This is from a talk I gave at UberConf 2011 in Denver, CO.

1. JRuby in the Enterprise

2. About Me
Advisory Engineer at Constant Contact
Spent several years working for Sun/Javasoft in
the distributed computing group
Email: jerry@gulla.com
Twitter: @jerrygulla
Github: github.com/jgulla

3. What is JRuby?
Just a Ruby interpreter running on the JVM
Ruby 1.8.7 & 1.9.2 compatible.

4. Text-To-Join
Distributed app
Written in Ruby as a Rails app
Four rails apps, actually
UI, API, Console, SMS Processor.

7. JRUBY.ORG

8. Why Ruby?
Ruby is…A dynamic, open source programming
language with a focus on simplicity and
productivity. It has an elegant syntax that is natural
to read and easy to write.

10. WHY SHOULD YOU SWITCH TO RUBY? IF YOU ARE HAPPY WITH
PERL OR PYTHON, YOU DON'T HAVE TO. BUT IF YOU DO FEEL
THERE MUST BE A BETTER LANGUAGE, RUBY MAY BE YOUR
LANGUAGE OF CHOICE. LEARNING A NEW LANGUAGE IS
HARMLESS. IT GIVES YOU NEW IDEAS AND INSIGHTS. YOU
DON'T HAVE TO SWITCH, JUST LEARN AND TRY IT. YOU MAY
FIND YOURSELF COMFORTABLE ENOUGH WITH RUBY TO
DECIDE TO SWITCH TO IT.
-- YUKIHIRO MATSUMOTO (“MATZ”)
HTTP://LINUXDEVCENTER.COM/PUB/A/LINUX/2001/11/29/
RUBY.HTML

11. Rails 3.x
“Optimized for programmer happiness”.

12. Why Not Grails?
Grails is great
Not as big of a break with Java
Wanted a bigger shift to bring new ways of doing
things into perspective.

13. Why JRuby?
High performance
JVM Highly Tuned
Real threading
Many “pure Ruby” shops using JRuby just for
this
Vast array of libraries
No need to abandon Java libraries.

14. Why JRuby Continued
Deployment Options
Can deploy as a WAR file
Monitoring Options
JVM tools to monitor all available
Speed of Development.

15. Don’t Freak the Ops
Guys Out
HTTP://UPLOAD.WIKIMEDIA.ORG/WIKIPEDIA/EN/F/F4/THE_SCREAM.JPG

16. http://commons.wikimedia.org/wiki/File:Everest-fromKalarPatar.jpg
Scalability

17. Concurrency is a Myth
HTTP://WWW.IGVITA.COM/2008/11/13/CONCURRENCY-IS-A-MYTH-IN-RUBY/

18. ILYA GRIGORIK
HTTP://WWW.IGVITA.COM/ABOUT/
JRUBY IS, IN FACT, THE ONLY RUBY IMPLEMENTATION
THAT WILL ALLOW YOU TO NATIVELY SCALE YOUR RUBY
CODE ACROSS MULTIPLE CORES. BY COMPILING RUBY
TO BYTECODE AND EXECUTING IT ON THE JVM, RUBY
THREADS ARE MAPPED TO OS THREADS WITHOUT A GIL
IN BETWEEN - THAT'S AT LEAST ONE REASON TO LOOK
INTO JRUBY.
HTTP://WWW.IGVITA.COM/2008/11/13/CONCURRENCY-IS-A-MYTH-IN-RUBY/

19. “Enterprise” JRuby

20. “Enterprise” JRuby Cont.
Maven
Liquibase
JDBC
JNDI
Containers
You’re favorite commercial, open-source or home-
grown library.

21. Let’s Begin
http://commons.wikimedia.org/wiki/File:Begin_road.JPG

22. http://commons.wikimedia.org/wiki/File:Panama_Canal_Locks_Construct.jpeg
Set up Ruby

23. Ruby Version Manager
HTTPS://RVM.BEGINRESCUEEND.COM/

24. Installing RVM
Via git repo (preferred method)
bash < <(curl -s https://rvm.beginrescueend.com/install/rvm)
Other methods at https://rvm.beginrescueend.com/rvm/install/

25. Install JRuby (via rvm)
rvm install jruby-1.6.3
When it’s done, use it:
rvm use jruby-1.6.3
List of other ruby versions to install:
rvm list known
List versions of ruby you have installed:
rvm list

26. JRuby Without RVM
Assume Java, JRuby in your path
jruby -S gem ...

27. Install Rails
gem install rails
Can pick a specific version with a
“-v” flag.

28. Create Your Rails App
Jruby.org hosts a rails template
Sets things up to run under native ruby or JRuby
You can do this yourself, but it’s handier to start this
way
rails new uberconf_demo --template=http://jruby.org
Works with native ruby or JRuby.

