CODEWITHSUNDEEP
web-servicesrest
Java Surfer
Java Surfer

Reputation: 623

What exatly is a REST resource and a representation?

I am very new in RESTful application and I have some doubts related to some REST concept.

I know that the fundamental concept in any RESTful API is the resource. A resource is an object with a type, associated data, relationships to other resources, and a set of methods that operate on it (the HTTP methods: GET, POST, PUT and DELETE)

So my first doubt is related to the resource concept. I am trying to do myself some example and I don't know if I have correctly understand what a resource is.

In my mind a resource is "what I have to transmit with my REST web sercice". So for example if I have a REST web service that given a VAT number come backs the invoices related to this VAT number. So these returned invoices "objects" are my resources.

So a resource is something that I can working on: I can obtain an existing reourcem add a new resource, update an existing resource or delete an existing resource.

Is it correct or am I missing something?

If it correct the second doubt is on the representation concept.

From what I have understand I can see a resource in serveral differents shapes (or a resource can be exposed in several different ways), for example as HTML or as XML or as JSON and so on.

So the same resource can be exposed in different ways and exist a mecchanism that convert a resource (that can be a row stored into a database table) into an HTML message or into an XML message or into a JSON message.

Is this interpratation correct?

Upvotes: 1

Views: 94

Answers (1)

Luiggi Mendoza
Luiggi Mendoza

Reputation: 85781

From this paragraph (emphasys mine):

In my mind a resource is "what I have to transmit with my REST web sercice". So for example if I have a REST web service that given a VAT number come backs the invoices related to this VAT number. So these returned invoices "objects" are my resources.

You got it wrong. By reviewing the concept of a resource (stated in your question, emphasys mine):

A resource is an object with a type, associated data, relationships to other resources, and a set of methods that operate on it (the HTTP methods: GET, POST, PUT and DELETE)

From your example, the invoices objects don't have any set of methods that operate them. They are part of the response of the REST service. Instead, the component (that may be a Java or a C# class) that has a method to receive the VAT number and will return the invoices associated to the VAT number and that will be called to support the proper HTTP method (in this case, GET) is the resource.

Now, after understanding this, there's this other paragraph:

From what I have understand I can see a resource in serveral differents shapes (or a resource can be exposed in several different ways), for example as HTML or as XML or as JSON and so on.

The resource will return the response in the proper format: HTML, XML, JSON, plain text, ect. Again, your invoices are not the resource, and they should not choose the format they should be returned.

Upvotes: 3

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