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BUILDING AMBITIOUS APIS WITH RUBY Dan Gebhardt @dgeb Burlington Ruby 2013

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DO YOU NEED AN API?

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CLIENT-SIDE JS APPLICATION?

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CLIENT-SIDE JS APPLICATION? YOU NEED AN API

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NATIVE APPLICATION?

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NATIVE APPLICATION? YOU NEED AN API

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3RD PARTY INTEGRATION? Creative Commons image courtesy of Kamil Porembiński

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3RD PARTY INTEGRATION? YOU NEED AN API Image credit: http://up1ter.deviantart.com/art/Twilight-Sparkle-is-flying-286029311

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SCRIPTABLE?

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SCRIPTABLE? YOU NEED AN API @devops_borat @hipsterhacker @neckbeardhacker

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SO DO YOU NEED AN API?

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SO DO YOU NEED AN API? *PROBABLY*

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LET'S BUILD SOMETHING THAT DOES

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RubyPets!

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RubyPets!

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EMBER UI

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ANDROID & IOS APPS EMBER UI

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ANDROID & IOS APPS EMBER UI LOLCATS INTEGRATION

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ANDROID & IOS APPS LOLCATS INTEGRATION EMBER UI NEEDS AN API

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"WE NEED A RESTFUL API"

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"...AFTER YOU FEED ME!"

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RESTFUL API BASICS

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Your application's NOUNS are modeled as RESOURCES

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OUR RESOURCES Pets

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OUR RESOURCES People

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Every RESOURCE has a URI

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OUR RESOURCES # all pets /pets # each pet /pets/123

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OUR RESOURCES # all people /people # each person /people/123

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Resources are acted upon with HTTP METHODS

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POST GET UPDATE PATCH DELETE /pets/123 /pets/ /pets/123 /pets/123 /pets/123

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POST GET UPDATE PATCH DELETE /pets/123 /pets/ /pets/123 /pets/123 /pets/123

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POST GET UPDATE PATCH DELETE /pets/123 /pets/ /pets/123 /pets/123 /pets/123

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POST GET UPDATE PATCH DELETE /pets/123 /pets/ /pets/123 /pets/123 /pets/123

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POST GET UPDATE PATCH DELETE /pets/123 /pets/ /pets/123 /pets/123 /pets/123

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POST GET UPDATE PATCH DELETE /pets/123 /pets/ /pets/123 /pets/123 /pets/123 + MORE

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"WE NEED AN AMBITIOUS RESTFUL API!"

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DEFINE AMBITIOUS

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DEFINE AMBITIOUS •Flexible

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DEFINE AMBITIOUS •Flexible •Consistent

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DEFINE AMBITIOUS •Flexible •Consistent •Efficient

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DEFINE AMBITIOUS •Flexible •Consistent •Efficient •Secure

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DEFINE AMBITIOUS •Flexible •Consistent •Efficient •Secure •Discoverable

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IS THERE ANYTHING WE WON'T DO?

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LET'S STICK WITH JSON ... AND SKIP XML

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OK, LET'S GET STARTED!

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OK, LET'S GET STARTED!

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LET'S START SIMPLE $ rails new rubypets $ cd rubypets $ rails g scaffold pet name:string $ rails g scaffold toy name:string pet:references $ rake db:migrate # set a default route, define relationships, etc ...

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LET'S START SIMPLE $ rails new rubypets $ cd rubypets $ rails g scaffold pet name:string $ rails g scaffold toy name:string pet:references $ rake db:migrate # set a default route, define relationships, etc ...

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LET'S START SIMPLE $ rails new rubypets $ cd rubypets $ rails g scaffold pet name:string $ rails g scaffold toy name:string pet:references $ rake db:migrate # set a default route, define relationships, etc ...

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LET'S START SIMPLE $ rails new rubypets $ cd rubypets $ rails g scaffold pet name:string $ rails g scaffold toy name:string pet:references $ rake db:migrate # set a default route, define relationships, etc ...

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LET'S START SIMPLE $ rails new rubypets $ cd rubypets $ rails g scaffold pet name:string $ rails g scaffold toy name:string pet:references $ rake db:migrate # set a default route, define relationships, etc ...

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LET'S START SIMPLE $ rails new rubypets $ cd rubypets $ rails g scaffold pet name:string $ rails g scaffold toy name:string pet:references $ rake db:migrate # set a default route, define relationships, etc ...

