Ruby off Rails (english)

Ruby off Rails

by Stoyan ZhekovKyoto, 17-May-2008

08/05/19 2

Table of content● Coupling and Cohesion● Common needs for various web apps● ORM - Sequel (short overview)● Ruby Web Evolution● Enter Rack - The Middle Man● Thin, Ramaze, Tamanegi● Summary, Extras, Questions

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Coupling and Cohesion (1)● Cohesion

http://en.wikipedia.org/wiki/Cohesion_(computer_science)● Coupling

http://en.wikipedia.org/wiki/Coupling_(computer_science)

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Coupling and Cohesion (2)

Applications should be composed of components that show:

● High cohesion– doing small number of things and do them well

● Low (loosely) coupling– easy replace any component with another one

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Coupling and Cohesion (3)

Google vs Amazon

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Coupling and Cohesion (4)

VS

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What about Rails?

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Ruby on Rails● Full Stack – was good. Now?● Convention over configuration – good?● DRY – possible?

– Generators– Plugins– Libraries

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Life without Rails

Is it possible?

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Common needs for various web apps

● Database handling: ORM● Request processing: CGI env, uploads● Routing/dispatching: map URLs to classes● Rendering/views: rendering libraries● Sessions: persist objects or data

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Database ORM● Active Record ?= ActiveRecord● ActiveRecord – a lot of problems

– http://datamapper.org/why.html● Data Mapper – fast, but not ready

– No composite keys (when I started using it)– Have it's own database drivers

● Sequel – good, I like it

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ORM – Sequel (Why?)● Pure Ruby● Thread safe● Connection pooling● DSL for constructing DB queries● Lightweight ORM layer for mapping records to

Ruby objects● Transactions with rollback

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ORM – Sequel (Core)● Database Connect

require 'sequel'DB = Sequel.open 'sqlite:///blog.db'

DB = Sequel.open 'postgres://cico:12345@localhost:5432/mydb'

DB = Sequel.open("postgres://postgres:postgres@localhost/my_db", :max_connections => 10, :logger => Logger.new('log/db.log'))

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ORM – Sequel (Core, 2)

DB << "CREATE TABLE users (name VARCHAR(255) NOT NULL)"

DB.fetch("SELECT name FROM users") do |row| p r[:name]end

dataset = DB[:managers].where(:salary => 50..100).order(:name, :department)

paginated = dataset.paginate(1, 10) # first page, 10 rows per pagepaginated.page_count #=> number of pages in datasetpaginated.current_page #=> 1

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ORM – Sequel (Model)

class Post < Sequel::Model(:my_posts) set_primary_key [:category, :title]

belongs_to :author has_many :comments has_and_belongs_to_many :tags

after_create do set(:created_at => Time.now) end

end

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ORM – Sequel (Model, 2)

class Person < Sequel::Model one_to_many :posts, :eager=>[:tags]

set_schema do primary_key :id text :name text :email foreign_key :team_id, :table => :teams endend

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Evolution

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Ruby Web Evolution

Mongrel EventMachine

ThinWebrick Ebb

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Thin web server● Fast – Ragel and Event Machine● Clustering● Unix sockets (the only one I found) - nginx● Rack-based – Rails, Ramaze etc.● Rackup files support (follows)

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Thin + Nginx

thin start --servers 3 --socket /tmp/thinthin start --servers 3 –post 3000

# nginx.confupstream backend { fair; server unix:/tmp/thin.0.sock; server unix:/tmp/thin.1.sock; server unix:/tmp/thin.2.sock;}

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The problem

Merb Ramaze Sinatra ...

CGI Webrick Mongrel Thin

How to connect them?

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The solution - Rack

Merb Ramaze Sinatra ...

CGI Webrick Mongrel Thin

Rack – The Middle Man

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What is Rack?

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What IS Rack?

http://rack.rubyforge.org/

By Christian Neukirchen

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WHAT is Rack?● Specification (and implementation) of a minimal

abstract Ruby API that models HTTP– Request -> Response

● An object that responds to call and accepts one argument: env, and returns:– a status, i.e. 200– the headers, i.e. {‘Content-Type’ => ‘text/html’}– an object that responds to each: ‘some string’

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This is Rack!

class RackApp def call(env) [ 200, {"Content-Type" => "text/plain"}, "Hi!"] endend

app = RackApp.new

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Free Hugs

http://www.freehugscampaign.org/

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Hugs Application

p 'Hug!'

