Ruby for Java Developers

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Ruby introduction specially for Java Developers.

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  • Ruby for Java Developers

    1. 1. Ruby for Java Developers ! Robert Reiz
    2. 2. Robert Reiz http:/ /robert-reiz.com https:/ /twitter.com/robertreiz ! http:/ /about.me/robertreiz ! http:/ /www.VersionEye.com
    3. 3. Agenda History Java/Ruby Culture Background Java/Ruby Tech. Background Ruby Lang Rails - Short Intro + Tools Rails Demo App Performance Else The End
    4. 4. A Presentation is no Documentation A good presentation supports only the speaker
    5. 5. History Yukihiro Matsumoto in Japan 1993 first ideas 1995 Version 0.95 released
    6. 6. History "I wanted a scripting language that was more powerful than Perl, and more object-oriented than Python. That's why I decided to design my own language." - Matsumoto
    7. 7. History "Often people, especially computer engineers, focus on the machines. They think, "By doing this, the machine will run faster. By doing this, the machine will run more effectively. By doing this, the machine will something something something." They are focusing on machines. But in fact we need to focus on humans, on how humans care about doing programming or operating the application of the machines. We are the masters. They are the slaves." - Matsumoto
    8. 8. History for (int i = 0 ; i < 3 ; i++){ System.out.println(“Hallo World”); } 3.times{ print “Hallo World” }
    9. 9. History Language developed by Open Standards Promotion Center of the InformationTechnology Promotion Agency 2011: Japanese Industrial Standard (JIS X 3017) 2012: International standard (ISO/IEC 30170)
    10. 10. Culture Background “Java Programmers are writing strange Ruby Code.”
    11. 11. Java Culture JME Java for Desktops (Swing, AWT, JavaFX) J EE
    12. 12. Java Culture = Enterprise Culture Enterprise Environment
    13. 13. Java Culture Waterfall Servlet LDAP Intranet Eclipse Excel Application Server Oracle Jira Deadlines Outlook Requirements SVN SLAs EJB
    14. 14. Ruby Culture Start-Up Culture in Silicon Valley
    15. 15. Ruby Culture Start-Up Environment (Epicenter Cafe @ SF)
    16. 16. Ruby Culture Start-Up Environment (The Summit @ SF)
    17. 17. Ruby Culture Hackathon
    18. 18. Fail fast Fail early
    19. 19. Ruby Culture Login with Twitter / Facebook OAuth Cloud Internet GMail SaaS Agile PostgreSQL SimpleNote RTM Heroku NoSQL Textmate Dropbox Ideas GitHub
    20. 20. Java Tech. Background WAR EAR WAR EAR WAR App-Server DB SAP LDAP This makes sense for big companies with different apartments. But it doesn’t make sense for a small Start-Up!
    21. 21. Ruby Tech. Background In a typical Ruby environment there is usually ... No SAP No LDAP No Oracle No App-Server No WAR No EAR
    22. 22. Ruby Tech. Background Just the App! Application Everything else is secondary!
    23. 23. Java Language 640 Pages
    24. 24. Java Language Inheritance Polymorphismus AutoBoxing Interfaces Object Oriented Annotations Generics static typing Enums
    25. 25. Java Language More language features don’t make a language better. Just more complicated and more difficult to learn. Without monster tools like Eclipse it is nearly not possible to use the language.
    26. 26. Can you write down the Java code to open this file and output the content? ! - Without IDE - Without Google text_file.txt
    27. 27. Java import java.io.*; ! class FileRead { public static void main(String args[]) { try{ FileInputStream fstream = new FileInputStream("text_file.txt"); DataInputStream in = new DataInputStream(fstream); BufferedReader br = new BufferedReader(new InputStreamReader(in)); String strLine; while ((strLine = br.readLine()) != null) { System.out.println (strLine); } in.close(); } catch (Exception e) { System.err.println("Error: " + e.getMessage()); } } }
    28. 28. Ruby puts File.read 'text_file.txt'
    29. 29. Python f = open('text_file.txt', 'r') Perl open FILE, "text_file.txt" or die $!;
    30. 30. Ruby Language Polymorphismus Inheritance Object Oriented Duck typing dynamic typing
    31. 31. Ruby Language No Interfaces No static types No Generics No Annotations
    32. 32. Java Ruby package xyz; ! import xyz; ! public class User { ! public void sayHello(){ System.out.println(“Hello”); } ! class User ! def say_hello p “Hello” end ! } end User user = new User() user.sayHello() user = User.new user.say_hello
