Moving To Ruby on RailsA Love Story

Part IRuby and Rails

“Ruby on Rails is astounding. Using it is like watching a kung-fu movie, where a dozen bad-ass frameworks prepare

to beat up the little newcomer only to be handed their asses in a variety of imaginative ways.”

- Nathan TorkingtonO'Reilly Program Chair for OSCON

• An interpreted scripting language, like PHP.

• Created in 1993 by Yukihiro “Matz” Matsumoto

• “I wanted a scripting language that was more powerful than Perl, and more object-oriented than Python.”

• An attempt to create a more natural programming language using “the principle of least surprise”

["item1","item2","item3"].length=> 3

"the quick fox jumped over the lazy dog".length  => 38{:key => 'value'}.length

=> 1

What is Ruby? Basic History

• All classes are open

• Closures and Namespacing

• Excels at Meta-Programming

• Strives for Code Readability and simplicity (Syntactic Sugar)

class Greeter  attr_accessor :name  def say_hi    "hey #{name}"  endend

greeter = Greeter.newgreeter.name = 'Casey'greeter.say_hi

=> "hey Casey"

class Greeter {  private name = null;  public function set_name($name) {    $this->name = $name;  }  public function get_name() {    return $this->name;  }  public function say_hi() {    return "hey " + $this->get_name();  }}

greeter = new Greeter();greeter->set_name('Casey');greeter->say_hi();    => "hey Casey"

Ruby PHP5

What is Ruby? Some Defining Features

What is Ruby? Cool Syntax Examples

(0..20).inject {|sum,n| sum + n * n}=> 2870

Calculate Sum of the Squares of the Integers Between 0 and 20:

(5.minutes + 30.days).from_now   => Fri, 11 Dec 2009 16:09:11 EST -05:00

class Fixnum  # You can, but please don't do this  def +( other )    self - other  endend

Operators are actually Methods (and you can override them)

Time Arithmetic

What is Rails? The Basics

• A powerful, MVC-structured, web application development framework.

• Ruby's Killer App.

• Full Stack Web Application Framework (web server, database, business logic, routing, testing framework.

• Created by Danish programmer David Heinemeier Hannson in 2004 for 37Signals' Basecamp.

• A system written to make programmers' lives happier by solving common problems encountered during web development (i.e. data validation, SQL queries, caching).

What is Rails? Opinions

• Model-View-Controller Archetecture

• Don’t Repeat Yourself (DRY)

• You Aren’t Gonna Need It (YAGNI)

• Keep It Simple, Stupid (KISS)

• Convention Over Configuration

• Elegance of code

• TDD or BDD

What is Rails? Structure

• Model => Database, View => HTML/Layout, Controller => Business Logic

• ORM for your Model to your DB Table

request

widgets/show/1

class WidgetController

def show

@widget =

Widget.find(1)

end

end

class Widget

end

<h2>

<%= @widget.name %>

</h2>

<p>

<b>Size:</b>

<%= @widget.size %>

</p>

show.html.erb widget_controller.rb

widget.rb

Fire Gasket Show

Rails enforces an MVC approach to code.

class Widget < ActiveRecord::Baseend

What is Rails? Code Example

widgets = Widget.find(:all) => “SElECT * FROM widgets”

new_widgets = Widget.all(:order => “created_at DESC”, :conditions => [“created_at >”, 2.weeks.ago] ) => “SELECT * FROM widgets WHERE created_at > ‘10-28-2009’ ORDER BY created_at DESC”

new_widgets.first.name => “My Widget Name”

CREATE TABLE widgets ( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, name VARCHAR(100), desc VARCHAR(255),

created_at DATE, updated_at DATE

);

SQL

Model

Usage

What Rails Is Not Important Note

* or at least web development problems.

The answer to all life’s problems.*

ExampleBuilding a (very) Basic Web App in 15 minutes

Part IIComing Down to Earth

“cru ext/apache2/libboost_oxt.a ext/apache2/libboost_oxt/boost/*.o ext/apache2/libboost_oxt/oxt/*.o ranlib ext/apache2/libboost_oxt.a -mtune=pentium4 -I/usr/kerberos/include -I/usr/

include/httpd -D_REENTRANT -I/usr/local/include -Wall -g -DPASSENGER_DEBUG -DBOOST_DISABLE_ASSERTS ext/apache2/usr/lib/libaprutil-0.so:

undefined reference to `XML_GetErrorCode' collect2: ld returned 1 exit status

rake aborted! Command failed with status (1): [g++ ext/common/ApplicationPoolServerExecut...]”

- make

• We spend a lot of time fixing old, buggy code.

• Old code very hard to read (not best practices!)

• Wanted to spend more time writing new stuff for our clients instead of fixing old stuff.

• Wanted a way to easily test our code.

• FoxPro is going the way of Esperanto.

Reasons We’re Moving

• The Hotel School currently uses PHP, with some Perl and some large FoxPro systems.

• Database by Oracle.

• Web-centric code goes back to 2000, FoxPro potentially older.

• Version control via Perforce, with custom Development server/Production server Apache environment.