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MODELS # /app/models/pet.rb class Pet < ActiveRecord::Base has_many :toys end # /app/models/toy.rb class Toy < ActiveRecord::Base belongs_to :pet end

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CONTROLLERS class PetsController < ApplicationController before_action :set_pet, only: [:show, :edit, :update, :destroy] # GET /pets # GET /pets.json def index @pets = Pet.all end # GET /pets/1 # GET /pets/1.json def show end ..... end

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JBUILDER VIEWS # pets/index.json.jbuilder json.array!(@pets) do |pet| json.extract! pet, :name json.url pet_url(pet, format: :json) end # pets/show.json.jbuilder json.extract! @pet, :name, :created_at, :updated_at

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OUTPUT # /pets.json [ {"name":"Cashew", "url":"http://localhost:3000/pets/1.json"}, {"name":"Ginkgo", "url":"http://localhost:3000/pets/2.json"} ] # /pets/2.json {"name":"Ginkgo", "created_at":"2013-08-02T04:03:06.958Z", "updated_at":"2013-08-02T04:03:06.958Z"} JSON

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OUTPUT # /pets.json [ {"name":"Cashew", "url":"http://localhost:3000/pets/1.json"}, {"name":"Ginkgo", "url":"http://localhost:3000/pets/2.json"} ] # /pets/2.json {"name":"Ginkgo", "created_at":"2013-08-02T04:03:06.958Z", "updated_at":"2013-08-02T04:03:06.958Z"} JSON

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OUTPUT # /pets.json [ {"name":"Cashew", "url":"http://localhost:3000/pets/1.json"}, {"name":"Ginkgo", "url":"http://localhost:3000/pets/2.json"} ] # /pets/2.json {"name":"Ginkgo", "created_at":"2013-08-02T04:03:06.958Z", "updated_at":"2013-08-02T04:03:06.958Z"} "WE NEED CONSISTENCY !!!" JSON

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JBUILDER VIEWS # pets/index.json.jbuilder json.array!(@pets) do |pet| json.extract! pet, :name json.url pet_url(pet, format: :json) end # pets/show.json.jbuilder json.extract! @pet, :name, :created_at, :updated_at

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"CUSTOM" ISN'T ALWAYS A GOOD THING

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WE NEED MORE CONVENTION AND LESS CONFIGURATION

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LET'S TRY IT OUT # Gemfile # gem 'jbuilder', '~> 1.2' gem 'active_model_serializers'

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LET'S TRY IT OUT # Gemfile # gem 'jbuilder', '~> 1.2' gem 'active_model_serializers' $ bundle install $ rails g serializer pet $ rails g serializer toy

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LET'S TRY IT OUT # Gemfile # gem 'jbuilder', '~> 1.2' gem 'active_model_serializers' $ bundle install $ rails g serializer pet $ rails g serializer toy

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LET'S TRY IT OUT # Gemfile # gem 'jbuilder', '~> 1.2' gem 'active_model_serializers' $ bundle install $ rails g serializer pet $ rails g serializer toy

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SERIALIZERS # app/serializers/pet_serializer.rb class PetSerializer < ActiveModel::Serializer attributes :id, :name, :created_at, :updated_at end # app/serializers/toy_serializer.rb class ToySerializer < ActiveModel::Serializer attributes :id, :name, :created_at, :updated_at end

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CONTROLLERS class PetsController < ApplicationController before_action :set_pet, only: [:show, :edit, :update, :destroy] # GET /pets # GET /pets.json def index render json: Pet.all end # GET /pets/1 # GET /pets/1.json def show render json: @pet end ..... end

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OUTPUT # /pets.json {"pets": [{"id":1, "name":"Cashew", "created_at":"2013-08-02T04:02:58.467Z", "updated_at":"2013-08-02T04:02:58.467Z"}, {"id":2, "name":"Ginkgo", "created_at":"2013-08-02T04:03:06.958Z", "updated_at":"2013-08-02T04:03:06.958Z"}]} # /pets/2.json {"pet": {"id":2, "name":"Ginkgo", "created_at":"2013-08-02T04:03:06.958Z", "updated_at":"2013-08-02T04:03:06.958Z"}} JSON

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OUTPUT # /pets.json {"pets": [{"id":1, "name":"Cashew", "created_at":"2013-08-02T04:02:58.467Z", "updated_at":"2013-08-02T04:02:58.467Z"}, {"id":2, "name":"Ginkgo", "created_at":"2013-08-02T04:03:06.958Z", "updated_at":"2013-08-02T04:03:06.958Z"}]} # /pets/2.json {"pet": {"id":2, "name":"Ginkgo", "created_at":"2013-08-02T04:03:06.958Z", "updated_at":"2013-08-02T04:03:06.958Z"}} JSON

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OUTPUT # /pets.json {"pets": [{"id":1, "name":"Cashew", "created_at":"2013-08-02T04:02:58.467Z", "updated_at":"2013-08-02T04:02:58.467Z"}, {"id":2, "name":"Ginkgo", "created_at":"2013-08-02T04:03:06.958Z", "updated_at":"2013-08-02T04:03:06.958Z"}]} # /pets/2.json {"pet": {"id":2, "name":"Ginkgo", "created_at":"2013-08-02T04:03:06.958Z", "updated_at":"2013-08-02T04:03:06.958Z"}} "THAT'S BETTER, BUT..." JSON

