REST & ActiveResource
Matthijs Langenberg

Webservices

Wat zijn webservices

”The W3C defines a Web Service as a software system designed to support
interoperable machine to machine interaction over a network.”
-- Wikipedia

Bevorder ‘machine to machine interaction’

HTML is moeilijk te parsen

Geef iets anders terug
XML?

Just Another View

respond_to

class ArticlesController < ApplicationController
def show
@article = Article.find(params[:id])
respond_to do |format|
format.html
format.xml { render :xml => @article }
end
end
end

Soorten Webservices
• Remote procedure calls (RPC)
• Service-oriented architecture (SOA)
• Representational state transfer (REST)

Rails votes REST

Rails votes REST
BIG TIME!

Wat is REST?

REpresentional State Transfer

HTTP’s:
“convention over configuration”

Schreef geen vervanging voor iets wat HTTP je gratis geeft

HTTP Abuse
Wat is er mis met dit request?
GET http://myblog.com/articles/destroy/1

HTTP Abuse
Wat is er mis met dit request?
GET http://myblog.com/articles/destroy/1
Conflict

HTTP Abuse
Wat is er mis met dit request?
GET http://myblog.com/articles/destroy/1
Conflict
• Actie staat in URL
• Uitgevoerd actie is in conflict met HTTP methode

The REST-way
DELETE http://myblog.com/articles/1

URI’s

URI’s
GET /articles/create
GET /articles/show/1
GET /articles/update/1
GET /articles/destroy/1

URI’s
GET /articles/create
GET /articles/show/1
GET /articles/update/1
GET /articles/destroy/1

Mapping

Mapping
HTTP
GET
POST
PUT
DELETE

Mapping
HTTP Controller
GET SHOW
POST CREATE
PUT UPDATE
DELETE DESTROY

Resourceful URI’s

Resourceful URI’s
GET /articles
POST /articles/create
GET /articles/show/1
POST /articles/update/1
GET /articles/destroy/1

Resourceful URI’s
➡ GET /articles
GET /articles
➡ POST /articles
POST /articles/create
➡ GET /articles/1
GET /articles/show/1
➡ PUT /articles/1
POST /articles/update/1
➡ DELETE /articles/1
GET /articles/destroy/1

Gratis named routes

ActionController::Routing::Routes.draw do |map|
map.resources :articles do |articles|
articles.resources :comments
end
end

ActionController::Routing::Routes.draw do |map|
map.resources :articles do |articles|
articles.resources :comments
end
end

ActionController::Routing::Routes.draw do |map|
map.resources :articles do |articles|
articles.resources :comments
end
end
articles_url
article_url
new_article_url
edit_article_url
article_comments_url
article_comment_url
article_new_comment_url
article_edit_comment_url

ActionController::Routing::Routes.draw do |map|
map.resources :articles do |articles|
articles.resources :comments
end
end
articles_url ➡ /articles
article_url ➡ /articles/:id
new_article_url ➡ /articles/new
edit_article_url ➡ /articles/:id/edit
article_comments_url ➡ /articles/:article_id/comments
article_comment_url ➡ /articles/:article_id/comments/:id
article_new_comment_url ➡ /articles/:article_id/comments/new
article_edit_comment_url ➡ /articles/:article_id/comments/:id/edit

link_to article.title,
{
:controller => ‘article’,
:action => ‘show’,
:id => article }

link_to article.title,
{
:controller => ‘article’,
:action => ‘show’,
:id => article }

link_to article.title,
{
:controller => ‘article’,
:action => ‘show’,
:id => article }
link_to article.title, article_url(article)

link_to article.title,
{
:controller => ‘article’,
:action => ‘show’,
:id => article }
link_to article.title, article_url(article)
link_to article.title, article

Wat zou je doen?
Je wilt comments aan articles toevoegen,
ArticlesController is aanwezig.

Wat zou je doen?
Je wilt comments aan articles toevoegen,
ArticlesController is aanwezig.
1) Voeg een actie ‘add_comment’ aan ArticlesController toe.
(POST /articles/1/add_comment)

Wat zou je doen?
Je wilt comments aan articles toevoegen,
ArticlesController is aanwezig.
1) Voeg een actie ‘add_comment’ aan ArticlesController toe.
(POST /articles/1/add_comment)
2) Maak een CommentsController, met een ‘create’ actie.
(POST /comments/create?article_id=1)

Mr. RESTful zegt:

Mr. RESTful zegt:
Antwoord 2

Mr. RESTful zegt:
Antwoord 2
• Een comment is een een aparte resource

Mr. RESTful zegt:
Antwoord 2
• Een comment is een een aparte resource
• Er bestaat geen ‘add_comment’ methode in HTTP

Mr. RESTful zegt:
Antwoord 2
• Een comment is een een aparte resource
• Er bestaat geen ‘add_comment’ methode in HTTP
• Er bestaat wel een ‘create’ (POST) methode in HTTP

Geen Namespaces!
• POST /articles/create
• POST /articles/create_comment
• GET /articles/destroy
• GET /articles/destroy_comment