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ruby hugs.rb

%w(rubygems rack).each { |dep| require dep }

class HugsApp def call(env) [ 200, {"Content-Type" => "text/plain"}, "Hug!"] endend

Rack::Handler::Mongrel.run(HugsApp.new, :Port => 3000)

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Rack::Builderrequire 'hugs'app = Rack::Builder.new { use Rack::Static, :urls => ["/css", "/images"], :root => "public" use Rack::CommonLogger use Rack::ShowExceptions map "/" do run lambda { [200, {"Content-Type" => "text/plain"}, ["Hi!"]] } end map "/hug" do run HugsApp.new end}

Rack::Handler::Thin.run app, :Port => 3000

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Rack Building Blocks● request = Rack::Request.new(env)

– request.get?● response = Rack::Response.new('Hi!')

– response.set_cookie('sess-id', 'abcde')● Rack::URLMap● Rack::Session● Rack::Auth::Basic● Rack::File

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Rack Middleware

Can I create my own use Rack::... blocks?

class RackMiddlewareExample def initialize app @app = app end

def call env @app.call(env) endend

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Common needs for various web apps

● Database handling: ORM Sequel● Request processing: Rack::Request(env)● Routing/dispatching: Rack 'map' and 'run'● Rendering/views: Tenjin, Amrita2● Sessions: Rack::Session

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Does it scale?

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rackup hugs.ru

require 'hugs'app = Rack::Builder.new {use Rack::Static, :urls => ["/css", "/images"], :root => "public" map "/" do run lambda { [200, {"Content-Type" => "text/plain"}, ["Hi!"]] }end map "/hug" do run HugsApp.newend}Rack::Handler::Thin.run app, :Port => 3000

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Hugs Service● rackup -s webrick -p 3000 hugs.ru● thin start --servers 3 -p 3000 -R hugs.ru● SCGI● FastCGI● Litespeed● ....

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Rack-based frameworks● Invisible – thin-based framework in 35 LOC

– http://github.com/macournoyer/invisible/● Coset – REST on Rack● Halcyon – JSON Server Framework● Merb● Sinatra● Ramaze● Rails !?

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Rack coming to Rails● Rails already have Rack, but:

– raw req -> rack env -> Rack::Request ->CGIWrapper -> CgiRequest

● Ezra Zygmuntowicz (merb)'s repo on github– http://github.com/ezmobius/rails– raw req -> rack env -> ActionController::RackRequest– ./script/rackup -s thin -c 5 -e production

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Ramaze● What: A modular web application framework● Where: http://ramaze.net/● How: gem install ramaze● git clone http://github.com/manveru/ramaze.git● Who: Michael Fellinger and Co.

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Why Ramaze?● Modular (low [loosely] coupling)● Rack-based● Easy to use● A lot of examples (~25) – facebook, rapaste● Free style of development● Friendly community - #ramaze● “All bugs are fixed within 48 hours of reporting.”

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Deployment options

● CGI● FastCGI● LiteSpeed● Mongrel● SCGI● Webrick

● Ebb● Evented Mongrel● Swiftiplied Mongrel● Thin● Whatever comes along

and fits into the Rack

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Templating engines● Amrita2● Builder● Erubis● Ezmar● Haml● Liquid● Markaby

● RedCloth● Remarkably● Sass● Tagz● Tenjin● XSLT

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Ezamar

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Easy to use?

%w(rubygems ramaze).each {|dep| require dep}

class MainController < Ramaze::Controller def index; "Hi" endend

class HugsController < Ramaze::Controller map '/hug' def index; "Hug!" endend

Ramaze.start :adapter => :thin, :port => 3000

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Ramaze Usage

class SmileyController < Ramaze::Controller map '/smile' helper :smiley

def index smiley(':)') endend

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Ramaze Usage (2)module Ramaze module Helper module SmileyHelper FACES = { ':)' => '/images/smile.png', ';)' => '/images/twink.png'} REGEXP = Regexp.union(*FACES.keys)

def smiley(string) string.gsub(REGEXP) { FACES[$1] } end end endend

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Alternative Stack● ORM – Sequel● Web server – Thin + NginX● Rack Middleware● Ramaze framework● Templates – HAML, Tenjin, Amrita2

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Summary● Not trying to tell you to not use Rails● Just keep your mind open● Sequel is good ORM● Use Rack – DIY framework, DIY server● Ramaze is cool and easy to use