Sinatra: a Micro-framework for Web Applications

http://www.sinatrarb.com/

Kevin ReissOffice of Library Services

What is Sinatra?

• A web application micro-framework• Minimal stack framework

• A ruby Domain Specific Language (DSL)

• A ruby “rack” application

• A ruby “gem”• Gems are the ruby equivalent of• Perl modules• PHP PEAR• Managing gems is very easy

- Gem install sinatra is all you need

Why Sinatra?

• It is lightweight

• Built on the rack “gem”• Rack is a generic ruby library for building web applications

• It is nicely pluggable within other applications• Rails3 has featured support for sinatra apps as middleware

• Good tool for creating REST-like interfaces

• Supports many different template syntaxes

• It has it’s own web server: default thin

• Convention over Configuration: the Ruby Framework Way

Hello World?

# hello_world.rb require 'sinatra' # a single sinatra block with a return valueget '/' do 'Hello world!' # return the string “Hello World”end

To run the app:> ruby hellow_world.rb

Second Hello World App

• Sinatra configuration

• Sinatra routes

• Sinatra helpers

• Watch your Request values

Sinatra: Helpers, Routes, and Blocks

helpers do def format_title(name) name.capitalize # your return value endEnd

get '/library/:department' do @title = "#{format_title(params[:department])} Department".strip haml :department # invoke a templateend

Views with Sinatra

• Standard convention• Views always go in the “views” directory• Templates marked “layout.ext” are automatically used

as wrappers for “content-like templates” like “mycustomdisplay.ext”

• Static files (stylesheets, images, etc.) are served up out of the “public” directory

• Support a wide variety of template options to generate XHTML, HTML5, XML, etc.

• Can easily define custom formats• Integration with RACK makes it easy to deal with the

parts of an HTTP Request

HAML Templates

• HAML – HTML Templates for the Lazy

• Also bundled with a CSS Template: SASS%html{:"xml:lang"=>"en"} %head %title My Library Web: #{@title} %link{:type=>"text/css",:rel=>"stylesheet",:media=>"screen",:href=>"/stylesheet.css"} %body #pageContent #header %ul.nav %li %a{:href=>"/"} Home #body =yield #footer %p Office of Library Services

Where is the Registry?

• Set configuration options and constants easily

• Sinatra’s integration with rack makes it easy to access and manipulate the contents of the http.request associated

What about Testing?• Unit tests are built into rack

set :environment, :test

class LibraryTest < Test::Unit::TestCase

def test_it_says_hello_world browser = Rack::Test::Session.new(Rack::MockSession.new(Sinatra::Application)) browser.get '/' assert browser.last_response.ok? assert_equal '<h1>Hello World!</h1>', browser.last_response.body end

def test_it_says_hello_to_a_department browser = Rack::Test::Session.new(Rack::MockSession.new(Sinatra::Application)) browser.get '/library/ill' assert browser.last_response.body.include?('ill') endend

Deployment Options

• Launch Locally with ruby thin web server• This is built into the application

• Publish directly to heroku

• Launch via apache• proxy_balancer module• passenger module

• ngnix

Heroku Features

• Read-only filesystem

• Installed as a ruby gem

• Integrated with git and ssh

• Free for low-volume applications

• Add-ons to expand functionality• Memcache• Databases,DNS,

• heroku logs

• Good documentation

• Not just sinatra, rails and any other rack-based application

• Similar to the “Google App Engine”

Heroku Deployment

• Ruby Platform as a Service – http://heroku.com/

• Rails, Sinatra, generic Rack Applications

• Integrated directly with git version to control

• To Deploy:• create “config.ru” file – defines your rack application• create .gems file – defines libraries your app requires• git init• git add .• git commit –m “Initial Commit”• heroku create• git push heroku master

Thin Server Configuration

--- chdir: /home/kreiss/ruby/lookup/rackup: /home/kreiss/ruby/lookup/config.ru environment: productionaddress: 127.0.0.1port: 5000timeout: 30log: /home/kreiss/ruby/lookup/log/thin.logpid: /home/kreiss/ruby/lookup/tmp/pids/thin.pidmax_conns: 1024max_persistent_conns: 512require: []wait: 30servers: 3daemonize: true

An Actual Application

• Standard number checker

• Wrapper for our web services provided by our ILS

• Embed this as a web service in other application/scripts

REST-Like Interface

• Output multiple formats• JSON• Custom XML with builder gem

• XML parsing handled by the nokogiri ruby gem

More Complicated Sample Route

get '/:campus/isbn/:isbn' do lookup_base = is_valid_sublibrary(params[:campus]) @number = is_valid_isbn(params[:isbn]) @type = "ISBN" @title = “#{@type}: #{@number} for campus #{lookup_base}" @items = standard_lookup(@number, "bath.isbn", lookup_base) if params[:format] == "xml" builder :bib elsif params[:format] == "json" @items.to_json else haml :standard endend

Heroku Deployment

• 486 curl http://cunylookup.heroku.com/laguardia/barcode/33324001754295• 487 curl http://cunylookup.heroku.com/city/isbn/0800630807• 488 curl http://cunylookup.heroku.com/city/isbn/0800630807?format=xml• 489 curl http://cunylookup.heroku.com/city/isbn/0800630807?format=json• 490 curl http://cunylookup.heroku.com/cun01/isbn/0800630807• 491 curl http://cunylookup.heroku.com/cun01/isbn/0800630807?format=json• 492 curl http://cunylookup.heroku.com/cun01/isbn/0800630807?format=xml• 493 curl http://cunylookup.heroku.com/cun01/isbn/0800630807?format=xml• 494 curl http://cunylookup.heroku.com/cun01/issn/1092-7735?format=xml• 495 curl http://cunylookup.heroku.com/city/issn/1092-7735?format=xml• 496 curl http://cunylookup.heroku.com/laguardia/issn/1092-7735?format=xml• 497 curl http://cunylookup.heroku.com/laguardia/lccn/96042502?format=xml• 498 curl http://cunylookup.heroku.com/cun01/lccn/96042502?format=xml

Gotchas

• Ruby 1.8 v. Ruby 1.9• Heroku supports both• Gems need to be called differently in ruby 1.8

• Name your gems sensibly – annoying rubyism• Dalli: name for memcache gem• Nokogiri: name for xml processing gem

• Sinatra vs. Sinatra Base• If you plan to use as middleware in another ruby

app you need to define your application with sinatra base

Other frameworks in Libraries

• Rails (Blacklight)

• PHP Zend (Omeka)

• Django (Solr front-end)

• Xerxes (Metasearch)

Drupal Platform

• Services

• Views datasource

• Drupal Workflow building capabilities• Workflow module• New workbench toolkit

• D7 Rest Server

Code4lib Report

• Looks of repository middleware

Code4libNYC

• Suggestion to host day long event