Understand Rack, an essential component of Rails.
Rack provides a minimal, modular and adaptable interface for developing web applications in Ruby. It includes basic implementations of request, response, cookies & sessions. And a good number of useful middlewares.
Bundler is a package manager that sandboxes an application or library. Libraries are called gems.
Create a Gemfile that requires Rack and Mongrel, a web server.
source "http://rubygems.org"
gem "rack", "1.3.5"
gem "mongrel", "1.2.0.pre2"Install bundler with RubyGem.
$ gem install bundler
Install gems.
$ bundle install
Your bundle is complete! Use `bundle show [gemname]` to see where a bundled gem is installed.
A simple Rack server responds to a single HTTP request. The call method takes one parameter - an environment that contains information about the HTTP request. The response from the call method must be an array of three elements: an HTTP return code, headers and an array of body parts.
require 'rubygems'
require 'rack'
class HelloWorld
def call(env)
[200, {"Content-Type" => "text/html"}, ["Hello Rack!"]]
end
end
Rack::Handler::Mongrel.run HelloWorld.new, :Port => 9292 # Remember the uppercase 'P'It can be run with ruby.
$ ruby server.rb
Navigate to localhost:9292.