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CUSTOM FIELDS # app/serializers/base_serializer.rb class PetSerializer < ActiveModel::Serializer attributes :id, :created_at, :updated_at # allow custom inclusion of a single field def include_created_at? if @options.key?(:fields) return @options[:fields][:created_at] end true end end

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CUSTOM FIELDS # app/serializers/base_serializer.rb class PetSerializer < ActiveModel::Serializer attributes :id, :created_at, :updated_at # allow custom inclusion of a single field def include_created_at? if @options.key?(:fields) return @options[:fields][:created_at] end true end end "THAT'S BETTER, BUT..."

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BASE SERIALIZER # app/serializers/base_serializer.rb class BaseSerializer < ActiveModel::Serializer attributes :id, :created_at, :updated_at end # app/serializers/pet_serializer.rb class PetSerializer < BaseSerializer attributes :name end # app/serializers/toy_serializer.rb class ToySerializer < BaseSerializer attributes :name end

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CUSTOM FIELDS + # app/serializers/base_serializer.rb class BaseSerializer < ActiveModel::Serializer attributes :id, :created_at, :updated_at # allow custom inclusion of ANY field # via options passed in from the controller def include?(field) if @options.key?(:fields) return @options[:fields][field] end super(field) end end

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ONE-TO-MANY # /app/models/pet.rb class Pet < ActiveRecord::Base has_many :toys end # app/serializers/pet_serializer.rb class PetSerializer < BaseSerializer attributes :name has_many :toys end

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OUTPUT JSON # /pets/2.json {"pet": {"id":2, "name":"Ginkgo", "toys":[ {"id":3, "name":"Busy Bee"}, {"id":4, "name":"Dan's sock"}]}}

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ONE-TO-ONE # /app/models/pet.rb class Pet < ActiveRecord::Base has_many :toys belongs_to :person end # app/serializers/pet_serializer.rb class PetSerializer < BaseSerializer attributes :name has_many :toys has_one :person end

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OUTPUT JSON # /pets/2.json {"pet": {"id":2, "name":"Ginkgo", "toys":[ {"id":3, "name":"Busy Bee"}, {"id":4, "name":"Dan's sock"}] "person": {"id":1,"name":"Dan"}}}

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OUTPUT JSON # /pets.json {"pets": [{"id":1, "name":"Cashew", "toys":[...], "person":{"id":1,"name":"Dan"}}, {"id":2, "name":"Ginkgo", "toys":[...], "person":{"id":1,"name":"Dan"}}]}

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OUTPUT JSON # /pets.json {"pets": [{"id":1, "name":"Cashew", "toys":[...], "person":{"id":1,"name":"Dan"}}, {"id":2, "name":"Ginkgo", "toys":[...], "person":{"id":1,"name":"Dan"}}]} "DUPLICATION!"

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BASE SERIALIZER # app/serializers/base_serializer.rb class BaseSerializer < ActiveModel::Serializer # sideload related data by default embed :ids, include: true attributes :id, :created_at, :updated_at end

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OUTPUT JSON # /pets.json {"toys":[ {"id":1, "name":"BTVRuby catnip"}, {"id":2, "name":"Mr Smoochums"}, {"id":3, "name":"Busy Bee"}, {"id":4, "name":"Dan's sock"}], "people":[ {"id":1, "name":"Dan"}], "pets":[ {"id":1, "name":"Cashew", "toy_ids":[1,2], "person_id":1}, {"id":2, "name":"Ginkgo", "toy_ids":[3,4], "person_id":1}]}

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OUTPUT JSON # /pets.json {"toys":[ {"id":1, "name":"BTVRuby catnip"}, {"id":2, "name":"Mr Smoochums"}, {"id":3, "name":"Busy Bee"}, {"id":4, "name":"Dan's sock"}], "people":[ {"id":1, "name":"Dan"}], "pets":[ {"id":1, "name":"Cashew", "toy_ids":[1,2], "person_id":1}, {"id":2, "name":"Ginkgo", "toy_ids":[3,4], "person_id":1}]}

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OUTPUT JSON # /pets.json {"toys":[ {"id":1, "name":"BTVRuby catnip"}, {"id":2, "name":"Mr Smoochums"}, {"id":3, "name":"Busy Bee"}, {"id":4, "name":"Dan's sock"}], "people":[ {"id":1, "name":"Dan"}], "pets":[ {"id":1, "name":"Cashew", "toy_ids":[1,2], "person_id":1}, {"id":2, "name":"Ginkgo", "toy_ids":[3,4], "person_id":1}]}

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OUTPUT JSON # /pets.json {"toys":[ {"id":1, "name":"BTVRuby catnip"}, {"id":2, "name":"Mr Smoochums"}, {"id":3, "name":"Busy Bee"}, {"id":4, "name":"Dan's sock"}], "people":[ {"id":1, "name":"Dan"}], "pets":[ {"id":1, "name":"Cashew", "toy_ids":[1,2], "person_id":1}, {"id":2, "name":"Ginkgo", "toy_ids":[3,4], "person_id":1}]} "NO DUPLICATION... I APPROVE."

