6 (J)Ruby on Rails-Sang Shin

8/14/2019 6 (J)Ruby on Rails-Sang Shin

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(J)Ruby on Rails(J)Ruby on Rails

Sang Shin, Technology ArchitectSang Shin, Technology Architect

Sun Microsystems, Inc.Sun Microsystems, Inc.


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Topics

What is and Why Ruby on Rails?

Building HelloWorld Rails application step bystep> App directory structure (MVC), Environment, Rake,

Generator, Migration, Rails console, etc Scaffolding

JRuby

Testing Ajax

REST support

Deployment


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What is and WhyWhat is and Why

Ruby on Rails (RoR)?Ruby on Rails (RoR)?


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What Is Ruby on Rails?

A full-stack MVC web development framework

Written in Ruby> Rails is the killer application that leverages various

characteristics of Ruby language - meta-programming,

closure, etc.

First released in 2004 by David HeinemeierHansson

Gaining popularity


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Ruby on Rails MVC

source: http://www.ilug-cal.org


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Ruby on Rails Principles

Convention over configuration> Why punish the common cases?

> Encourages standard practices

> Everything simpler and smaller

Dont Repeat Yourself (DRY)> Framework written around minimizing repetition

> Repetitive code harmful to adaptability

Agile development environment> No recompile, deploy, restart cycles> Simple tools to generate code quickly

> Testing built into the framework


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Step By Step ProcessStep By Step Process

of Building Hello Worldof Building Hello WorldRails ApplicationRails Application

www.javapassion.com/handsonlabs/rawww.javapassion.com/handsonlabs/rails_basics/#Exercise_1ils_basics/#Exercise_1


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1. Create Ruby on Rails1. Create Ruby on Rails

ProjectProject


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1. Create Ruby on Rails Project

Directory structure and boilerplate files of theapplication are created


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Directory Structure of a Rails

Application When you ask NetBeans to create a Rails

project - internally NetBeans uses the rails'helper script -, it creates the entire directory

structure for your application.> The boiler plate files are also created

> The names of the directories and files are the samefor all Rails projects

Rails knows where to find things it needs withinthis structure, so you don't have to tell itexplicitly.


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Directory Structure of a Rails Application

app: Holds all the code that's specific to thisparticular application.> app/controllers: Holds controllers that should be

named like hello_controller.rb for automated URL

mapping. All controllers should descend fromApplicationControllerwhich itself descends fromActionController::Base.

> app/models: Holds models that should be named likemessage.rb. Most models will descend fromActiveRecord::Base.

> app/views: Holds the template files for the view thatshould be named like hello/say_hello.rhtmlfor theHelloController#say_hello action.


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app> app/views/layouts: Holds the template files for layouts

to be used with views. This models the commonheader/footer method of wrapping views. In yourviews, define a layout using the layout :defaultand create a file named default.rhtml. Insidedefault.rhtml, call to render the viewusing this layout.

> app/helpers: Holds view helpers that should be namedlike hello_helper.rb. These are generated for you

automatically when using script/generate (Generator)for controllers. Helpers can be used to wrapfunctionality for your views into methods.


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config: Holds configuration files for the Railsenvironment, the routing map, the database, andother dependencies.> config/environments

> config/initializers> boot.rb

> database.yml

> environment.rb

> routes.rb


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Demo:Demo:

Building Hello WorldBuilding Hello WorldRails Application Step by Step.Rails Application Step by Step.


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Learning Point:Learning Point:

EnvironmentsEnvironments


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What is an Environment?

Rails provides the concept of environments -development, test, production

As a default, different databases are used fordifferent environments.> You can set each environment with its own database

connection settings.

It is easy to add custom environments> For example, staging server environment


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config/database.yml

development:adapter: mysqlencoding: utf8database: helloname_developmenusername: root

password:host: localhost

test:adapter: mysql

encoding: utf8database: helloname_testusername: rootpassword:host: localhost


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2. Create Database2. Create Database

using Rakeusing Rake


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Creating Database

Creating and dropping of databases are doneusing Rake


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Creating Database

After create rake task is performed,_developmentdatabase, forexample, helloworld_developmentis created


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What is Rake?What is Rake?


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What is Rake?

Rake is a build language for Ruby.

Rails uses Rake to automate several tasks suchas creating and dropping databases, runningtests, and updating Rails support files.

Rake lets you define a dependency tree of tasksto be executed


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How does Rake Work?

Rake tasks are loaded from the file Rakefile

Rails rake tasks are under/lib/tasks

You can put your custom tasks underlib/tasks


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3. Create a Model3. Create a Model

through Generatorthrough Generator


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What is a Model?

In the context of MVC pattern, a Modelrepresents domain objects such as message,school, product, etc.

A model has attributes and methods.> The attributes represents the characteristics of the

domain object, for example, a message model mighthave length, creator as attributes.

> The methods in a model contains some businesslogic.

Most models have corresponding databasetables. For example, a message model will havemessages table.

Most model classes are ActiveRecord type


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Creating a Model using Generator


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Creating a Model using Generator


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Files That Are Created

app/models/message.rb (Model file)> Models/messages.rb in logical view> A file that holds the methods for the Message model.

test/unit/message_test.rb

> Unit Tests/message_test.rb in logical view> A unit test for checking the Message model. test/fixtures/messages.yml

> Test Fixtures/messages.yml in logical view> A test fixture for populating the model.

db/migrate/migrate/001_create_messages.rb> Database Migrations/migrate/001_create_messages.rb in

logical view> A migration file for defining the initial structure of the

database.


