To advantages and disadvantages of the Ruby programming language and the Rails framework. Includes advise when to use it and comparisons to PHP.

1. When to use Ruby on Rails?
Sytse Sijbrandij
sytse@dosire.com

2. Contents
• Ruby
– What is it?
– Advantages
– Disadvantages
• Rails
– What is it?
– Advantages
– Disadvantages
• When to use it
• Reusable best practices
Ruby Beach, Washington, U.S.
Kevin Mc Neal

3. What is Ruby?
• A scripting language more powerful than
Perl and more object-oriented than Python.
• Invented in 1993 with inspiration from Perl,
Phyton, Smalltalk, Eiffel, Ada, and Lisp.
• Designed for programmer productivity and
joy instead of machine efficiency.
• Follows the principle of least surprise, the
language should minimize confusion.
Yukihiro 'Matz' Matsumoto
• It's easy to work with and to love Ruby. Ruby's Architect

4. Ruby Advantages
Elegant
•
Powerful
•
Readable
•
Concise
•
Ruby and Diamond ring
R. M. Rayner

5. describe Bowling do
before(:each) do
Ruby is @bowling = Bowling.new
end
Elegant it quot;should score 0 for gutter gamequot; do
20.times { @bowling.hit(0) }
@bowling.score.should == 0
end
end
class NewBowlingGame extends PHPSpec_Context
{
private $_bowling = null;
public function before()
{
$this->_bowling = new Bowling;
}
public function itShouldScore0ForGutterGame()
{
for ($i=1; $i<=20; $i++) {
$this->_bowling->hit(0);
} $this->spec($this->_bowling->score)->should->equal(0);
}
}

6. Ruby is Powerful
• Object-oriented (everything is an object)
• Dynamic (duck typing)
# Open Ruby's Time class and add a method
class Time
def yesterday
self - 86400
end
end
today = Time.now # => Thu Aug 14 16:51:50 +1200 2008
yesterday = today.yesterday # => Wed Aug 13 16:51:50 +1200 2008

7. Ruby is Readable
• The code comments itself
• Leads to better naming practices
# An example example function for a photo camera program
def shutter_clicked
capture_image if @camera.on? and @camera.memory_available?
end

8. Ruby is Concise
• Very expressive language
• Less lines of code, higher productivity
-199.abs # 199
quot;ruby is coolquot;.length # 12
quot;Your Momquot;.index(quot;uquot;) #2
quot;Nice Day!quot;.downcase.split(//).sort.uniq.join # quot; !acdeinyquot;
say = quot;I love Rubyquot;
say['love'] = quot;*love*quot;
5.times { puts say }
=> quot;I *love* Rubyquot; quot;I *love* Rubyquot; quot;I *love* Rubyquot; quot;I
*love* Rubyquot; quot;I *love* Rubyquot;

9. Ruby Disadvantages
• Ruby is Slow
• Ruby is New
Ruby Fails Falls, Lookout Mountain, U.S.
Oscar & L

10. Ruby is Slow
• About 10x slower than Java, 2x slower than PHP
All benchmarks, x64 Ubuntu, Intel Q6600 Quad
Computer Language Benchmarks Game

11. Ruby is New
• Not many developers or customers
• No common IDE
– Most coders use the Mac text-editor Textmate
– IDEs: RadRails, RubyMine, 3rd Rail, Netbeans
• No common application server
– Passenger's Apache module has momentum

12. Evolution to web frameworks
From 1990 to 2009
Time
Static Dynamic Integrated
Type of site
Marketing Front office Back office
Business role
• Brochure • Communication • Quotations
• Advertising • Ordering • Fulfillment
• Mailings • Legacy systems
Tools HTML editors: PHP + MySQL: Frameworks:
Frontpage Joomla CakePHP (PHP)
Dreamweaver Drupal Grails (Groovy)
Wordpress Django (Phyton)
Typo3 Ruby on Rails (Ruby)
Merb (Ruby)
.Net Sanatra (Ruby)
Sharepoint

13. What is ?
Creator of Ruby on Rails
• Web application framework David Heinemeier Hansson
• Open Source (MIT license)
• Based on a existing
application (Basecamp)
• Provides common needs:
Routing, sessions
–
Database storage
–
Business logic
–
Generate HTML/XML/CSS/Ajax
–
Testing
–

14. Who uses Rails
Internally:
•
Externally:
•
style.mtv.com
•
www.getsatisfaction.com
•
www.basecamp.com
•
www.yellowpages.com
•
www.twitter.com
•
www.yelloyello.nl
•

15. Rails Advantages
Convention over configuration
•
Don’t Repeat Yourself
•
Object Relational Mapping
•
Model View Controller
• Tay Rail Bridge, Scotland
Ross2085
Reuse of code
•
Agile practices
•
Security
•

16. Convention over Configuration
• Table and foreign key naming
– Tables are multiples
(users, orders, etc.)
– Foreign key naming: user_id
• Default locations
– MVC, Tests, Languages, Plugins
• Naming
– Class names: CamelCase
– Files: lowercase_underscored.rb

