Web application intro + a bit of ruby (revised)

Introduction to Web
Applications
Tobias Pfeiffer
@PragTob
pragtob.wordpress.com

What you are going
to build today

High level overview

Request

High level overview

Answer

What parts does a web
application consist of?

CSS
JavaScript

HTML

CSS
JavaScript
Back End
HTML

Logic
● Behaviour
● Implements the business logic
● Ties all the parts together
● Generates content

Web Application Landscape

CSS

St
or
JavaScript

ag
Logic

e
HTML
Infrastructure

Web Application Landscape

Django
Bootstrap

Mo
Ruby on Rails
CSS

St oDB
ng
or
JavaScript Logic

ag
e
jQuery PHP Java
Ruby

Sq
lite
HTML Python

XML DOM WEBrick
Infrastructure
Apache
Thin

A web application
framework written in Ruby

● A general purpose programming
language
● Principle of least surprise
● Invented by Yukihiro Matsumoto

"I hope to see Ruby help
every programmer in the
world to be productive, and to
enjoy programming, and to be
happy. That is the primary
purpose of Ruby language."
Yukihiro Matsumoto

Ruby on Rails
● Framework written in Ruby
● set of functionality to help write web
applications
– Connecting to the database (ActiveRecord)
– Generating HTML (ERB)
– Pays attention to security
– … and so much more!
● Model View Controller
● You write in Ruby

tobi@speedy:~$ irb
1.9.3p194 :001 >

irb – interactive ruby
● talking to ruby
● You tell ruby something
● Ruby responds with what it understood
● Coaches are going to help you!

1.9.3p194 :004 > "Tobias Pfeiffer"
=> "Tobias Pfeiffer"

1.9.3p194 :005 > name = "Tobi"
=> "Tobi"

1.9.3p194 :005 > coach = "Tobi"
=> "Tobi"

1.9.3p194 :005 > dhaksdhak = "Tobi"
=> "Tobi"

1.9.3p194 :006 > name
=> "Tobi"

1.9.3p194 :007 > result = 8 * 7
=> 56

1.9.3p194 :007 > result = 8 * 7
=> 56

56 res ult

1.9.3p194 :008 > result * 10
=> 560

1.9.3p194 :009 > name + " likes Sweden"
=> "Tobi likes Sweden"

1.9.3p194 :010 > puts "Hello World!"
Hello World!
=> nil

1.9.3p194 :011 > fruits = ["apple", "keewee",
"orange"]
=> ["apple", "keewee", "orange"]

1.9.3p194 :013 > fruits.each do |fruit| puts
fruit end
apple
keewee
orange

1.9.3p194 :013 > fruits.each do |bob| puts
bob end
apple
keewee
orange

1.9.3p194 :013 > fruits.each do |anything|
puts anything end
apple
keewee
orange

1.9.3p194 :014 > fruits[0]
=> "apple"

1.9.3p194 :015 > symbol = :wuh
=> :wuh
1.9.3p194 :016 > symbol
=> :wuh

1.9.3p194 :017 > dictionary = {:hi =>
"Hej", :good => "bra", :cookie => "kaka"}
=> {:hi=>"Hej", :good=>"bra",
:cookie=>"kaka"}
1.9.3p194 :018 > dictionary[:hi]
=> "Hej"
1.9.3p194 :019 > dictionary[:cookie]
=> "kaka"

1.9.3p194 :020 > def hello
1.9.3p194 :021?> puts "Hello there!"
1.9.3p194 :022?> end
=> nil

1.9.3p194 :026 > hello
Hello there!
=> nil

1.9.3p194 :023 > def greeter(person)
1.9.3p194 :024?> puts "Hello " + person
1.9.3p194 :025?> end
=> nil

1.9.3p194 :027 > greeter("Fanny")
Hello Fanny
=> nil

1.9.3p194 :028 > greeter
ArgumentError: wrong number of arguments (0
for 1)
from (irb):23:in `greeter'
from (irb):28
from /home/tobi/.rvm/rubies/ruby-1.9.3-
p194/bin/irb:16:in `<main>'

1.9.3p194 :029 > class Person
1.9.3p194 :030?> attr_accessor :name, :age
1.9.3p194 :031?> end
=> nil
1.9.3p194 :032 > tobi = Person.new
=> #<Person:0x0000000205f080>

1.9.3p194 :033 > tobi.name
=> nil
1.9.3p194 :034 > tobi.name = "Tobi"
=> "Tobi"
1.9.3p194 :035 > tobi.age = 23
=> 23
1.9.3p194 :036 > tobi.name
=> "Tobi"
1.9.3p194 :037 > tobi.age
=> 23

1.9.3p194 :038 > tobi.age * 365
=> 8395
1.9.3p194 :039 > puts "This was a talk by " +
tobi.name + " - thank you!"
This was a talk by Tobi - thank you!
=> nil

Where to go from here?
● I gather resources here, such as:
– http://tryruby.org
– http://ruby.railstutorial.org/
– http://rubymonk.com/
– http://www.codeschool.com/courses/rails-for-zombies
– http://rubykoans.com/
– http://railscasts.com/
● Rails Girls Berlin project groups

Thank you and enjoy
coding!
Tobias Pfeiffer
@PragTob
pragtob.wordpress.com
listen to me talking about learning Ruby (German)

Photo credit
● http://www.flickr.com/photos/captainkimo/5918836159/
● http://www.flickr.com/photos/weppos/7486411688/
● http://www.flickr.com/photos/railsgirlsberlin/7882839698/in/photostream
● http://www.flickr.com/photos/nirak/644336486/

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