JRuby in the Enterprise

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

What is JRuby?

Just a Ruby interpreter running on the JVM

Ruby 1.8.7 & 1.9.2 compatible.

Text-To-Join

Distributed app

Written in Ruby as a Rails app

Four rails apps, actually

UI, API, Console, SMS Processor.

JRUBY.ORG

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.

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

Rails 3.x

“Optimized for programmer happiness”.

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.

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.

Why JRuby Continued

Deployment Options

Can deploy as a WAR file

Monitoring Options

JVM tools to monitor all available

Speed of Development.

Don’t Freak the Ops Guys Out

HTTP://UPLOAD.WIKIMEDIA.ORG/WIKIPEDIA/EN/F/F4/THE_SCREAM.JPG

Scalabilityhttp://commons.wikimedia.org/wiki/File:Everest-fromKalarPatar.jpg

Concurrency is a Myth

HTTP://WWW.IGVITA.COM/2008/11/13/CONCURRENCY-IS-A-MYTH-IN-RUBY/

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/

ILYA GRIGORIKHTTP://WWW.IGVITA.COM/ABOUT/

“Enterprise” JRuby

“Enterprise” JRuby Cont.

Maven

Liquibase

JDBC

JNDI

Containers

You’re favorite commercial, open-source or home-grown library.

Let’s Beginhttp://commons.wikimedia.org/wiki/File:Begin_road.JPG

Set up Ruby

http://commons.wikimedia.org/wiki/File:Panama_Canal_Locks_Construct.jpeg

Ruby Version Manager

HTTPS://RVM.BEGINRESCUEEND.COM/

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/

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

JRuby Without RVM

Assume Java, JRuby in your path

jruby -S gem ...

Install Rails

gem install rails

Can pick a specific version with a “-v” flag.

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.

Jruby.org Template

Demo

Packaging Your App

http://en.wikipedia.org/wiki/File:Distribution_differences.jpg

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/

Install it

Easy!

gem install warbler

Run It

Easy!

warble war

http://en.wikipedia.org/wiki/File:Jeanette_Kwakye_cropped.jpg

Other Useful Optionswarble 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

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.

Database Migrations

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

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.

Enter

liquibase.org

Version control for your database

Other frameworks (Grails) will be adopting it for migrations

Language/Database agnostic.

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.

Liquibase

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

Handy Liquibase Commands

USING LIQUIBASE

WITH MAVEN

Liquibase with Rails Directly

https://github.com/redbeard/liquibase-rails

Supposed to add “drop in” migration tasks for JRuby/Rails.

Liquibase Changeset

JNDI Database AccessDATABASE.YML

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

web.xml.erb Filter Entry

Java Integration

Nothing special, just the usual JRuby/Java integration

Looks for JARs in the container classpath, WAR or in yourapp/lib

Calling Java

HTTPS://GITHUB.COM/JRUBY/JRUBY/WIKI/CALLINGJAVAFROMJRUBY

Tips, Tricks and Lessons

http://en.wikipedia.org/wiki/File:Coolidge_after_signing_indian_treaty.jpg

Warbler Config

generate a warbler config file

warble config

Pre-Compile Ruby Classes

config.features = %w(compiled)

Set Min/Max Runtimes

Set JNDI Source Name

Set Root Path for App

By default, the root of your app is the WAR name

This may not be what you want.

Set the Root Path

Create file jboss-web.xml in root of app directory

Tell warbler to include it via warble.rb

Bundle Up Files into A GemCan be much faster to build/deploy depending on how you do it (there are a lot of files!)

Make sure to test it

Make Your War Executable

Command Line:warble executable war

In warble.rb:config.features = %w(executable)

Rails Console

Rails has a “Console Mode” for testing

Great for trying out ActiveRecord queries, etc.

Just use “rails console” to invoke it.

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.

Basic Versioning RulesAfter 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/

Handle Database Connection Outage

This is the “default” 500 error page.

You can Customize this but...

You can do better

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).

Insert Your Own MiddlewareCreate lib/db_check.rb

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

You Now Have Generic Status Ability

Extend for other things useful to your application.

HTTP://TORQUEBOX.ORG/

IDEs

Resources

Books

Websites

http://www.jruby.org/

http://jrubyconf.com/

http://vimeo.com/groups/87639(talks from 2010 JRubyConf)

http://www.engineyard.com/open-source

Twitter Users

http://twitter.com/#!/headius

http://twitter.com/#!/nicksieger

http://twitter.com/#!/jruby

Questions?

Thank You!

Don’t forget to fill out a session evaluation!