The Enterprise Strikes Back

The Enterprise
Strikes Back
Burke Stefan
Libbey Penner

Wednesday, 23 November, 11

Burke Stefan
Libbey Penner


Burke Libbey Stefan Penner
@burkelibbey @stefanpenner


Overview
• Core concepts
• Ruby on the JVM (and the CLR, sort of)
• Data
• Integration
• Deployment
• Sysadmin
• The Cloud

Ruby’s weaknesses

• Poor performance
• Type system sometimes causes
headaches in large codebases

• No compiler to catch certain bugs
But your tests catch these, right?


Why ruby is slow

• Late method lookup
• Lots of context tracking to allow for eval
• Stop-the-world Mark & Sweep GC
• Runtime modiﬁcation of code


Ruby’s strengths

• Developing working code quickly
• Reducing incidental complexity
Especially when best practices are adhered to

• Ease of developing powerful libraries
and succinct DSLs


Uniform Access Principle
All services o ered by a
module should be available
through a uniform notation,
which does not betray whether
they are implemented through
storage or through
computation.

- Bertrand Meyer


Two Rules

• Everything is an object
• Objects expose methods and only methods


</background>


Ruby Java

+ Productive + Not Scary
- Scary - Less productive


Ruby in Java

+ Not Scary
+ Productive


http://jruby.org


• Full ruby implementation on the JVM
• Access to both ruby and Java libraries
• Can be deployed to existing Java
infrastructure


The many ﬂavours of ruby
• MRI (and YARV)
• JRuby
• IronRuby
• MacRuby
• Rubinius
• ...and several more...


java.lang.System.out.println("Hello World")


The Magic Sauce

require 'java'
(contains up to 30% midichlorians)


Calling Java from ruby

f = javax.swing.JFrame.new
f.getContentPane.add(javax.swing.JLabel.new("Hello World"))
close_operation = javax.swing.JFrame::EXIT_ON_CLOSE
f.setDefaultCloseOperation(close_operation)
f.pack
f.setVisible(true)


Impedance Mismatch

f.pack
f.setVisible(true)

Let’s break this down.


Impedance Mismatch
“Getters” and “Setters” are non-idiomatic in ruby.
getContentPane
f.pack
f.setVisible(true)

snake_case is generally preferred to CamelCase


Impedance Mismatch
JavaBean properties can be accessed like this:
f.content_pane.add(javax.swing.JLabel.new("Hello World"))
f.pack
f.setVisible(true)
(UA P in action!)
“get” disappears, CamelCase changes to snake_case


Impedance Mismatch
“set” is replaced by “=”

f.default_close_operation = close_operation
f.pack
f.visible = true
“setDefaultCloseOperation(x)”
becomes
“default_close_operation = x”


Ugliness Abounds

f = javax.swing.
javax.swing.JFrame.new
javax.swing.
close_operation = javax.swing.
javax.swing.JFrame::EXIT_ON_CLOSE
f.pack
f.visible = true

Namespaces everywhere!


Ugliness Abounds
java_import 'javax.swing.JFrame'
java_import 'javax.swing.JLabel'
f = JFrame.new
f.content_pane.add(JLabel.new("Hello World"))
JLabel.new
close_operation = JFrame::EXIT_ON_CLOSE
f.pack
f.visible = true

java_import adds classes to a ruby context


100% Rubiﬁed™

java_import 'javax.swing.JFrame'
java_import 'javax.swing.JLabel'

JFrame.new.tap do |f|
f.content_pane.add JLabel.new("Hello World")
f.default_close_operation = JFrame::EXIT_ON_CLOSE
f.pack
f.visible = true
end


Method Rubiﬁcation™

• In general, CamelCase Java methods
can optionally be transliterated to snake
case.



Java System.currentTimeMillis()
Ruby System.current_time_millis


Seriously though, not
actually trademarked.


Java person.getName()
Ruby person.name


Someone should
get on that.


Java person.setAge(42)
Ruby person.age = 42


FALSE! TRUE!

Java person.isJedi()
Ruby person.jedi?


