Rails%203%20In%20Action

Mounting a Rack application with Rails
(which is what normally happens in a standard Rails request), a Rack class is much
lighter and is perfect for serving high-intensity requests that don’t require views, like
the response from your Heartbeat::Application and the responses from your API.
So now that you’ve learned how you can mount your Heartbeat::Application,
let’s build this slightly more complex Rack application that will serve JSON API
requests for tickets. To make sure everything works, you’ll be writing tests using the
same Rack::Test::Methods helpers that you used back in chapter 13. These helpers
are designed for Rack applications, but they worked with your Rails application
because... well, it’s a Rack app too.
Rather than writing this application as a standard Rack app, let’s branch out and
use another Ruby web framework called Sinatra.
18.3.2 Introducing Sinatra
Sinatra is an exceptionally lightweight Ruby web framework that’s perfect for building
small applications, such as those that serve an API. Like Rails, it’s built on top of Rack
and so you’ll have no worries about using them together. You’ll use it here to create
version 3 of your API. Building you app this way not only demonstrates the power of
Sinatra, but also shows that there’s more than one way to skin this particular cat. 4
To install the sinatra gem, run this command:
gem install sinatra
You can make a small Sinatra script now by creating a file called sin.rb, as shown in the
following listing.
Listing 18.6 sin.rb
require 'sinatra'
get '/' do
"Hello World"
end
This is the smallest Sinatra application that you can write. On the first line you require
the Sinatra file, which gives you some methods you can use to define your application,
such as the get method you use on the next line. This get method is used to define a
root route for your application, which returns the string “Hello World” for GET
requests to /. You could also make it into a class, which is what you’ll need to do for it
to be mountable in your application:
require 'sinatra'
class Tickets < Sinatra::Base
get '/' do
"Hello World"
end
end
4 Although why anybody would skin a cat these days is unknown to the authors.
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