What Are Rest Resources?
And How Do They Relate to Resource Names and Resource Representations? I Read a Few Articles on the Subject, but They Were Too Abstract and They Left Me More...
What are REST resources and how do they relate to resource names and resource representations?
I read a few articles on the subject, but they were too abstract and they left me more confused than I was before.
Is the following URL a resource? If it is, what is the name of that resource and what is its representation?
The GET response of the URL should look something like:
[
{
id: 6,
name: "John"
},
{
id: 7,
name: "Jane"
}
]
11 Answers
The reason why articles on REST resources are abstract is because the concept of a REST resource is abstract. It's basically "whatever thing is accessed by the URL you supply". So, in your example, the resource would be the list of two users starting at offset 5 in some bigger list. Note that, how the resource is implemented is a detail you don't care about unless you are the one writing the implementation.
Is the following URL a resource?
The URL is not a resource, it is a label that identifies the resource, it is, if you like, the name of the resource.
The JSON is a representation of the resource.
Must Read
What’s a Resource?
A resource is anything that’s important enough to be referenced as a thing in itself. If your users might “want to create a hypertext link to it, make or refute assertions about it, retrieve or cache a representation of it, include all or part of it by reference into another representation, annotate it, or perform other operations on it”, then you should make it a resource.
Usually, a resource is something that can be stored on a computer and represented as a stream of bits: a document, a row in a database, or the result of running an algorithm. A resource may be a physical object like an apple, or an abstract concept like courage, but (as we’ll see later) the representations of such resources are bound to be disappointing. Here are some possible resources:
- Version 1.0.3 of the software release
- The latest version of the software release
- The first weblog entry for October 24, 2006
- A road map of Little Rock, Arkansas
- Some information about jellyfish
- A directory of resources pertaining to jellyfish
- The next prime number after 1024
- The next five prime numbers after 1024
- The sales numbers for Q42004
- The relationship between two acquaintances, Alice and Bob
- A list of the open bugs in the bug database
The text is from the O'Reilly book "RESTful Web Services".
The URL is never a resource or its name or its representation.
URL just tells where the resource is located and You can invoke GET,POST,PUT,DELETE etc on this URL to invoke the resource.
Data responded back are the resources while the form of the data is its representation.
Let's say Your URL with given GET parameters can output a JSON resource - this is the JSON representation of this resource. While with other flag in the GET it could respond with the same data in XML - that will be another representation of the very same resource.
EDIT: Due to the comments to the OP and to my answer I'm adding another explanations.
Also the resource name is considered to be the 'script name', e.g. in this case it is users.json while this resource name is self describing the resource representation itself - when calling this resource we expect the resource is in JSON, while when calling e.g. users.xml we would expect the data in XML.
- When I change the
offsetparameter in GET the response contains different data set - is it a new resource or its representation?- When I define which columns are returned in response in GET, is it a different resource or different representation, or?
- Well, here the problem and answer are clear - we still call the same URL, the server responses with the data in the same form (still it is JSON), data still contains information about users - just the information itself has changed due to the new offset parameter. So it is obvious that it is still the same resource with the same representation and the same resource name as before.
- Second problem could be a little confusing. Though we are calling the same resource, though the resource contains the same data (just with only predefined column set) and though the data is in the same representation it could seem to us as a different resource. But due to the points in the paragraph above it is nor the different resource or different representation. Though the data set contains less information the requesting side (filtering this data set) should be considering this and behave accordingly. So again: it is the same resource with the same resource name and the same resource representation.