Is ruby an acceptable
Java? (http://bit.ly/pfNluA)

• Most Java code can literally be written
as ruby with few high-level changes.

• A more relaxed type system and syntax
often has productivity beneﬁts.


Exhibit A
// interfaces = HashMap{ label => NetworkInterface }
Java Collection c = interfaces.values();
Iterator itr = c.iterator();

while(itr.hasNext()) {
NetworkInterface interface = itr.next();
if (interface.isLoopback()) {
return interface.getDisplayName();
}
}
VS.

# interfaces = {label => NetworkInterface}
Ruby interfaces.values.find(&:loopback?).display_name


Exhibit A
// interfaces = HashMap{ label => NetworkInterface }
Java Collection c = interfaces.values();
Iterator itr = c.iterator();

while(itr.hasNext()) {
NetworkInterface interface = itr.next();
if (interface.isLoopback()) {
return interface.getDisplayName();
}
}
VS.

# interfaces = {label => NetworkInterface}
Ruby interfaces.values.find(&:loopback?).display_name
1 2 345 67

Only 7 characters of syntactic support!


“Are you suggesting I write
all my Java in ruby?!”

• Not really...
• JRuby is much slower than Java
(doesn’t matter as often as you’d think)

• Ruby’s added expressiveness makes it
easier to shoot yourself in the foot.
(or, in fact, to lazily clone an inﬁnite number of your feet every
planck length between your gun and your target)


“Are you suggesting I write
all my Java in ruby?!”
• ...but maybe sometimes.
• One possibility:
• Encode high-level logic in expressive
and concise ruby code

• Supporting code in fast, safe Java
• Mix and match as appropriate


Ruby as Glue

• Ruby is great for:
• wiring existing codebases together
• other miscellaneous tasks


Perl The original
“Swiss Army Knife”


Perl Pretty much mean
the same thing.

• “glue”
• “duct tape”
• “swiss army knife”


Perl Ruby

Subcategories of “Glue”

• Wiring stu together
• Sysadmin tasks


Wiring stu together

• There’s a lot we could cover here, but:


Nokogiri

• An extremely user-friendly XML library
• fast! (wraps libxml2)


Nokogiri
require 'open-uri'
require 'nokogiri'
html = open("http://slashdot.org").read
doc = Nokogiri::XML(html)
(doc/".story a").each do |link|
puts "#{link.text} (#{link.attr('href')})"
end

# Britain's Broadband Censors: a Bunch of Students (//yro.slashdot...
# ...


Don’t do this.

(Nokogiri::XML(open("http://slashdot.org").read)/".story a").each{|a|puts
"#{a.text} (#{a.attr("href")})"}


Sysadmin with Ruby

• Nice system APIs
(quite similar to perl’s)

• System provisioning libraries/DSLs


Provisioning systems

• Puppet
• Chef
• Vagrant


Puppet
• Describe system, and puppet sets it up
• Nontrivial, but the general idea is:
• I want mysql
• I want nginx < 0.8
• I want this cron job: “....”
• Go.
http://puppetlabs.com/


Puppet
class postgres-server {
package { postgresql-server:
ensure => latest
}
group { postgres: gid => 26 }
user { postgres:
comment => "PostgreSQL Server",
uid => 26,
gid => 26,
home => "/var/lib/pgsql",
shell => "/bin/bash"
}
service { postgresql:
running => true,
pattern => "/usr/bin/postmaster",
require => package["postgresql-server"]
}
}


Puppet

• Fantastic for deﬁning a reproducible
production environment


Chef

• Same idea as puppet
• Somewhat less powerful
• Slightly more approachable to most
ruby developers

http://www.opscode.com/chef/

Chef
package "sudo" do
action :upgrade
end

template "/etc/sudoers" do
source "sudoers.erb"
mode 0440
owner "root"
group "root"
variables(
:sudoers_groups => node['authorization']['sudo']['groups'],
:sudoers_users => node['authorization']['sudo']['users'],
:passwordless => node['authorization']['sudo']['passwordless']
)
end


