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REST with Sinatra Emanuele DelBono @emadb

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Thanks to the sponsors

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About meI’m a software developer inCodicePlastico.I write Web applications in C# withASP.NET MVC. I’m a member of<WEBdeBS/> a local webcommunity....and I’m a wannabe Rubydeveloper ;-)

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Agenda‣ Philosophy. Sweet and easy.‣ REST. Yet another boring introduction.‣ Hello world. Show some magic.‣ Features. Amazing!‣ Inside. How it works?‣ Q&A. ...and thanks.

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Sinatra as a REST server

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What is isn’t‣ Sinatra is not -another MV* framework -a full framework like Rails -an ORM -a game project

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Sinatra is just a DSL written in ruby

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Hello world

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Hello world~$ gem install sinatra~$ vi app.rb

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Hello world~$ gem install sinatra~$ vi app.rbrequire sinatraget / do hello world!end

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Hello world~$ gem install sinatra~$ vi app.rbrequire sinatraget / do hello world!end~$ ruby app.rb

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Is it really so easy?‣ Yep! (special thanks to Ruby sweeties) - get is a just a method (more later) - the route is the parameter - the block is what should be executed - the block returns the result - the server is built in (based on Rack)

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Let’s go RESTWhat? Yet another REST introduction?

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5 REST principles‣ Uniform Interface ‣ HATEAOS‣ Stateless‣ Cacheable‣ Client-Server‣ Layered System

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Sinatra and REST‣ Sinatra supports - All HTTP verbs - Caching - Content types - Routes - ....and all you need to build a rest server

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Give a look at the

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Verbs‣ Support for all verbs - Get, Post, Put, Delete, Head, Options, Patch‣ They are just methods

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Routing‣ No need of route files or route maps‣ The verb method takes the route as parameter

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Routingget ( ‘/todos’ ) {...}get ( ‘/todo/:id’ ) {...}get ( ‘/*’ ) {...}

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Routing Conditionsget /foo, :agent => /Mozilla/(d.d)sw?/ do "Youre using Mozilla version#{params[:agent][0]}"endget /foo do # Matches non-Mozilla browsersend

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Routing Customset(:prob) { |v| condition { rand <= v } }get /win_a_car, :prob => 0.1 do "You won!"endget /win_a_car {"Sorry, you lost."}

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Xml or Json‣ You can set the content_type to whatever you needcontent_type :jsoncontent_type :xml

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Status codes‣ Set the HTTP status code is status 200 status 403

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Http Headers‣ You can add your own headersheaders "X-My-Value" => "this is myheader"

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Redirectredirect to ‘/todos’

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Cache‣ You can set your cache information using the headers methodheaders "Cache-Control" => "public,must-revalidate, max-age=3600","Expires" => Time.at(Time.now.to_i + (60

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Cache‣ Or better, you can use the expiresexpires 3600, :public

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Filtersbefore do #...endafter do #...

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Authentication‣ Basic authentication support through Rack‣ Key-based authentication

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Basic Authenticationuse Rack::Auth::Basic, "Private area" do|usr, pwd| [usr, pwd] == [admin, admin]end

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Token authenticationbefore do if env[‘HTTP_MY_KEY’] ==’rubyrocks‘ error 401 endend

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Demo

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Stream‣ Supports streamed content‣ Streamed responses have no Content- Length header‣ But have Transfer-Encoding: chunked

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Inside

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Inside‣ Sinatra source code is on github: http://github.com/sinatra/sinatra‣ Less than 2k lines of code‣ Based on Rack

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Application styleClassic application vsModular application

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Classic App Single file Standalone

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Modular Apps Multi fileSubclassing Sinatra::Base Distributed as library

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The codeWhat happen when a request arrives?get (‘/hello’) do { ‘hello world’ }

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Where do get come from?require "sinatra"outer_self = selfget / do "outer self: #{outer_self}, inner self: #{self}"end outer self: main, inner self: #<Sinatra::Application: closures in ruby are “scope gate”

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$ irb

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$ irbruby-1.9.2-p180 > require sinatra

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$ irbruby-1.9.2-p180 > require sinatra=> true

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$ irbruby-1.9.2-p180 > require sinatra=> trueruby-1.9.2-p180 > method(:get)

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$ irbruby-1.9.2-p180 > require sinatra=> trueruby-1.9.2-p180 > method(:get)=> #<Method: Object(Sinatra::Delegator)#get>

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$ irbruby-1.9.2-p180 > require sinatra=> trueruby-1.9.2-p180 > method(:get)=> #<Method: Object(Sinatra::Delegator)#get>ruby-1.9.2-p180 > Sinatra::Delegator.methods(false)

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$ irbruby-1.9.2-p180 > require sinatra=> trueruby-1.9.2-p180 > method(:get)=> #<Method: Object(Sinatra::Delegator)#get>ruby-1.9.2-p180 > Sinatra::Delegator.methods(false)=> [:delegate, :target, :target=]

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$ irbruby-1.9.2-p180 > require sinatra=> trueruby-1.9.2-p180 > method(:get)=> #<Method: Object(Sinatra::Delegator)#get>ruby-1.9.2-p180 > Sinatra::Delegator.methods(false)=> [:delegate, :target, :target=]ruby-1.9.2-p180 > Sinatra::Delegator.target

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$ irbruby-1.9.2-p180 > require sinatra=> trueruby-1.9.2-p180 > method(:get)=> #<Method: Object(Sinatra::Delegator)#get>ruby-1.9.2-p180 > Sinatra::Delegator.methods(false)=> [:delegate, :target, :target=]ruby-1.9.2-p180 > Sinatra::Delegator.target=> Sinatra::Application

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$ irbruby-1.9.2-p180 > require sinatra=> trueruby-1.9.2-p180 > method(:get)=> #<Method: Object(Sinatra::Delegator)#get>ruby-1.9.2-p180 > Sinatra::Delegator.methods(false)=> [:delegate, :target, :target=]ruby-1.9.2-p180 > Sinatra::Delegator.target=> Sinatra::Applicationruby-1.9.2-p180 > Sinatra::Application.method(:get)

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$ irbruby-1.9.2-p180 > require sinatra=> trueruby-1.9.2-p180 > method(:get)=> #<Method: Object(Sinatra::Delegator)#get>ruby-1.9.2-p180 > Sinatra::Delegator.methods(false)=> [:delegate, :target, :target=]ruby-1.9.2-p180 > Sinatra::Delegator.target=> Sinatra::Applicationruby-1.9.2-p180 > Sinatra::Application.method(:get)=> #<Method:Sinatra::Application(Sinatra::Base).get>

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Where do get come from?‣ get is defined twice: – Once in Sinatra::Delegator a mixin extending Object – Once in Sinatra::Application‣ The Delegator implementation simply delegate to Application‣ That’s why we have get/post/... methods on main

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How the block is invoked?‣ The route! method finds the correct routedef route_eval throw :halt, yieldend‣ throw is used to go back to the invoker

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In base.rb‣ The invokerdef invoke res = catch(:halt) { yield } # .... other code...end

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It’s a kind of magic!

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Sinatra has ended his set (crowd applauds)

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Questions?

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demos at:http://github.com/emadb/ webnetconf_demo

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