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Building with Rack Alexander Clark

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What is Rack?

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What does a Rack app look like? ?

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What does a Rack app look like? GET /foo HTTP/1.1 Host: localhost:9292 Accept: text/html … ?

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What does a Rack app look like? GET /foo HTTP/1.1 Host: localhost:9292 Accept: text/html … ? …

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run Proc.new { |env| ['200', {'Content-Type' => 'text/html'}, ['get rack\'d']] }

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run Proc.new { |env| ['200', {'Content-Type' => 'text/html'}, ['get rack\'d']] } Responds to #call HTTP Status code Headers Response body Run

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run Proc.new { |env| ['200', {'Content-Type' => 'text/html'}, ['get rack\'d']] } Responds to #call Much HTTP Status code Such Headers Response body Wow Run

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Let’s build something!

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Is it April Fools?

<%= @april_fools ? 'YES' : 'NO' %>

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require 'erb' class MyRackApp def initialize @april_fools = Time.now.strftime('%m%d') == '0401' end def call(_env) ['200', {'Content-Type' => 'text/html'}, view] end def view [ERB.new(template).result(binding)] end def template File.open('index.html.erb', 'r').read end end

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require './my_rack_app' run MyRackApp.new

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run Proc.new { |env| ['200', {'Content-Type' => 'text/html'}, ['get rack\'d']] } run MyRackApp.new ... def call(_env) ['200', {'Content-Type' => 'text/html'}, view] end

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run MyRackApp.new run Rails.application

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Middleware

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TL;DL

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Further Reading • https://rack.github.io/ • http://alexander-clark.com/blog/building-a-rack-app/ • http://www.justinweiss.com/articles/a-web-server-vs- an-app-server/ • https://www.amberbit.com/blog/2011/07/13/ introduction-to-rack-middleware/

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Thanks for Listening Alexander Clark atheclark alexander-clark.com alexander-clark