5. REST: Understanding the architectural style

 1.What is REST?
2. Resources
3. Representations
4.Advantages & Disadvantages : REST:
5.WADL
6. Tools & Plateforms: 








 1.What is REST?


REST is an architectural style which is based on web-standards and the HTTP protocol.
REST was first described by Roy Fielding in 2000.

Be Careful: REST is not a format Neither a protocol Neither standard .

Difference between REST & RESTfull:


-REST is the Web Service.
            it is also called: DOA (DATA.OA) aet ROA (Ressources.OA)
-RESTfull: is the application that respects the architecture ROA.




What's REST?

WS-Rest
       1.is Stateless
       2.Minimise system resources, but no session state.
-Resources  are uniquely identified by URIs.


REST request:
   1) Resources: -identified by URI.
               Exple: http://localhost:8080/insatdb/books
   2) Methods: Methods To manipulate the identifier:

       The HTTP standards methods which are typical used in REST are PUT, GET, POST, DELETE.

• GET defines a reading access of the resource without side-effects. The resource is never changed via a GET request, e.g. the request has no side effects (idempotent).
  
• PUT creates a new resource, must also be idempotent.
  
• DELETE removes the resources. The operations are idempotent, they can get repeated without leading to different results.
  
• POST updates an existing resource or creates a new resource.                                                        
  

   3) Representation of data transferred between server & client:
         => Example: XML, JSON, CSV, HTML ......


-The client is responsible for the state of resource.






2. Resources

-A resource can have multiple URIs.
      Example: Resource as: Books, Person
      Example: URI: http://localhost:8080/insatdb/books
            

-A resource may undergo(subir) four basic operations designated by CRUD (Create, Retrieve, Update, Delete)
 =>Create by the POST method
=> Retrieve by GET
=>Update = PUT-method
 =>Delete the DELETE method




3. Representations
   1)

	Example Json format:	Example XML format:
	GET https://www.googleapis.com/urlshortener/v1/url?shortUrl=http://goo.gl/fbsS	GET http://localhost:8080/librarycontentrestwebservice/contentbooks/string
	{ "kind": "urlshortener#url", "id": "http://goo.gl/fbsS", "longUrl": "http://www.google.com/", "status": "OK" }	<?xml version="1.0"?> <details> Ce livre est une introduction sur la vie </details>

NOTE: -Poster plugin available for Firefox for HTTP request issuing

Clear Difference: SOAP vs REST, 
             SOAPit sends an envelope,
              Rest is sent in an URI


4.Advantages & Disadvantages : REST:

	SOA	REST
Avantages	Standardized # Interoperability # Security (WS-Security)	Ease of implementation # Readability by humans # Scalability # Relies on the principles of the Web # Multiple Views
Disavantages	Performance (SOAP envelope additional) # Complexity, heaviness	Security restricted by the use of HTTP methods - call resource only

Extended Web services (SOAP)
5.WADL: 
WDAL:Web Application Description Language)
=> is an XML description language for RESTful services.
=> Describe Service For elements of type:
      Resource, method, parameter, Request, Response
=> Example: http://localhost:8088/librarycontentrestwebservice/application.wadl

<?xml version="1.0"?>

<application>

<doc jersey:generatedBy="Jersey: 1.4 09/11/2010 10:30 PM" />

<resources base="http://localhost:8088/librarycontentrestwebservice/" >

<resource path="/contentbooks" >

<resource path="uribuilder2" >

  <method id="createURIBooks" name="POST" >

         <request>

                 <representation mediaType="application/xml" />

     </request>

     <response>

                 <representation mediaType="*/*" />

     </response>

   </method>

</resource>

<resource path="uribuilder1" >

    <method id="createBooksFromURI" name="POST" >

       <request>

            <representation mediaType="application/xml" />

      </request>

     <response>

           <representation mediaType="*/*" />

      </response>

     </method>

</resource>

...

</resource>

</resources>

</application>

6. Tools & Plateforms: 

Tools	Plateforms
CURL PSTER(Firefox) SoapUI	-Jax-Rs(Jersy) .NET .PHP Python

Reference : 

http://mbaron.developpez.com/