Teveel vrijheid is niet goed

class ArticlesController < ApplicationController
def show
@article = Article.find(params[:id])
end
def show_rss
@article = Article.find(params[:id])
render :rss => @article.to_rss
end
def show_atom
@article = Article.find(params[:id])
render :atom => @article.to_atom
end
def show_xml
@article = Article.find(params[:id])
render :xml => @article.to_xml
end
def show_ajax
@article = Article.find(params[:id])
render :template => show_article.rjs
end
end

Geen aparte actie voor alternatieve view!

class ArticlesController < ApplicationController
def show
@article = Article.find(params[:id])
respond_to do |format|
format.html
format.rss { render :rss => @article.to_rss }
format.atom { render :atom => @article.to_atom }
format.xml { render :xml => @article.to_xml }
format.rjs { render :template => ‘show_article.rjs’ }
end
end
end

Wauw!
HTTP method naar controller actie mapping actie klinkt tof!

Maar er zit een adder ...

Maar er zit een adder ...

Browsers ondersteunen PUT en DELETE niet!

Browsers ondersteunen PUT en DELETE niet!
<input name=\"_method\" type=\"hidden\" value=\"put\" />

Gelukkig zijn de helpers ook
aangepast. ;-)

HTML_options
• link_to “delete”, article_path(1), :method => ‘delete’
• link_to_remote, “delete”, article_path(1), :method => ‘delete’
• form_tag(member_path(2), :method => :put)

form_for
remote_form_for
Bepalen op basis van AR object de method:
form_for(Movie.new):
<form action=\"/movies\" class=\"new_movie\" id=\"new_movie\" method=\"post\">
form_for(Movie.find(:first)):
<form action=\"/movies/1\" class=\"edit_movie\"
id=\"edit_movie_1\" method=\"post\">
<input name=\"_method\" type=\"hidden\" value=\"put\" />

Controller Acties

MoviesController#index

MoviesController#index
# GET /movies
# GET /movies.xml
def index
@movies = Movie.find(:all)
respond_to do |format|
format.html # index.html.erb
format.xml { render :xml => @movies }
end
end

MoviesController#index
<?xml version=\"1.0\" encoding=\"UTF-8\"?>
# GET /movies
<movies>
# GET /movies.xml <movie>
def index <director>Chris Miller</director>
@movies = Movie.find(:all) <id type=\"integer\">1</id>
<rating type=\"decimal\">7.0</rating>
respond_to do |format| <title>Shrek the Third</title>
format.html # index.html.erb </movie>
<movie>
format.xml { render :xml => @movies }
<director>Sam Raimi</director>
end
<id type=\"integer\">2</id>
end
<rating type=\"decimal\">6.9</rating>
<title>Spider-Man 3</title>
</movie>
<movie>
<director>Juan Carlos Fresnadillo</director>
<id type=\"integer\">3</id>
<rating type=\"decimal\">7.7</rating>
<title>28 Weeks Later</title>
</movie>
</movies>

MoviesController#show

MoviesController#show
# GET /movies/1
# GET /movies/1.xml
def show
@movie = Movie.find(params[:id])
respond_to do |format|
format.html # show.html.erb
format.xml { render :xml => @movie }
end
end

MoviesController#show
# GET /movies/1 <?xml version=\"1.0\" encoding=\"UTF-8\"?>
<movie>
# GET /movies/1.xml
<director>Chris Miller</director>
def show
<id type=\"integer\">1</id>
@movie = Movie.find(params[:id]) <rating type=\"decimal\">7.0</rating>
<title>Shrek the Third</title>
respond_to do |format| </movie>
format.html # show.html.erb
format.xml { render :xml => @movie }
end
end

MoviesController#create

MoviesController#create
# POST /movies
# POST /movies.xml
def create
@movie = Movie.new(params[:movie])
respond_to do |format|
if @movie.save
flash[:notice] = 'Movie was successfully created.'
format.html { redirect_to(@movie) }
format.xml { render :xml => @movie,
:status => :created,
:location => @movie }
else
format.html { render :action => \"new\" }
format.xml { render :xml => @movie.errors, :status => 422 }
end
end
end

MoviesController#create
Status: 201 Created
Location: http://localhost:3000/movies/16
# POST /movies
<?xml version=\"1.0\" encoding=\"UTF-8\"?>
# POST /movies.xml
<movie>
def create
<director>Steven Spielbergh</director>
@movie = Movie.new(params[:movie])
<id type=\"integer\">15</id>
<rating type=\"decimal\">8.3</rating>
respond_to do |format|
<title>Letters from Iwo Jima</title>
if @movie.save
</movie>
flash[:notice] = 'Movie was successfully created.'
format.html { redirect_to(@movie) }
format.xml { render :xml => @movie,
:status => :created,
:location => @movie }
else
format.html { render :action => \"new\" }
format.xml { render :xml => @movie.errors, :status => 422 }
end
end
end