Puppet Chef

Conﬁguration Language custom ruby

Targeted at production production

“Powerfulness” Lots Mostly lots

Verdict Good Di erent

Written in ruby ruby


Vagrant

• Uses puppet and/or chef
• End product is a virtual machine for
development use

• Consistent system for all developers, per
project


Vagrant

• If you use puppet or chef, vagrant lets
you test production locally


Suggestions

• As a non-ruby-dev:
• Use puppet
• Consider vagrant


Suggestions

• As a ruby developer:
• Consider chef and puppet, use
whichever suits your taste and needs

• Consider vagrant


Databases


In the Real World,


In the Real World,

We have Data


In the Real World,

We have Data

Which lives in Databases


Databases Are Always
simple


All our data is
ALWAYS
in the same DBMS


Reality Check


Luckily
We have

ODBC + JDBC


Luckily
We have

ODBC + JDBC
+
Ruby

Ruby Gives you Options
• Active Record
• Sequel
• DataMapper
• more


Active Record
Design pattern coined by Martin Fowler in
“Patterns of enterprise application
architecture”.

Also, Ruby on Rails’s default ORM.

• Lots of Power
• Lots of Opinion
• Might ﬁght with you (for non-standard uses)
https://github.com/rails/rails/tree/master/activerecord


Active Record Syntax (Raw)
require 'active_record'

ActiveRecord::Base.establish_connection({
:adapter => 'mysql',
:database => 'test_database',
:username => 'tester',
:password => 'test22'
})

connection = ActiveRecord::Base.connection

connection.tables
> ['users', 'products', 'ducks', 'oranges']

users = []
connection.execute('SELECT * FROM users').each_hash do |user|
users << user
end

users
> .... array of users, each user as a hash.

users.first
> { :id => 1, :username => 'stefan', :password => 'is_super_secure' }


Active Record Syntax (ORM)

require 'active_record'

ActiveRecord::Base.establish_connection({
:adapter => 'mysql',
:database => 'test_database',
:username => 'tester',
:password => 'test22'
})

# class <camel_case_singular_table_name> < ActiveRecord::Base
class User < ActiveRecord::Base
# if the table's name does not fit convention, it can be manually overridden.
# table_name :users_table
end

User.first
> #<User id: 2, :name => 'stefan', :password => 'is_super_secure' >

User.find(2)

User.where(:name => 'stefan')


Active Record Syntax (AREL)

User.first

User.find(2)

User.where(:name => 'stefan')

User.where(:name => 'stefan').order('id ASC')


Sequel
Elegant Full featured database toolkit for ruby.
• Supports a ton of DBMS’s
• DSL
• ORM

http://sequel.rubyforge.org/

Supports
- ADO, Amalgalite, DataObjects, DB2, DBI, DO, Firebird, ibmdb, Informix,
JDBC, MySQL, Mysql2, ODBC, OpenBase, Oracle, PostgreSQL, SQLite3,
Swift, and tinytds


require "sequel"
Sequel Example
# connect to an in-memory database
DB = Sequel.sqlite

# create an items table
DB.create_table :items do
primary_key :id
String :name
Float :price
end

# create a dataset from the items table
items = DB[:items]

# populate the table
items.insert(:name => 'abc', :price => rand * 100)
items.insert(:name => 'def', :price => rand * 100)
items.insert(:name => 'ghi', :price => rand * 100)

# print out the number of records
puts "Item count: #{items.count}"

# print out the average price
puts "The average price is: #{items.avg(:price)}"


Sequel ORM
require "sequel"

# connect to an in-memory database
DB = Sequel.sqlite

# create an items table
DB.create_table :items do
primary_key :id
String :name
Float :price
end

# create a dataset from the items table
class Item < Sequel::Model(:items)
# associations
# validations
end

# populate the table
Item.create(:name => 'abc', :price => rand * 100)
Item.create(:name => 'def', :price => rand * 100)
Item.create(:name => 'ghi', :price => rand * 100)

# print out the number of records
puts "Item count: #{Item.count}"

# print out the average price
puts "The average price is: #{Item.avg(:price)}"


Sequel ORM

+
jRuby
ready out of the box


Sequel ORM

+
IRONRuby
apparently works?


