Building with Rack

Building with Rack Alexander Clark

What is Rack?

What does a Rack app look like? ?

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

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

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

} Responds to #call HTTP Status code Headers Response body Run

} Responds to #call Much HTTP Status code Such Headers Response body Wow Run

Let’s build something!

<!DOCTYPE html> <html> <head> <title>Is it April Fools?</title> </head> <body>
<h1><%= @april_fools ? 'YES' : 'NO' %></h1> </body> </html>

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

require './my_rack_app' run MyRackApp.new

} run MyRackApp.new ... def call(_env) ['200', {'Content-Type' => 'text/html'}, view] end

run MyRackApp.new run Rails.application

Middleware

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/

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

Building with Rack

Building with Rack

Alexander Clark

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