MoviesController#create
Status: 201 Created
Location: http://localhost:3000/movies/16
# POST /movies
<?xml version=\"1.0\" encoding=\"UTF-8\"?>
# POST /movies.xml
<movie>
def create
<director>Steven Spielbergh</director>
@movie = Movie.new(params[:movie])
<id type=\"integer\">15</id>
<rating type=\"decimal\">8.3</rating>
respond_to do |format|
<title>Letters from Iwo Jima</title>
if @movie.save
</movie>
flash[:notice] = 'Movie was successfully created.'
format.html { redirect_to(@movie) }
format.xml { render :xml => @movie,
:status => :created,
Status: 422 Unprocessable Entity
:location => @movie }
<?xml version=\"1.0\" encoding=\"UTF-8\"?>
else
<errors>
format.html { render :action => \"new\" }
<error>Rating can't be blank</error>
format.xml { render :xml => @movie.errors, :status => 422 }
<error>Director can't be blank</error>
end
<error>Title can't be blank</error>
end
</errors>
end

MoviesController#update

MoviesController#update
# PUT /movies/1
# PUT /movies/1.xml
def update
@movie = Movie.find(params[:id])
respond_to do |format|
if @movie.update_attributes(params[:movie])
flash[:notice] = 'Movie was successfully updated.'
format.html { redirect_to(@movie) }
format.xml { head :ok }
else
format.html { render :action => \"edit\" }
format.xml { render :xml => @movie.errors, :status => 422 }
end
end
end

MoviesController#update
Status: 200 OK
# PUT /movies/1
# PUT /movies/1.xml
def update
@movie = Movie.find(params[:id])
respond_to do |format|
if @movie.update_attributes(params[:movie])
flash[:notice] = 'Movie was successfully updated.'
format.html { redirect_to(@movie) }
format.xml { head :ok }
else
format.html { render :action => \"edit\" }
format.xml { render :xml => @movie.errors, :status => 422 }
end
end
end

MoviesController#update
Status: 200 OK
# PUT /movies/1
# PUT /movies/1.xml
def update
@movie = Movie.find(params[:id])
Status: 422 Unprocessable Entity
respond_to do |format|
<?xml version=\"1.0\" encoding=\"UTF-8\"?>
if @movie.update_attributes(params[:movie])
<errors>
flash[:notice] = 'Movie was successfully updated.'
<error>Title can't be blank</error>
format.html { redirect_to(@movie) }
</errors>
format.xml { head :ok }
else
format.html { render :action => \"edit\" }
format.xml { render :xml => @movie.errors, :status => 422 }
end
end
end

MoviesController#destroy

MoviesController#destroy
# DELETE /movies/1
# DELETE /movies/1.xml
def destroy
@movie = Movie.find(params[:id])
@movie.destroy
respond_to do |format|
format.html { redirect_to(movies_url) }
format.xml { head :ok }
end
end

MoviesController#destroy
# DELETE /movies/1 Status: 200 OK
# DELETE /movies/1.xml
def destroy
@movie = Movie.find(params[:id])
@movie.destroy
respond_to do |format|
format.html { redirect_to(movies_url) }
format.xml { head :ok }
end
end

Scaffolding

maar er is meer!

ActiveResource

ActiveResource
• Object-oriented REST services
• Transparent met een RESTful service (Rails) werken
• Net als ActiveRecord, maar dan voor REST

Browser

Browser
GET /movies.html
Controller
(RESTful)

Browser
GET /movies.html
Controller
(RESTful)
Movie.find(:all)
ActiveRecord

Browser
GET /movies.html
Controller
(RESTful)
Movie.find(:all)
ActiveRecord
SELECT * FROM MOVIES
DB

Browser Browser
GET /movies.html
Controller
(RESTful)
Movie.find(:all)
ActiveRecord
SELECT * FROM MOVIES
DB

Browser Browser
GET /movies.html GET /movies.html
Controller
Controller
(RESTful)
Movie.find(:all)
ActiveRecord
SELECT * FROM MOVIES
DB

Browser Browser
GET /movies.html GET /movies.html
Controller
Controller
(RESTful)
Movie.find(:all) Movie.find(:all)
ActiveResource ActiveRecord
SELECT * FROM MOVIES
DB

Browser Browser
GET /movies.html GET /movies.html
Controller
Controller
(RESTful)
Movie.find(:all) Movie.find(:all)
GET /movies.xml
ActiveResource ActiveRecord
SELECT * FROM MOVIES
DB

Configuratie

Werken met RESTful webservices
(ActiveResource)

Create

Create

Read

Read

Update

Update

Destroy

Destroy

Wat doet ARes?

Wat doet ARes?
• Genereer URL

Wat doet ARes?
• Genereer URL
• Request URL (XML)

Wat doet ARes?
• Genereer URL
• Request URL (XML)
• Verwerk request (XML)

Wat doet ARes?
• Genereer URL
• Request URL (XML)
• Verwerk request (XML)
• Biedt ActiveRecord-like API

Demo

Demo
1) RESTful Rails applicatie (met curl)

Demo
1) RESTful Rails applicatie (met curl)
2) Rails applicatie met ActiveResource

Demo
1) RESTful Rails applicatie (met curl)
2) Rails applicatie met ActiveResource
3) ActiveResource gem

Vragen?
<mlangenberg@gmail.com>
#rubyenrails at irc.freenode.org