29. Jruby.org Template

31. Demo

32. Packaging Your App
http://en.wikipedia.org/wiki/File:Distribution_differences.jpg

33. JRuby/Rails/WAR files
In the Java world, WAR files are standard
Fortunately, we have bundler
Gem to package your Rails app as a WAR file
Can even make it “Executable” for stand-alone
testing!
http://caldersphere.rubyforge.org/warbler/

34. Install it
Easy!
gem install warbler

35. Run It
http://en.wikipedia.org/wiki/File:Jeanette_Kwakye_cropped.jpg
Easy!
warble war

36. Other Useful Options
warble compiled # Feature: precompile all Ruby files
warble config # Generate a configuration file to customize your archive
warble executable # Feature: make an executable archive
warble gemjar # Feature: package gem repository inside a war
warble pluginize # Install Warbler tasks in your Rails application
warble version # Display version of Warbler
warble war # Create the project war file
warble war:clean # Remove the project war file
warble war:debug # Dump diagnostic information

37. Maven
In the Java world, Maven is still pretty popular
For better or for worse
You can use Maven to invoke warbler to package
your app.

39. Database Migrations
http://en.wikipedia.org/wiki/File:Connochaetes_taurinus_-Wildebeest_crossing_river_-East_Africa.jpg

40. Database Migrations
Rails uses Rake for ActiveRecord migrations
Nice, but
Hard to scale to multiple developers
Hard to deploy to QA/Production systems
without using ruby toolset
Paranoid DBAs can’t see the SQL before
running it.

41. Enter
liquibase.org
Version control for your database
Other frameworks (Grails) will be adopting it for
migrations
Language/Database agnostic.

42. Liquibase
Nothing special about using Liquibase with Rails
Use ActiveRecord migrations for initial dev/testing,
then migrate to Liquibase
When ready, just take “snapshot” of DB config,
then roll out new Liquibase changesets.

43. Handy Liquibase Commands
Generate initial changelog:
java -jar liquibase.jar --classpath=mysql-connector-
java-5.1.14-bin.jar --url=jdbc:mysql://localhost/
api_development --driver=com.mysql.jdbc.Driver --
username=demo --password=password --
changeLogFile=db-changelog.xml generateChangeLog
Drop all tables so you can start over:
dropAll
Run updates against a DB:
liquibase --changeLogFile=myChangeLog update
Just output SQL, don’t run: updateSQL

44. USING
LIQUIBASE
WITH MAVEN

45. Liquibase with Rails Directly
https://github.com/redbeard/liquibase-rails
Supposed to add “drop in” migration tasks for
JRuby/Rails.

46. Liquibase Changeset

47. JNDI Database Access
DATABASE.YML

48. Servlet Filters
You’ll need a custom web.xml config
Copy WARBLER_HOME/web.xml.erb to
config/web.xml.erb
Look for it at ~/.rvm/gems/jruby-1.6.2/gems/
warbler-1.3.1/web.xml.erb
HTTP://EN.WIKIPEDIA.ORG/WIKI/FILE:DICHROIC_FILTERS.JPG

49. web.xml.erb Filter Entry

50. Java Integration
Nothing special, just the usual JRuby/Java
integration
Looks for JARs in the container classpath, WAR or
in yourapp/lib

51. Calling Java
HTTPS://GITHUB.COM/JRUBY/JRUBY/WIKI/CALLINGJAVAFROMJRUBY

52. Tips, Tricks and Lessons
http://en.wikipedia.org/wiki/File:Coolidge_after_signing_indian_treaty.jpg

53. Warbler Config
generate a warbler config file
warble config

55. Pre-Compile Ruby Classes
config.features = %w(compiled)

56. Set Min/Max Runtimes

57. Set JNDI Source Name

58. Set Root Path for App
By default, the root of your app is the WAR name
This may not be what you want.

59. Set the Root Path
Create file jboss-web.xml in root of app directory
Tell warbler to include it via warble.rb

60. Bundle Up Files into A
Gem
Can be much faster to build/deploy depending on
how you do it (there are a lot of files!)
Make sure to test it

61. Make Your War Executable
Command Line:
warble executable war
In warble.rb:
config.features = %w(executable)

62. Rails Console
Rails has a “Console Mode” for testing
Great for trying out ActiveRecord queries, etc.
Just use “rails console” to invoke it.

63. Gem Versions
Be sure to lock down Gem versions when you’re
happy with them
Don’t want any last minute “upgrades!”
Use bundler
Put Gemfile.lock under source control.

64. Basic Versioning Rules
After bundling, always check your Gemfile.lock
into version control
After updating your Gemfile, always run
bundle install first.
When running an executable, ALWAYS use
bundle exec [command]
The only exception is the rails command!
http://yehudakatz.com/2011/05/30/gem-versioning-and-bundler-doing-it-right/

65. Handle Database Connection Outage
This is the “default” 500 error page.

66. You can Customize this
but...
You can do better

67. Create “Status” URL
Want a well known URL that Nagios or a Load
Balancer can check
Should return something useful (and specific to
your test).

68. Insert Your Own Middleware
Create lib/db_check.rb

69. Insert Your Own Middleware
Insert it into the stack (application.rb)

71. You Now Have Generic Status Ability
Extend for other things useful to your application.

72. HTTP://TORQUEBOX.ORG/

73. IDEs

78. Resources

79. Books

80. Websites
http://www.jruby.org/
http://jrubyconf.com/
http://vimeo.com/groups/87639
(talks from 2010 JRubyConf)
http://www.engineyard.com/open-source

81. Twitter Users
http://twitter.com/#!/headius
http://twitter.com/#!/nicksieger
http://twitter.com/#!/jruby

82. Questions?

83. Thank You!
Don’t forget to fill out a session evaluation!