The document discusses using JRuby to leverage Java libraries and the JVM while still programming in Ruby. Some key points made include: - Most developers are familiar with Java and its libraries, and JRuby allows using these from Ruby - JRuby provides features like real threads and a functioning garbage collector that vanilla Ruby lacks - It leverages the performance benefits of the JVM like just-in-time compilation while maintaining Ruby's simplicity - Examples show how to easily interface with Java libraries for things like RabbitMQ and use Java concepts like threads from Ruby

1. STANDING ON
THE SHOULDERS
OF GIANTS
WITH JRUBY
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2. Theo
@iconara
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3. Chief Architect at
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4. måndag 19 mars 12

5. ruby
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6. TL;DR
Most of you are Java developers
Writing Java is tedious
There’s truckloads of great Java libraries
The JVM is awesome
Ruby is awesome
∴ JRuby FTW
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7. just
I’M NOT HERE TO
MAKE FUN OF JAVA
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8. JRuby vs. vanilla Ruby
Real threads
A working GC
Every Java, Scala and Ruby library ever made
All the JVM awesomeness, JIT, the lot
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9. JRuby vs. Java
It doesn’t make you want to stab yourself
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10. måndag 19 mars 12

11. JRUBY ♥ JAVA
A WHIRLWIND TOUR
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12. JRuby ♥ Java
stuff = TreeMap.new
stuff['windmill'] = 'rocket'
stuff['pirate'] = 'bees'
stuff.each do |something|
# redacted
end
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13. JRuby ♥ Java
require 'java'
require 'rabbitmq-client.jar'
import 'com.rabbitmq.client.ConnectionFactory'
factory = ConnectionFactory.new()
factory.setUri('amqp://localhost:5672/')
connection = factory.newConnection()
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14. JRuby ♥ Java
require 'java'
require 'rabbitmq-client.jar'
import 'com.rabbitmq.client.ConnectionFactory'
factory = ConnectionFactory.new
factory.uri = 'amqp://localhost:5672/'
connection = factory.new_connection
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15. JRuby ♥ Java
class Worker < Thread
def run
puts 'Hard work, no play'
end
end
# or
class Worker
include Runnable
def run
puts 'Hard work, no play'
end
end
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16. JRuby ♥ Java
pool = Executors.new_fixed_thread_pool(3)
memes = LinkedBlockingQueue.new
10.times do
pool.submit do
open('http://api.autome.me/text').read.each_line do |meme|
memes << meme
end
end
end
pool.shutdown
pool.await_termination(3, TimeUnit::DAYS)
memes.each { |m| puts(m) }
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17. JRUBY FOR
REPRESSED JAVA
DEVELOPERS
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18. Made up fact
84% of Java devs don’t write tests because it’s
way too much extra code to type.
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19. Testing
public class Person {
public final String firstName;
public final String lastName;
public Person(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
public String getFullName() {
return String.format("%s %s", firstName, lastName);
}
// omg I’m already bored
}
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20. Testing
class TestPerson < Test::Unit::TestCase
def setup
@person = Person.new('James', 'Gosling')
end
def test_full_name
assert_equal('James Gosling', @person.full_name)
end
end
# this is TestUnit, it’s part of the stdlib
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21. Testing
describe Person do
describe '#full_name' do
before do
@person = Person.new('James', 'Gosling')
end
it 'is the first name and the last name with a space in-between' do
@person.full_name.should == 'James Gosling'
end
end
end
# this is RSpec, read more at rspec.info
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22. Made up fact
Ant was designed by the same people who
came up with the QWERTY layout.
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23. Automation
<?xml version="1.0"?>
<project name="MyProject" default="dist" basedir=".">
<description>
simple example build file
</description>
<!-- set global properties for this build -->
<property name="src" location="src"/>
<property name="build" location="build"/>
<property name="dist" location="dist"/>
<target name="init">
<!-- Create the time stamp -->
<tstamp/>
<!-- Create the build directory structure used by compile -->
<mkdir dir="${build}"/>
</target>
<target name="compile" depends="init" description="compile the source ">
<!-- Compile the java code from ${src} into ${build} -->
<javac srcdir="${src}" destdir="${build}"/>
</target>
<target name="dist" depends="compile" description="generate the distribution">
<!-- Create the distribution directory -->
<mkdir dir="${dist}/lib"/>
<!-- And don’t get me started on Maven, $%&@*! -->
<!-- Put everything in ${build} into the MyProject-${DSTAMP}.jar file -->
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24. Automation
require 'ant'
src_dir = 'src'