Case Study (Access)
• Access (top 2 solutions)

• Solution 1 (Cross Platform)

• jRuby

• JDBC

• HXTT’s driver (www.hxtt.com)

• Sequel

• Solution 2 (Windows Only)

• Ruby

• ADO via WIN32OLE

• Sequel


Case Study (Access)


Case Study (Access)
1. Download jRuby
http://jruby.org/


Case Study (Access)
1. Download jRuby
http://jruby.org/

2. Install Sequel
gem install Sequel


Case Study (Access)
1. Download jRuby
http://jruby.org/

2. Install Sequel
gem install Sequel

3. Download JDBC Access Driver
http://www.hxtt.com/access.html


Case Study (Access)
require 'rubygems'
require 'sequel'
require 'sequel/adapters/jdbc'
require 'sequel/jdbc_hxtt_adapter'
require '../Support/Access_JDBC40.jar'

root = File.expand_path "../../", __FILE__
path_to_db = root + "/Support/AccessThemeDemo.mdb"
DB = Sequel.connect("jdbc:access:////#{path_to_db}")
puts DB.tables

class Notes < Sequel::Model(:Notes)
end

class ThemeImages < Sequel::Model(:tbl_ThemeImages)
end

class Users < Sequel::Model(:tbl_Users)
end

ba-da-bing


But our new app
and our old database
have di erent
system requirements.


We Want Isolation


_
-Need
We Want Isolation


Power by.. Sinatra
Web DSL

get '/pictures' do
['picture1','picture2','picture2']
end

post '/pictures' {}
put '/pictures/:id' {}
delete '/pictures/:id' {}

used at linkedIn
http://engineering.linkedin.com/44/linkedin-app-end-end-jruby-frontier-and-voldemort


sooo... big deal?


RestServer

• any jdbc database into a restful json
service

• https://github.com/stefanpenner/restserver


Portability/Bundling

• Warbler
http://github.com/nicksieger/warbler

• single jar/war ﬁle
• compiled (if needed)


it’s an app!


Putting it all together (p1)
ScreenShotr
download:
https://github.com/stefanpenner/screenshotr/zipball/master

git@github.com:stefanpenner/screenshotr


Sorry, contrived
example!


anyways...

Java Gives Us
• Portability

Ruby Gives Us
• Happiness


ScreenShotr

Normally Annoying re: Portability

• screen capture
• GUI

but thx jRuby

Lets Shoot some Screens
require 'java'

java_import 'java.awt.Robot'
java_import 'java.awt.Toolkit'
java_import 'java.awt.Rectangle'
java_import 'java.awt.Image'
java_import 'java.awt.image.BufferedImage'
java_import 'javax.imageio.ImageIO'

screenRect = Rectangle.new(Toolkit.default_toolkit.getScreenSize())
capture = Robot.new.createScreenCapture(screenRect)

ImageIO.write(capture,'jpg',java.io.File.new('some_tmp_file.jpg'))


Hold UP


Hold UP
java_import ?


Hold UP
java_import ?

why not require?


Hold UP
java_import ?

why not require?
requiring classes just makes them discoverable later.


Hold UP
java_import ?

why not require?

why not import?


Hold UP
java_import ?

why not require?

why not import?
Rake deﬁnes import


Hold UP
java_import ?

why not require?

why not import?
Rake deﬁnes import

weird...

And ﬁll some clipboards

require 'java'

java_import 'java.awt.Toolkit'
java_import 'javax.imageio.ImageIO'

ss = StringSelection.new(public_url)
Toolkit.getDefaultToolkit().getSystemClipboard().setContents(ss, nil)


upload to server
gem install rest-client

require 'rubygems'

require 'rest-client'

RestClient.post('http://../resource',
:file => File.new('path/to/file'))


...and Vice Versa

• We’ve done a lot of calling Java from ruby.
• The reverse is possible as well.


...and Vice Versa

import org.jruby.embed.InvokeFailedException;
import org.jruby.embed.ScriptingContainer;

// ...
ScriptingContainer container = new ScriptingContainer();
container.runScriptlet("puts "That's no Moon"");

http://en.wikipedia.org/wiki/Jruby

Testing Java with Ruby

“i find your lack of
tests disturbing.”

