JRuby + Rails = Awesome Java Web Framework at Jfokus 2011

JRuby
+ Rails =
Awesome Java Web Framework!
Nick Sieger
nsieger@engineyard.com
Jfokus 2011

Ruby: Developer
Happiness

=

“Ruby is the glue
that doesn't set”
– Dave Thomas

http://pragdave.pragprog.com/pragdave/2006/06/glue_that_doesn.html

Ruby =
innovation

http://www.flickr.com/photos/vermininc/2777441779/

Testing

RSpec
http://rspec.info/ http://cukes.info/

Ruby
Dynamic language of the cloud

Ruby: Dynamic,
Object-Oriented

http://www.ﬂickr.com/photos/listenmissy/4869202176/

Duck-Typing
def area(width = 10, height = 2 * width)
width * height
end

p area # => 200
p area 5 # => 50
p area 5, 20 # => 100
p area "10", 4 # => ?

Duck-Typing
p area "10", 4 # => "10101010"

# From Ruby API docs:

# String#*(num)
#
# Returns a new String containing num copies of
# the receiver.
#
# "Ho! " * 3 #=> "Ho! Ho! Ho! "

area true, false
# => NoMethodError: undefined method `*' for
# true:TrueClass

Flexible Syntax
def set_options(env, opts)
end

set_options(:production, {"caching" => "on", "debug" => "false"})

set_options(:production, "caching" => "on", "debug" => "false")

set_options :production, {"caching" => "on", "debug" => "false"}

set_options :production, "caching" => "on", "debug" => "false"

Blocks
list = [1, 2, 3, 4]

list.each {|n| puts n }
Ruby
list.each do |n|
puts n
end

List<Integer> list = Arrays.asList(1, 2, 3, 4);

Java for (Integer n : list) {
System.out.println(n);
}

Blocks
File.open(__FILE__) do |file|
file.each_line do |line|
Ruby puts line
end
end

BufferedReader file =
new BufferedReader(new FileReader("Blocks.java"));
try {
String line;
while ((line = buf.readLine()) != null) {
Java System.out.println(line);
}
} finally {
file.close();
}

Open Classes

msg = "Scramble this so you can't read it!"
msg.rot13!

# => NoMethodError: undefined method `rot13!' for
# "Scramble this so you can't read it!":String

Open Classes
class String
def rot13!
0.upto(length - 1) do |i|
case self[i]
when ?a..?z
self[i] = ?a + ((self[i] - ?a) + 13) % 26
when ?A..?Z
self[i] = ?A + ((self[i] - ?A) + 13) % 26
end
end
self
end
end

Open Classes

puts msg.rot13!
# => "Fpenzoyr guvf fb lbh pna'g ernq vg!"
puts msg.rot13!
# => "Scramble this so you can't read it!"

Rails 3
Dynamic framework of the cloud

Opinionated
Framework

Request- Convention Defaults
Place for
based over with
everything Conﬁguration
MVC Choices

Place for everything
application code
configuration &
environments
routes
(URL structure)
database migrations
static assets
(images, js, css)
tests

Request-based MVC
Request Routing Controller
Model
Action Action
ActiveRecord
Dispatch Controller

View
Database
Response ActionView

Convention over Configuration
URL GET /people

resources :people
Routing #=> people#index

# app/controllers/people_controller.rb
class PeopleController < ApplicationController
def index
Controller @people = Person.all
end
end

# app/models/person.rb
Model class Person < ActiveRecord::Base
end

View app/views/people/index.html.erb

Defaults with Choices
Default Alternatives

DataMapper, MongoMapper,
ORM ActiveRecord Sequel, Any object with
ActiveModel
HAML, XML Builder,
View Templates ERb Markaby, RedCloth (Textile),
BlueCloth (Markdown)
JavaScript
Prototype jQuery
Framework
MySQL, PostgreSQL,
Database SQLite3 Oracle, more via JRuby +
JDBC

Test Framework Test::Unit RSpec, Cucumber

Why Rails?

