_in_krakow.JPG
http://www.flickr.com/photos/epingchris/5110376533/
http://www.flickr.com/photos/bazylek/3194294047/
http://www.flickr.com/photos/58847482@N03/5920653295/
http://www.flickr.com/photos/nancybaym/3828905896/
http://www.flickr.com/photos/anitagould/5501316782/