Testing Java with Ruby

• JtestR is wonderful
• Includes most of ruby’s leading
testing libraries

• supports ant and maven
• easy to add to a project
• takes advantage of jruby/java bridge


JtestR Installation

• Download jarﬁle from jtestr.codehaus.org
• Add to classpath
• Add a task to maven/ant
• Create tests in ./test or ./spec
• Run task


Example!
import java.util.HashMap

describe "An empty", HashMap do
before :each do
@hash_map = HashMap.new
end

it "accepts new entries" do
@hash_map.put "foo", "bar"
@hash_map.get("foo").should == "bar"
end

it "returns a keyset iterator that throws an exception on next" do
proc do
@hash_map.key_set.iterator.next
end.should raise_error(java.util.NoSuchElementException)
end
end


BDD Any language

• Cucumber
• http://cukes.info


“i saw a city
in the clouds”


MYTH: Ruby can’t scale.


FACT: Ruby scales like a BOSS


FACT: Ruby scales like a BOSS
(because it has to)


Fog

• “The Ruby Cloud Services Library”
• Lets you upload to S3, provision
instances in EC2, set DNS records in
DNSimple...

• ...and much more.


Fog

“
• Chewbacca-approved.
whargarblbgarblgr-

”
garblgragh

Fog

“
• Chewbacca-approved. (chewbaccaproved?)
whargarblbgarblgr-

garblgragh ”

2.5 imperial tons of
providers


( )eh.
2.5 imperial tons of
H
providers


Sinatra Example

#config.ru
require './lib/screen_shotr/server'
run ScreenShotr::Server.new


require 'sinatra'
require 'fog'
require 'digest/sha1'


module ScreenShotr
class Server < Sinatra::Base
def storage
#@storage ||= Fog::Storage.new({
# :provider => 'AWS',
# :aws_access_key_id => ACCESS_KEY_ID,
# :aws_secret_access_key => SECRET_ACCESS_KEY})

@storage ||= Fog::Storage.new({
:local_root => '~/fog',
:provider => 'Local'
})

def directory
storage.directories.find("data").first or
storage.directories.create(:key => 'data' )
end

# snip ....


get '/' do
"hello, world!"
end


post '/picture/create' do
file = params[:file]
data = file[:tempfile]

#super secure filename
filename = file[:filename]

key = Digest::SHA1.hexdigest("super random seed"+Time.now.to_s)
key << '.jpg'

file = directory.files.create(
:body => data.read,
:key => key
)
file.public_url or "http://0.0.0.0:9292/picture/#{key}"
end


get '/picture/:key' do
file = directory.files.get(params[:key])
send_file file.send(:path)
end


rackup


and...


Fog Storage:
Kind of cool.


Fog Compute:
Wicked cool.


Heroku

Classic Stack (run rack/rails)
Cedar Stack (run “anything”)


Heroku
Classic Stack (run rack/rails)
$ heroku create
Created sushi.herokuapp.com | git@heroku.com:sushi.git

$ git push heroku master
-----> Heroku receiving push
-----> Rails app detected
-----> Compiled slug size is 8.0MB
-----> Launching... done, v1
http://sushi.herokuapp.com deployed to Heroku


Heroku
Cedar Stack (run “anything”)
$ cat Procfile
web: bundle exec rails server -p $PORT
worker: bundle exec rake resque:work QUEUE=*
urgentworker: bundle exec rake resque:work QUEUE=urgent
clock: bundle exec clockwork clock.rb

$ heroku scale web=4 worker=2 urgentworker=1 clock=1
Scaling processes... done

“O cially Everything”:
Ruby, Node.js,Clojure, Java, Python, and Scala


Recap
• Core concepts
• Ruby on the JVM (and the CLR, sort of)
• Data
• Integration
• Deployment
• Sysadmin
• The Cloud

“help me ruby...
you’re my only hope!”

“good... the force is
strong with you.

Thanks!

a powerful rubyist you
will become.”

The Enterprise Strikes Back

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