COMPARING JVM WEB
FRAMEWORKS
Matt Raible
http://raibledesigns.com

Images by Stuck in Customs - http://www.ﬂickr.com/photos/stuckincustoms
© 2010, Raible Designs
© 2010 Raible Designs

http://j.mp/raible-jvm-frameworks

Why Rails?
Consider...

Information Available
Project Development
Books, skilled
maturity Docs
speed
developers

Installing Rails

INSTALL gem install rails

New Application

$ rails new coolapp -m http://jruby.org
create
create README
create Rakefile
...

Dependencies with Bundler

$ cd coolapp

$ bundle install
Fetching source index for http://rubygems.org/
Using rake (0.8.7)
Using abstract (1.0.0)
...
Using rails (3.0.3)
Your bundle is complete!

Generate Scaffolding

$ rails generate scaffold person email:string password:string
invoke active_record
create db/migrate/20101214020707_create_people.rb
create app/models/person.rb
invoke test_unit
create test/unit/person_test.rb
create test/fixtures/people.yml
route resources :people
...

Migrate Database

$ rake db:migrate
(in /Users/nicksieger/Projects/rails/coolapp)
== CreatePeople: migrating ===========================
-- create_table(:people)
-> 0.0040s
-> 0 rows
== CreatePeople: migrated (0.0040s) ==================

Start Dev Server

$ rails server
=> Booting WEBrick
=> Rails 3.0.3 application starting in development on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
[2010-12-13 20:11:28] INFO WEBrick 1.3.1
[2010-12-13 20:11:28] INFO ruby 1.8.7 (2010-12-10) [java]
[2010-12-13 20:11:28] INFO WEBrick::HTTPServer#start: pid=21022 port=3000

Controller
class PeopleController < ApplicationController
# GET /people
# GET /people.xml
def index
@people = Person.all

respond_to do |format|
format.html # index.html.erb
format.xml { render :xml => @people }
end
end

def show; end
def new; end
def edit; end
def create; end
def update; end
def destroy; end
end

Model

class Person < ActiveRecord::Base
end

Console

$ rails console
Loading development environment (Rails 3.0.3)
irb(main):001:0> Person.create :email => "nsieger@engineyard.com", ...
=> #<Person id: 1, email: "nsieger@engineyard.com", ...>

Rails 3 and JRuby

http://weblog.rubyonrails.org/2010/8/29/rails-3-0-it-s-done

JRuby
Dynamic toolkit of the cloud

Getting JRuby
http://jruby.org/download

JRuby via Maven
Group ID: org.jruby
Artifact IDs: jruby, jruby-complete

JRuby
drive java • embed • compile

Drive Java
synth = javax.sound.midi.MidiSystem.synthesizer
Ruby synth.open
channel = synth.channels[0]

import javax.sound.midi.*;

Java Synthesizer synth = MidiSystem.getSynthesizer();
synth.open();
final MidiChannel channel = synth.getChannels()[0];

Drive Java
frame = javax.swing.JFrame.new "Music Frame"
Ruby frame.set_size 600, 100
frame.layout = java.awt.FlowLayout.new

import java.awt.*;

Java JFrame frame = new JFrame("Music Frame");
frame.setSize(600, 100);
frame.setLayout(new java.awt.FlowLayout());

Drive Java
KEYS.each do |value, char|
button = javax.swing.JButton.new char
button.add_action_listener do |e|
Ruby channel.note_on value, 99
end
frame.add button
end

for (Iterator i = keys.entrySet().iterator(); i.hasNext(); ) {
Map.Entry entry = (Map.Entry) i.next();
final Integer value = (Integer) entry.getKey();
String name = (String) entry.getValue();
JButton button = new JButton(name);

Java button.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent e) {
channel.noteOn(value, 99);
}
});
frame.add(button);
}