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API DESIGN

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FILTERING DATA /pets/cats /pets/dogs

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FILTERING DATA /pets/cats /pets/dogs ~ VS. ~ /pets?type=cats /pets?type=dogs

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FILTERING DATA /pets/cats /pets/dogs ~ VS. ~ /pets?type=cats /pets?type=dogs /pets?type=cats,dogs

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FILTERING DATA /pets/cats /pets/dogs ~ VS. ~ /pets?type=cats /pets?type=dogs /pets?type=cats,dogs /pets?type=cats,dogs&color=red

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INCLUDING RELATIONSHIPS Best guess inclusions (e.g. always include toys with pets)

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INCLUDING RELATIONSHIPS /pets?include=toys,people Best guess inclusions (e.g. always include toys with pets) ~ VS. ~ No inclusions by default. Custom inclusions as requested.

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EMBEDDING RELATIONSHIPS Always embed any related data (i.e. JBuilder approach)

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EMBEDDING RELATIONSHIPS Always embed any related data (i.e. JBuilder approach) ~ VS. ~ Favor "side-loading" and embed data very selectively (and only when it won't be shared)

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VERSIONING One version that's never broken

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VERSIONING One version that's never broken ~ VS. ~ Version by host or path api.rubypets.org v1.api.rubypets.org rubypets.org/api/v1

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SPARSE FIELDSETS Include all fields

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SPARSE FIELDSETS Include all fields ~ VS. ~ Allow for custom inclusion of fields: /pets?fields=id,name,age

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SPARSE FIELDSETS Include all fields ~ VS. ~ Allow for custom inclusion of fields: /pets?fields=id,name,age /pets?include=toys,people& pet_fields=id,name,age& people_fields=id,name& toy_fields=name

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SORTING Default sort order only

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SORTING Default sort order only ~ VS. ~ Allow for custom sort order: /pets?sort=name # ascending /pets?sort=-name # descending

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PAGINATION No limits on resources

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PAGINATION No limits on resources ~ VS. ~ Provide a default page size, a max page size, and allow custom requests: /pets?page=2&per_page=100

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PAGINATION No limits on resources ~ VS. ~ Provide a default page size, a max page size, and allow custom requests: /pets?page=2&per_page=100 Opinion! JSON API should separate the primary resource from its related resources when "side-loading" in order to clarify issues of primacy like pagination.

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PAGINATION, CONT. As per RFC 5988, return a LINK header to allow for navigation: Link: ; rel="next", ; rel="last" Possible values for `rel`: first, last, next, prev

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TL;DR A Hypermedia API makes full use of HTTP and a hypermedia content type to be as as navigable as the web itself. REST was a term originally invented by Roy Fielding, but since most "REST" APIs aren't in line with his definition, the term "Hypermedia API" was created. HYPERMEDIA APIS

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HYPERMEDIA APIS Designing Hypermedia APIs by Steve Klabnik designinghypermediaapis.com Recommendation: It's not TL, so there's no reason for DR !

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HYPERMEDIA APIS "Hypermedia designs promote scalability, allow resilience towards future changes, and promote decoupling and encapsulation, with all the benefits those things bring. On the downside, it is not necessarily the most latency-tolerant design, and caches can get stale if you’re not careful. It may not be as efficient on an individual request level as other designs." Steve Klabnik Designing Hypermedia APIs designinghypermediaapis.com

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SECURITY

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SECURITY A Brief History of OAuth

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SECURITY A Brief History of OAuth

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*BASIC* SECURITY RECOMMENDATIONS • Restrict access to particular users (e.g. non-admins) as needed in your controller and serializer layers

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*BASIC* SECURITY RECOMMENDATIONS • Restrict access to particular users (e.g. non-admins) as needed in your controller and serializer layers • HTTPS for all the things

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*BASIC* SECURITY RECOMMENDATIONS • Restrict access to particular users (e.g. non-admins) as needed in your controller and serializer layers • HTTPS for all the things • Use token-based security

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*BASIC* SECURITY RECOMMENDATIONS • Restrict access to particular users (e.g. non-admins) as needed in your controller and serializer layers • HTTPS for all the things • Use token-based security • If you want to build an OAuth provider, don't go it alone. Use a gem like James Coglan's oauth2-provider: https://github.com/songkick/oauth2-provider

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THANKS! @dgeb Burlington Ruby 2013