When To Use Ruby On Rails

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

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

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

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

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); } }

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

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

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;

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

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

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

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

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 –

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

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 •

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

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

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

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

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>

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

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

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

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

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 %>

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

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

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

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 • •

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

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When To Use Ruby On Rails

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