17. Don’t repeat yourself
• Everything is defined in a single,
unambiguous place
• Easier to find code
– Only need to look once
– Can stop looking when found
– Well defined places for most items
• Much easier to maintain code
– Faster to change
– Less inconsistency bugs

18. Model View Controller
• Model
– Object relationships
(users, orders)
• Controller
– Business logic
(perform a payment)
• View
– Visual representation
(generate HTML/XML)

19. Model
• Contains validation and object methods
• Use 'fat' models and 'skinny' controllers to
increase reuse of methods across controllers
class Order < ActiveRecord::Base
has_many :line_items
has_one :user
has_one :email, :through => :user
validates_presence_of :user
validates_numericality_of :amount
def purchase
self.purchase_time = Now
end
end

20. View
• DSL languages #content
.left.column
Erb for ruby & html
• %h2 Welcome to our site!
%p= print_information
Haml improves on erb
• .right.column= render quot;sidebarquot;
Textile for html
•
Sass for css
•
<div id='content'>
<div class='left column'>
<h2>Welcome to our site!</h2>
<p>
<%= print_information %>
</p>
</div>
<div class=quot;right columnquot;>
<%= render quot;sidebarquot; %>
</div>
</div>

21. Controller
Method Resource Verb
• RESTful index /people GET
show /people/12 GET
– Better than SOAP create /people POST
– Easy to understand update /people/12 PUT
delete /people/12 DELETE
– Easy to debug
GET /people/12.xml
– Easy to cache
def show
– Easy to prioritize @person =
Person.find(params[:id])
– No bottleneck respond_to do |wants|
– HTML/XML/JSON wants.html
wants.xml { render :xml
=> @person.to_xml }
end
end

22. Object Relational Mapping
find
Programming object Database row
ORM Tools:
#<User id: 1, login: quot;Sytsequot;, -ActiveRecord
email: quot;sytse@comcoaster.comquot;,
-DataMapper
description: quot;<p>Sytse studied
-iBATIS
Management Science at the
Universi...quot;, avatar_id: 1,
crypted_password:
quot;b6675cab85b541a91e6d0
save
# Examples of finding records
User.find(:all)
User.find(23).articles
User.find_by_first_name('Johnny')
User.order.find(:last).lines_items.count

23. Re-use of code
• Gems and plugins, more then 1300
– For authentication, pagination, testing, etc.
• Git allows easy forking and merging
• Github website allows you to give back
• Acts as a portfolio

24. Agile practices
• Iterations (branch often, merge often)
• Test all the time (TDD, BDD)
Stories > Tests > Code > Continuous Integration
Story example
Feature: Log-in
In order to view my profile
As a Registered member
I want to be required to log-in
Test example
Given /I am the registered member quot;quirequot;/ do
@user = User.new({ :login => 'quire})
@user.save!
end

25. Security
• Rails prevents SQL injection attacks
– Attacher post in form: quot;some_title; DROP TABLE articles;quot;
– In bad code this can be injected:
quot;SELECT * FROM ARTICLES WHERE TITLE = $TITLEquot;
– Rails will be escape the input automatically:
@articles = Article.find(:all,
:conditions => [:title => params[:title]])
• Rails prevents Cross Site Scripting (XSS)
– With html_escape in view: <%=h comment.body %>

26. Rails Disadvantages
• Rails is inefficient
• Rails is hard to deploy
Montparnesse 1895
Jeff Mc Neill

27. Rails is inefficient
• Rails uses a lot of memory,
up to 150MB per instance
• Requires more application servers
• Where are your development constrains?
Resource Example application Rails
Man hours 2.200 hours / e22.000 1.000 hours / e10.000
Project duration 15 weeks of changes / e3.000 10 weeks / e2.000
Computing power 2 servers / e2.000 5 servers / e5.000
Total e27.000 e17.000

28. Rails is hard to deploy
• Harder than PHP, better with Passenger
• Lots of moving parts
– Rails, apps, gems, plugins
– Application server, webserver
• Deployment via scripts
– Via the Capistrano tool
– Easy to break something
• Deployment to multiple servers

29. When to use Ruby on Rails?
New code base and DB Existing code and DB
• •
High development speed Low development speed
• •
Complex applications Simple applications
• •
Web deployment Client deployment
• •
Iterative projects Waterfall projects
• •
Development is expensive Deployment is expensive
• •
Fixed price project Hourly rate project
• •
Early adopter client/team Late majority client/team
• •

30. Re-usable best practices
• Don't Repeat Yourself
• 'Fat' model, 'skinny' controller
• MVC framework
– CakePHP
• Integration testing
– Selenium
• DSL's
– Textile for markup
• Source code repository
– GIT
• Project management Recycle shirt by Brian Damage
– Github, Lighthouse, Basecamp

31. Questions?
http://www.dosire.com/