1. JRuby: Ruby and Rails for the JVM Charles Nutter Except where otherwise noted, the content of this presentation is licensed under the Creative Commons Attribution-Share Alike 3.0 United States License (http://creativecommons.org/licenses/by-sa/3.0/us/).

2. 2 Your Humble Presenter Charles Oliver Nutter Longtime Java developer (10+ yrs) Shorttime engineer at Sun Microsystems Full-time JRuby developer Also working to build out JVM dynlang support Wide range of past experience C, C++, C#, Python, Delphi, Lisp, Scheme Java EE and ME

3. 3 Off We Go! Ruby 101

4. 4 What Is Ruby Dynamic-typed, pure OO language Interpreted Open source, written in C Good: easy to write, easy to read, powerful, “fun” Bad: green threads, unicode support, libraries, “slow” Created 1993 by Yukihiro “Matz” Matsumoto “More powerful than Perl and more OO than Python” Very active community, wide range of apps

5. 5 Why Ruby? Easy to learn Extremely powerful Potentially the “most” dynamic of dynlangs Large and growing set of libs and apps Large and growing community “Fun” factor can't be understated Fast growing popularity

6. 6 TIOBE Programming Community Index

7. 7 Pure OO Everything is an Object Circle.new(4)=> instance of Circle “abc”.length => 3 1.to_s => “1” All Objects are instances of Classes 1.class=> Fixnum Single-Inheritance Object is base class of all classes

8. 8 Literals Fixnum: 1 Float: 1.0 Bignum: 12345678987654321 String: “one” 'one' %Q[one] %q[one]... Multiline string (“here doc”): x = <<EOS extend across two lines EOS Regexp: /^foo\w+.*bar$/, %r[^foo$] Array: [1, “ein”, :ichi] Hash: {:one => 1, :two => 2}

9. 9 Basics String substitution a = “foo” b = “bar#{a}baz” => “barfoobaz” Operator overloading def +(arg);... Attributes class Foo attr_accessor :a end x = Foo.new x.a = “hello” puts x.a => “hello”

10. 10 Dynamically Typed Variables do not declare type a = 1 a = “one” a = [1, “ein”, a] Strongly typed: objects stay the same type...but type is less important than supported ops Don't rely on incoming types Rely on expected operations Often called “Duck Typing” today

11. 11 Duck Typing “If it waddles like a duck and it quacks like a duck...” Runtime errors seem scary, but rarely happen Good unit testing helps prevent those rare cases def make_it_waddle(waddler) waddler.waddle end make_it_waddle(Duck.new) make_it_waddle(Penguin.new) make_it_waddle(Octopus.new)

12. 12 A Simple Class class Circle < Object def initialize(radius) @radius = radius end... def area() return Math::PI * @radius ** 2 end Circle.new(4)

13. 13 Circle extends Object class Circle < Object def initialize(radius) @radius = radius end... def area() return Math::PI * @radius ** 2 end Circle.new(4)

14. 14 Constructors are named “initialize” class Circle < Object def initialize(radius) @radius = radius end... def area() return Math::PI * @radius ** 2 end Circle.new(4)

15. 15 Instance variables prefixed with @ class Circle < Object def initialize(radius) @radius = radius end... def area() return Math::PI * @radius ** 2 end Circle.new(4)

16. 16 Modules: Mixin inheritance module ShapeStuff def diameter return 2 * @radius end class Circle include ShapeStuff... end Circle.new(4).diameter => 8

17. 17 Blocks or Closures # Two syntaxes: Curly brackets {} or do... end [1, 2, 3].each {|number| puts “I see #{number}” } [1, 2, 3].each do |number| puts “I see #{number}” end def foo yield “hello” end def foo2(&block) block.call(“hello”) end

18. 18 Why Blocks? Removes repetitive code No need for the same old external iterator code list.each { |element|... do something... } Transactional logic can be internalized File.open(fname) {|file| line = file.gets... }

19. 19 Metaprogramming Create and modify classes Add, alias, remove, or replace methods Include a module at any time Add instance or class variables at any time Special hooks to lazily metaprogram send – call methods by name method_missing – for when methods don't exist const_missing – for when constants aren't defined

20. 20 NetBeans Ruby Support Best Ruby IDE available code completion in dozens of ways smart syntax highlighting more and more refactorings jump to method, variable, class declarations pop-up RDoc full project support for Ruby or Rails apps everything else IDEs do: version control, etc

21. 21 Demo Ruby Programming in NetBeans

22. 22 What is JRuby? Started in 2002 Java implementation of Ruby language Open source, many active contributors Compatible with current Ruby version Easy integration with Java libraries, infrastructure Call to Ruby from Java via JSR223, BSF Use Java classes from Ruby (e.g. Script Java) Growing set of external projects based on JRuby

23. 23 Getting JRuby Download from JRuby.org

24. 24 Getting JRuby Build it yourself

25. 25 Demo Interactive Java

26. 26 Why JRuby? JVM is an excellent platform Vast library of quality Java libraries Wide distribution Faster every day; microbenches faster now Potential for much better unicode, threading Deploy to standard app servers

27. 27 Java: The Everytool

28. 28 Java: The Everytool

29. 29 Demo Profligacy: The Swing Reducer ihate.rubyforge.org/profligacy/ prof·li·gate: adj. 1. Given over to dissipation; dissolute. 2. Recklessly wasteful; wildly extravagant.