    33. 33. Java Ruby package xyz; ! import xyz; ! class User ! def say_hello p “Hello” end public class User { ! public void sayHello(){ System.out.println(“Hello”); } ! private ! ! private String secretHero(){ return “secret hero”; } ! } def secret_hero “secret hero” end ! end
    34. 34. Java public String doubleIt(String name){ result = name + “ ” + name; return result; } Ruby def double_it name "#{name} #{name}" end
    35. 35. Java public String greetz(String name){ if (name != null){ result = “Hello” + name; else { result = “Hello”; } System.out.println( result ); }
    36. 36. Ruby def greetz( name ) if !name.nil? p "Hello #{name}" else p “Hello” end end
    37. 37. Ruby def greetz(name) p "Hello #{name}" if name p “Hello” unless name end
    38. 38. Ruby def greetz(name = “Rob”, say_name = true) p "Hello #{name}" if say_name p “Hello” unless say_name end user.greetz(“Bob”, false) user. greetz(“Bob”) user. greetz()
    39. 39. Java List<String> list = new ArrayList<String>(); ! list.add("Spiderman"); list.add("Batman"); list.add("Hulk"); ! for (String name : list){ System.out.println(name); }
    40. 40. Ruby names = Array.new names << “Hans” names << “Tanz” names[0] names[1] names.first names.last
    41. 41. Ruby names = [‘Spiderman’, ‘Batman’, ‘Hulk’] names.each do |name| print “#{name}” end
    42. 42. Ruby hash = Hash.new hash[“a”] = 100 hash[“b”] = 200 hash[“a”] hash.delete(“a”) hash.first hash.last hash.each {|key, value| puts "#{key} is #{value}" } hash.each_key {|key| puts key }
    43. 43. irb
    44. 44. Ruby on Rails Initial Release 2004 David Heinemeier Hansson Web application framework MIT License http:/ /rubyonrails.org/
    45. 45. Ruby on Rails activesupport : 3.2.8 bundler : ~>1.0 activerecord : 3.2.8 actionpack : 3.2.8 activeresource : 3.2.8 actionmailer : 3.2.8 railties : 3.2.8 http:/ /www.versioneye.com/package/rails
    46. 46. Ruby on Rails MVC Framework Convention over Configuration KIS Testable No UI Components You are in control
    47. 47. Ruby on Rails REST Stateless Session in cookies OR database
    48. 48. Ruby on Rails http:/ /www.myapp.com/photos http:/ /www.myapp.com/photos/17 http:/ /www.myapp.com/photos/17/edit
    49. 49. Bundler - Gemfile source 'https:/ /rubygems.org' ! gem 'rails', '3.2.6' gem 'sqlite3' gem 'jquery-rails' ! # Gems used only for assets and not required # in production environments by default. group :assets do gem 'sass-rails', '~> 3.2.3' gem 'coffee-rails', '~> 3.2.1' gem 'uglifier', '>= 1.0.3' end
    50. 50. Environments development: adapter: sqlite3 database: db/development.sqlite3 pool: 5 timeout: 5000 ! test: adapter: sqlite3 database: db/test.sqlite3 pool: 5 timeout: 5000 ! production: adapter: sqlite3 database: db/production.sqlite3 pool: 5 timeout: 5000 export RAILS_ENV=test export RAILS_ENV=production export RAILS_ENV=development
    51. 51. Rake require File.expand_path('../config/application', __FILE__) ! Myapp::Application.load_tasks rake db:create rake routes
    52. 52. Ruby on Rails DEMO live coding
    53. 53. Performance Ruby is slower than Java! ! ... True! But ...
    54. 54. Performance Client Request Response WEB Server 40 % 20 % READ, WRITE Response 40 % DB
    55. 55. Performance Request Response 1 HTML Page WEB Server N - Requests to load additional Resources
    56. 56. Performance
    57. 57. Performance
    58. 58. Performance Performance opt. for Web Apps. Minify Uglify CSS Stripes Opt. HTML Opt. Database Access
    59. 59. Performance http:/ /guides.rubyonrails.org/asset_pipeline.html http:/ /tools.pingdom.com/fpt/
    60. 60. Who is using Ruby? Ruby is just good small projects. Right? -> Right! Small Projects like ...
    61. 61. -> $ 800 Million worth
    62. 62. -> $ 1 Billion worth
    63. 63. Count of Open Source Projects Java Java Ruby PHP 0 12500 25000 37500 50000 4061 PHP R 12320 R Node.JS 23439 Node.JS Python 43620 Python Ruby 48034 2973
    64. 64. Ruby on Rails is very good solution for WebApplications!
    65. 65. What is not good for?
    66. 66. It is not good for ... Long living batch jobs parsing 2 million documents Use Java or C for that kind of jobs.
    67. 67. Links http:/ /www.ruby-lang.org/en/ http:/ /rubyonrails.org http:/ /ruby.railstutorial.org http:/ /rubygems.org/ http:/ /www.heroku.com http:/ /travis-ci.org
    68. 68. Links http:/ /www.engineyard.com/ https:/ /www.dotcloud.com/ http:/ /www.CloudControl.com/ http:/ /jruby.org/ http:/ /www.ironruby.net/
    69. 69. ???

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