Embed
import org.jruby.embed.ScriptingContainer;

public class EmbedJRuby {
public static void main(String[] args) {
ScriptingContainer container = new ScriptingContainer();
container.runScriptlet("puts 'Hello from Ruby'");
}
}

http://wiki.jruby.org/
RedBridge

Compile
# engine.rb
require 'java'
java_package 'demo'

class Engine
java_implements 'java.lang.Runnable'

java_signature 'void run()'
def run
puts "The #{self.inspect} is running."
end
end

Compile
// Starter.java
import demo.Engine;

public class Starter {
public static void main(String[] args) {
Runnable engine = new Engine();
engine.run();
}
}

Compile

$ jrubyc --javac engine.rb Starter.java
Generating Java class Engine to demo/Engine.java
javac -d . -cp jruby.jar:. demo/Engine.java Starter.java

Compile
// Engine.java
package demo;

public class Engine implements Runnable {
public void run() { ... }
}

Compile

$ java -cp jruby.jar:. Starter
The #<Engine:0x59c958af> is running.

JRuby 1.6
Release soon!
ruby 1.9.2 • c-ext • perf • dynopt • java

activerecord-jdbc
ActiveRecord with JDBC databases

INSTALL gem install activerecord-jdbc-adapter

Warbler
INSTALL gem install warbler

• Create a Java EE .war ﬁle from a Rails application
• “Looks like Java” to the ops staff

deploy
Rails
warble app.war to java
app
appserver

JRuby Deployment
Ruby servers WAR files Cloud

WEBrick GlassFish EY AppCloud

Trinidad Tomcat AppEngine

TorqueBox JBoss AWS EB

Enterprise Software
Evolving and adapting long-running
projects with legacy codebases

Sagrada Família,
Barcelona, Spain

passion
facade

nativity
facade

scaffolded interior

Ryugyuong Hotel,
2005 North Korea 2010

Hybrid Rails/Java App
ActionDispatch

Rails ActionController/ActionView
MVC

ActiveModel

Java Java JDBC SOAP
Backend POJOs DataSource interface

https://github.com/nicksieger/
spring-petclinic

Metaphor Use Ruby, JRuby, and Rails to...

Sagrada • Build new facade faster
Familia • Scaffolding during refactoring

Ryugyong
• Revive a project with a new face
Hotel

Seismic • Reinforce business rules with a DSL
retrofit • Harden security

Szkieletor • Find novel uses for abandoned code

Resources
Resources for
Getting Started with
JRuby.org Ruby on Rails

JRubyConf 2010 Rails for
Videos Zombies

Nick Sieger
nsieger@engineyard.com
Slides: http://j.mp/sieger-jfokus

Images
http://en.wikipedia.org/wiki/File:Sagrada_Familia_01.jpg
http://www.flickr.com/photos/gonzalvo/4257293127/
http://www.flickr.com/photos/mgrenner57/263392884/
http://www.flickr.com/photos/koocheekoo/38407225/
http://www.flickr.com/photos/27649557@N07/5000528445/
http://www.flickr.com/photos/gpaumier/446059442/
http://www.flickr.com/photos/ilm/12831049/
http://en.wikipedia.org/wiki/File:Ryugyong_Hotel_-_May_2005.JPG
http://en.wikipedia.org/wiki/File:Ryugyong_Hotel_October_2010.jpg
http://en.wikipedia.org/wiki/File:ExteiorShearTruss.jpg
http://en.wikipedia.org/wiki/File:ExtReenfDetail.jpg
http://en.wikipedia.org/wiki/File:Szkieleteor_in_krakow.JPG
http://www.flickr.com/photos/bazylek/3194294047/

JRuby + Rails = Awesome Java Web Framework at Jfokus 2011

JRuby + Rails = Awesome Java Web Framework at Jfokus 2011

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JRuby + Rails = Awesome Java Web Framework at Jfokus 2011