30. 30 Demo Cheri: A Builder Framework for (J)Ruby and Java cheri.rubyforge.org

31. 31 Now It Gets Interesting JRuby on Rails: The Basics

32. 32 What is Rails Full Stack Framework ActiveSupport provides base frameworks ActiveRecord for database access (model) ActionPack for controllers and views ActionWebService, ActionMailer Rapid Development Code generators for models, views, controllers, unit tests, plugins, ajax interfaces, web services, and more Schema management/versioning DSL (“migrations”)

33. 33 Why Rails Terse and Elegant “One-tenth as much code as Java” Convention over Configuration Don't Repeat Yourself A “DSL for web development” Agile A running application from day one A lightweight development server Incremental, test-driven development

34. 34 Why JRuby on Rails All the Ruby reasons are important for webapps Improved deployment story with Java app servers Native Unicode a must for i18n web dev Broader, more scalable database support Integration with Java libs, legacy services Easier to switch web framework than app arch

35. 35 Demo Creating a Simple Rails Application

36. 36 How Easy Can It Be? Rails Deployment

37. 37 Classic Option #1: Just use Mongrel

38. 38 Classic Mongrel is supported by JRuby Some bits won't work Forking off subprocesses Process management Some folks are running JRuby/Mongrel Most typical Mongrel setups should work Mongrel JCluster is recommended

39. 39 Normal RoR With Mongrel

40. 40 JRoR with Mongrel JCluster

41. 41 The New Way Option #2: Deploy to an app server

42. 42 East Meets West GoldSpike: Rails plugin for building WAR files One plugin, pure Ruby Out comes a deployable WAR file Server-agnostic But GlassFish fairly rocks (glassfish.dev.java.net)

43. 43 JRoR with GoldSpike

44. 44 Demo Using GoldSpike with GlassFish

45. 45 Middle Ground Option #3: GlassFish v3 Rails Support

46. 46 Best of Both Worlds? ~/work/jruby $ gem install glassfish-rails ~/work/jruby $ glassfish_rails ~/myapp => Starting GlassFish => Rails application at http://localhost:8080 => Admin services at http://localhost:4848 => Clustering enabled => Connection pooling enabled => Load balancing enabled => Server Ready.

47. 47 JRoR with GoldSpike

48. 48 Demo Glassfish v3 Rails Preview

49. 49 The Transformed Man Beyond Rails Creating your own Chimera

50. 50 Chimera Chimera, noun 1: (Greek mythology) fire-breathing she-monster with a lion's head and a goat's body and a serpent's tail; daughter of Typhon [syn: Chimera, Chimaera] 2: a grotesque product of the imagination [syn: chimaera]

51. 51 Chimera Chimera, noun 1: (Greek mythology) fire-breathing she-monster with a lion's head and a goat's body and a serpent's tail; daughter of Typhon [syn: Chimera, Chimaera] 2: a grotesque product of the imagination [syn: chimaera] 3: (JRuby mythology) fire-breathing program with a Rails head and a Java body and/or tail.

52. 52 There's a Whole Platform Out There Billions of lines of Java code out there Tens of thousands of deployments Thousands of libraries The Java platform is mature, trusted, reliable...and often boring! So why not combine two greats? Ruby as the programming language Java for the platform and libraries

53. 53 Java EE 5: The Choicest Cuts

54. 54 Our Chimera Combining features Ruby or Rails as the application layer Java libraries, alone or as ported gems Java-based services...legacy integration The JVM Acceptable to today's enterprise “Enterprise-ready” without losing the Ruby Way To them: “it's just Java”, to you: “It's just Ruby”

55. 55 Demo ActiveHibernate code.google.com/p/activehibernate/

56. 56 Other Projects to Watch ActiveMessaging JMS support Spring on Rails Rake/Rant/Buildr/Raven ActiveJPA?

57. 57 The Future of JRuby JRuby 1.0.1 to be released soon JRuby 1.1 by November Full compilation to bytecode Reworked IO library Intensive concurrency testing Enhancing Java integration Compile to static classes? Extend Ruby classes with Java subclasses?

58. 58 A New Beginning JRuby: www.jruby.org JRuby Wiki: www.headius.com/jrubywiki Ruby:www.ruby- lang.org Rails: www.rubyonrails.org NetBeans: www.netbeans.org NetBeans Ruby: wiki.netbeans.org/wiki/view/Ruby Blog: headius.blogspot.com

59. 59 Credits “The ultimate Swiss Army Knife for sale in Interlaken” by redjar, http://www.flickr.com/photos/redjar/113974357/, http://creativecommons.org/licenses/by-sa/2.0/ http://www.flickr.com/photos/redjar/113974357/