• Custom templating engine written in PHP that hooks into Perforce versioning system for public website at http://www.hotelschool.cornell.edu

Legacy Systems What We’re Starting With

The Approach

A Test Case

Side-by-Side

Rails Takes Over

LaunchPad

Intranet-Focused

Profit!

if success?

if success?

• We needed to answer the basic question, can Rails work in our current setup?

• To test that we decided to redo an old system in Rails.

• Criteria for a good test case:

• Old and buggy code?

• Is it an important system? (If yes, then no).

• Is it relatively atomic? That is, does it interconnect with other systems?

• LaunchPad, in our case.

Step 1: Test Approach

What Rails Likes We Do Not Have

System Rails Likes We Have

DB MySQL/Postgres Oracle

Versioning Git Perforce

DB Table Structurespecific

conventions wild, wild west

Convention Over Configuration

Can Rails Be Configured?

Yes!

• Easily handles legacy database schemas, you just need to add more information about the table.

• Flexible adapters for all major DBs.

• We can set Rails environment settings via Apache (for our Dev and Production differences).

Rails is Very Flexible

class Widget < ActiveRecord::Base set_table_name “ol_widget” set_primary_key “w_id”

belongs_to :owner, :foreign_key => “owner”end

class Owner < ActiveRecord::Base set_table_name “webadmin.widget_owner” set_primary_key “netid”

has_many :widgets, :foreign_key => “owner”end

How Did It Go?

• Short answer, it went well.

• Total time: ~ 7 mo

• Actual coding time: ~ 4 mo

• We proved Rails could work for us!

• Installed Rails on production and dev servers (not trivial).

• Handles deploys successfully.

• Connect to and manipulate legacy DB schemas.

Step 1: Test Approach

• We decided to move forward. Next focus is on our Intranet system, StatlerWire (~50 apps).

• Since we can’t replace all existing apps at once, we need to integrate them somehow.

• We put Rails in a subdirectory in our PHP system, and use a symlink to create a similar URL:

• http://statlerwire.sha.cornell.edu/mywire/admins/... (PHP)

• http://statlerwire.sha.cornell.edu/admins/... (Rails)

• We load the same CSS and use the same HTML layout.

• The client does not know the difference.

Step 2: Side-by-Side

PHP Rails

• Rails currently runs in a subdirectory within the Statlerwire filesystem.

• We were able to mimic behavior of the PHP-based system within our Rails app, and utilize the same database data and structure for Access Control.

• All future development is now done in Rails.

• Anytime significant upgrades are requested in existing systems, we try to take that opportunity to rewrite into Rails.

• This piece-wise approach seems to work pretty well.

Step 2: In Progress...

• I’ve focused mainly on our intranet, but what about our public site?

• Our font-facing website runs a custom-built PHP templating system (Enki) that uses XML for structural markup and inline PHP for DB access/data processing.

• It works very differently than how Rails “likes” to work.

• This is not a system we can convert in pieces, so how can we try to keep things DRY?

• Option 1 (easy): Continue to use Enki as normal, and access our Rails DB via PHP code in front end.

• Option 2 (harder): Instead of accessing the DB directly, attempt to use our Rails system as a Web Service. We can utilize Rails validation, ActiveRecord, etc, via JSON or XML.

Step 2: A Caveat

• We’re going to try Option 2, web services.

• Luckily, Rails makes it easy to support different types of requests at the controller-level.

• Built-in support for REST and HTTP verbiage.

• We’ll let you know how this goes.

Step 2: A Caveat

class WidgetController < ApplicationController def show @widget = Widget.find(params[:id]) respond_to do |format| format.html format.xml { render :xml => @item } format.json { render :json => @item.to_json } end endend

• There’s so much to work with, we have to accept that we’ll be using PHP for a while to come.

• Probably the last thing to go will be the front-facing website.

• Before that, we have a variety of internal FoxPro systems that are large and in charge that need to be rewritten.

• Timeline of 2 - 3 years (realistically).

Step 3: Rails Forever?

• Rails encourages good, well-tested code. Creates an “a priori” environment for future programming working with your code.

• Rails handles a lot of the basic, ugly stuff no one likes to work with.

• Rails embraces the best practices of the new web: AJAX, Logic Abstraction from the View, REST.

• Rails/Ruby is really fun to work (and fall in love) with.

• Large, active community creating plugins, documentation, gems, bug fixes.

In Summary - Benefits

• The learning curve.

• Initial server setup can be difficult.

• Need certain levels of write access to the filesystem by the web server.

• Windows server setup might be difficult.

• If you don’t like MVC, you’re outta luck.

In Summary - Drawbacks

Thanks!

• Gracious support from the Statler Web Team:

• John Cowan

• Dave DeHaan

• Steve Halasz

• Wioletta Holownia

Other Frameworks

• PHP

• CakePHP - http://www.cakephp.org

• CodeIgniter - http://codeigniter.com

• Python

• Pylons - http://pylonshq.com/

• Django - http://www.djangoproject.com/

• Java

• Don’t use Java.

Rails (and Ruby) isn’t the only way to go. Other languages have frameworks boast similar features like MVC, ORM, and Schema Generation.