Bitter Java?
Sweeten with JRuby
Brian Sam-Bodden

Java Today

Java is a 10+ year old programming language
Java is the new COBOL
Java is Dead
Long live Java!

Java is not going anywhere
Because Java is everywhere!
But Java is not perfect
and it is adjusting to keep up

Java has its jewels
JDBC, JMS, Servlets
and its blemishes...
EJB < 3, JSF

But we have a secret weapon...
On this corner...
presenting the amazing, highly tuned, multi-
platform computing engine that dominates the
present and permeates the future
The JVM

The are more than 200+ languages implementations
for the Java VM
The Java VM is like that neighborhood with low taxes
and good schools... everyone wants in
Regardless of where we go with Java “the language”,
Java “the platform” is here to stay

Groovy, JRuby and all the new kids on the block are
just new additions to our beloved Swiss army knife

What’s Missing?

Java is solid on the server-side
Java powers the enterprise
Web development with Java has not been all that
successful in the presentation tier
Dynamic languages and frameworks based on dynamic
languages have proved to be better suited for this

Why Ruby?

Why not?

✓Object-Oriented
✓Elegant ✓General Purpose
✓ Multi-paradigm
Ruby ✓ Interpreted
is...
✓Reflective ✓Dynamic
✓ Garbage-collected

Created by Yukihiro “Matz” Matsumoto
Developed in 1993, released in 1995
Blended parts of his favorite languages:
Perl, Smalltalk, Sather, Eiffel, CLU, Ada and Lisp
More popular than Python in Japan

Ruby Ideals:
Programming should be fun!
Principle of Least Surprise
“I believe people want to express themselves when
they program. They don’t want to fight with the
language. Programming languages must feel natural
to programmers.”
Matz

JRuby

A non-Java language for the Java platform
A Ruby interpreter written in Java
Started life in 2001
Current version is 1.0 (1.1b1)
Open Source

Oh, come on! Grow up!

Ruby libraries from Java (like ActiveRecord)
➡Using Bean Scripting Framework (JDK <= 1.5)
➡Using JSR 223 Scripting API (JDK > 1.5)
Java libraries from Ruby (Swing, SWT)

RubyGems comes pre-installed
Mongrel supports JRuby
Rails just works
No native extensions (unless by native you mean Java ;-)

JRuby does not produce bytecode artifacts for
the Ruby code (yet!)
This is key difference with Groovy*
Corporate backing :-) Sun and Thoughtworks
have folks working on JRuby full-time

All you need to run JRuby is the Java JDK (=>1.4)

Familiar?
pure Ruby with Java players

Let’s try some interactive JRuby
Fire up the JRuby console using Java Web Start
http://www.tc.umn.edu/%7Eenebo/webstart/jirb-console/console.jnlp
Java version of IRB (Interactive RuBy) tool

IRB is the best to get acquainted with Ruby

A Simple
Comparison

Let’s do some file I/O...
First we need a text file

package com.integrallis;
import java.io.BufferedReader; Let’s open the text file
import java.io.FileReader;
import java.io.IOException; and print out its contents
public class MyFileReader { ...in Java
public static void main(String[] args) {
try {
BufferedReader in = new BufferedReader(new FileReader(quot;read_me.txtquot;));
String str;
while ((str = in.readLine()) != null) {
System.out.println(str);
}
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

Let’s do it the Ruby way!

But wait! This just in...
... Ruby encapsulates common behaviors
➡ A one-liner version, yet is readable!

Why?

For Web applications...
Best of both worlds:
➡Dynamic-Framework on the Front End (Rails)
➡Solid Back End battle tested technologies (Spring/EJB3)

Got API-itis?
Ruby’s ability to create concise DSLs
paired with Java’s richness of APIs and frameworks
Java APIs are robust, fully-featured, flexible...
...which makes them complex
A JRuby DSL can help us in the 80-20 scenarios

Got API-itis? JRuby+SWT

There are JRuby DSLs all ready to use...
Today!
ActiveRecord-JDBC - OR-Wrapping
Raven - Wrapper for Rake, RubyGems and Maven
AntBuilder - Wrapper for Ant
JRake - Wrapper for Rake
JtestR - Test Java code with the best Ruby testing tools

JRuby on Rails

Java & JEE
the most prevalent language
the most complete enterprise platform
a rich ecosystem of web frameworks
a vibrant open source community

Java & JEE
plagued by mediocre web frameworks
not well suited for rapid prototyping
in need of a dynamic language web framework
one level of abstraction too low for the web

Who could help Java on the Web Tier?

Ruby on Rails
a revolutionary web framework
complete MVC solution
fast prototyping
killer AJAX support

Ruby on Rails
a DSL for the web
leading the pack on the web 2.0 front
born from a product, not a committee
a vibrant open source community

JRuby on Rails
the agility of rails - the scalability of Java
JRuby likely to surpass Ruby in speed
sneak Ruby and RoR into the enterprise!

JRuby on Rails

JRuby on Rails

JRuby on Rails
JEE servers are good at scaling up
no more multi-process management
use JRuby “multi-VM” support
leverage the maturity of the JVM and JEE servers

JRuby on Rails
deploy your Rails app as a WAR
leverage JDBC from ActiveRecord

JRuby &
Rapid Spring
Prototyping

JRuby+Spring RAD
a simple example by the folks at jobster
use JRuby for rapid prototyping
Spring controller that delegates to a JRuby controller
JRuby controllers live alongside your JSPs

JRuby+Spring RAD
Simple JRuby controller

JRuby+Spring RAD
JSP view provides input to the Ruby controller

JRuby+Spring RAD
JSP view provides input to the Ruby controller

JRuby+Spring RAD
this experimental library supports:
✓access to Spring beans from JRuby code
✓ access to Hibernate queries

JRuby on
Springy Rails

JRoR on Spring
Chris Nelson’s work
✓use rails-integration plugin
✓ expose WebApplicationContext in a RoR controller
✓include Spring - Spring plugin for JRuby

JRoR on Spring
✓install goldspike rails-integration plugin on you JRoR app
✓ rake war:standalone:create to package a WAR with:
➡Your RoR app
➡JRuby and Rails libraries

JRoR on Spring
rake war:standalone:create in action:

JRoR on Spring
generated WARs work on many servers:
✓Tomcat ✓Glassfish
✓Jetty ✓JBoss

JRoR on Spring
✓ add Chris’ Spring module:

JRoR on Spring
✓ Expand the generated WAR
✓Add Spring application
➡ Application Code
➡ Libraries (Jars)
➡ Config Files

JRoR on Spring
✓ access your Spring beans from a RoR controller

JRoR on Spring
✓add a new face to your Spring applications
✓ leverage thousands of open source projects
✓leverage the good parts of JEE like JDBC and JMS

Resources
JRuby
www.jruby.org
rubyforge.org/projects/jruby-extras
JRuby Rails Integration
www.headius.com/jrubywiki/index.php/Rails_Integration
headius.blogspot.com/2006/11/advanced-rails-deployment-with-jruby.html
RAD Spring Prototyping with JRuby
thebogles.com/blog/projects/ruby-on-spring/
www.botspiritcompany.com/src/springruby/example_ruby_spring.html
Chris Nelson’s Work
mysterycoder.blogspot.com/2007/06/spring-jruby.html
mysterycoder.blogspot.com/2007/06/include-spring.html

www.integrallis.com