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Model Class Example

Message mode in messages.rb fileclass Message < ActiveRecord::Base

end


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What is Generator?What is Generator?


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What is Generator?

You can often avoid writing boilerplate code byusing the built-in generator scripts of Rails tocreate it for you.> This leaves you with more time to concentrate on the

code that really matters--your business logic.


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Leaning Point:Leaning Point:

What is Rails Console?What is Rails Console?


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What is Rails Console?

The Rails console gives you access to your RailsEnvironment, for example, you can interact withthe domain models of your application as if theapplication is actually running.

> Things you can do include performing find operationsor creating a new active record object and then savingit to the database.

A great tool for impromptu testing


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What is Rails Script?What is Rails Script?


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Script

NetBeans runs Rails Script internally> You can run the Script at the command line

Useful scripts> console

> generate

> plugin

> server


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Create Database Table using Migration

You are going to create a database table (in apreviously created database) through migration> You also use migration for any change you are going to

make in the schema - adding a new column, forexample

When you create a Model, the first version of themigration file is automatically created> db/migrate/migrate/001_create_messages.rb, which

defines initial structure of the table

class CreateMessages < ActiveRecord::Migration def self.up

create_table :messages do |t|t.string :greetingt.timestamps

end

end


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Performing Migration


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What is Migration?What is Migration?


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Migration To the Rescue

Migration can manage the evolution of a schema

With migrations, you can describe schemachanges in self-contained Ruby classes -migration files

You can check these migration files into aversion control system

Migration files are part of an application structure

You (and others) can choose a schema versionof choice, for example, several versions backfrom the current one


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What is a Controller?

Action Controllers handle incoming Webrequests

A controller is made up of one or more actions

Actions are executed to handle the incomingrequests and then either render a template orredirect to another action.

An action is defined as a public method of acontroller

Mapping between a request URL and an actionis specified in the Rails routing map(configuration/routes.rb)


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Create a Controller using Generator

You are going to create a controller usingGenerator


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6. Write a View6. Write a View


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What is a View?

View is represented by a set of templates thatget displayed.

Templates share data with controllers throughmutually accessible variables.

A template can be either in the form of*.rhtmlor*.erb file.> The *.erb file is searched first by Rails. If there is no

*.erb file, then *.rhtmlfile is used.


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Creating *.rhmtl file (or *.erb file)

*.rhtmlor*.erb file is created under the directoryof/app/views/


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7. Set URL Routing7. Set URL Routing


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ScaffoldingScaffolding


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What Is Scaffolding?

Scaffolding is a way to quickly put an ActiveRecord class online by providing a series ofstandardized actions for listing, showing,creating, updating, and destroying objects of theclass.> Useful for quick prototyping

These standardized actions come with bothcontroller logic and default templates thatthrough introspection already know which fieldsto display and which input types to use.


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Scaffolding via Generator


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Why JRuby (over Ruby) &Why JRuby (over Ruby) &

JRuby on Rails (over RubyJRuby on Rails (over Rubyon Rails)?on Rails)?


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Why JRuby (over Ruby)

With JRuby you get the best of both worlds:> Ruby applications and libraries, plus Java libraries.

> You can access those Java libraries with Ruby syntax(or Java syntax, if you want).

On average JRuby, runs 2 and a half timesfaster than Ruby, except at startup

In addition to native threads, JRuby supportsUnicode natively

Code can be fully compiled ahead of time or justin time


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Why JRuby on Rails (over Ruby on Rails)

A JRuby on Rails application can be packagedinto a WAR, and then deployed onto anycompliant server.> The packaging of creating a war file from Rails can be

done with Goldspike, or with the new kid on the block:Warbler

Can use vast array of Java libraries> JPA, JTA, JMS, EJB, JDBC, JMX, JSF, etc.

> Database connections are made through JDBC, whichprovides broader, more scalable database support.

Glassfish--the Java web app server that scaleswell--is available as a JRuby gem.


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Demo:Demo:Build Ruby ApplicationBuild Ruby Applicationusing Java Libraryusing Java Library

javapassion.com/handsonlabs/ruby_jruby/#Exercise_3javapassion.com/handsonlabs/ruby_jruby/#Exercise_3


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TestingTesting


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Testing

Unit testing> Testing model classes

Functional testing> Testing controllers

Integration testing> Testing usage scenarios


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DeploymentDeployment


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Web Servers

By default, Rails will try to use Mongrel andlighttpd if they are installed, otherwise Rails willuse WEBrick, the webserver that ships withRuby.

Java Server integration> Goldspike

> GlassFish V3


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Goldspike

Rails Plugin Packages Rails application as WAR

WAR contains a servlet that translates data fromthe servlet request to the Rails dispatcher

Works for any servlet container

rake war:standalone:create


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GlassFish V3

Next version of GlassFish Ideal container for Web 2.0 applications

Small> Kernel < 100k

Fast> Starts up in < 1 second

Modular

> Java, Ruby, PHP, JavaScript, ... Will be Java EE 6 compatible


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Why Rails on GlassFish?

Java EE is tested deployment platform Integrate existing Java EE & RoR apps in one

container

Hot Deployment> No need to restart container

Database Connection Pooling

One instance, one process

OOTB Clustering and High Availability developers.sun.com/appserver/reference/techart/ra

ils_gf/


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Demo:Demo:Deployment throughDeployment through

GoldspikeGoldspike


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Thank You!Thank You!

Sang Shin

[email protected]

javapassion.com

6 (J)Ruby on Rails-Sang Shin

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