Angularjs & REST

ANGULARJS & REST
Gabriele Mittica
www.gabrielemittica.com - @gabrielemittica
Corley srl - www.corley.it
AngularJsDay 2014

What is REST?
“Representational State Transfer enables
intermediate processing by constraining
messages to be self-descriptive: interaction is
stateless between requests, standard
methods and media types are used to indicate
semantics and exchange information, and
responses explicitly indicate cacheability.”
Roy Fielding, 2000
Client-
Server
Stateless
Cacheable
Uniform
Interface

What is REST?
REST helps us to make apps with a frontend layer that works
with a separated backend layer that serves RESTful resources
Frontend Backend

Usually we create applications
that drive the logic, manage the
data and serve the html to the
client.
But now we can create an app
(for example with AngularJS and
HTML5) that works with RESTful
resources (JSON or XML)REST

AngularJS & REST
There are several ways to work with RESTful resources with
AngularJS.
The most used are:
• $http
• ngResource
• Restangular

$http
Main features:
• It’s a core Angular service
• is based on the deferred/promise APIs exposed by the $q service
• Useful methods $http.get(), $http.post() …
• Auto transforming requests and responses (XSFR, JSON)
• Cache support
• Interceptors for requests and responses

$http example
//GET request
$http({method: 'GET', url: '/user/123'}).
success(function(data, status, headers, config) {
// this callback will be called asynchronously
// when the response is available
}).
error(function(data, status, headers, config) {
// called asynchronously if an error occurs
// or server returns response with an error status.
});
//header config
$module.run(function($http) {
$http.defaults.headers.common.Authentication = 'Basic YmVlcDpib29w'
});

ngResource
Main features:
• Uses $resource (facotry that works with $http) to interact with
RESTful services
• You need to add the script
• <script src="//ajax.googleapis.com/ajax/libs/angularjs/X.Y.Z/angular-
resource.js">
• And load it into app
• angular.module('app', ['ngResource']);
• Its methods let to work directly with the RESTful resource

ngResource ($resource) example
//define the resource
var User = $resource('/user/:userId', {userId:'@id'});
//GET and SAVE requests
var user = User.get({userId:123}, function() {
user.newsletterSubscription = true;
user.$save(); //save is a POST request
});
//define the resource adding subscribe method
var User = $resource('/user/:userId', {userId:'@id'},
{subscribe: {method:'POST', params:{newsletterSubscription:true}}}
);
//GET and SAVE requests
var user = User.get({userId:123}, function() {
user.$subscribe();
});

Restangular
Main features:
• It’s an Angular service to simplify the consume of RESTful API
• Lodash (or Underscore) dependency
• Get it from https://github.com/mgonto/restangular
• Add to your APP:
• angular.module('your-app', ['restangular']);
• angular.module('your-app').controller('MainCtrl',
function($scope, Restangular) { ... });
• You don’t need to remember URLs
• It supports nested RestFUL resources and all HTTP methods.

Restangular example
//define a base path and extractor
Restangular.withConfig(function(RestangularConfigurer){
RestangularConfigurer.setBaseUrl("/api/v1/");
RestangularConfigurer.setResponseExtractor(function(response, op) {
return response.data;
});
});
//define the resource adding subscribe method
var baseUsers = Restangular.all('user');
baseUsers.getList().then(function (users) {
var firstUser = users[0];
firstUser.name = "Clark Kent";
firstUser.put();
});
{
"data": [
{
"id": 123,
"name": "Superman"
},
{
"id": 999,
"name": "Batman"
}
],
"status": {
"success": true,
"time": 201
}
}

Appendix A: the errors
HTTP has a lot of status code (4xx client errors, 5xx server errors)
But what if my request is correct, but the result of my request is not
correct (for example the users sends a wrong answer in a poll) ?
{
"data": [],
"status": {
"success": false,
"errorCode": 1001,
"errorString": "Wrong answer"
}
}

Appendix B: the authentication
HTTP supports authentication (basic, digest…).
In our AngularJS app we can add our authentication manager, using
the following process:
User signed in
Server returns
a secret key
The client uses
the key to sign
the requests

To do that we can use CryptoJS to sign each request:
getSignedParams: function(path, request, myKey, mySecret) {
var params = {};
if(request == null) {
request = "";
}
else {
request = JSON.stringify(request);
}
params.apiKey = myKey;
params.signature = CryptoJS.HmacSHA1(path+request, mySecret).toString();
return params;
}

There is a problem in this process:
If somebody steals my credentials, he can use them for the
whole session.
A solution is change the credentials in each request (useful
in a mobile app but complicated in a web app where the
user works on different tabs).

CODE GRUSP ON
CLOUDCONF.IT
THANK YOU
http://corsi.corley.it

Angularjs & REST

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