Ruby: Our First Web server with Sinatra

Agenda

• Quiz
• Introducing Sinatra
• Your first web server
  • Part 1: Gemfile
  • Part 2: Config.ru
  • Part 3: App.rb
• Let's run our server
• Viewing our resource

QUIZ

1. What is a popular way to iterate through collections such as Arrays and Hashes?
2. What is used to blueprint Objects in Ruby?
3. Name a use case for using *args with a method!
4. Classes are objects and therefore have _ and __.
5. To modify these, we create _ and _ methods (hint: mutator).

We need a few Gems...

• We'll need Sinatra
• Let's install it! gem install sinatra
• Finally, we want Bundler - gem install bundler
• This gem allows us to bundle all the things together to make an app

Introducing Sinatra

• http://www.sinatrarb.com/
• Lightweight, designed to get to the point
• Highly modular and built to scale
• The easiest way to write a server in Ruby

Your First Webserver

Let's get started by building a web server in Ruby

1. Gemfile

First, we need somewhere to store all of the Gems that our application needs...

• Gemfiles are where we store information about our application.
• They allow us to specify what gems we want our application to use.
• ...and where to get them from.

Gemfile

source 'https://rubygems.org'

gem 'sinatra'
gem 'json'

Oh wait... did you hear that?

The Gemfile had new Gems added to it!

• bundle
• Yes, bundle
• From terminal in the folder where your app lives...
• Run the bundle command
• Bundler will then grab all the gems and bundle them together for your app

2. Config.ru

• We now need a file to tell our application how it should be configured.
• This tells us what we need to do and what settings our app should use.
• Since we're using Sinatra, this will be pretty simple

require './app'
run Sinatra::Application

2. Config.ru

What was going on in that file?

• We required the app.rb file by using Ruby's Require statement
• This forces a file to be loaded once into our application, making all of its methods available
• We then run Sinatra::Application - or tell Sinatra to start.
• That's it!

3. App.rb

Our final app.rb will look like this.. but we're going to build it!

require 'bundler'
Bundler.require()

get '/' do
  {:name => 'test'}.to_json
end

3. App.rb

• In our app.rb file, we now need to to require Bundler.
• It is what bundles our gems.
• We need Gems in our app - you'll se why when we want to send JSON results.

app.rb

require 'bundler'
Bundler.require()

3. App.rb

• Now, we need to let users access resources on our server.
• But how will we tell them where to go?
• We provide Routers. These are similar to Controllers.
• These route the user to http://somedomain.com/route/
• We'll define a root route first to access http://localhost/
• If this were on a live server, it could be http://somedomain.com/

app.rb

require 'bundler'
Bundler.require()

get '/' do
  # some code goes here
end

App.rb

• Now that we can have a user access a resource via a route...
• Let's expose a resource to them!
• We'll use the JSON gem here to return a Hash back to a user as JSON

app.rb

require 'bundler'
Bundler.require()

get '/' do
  {:message => 'hello, world!'}.to_json
end

Save EVERYTHING

• Add
• Commit
• Pull
• Push

Let's run our server

• In terminal, let's run our app.
• Did you add any new gems? If so, bundle!
• If not, you heard nothing shifty_eyes
• Now, let's start our server

bundle exec rackup

• This tells the Rackup middleware to run our server

Viewing our resource

• Sinatra listens for requests on port 9292
• Let's browse to our resource!
• http://localhost:9292/
• ...what do you see!

Conclusion

• You just build a webserver!
• Is this awesome?
• Yes?
• HECK YEAH