JRuby allows Ruby code to run on the Java Virtual Machine. Warbler is a gem that can package JRuby or Rack applications into WAR files to deploy on Java application servers like Tomcat. The document demonstrates using Warbler to create a WAR file for a simple Sinatra app, then deploying it directly to Tomcat. Practical examples are also given of deploying Rails apps in Tomcat with filters and writing Ruby libraries deployed as JAR files.

1. Deploying JRuby
Webapps
Mike Berning - mberning@gmail.com
Demo App - https://github.com/mberning/warbler-demo-app
Slides -

2. What is JRuby?
• JRuby is an implementation of the Ruby language that
runs on the JVM (Java Virtual Machine)
• Runs Ruby code just like MRI/cruby, works with familiar
tooling such as Rubygems, Bundler, etc.
• JRuby 9K is the upcoming version of JRuby which is
compatible with Ruby version 2.2
• JRuby 1.7.x is the current version of JRuby which is
compatible with Ruby version 1.8.x and 1.9.x

3. Why?
Technical
• Runs anywhere Java does
• Mature ecosystem with many libraries
• Threading
• Performance of the JVM
Environmental/Political
• Perhaps you work in a ‘Java Only’ shop but want to introduce JRuby
• You need to integrate with or use legacy code that cannot be
rewritten in another language

4. Many Options
• Trinidad - Tomcat based server
• Puma - Inspired by Mongrel
• Phusion Passenger - Deploy behind Apache or nginx
• Cloud - Heroku, Engine Yard, et al.
• And plenty of others

5. Another Option
WAR file based deployment
• A WAR file (Web application ARchive) is a specialized
JAR file for deploying apps in a Java EE container
• If we can create a WAR file for our JRuby webapp we
can deploy it in any number of Java EE containers.
• Tomcat
• JBoss
• Websphere
• etc.

6. Enter Warbler
https://github.com/jruby/warbler
• Warbler is a Gem that can create a JAR or WAR for any
JRuby or Rack based application
• Create a JAR for standalone or command line utilities
• Run them with java -jar application.jar
• Create a WAR for Rack based webs
• Deploy the WAR file in an appropriate container (such as
Tomcat)

7. Demo
• We have a simple Sinatra app that will generate a
PowerPoint slideshow using JRuby and Java JARs
• Build a WAR file using Warbler
• Deploy the WAR file directly in Tomcat

8. Practical Examples
• Deploy a Rails app in Tomcat and use specialized
servlet filters to do things like SSO
• Use Tomcat to manage a large number of application
deployments
• Write Ruby applications - for example doing text
processing - that are deployed as JAR files in a larger
application