build_dir = 'build'
dist_dir = 'dist'
timestamp = Time.now
task :init do
mkdir_p build_dir
end
task :compile => :init do
ant.javac :srcdir => src_dir, :destdir => build_dir
end
task :dist => :compile do
mkdir_p "#{dist_dir}/lib"
ant.jar :jarfile => "#{dist_dir}/lib/MyProject-#{timestamp}.jar",
:basedir => build_dir
end
task :clean do
rm_rf build_dir
rm_rf dist_dir
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25. Made up fact
The average number of lines in a Java web
application is somewhere around 100 000
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26. Don’t make it so hard
get '/' do
erb :index
end
post '/register' do
stuff.save(params[:name], params[:email], params[:shoe_size])
redirect '/thanks'
end
get '/thanks' do
@name = params[:name]
erb :thanks
end
# this is Sinatra, read more at sinatrarb.com
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27. Pack it up in a
WAR and ship it
$ warbler war
# warbler can be found at github.com/jruby/warbler
# also check out torquebox.org, and github.com/trinidad/trinidad
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28. Make a console
$ hbase shell
HBase Shell; enter 'help<RETURN>' for list of supported commands.
Type "exit<RETURN>" to leave the HBase Shell
Version 0.90.4-cdh3u2, r, Thu Oct 13 20:32:26 PDT 2011
hbase(main):001:0> create 'test', 'cf'
0 row(s) in 1.2200 seconds
hbase(main):002:0> put 'test', 'row1', 'cf:a', 'value1'
0 row(s) in 0.0560 seconds
hbase(main):003:0> put 'test', 'row2', 'cf:b', 'value2'
0 row(s) in 0.0370 seconds
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29. Monitoring
require 'jmx'
client = JMX.connect(:port => 7199)
storage_service = client['org.apache.cassandra.db:type=StorageService']
storage_service.keyspaces.each do |keyspace|
puts keyspace
end
memory_mbean = client['java.lang:type=Memory']
puts memory_mbean.heap_memory_usage.used
memory_mbean.gc
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30. Configuration
conf = configuration do
base_keys :api_key, :date
dimension :path
dimension :section
dimension :country
dimension :section, :country
metric :pageviews
metric :reach, :user_id, :type => :unique
metric :clicks, :click?, :type => :predicate
end
counters = conf.build!
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31. SNEAK SOME RUBY INTO THAT
ENTERPRISE APPLICATION
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32. STANDING ON
THE SHOULDERS
OF GIANTS
WITH JRUBY
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33. LET’S STACK SOME
ABSTRACTIONS ON
TOP OF THEM THERE
ABSTRACTIONS
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34. Our stack: RabbitMQ
We use the Java driver, with a JRuby interface
we call HotBunnies
github.com/ruby-amqp/hot_bunnies
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35. Our stack: RabbitMQ
require 'hot_bunnies'
connection = HotBunnies.connect(:host => 'localhost')
channel = connection.create_channel
queue = channel.queue('test_queue')
queue.bind('test_exch', :routing_key => 'hi')
subscription = queue.subscribe(:ack => true, :blocking => false) do |headers, msg|
# do awesome stuff
end
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36. Our stack: MongoDB
Go listen to David’s talk tomorrow
We use the Ruby driver, because we wouldn’t
get anything done otherwise
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37. Our stack: MongoDB
BasicDBObject doc = new BasicDBObject();
doc.put("name", "MongoDB");
doc.put("type", "database");
doc.put("count", 1);
BasicDBObject info = new BasicDBObject();
info.put("x", 203);
info.put("y", 102);
doc.put("info", info);
coll.insert(doc);
vs.
coll.insert(
'name' => 'MongoDB',
'type' => 'database',
'count' => 1,
'info' => {'x' => 203, 'y' => 102}
)
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38. Our stack: Cassandra
We use a JRuby wrapper on top of Pelops
github.com/iconara/eurydice
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39. Our stack: Cassandra
Mutator mutator = Pelops.createMutator(pool);
Column nameColumn = mutator.newColumn("name", "Dan");
Column ageColumn = mutator.newColumn("age", Bytes.fromInt(33));
List<Column> columns = mutator.newColumnList(nameColumn, ageColumn);
mutator.writeColumns(columnFamily, rowKey, columns);
mutator.execute(ConsistencyLevel.ONE);
vs.
columns = {'name' => 'Dan', 'age' => 33}
column_family.update(row_key, columns, :consistency_level => :one)
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40. Our stack: Akka
Scala is nice, but we’ve got better things to do
than to wait for code to compile
Akka is awesome, so we created Mikka
github.com/iconara/mikka
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41. Our stack: Akka
class Ping < Mikka::Actor
def pre_start
@pong = context.actor_of(Pong)
@pong << :ping
end
def receive(message)
context.reply(:ping)
end
end
class Pong < Mikka::Actor
def receive(message)
context.reply(:pong)
end
end
ping = Mikka.actor_of(Ping).start
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42. Our stack: numbers
We process hundreds of millions of messages
per day, using less than 20K lines of JRuby
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43. twitter.com/iconara
architecturalatrocities.com
burtcorp.com
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