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Re: [ProgSoc] REST vs. HTTP in the real world



On Tue, 29 May 2007, John Elliot wrote:
> On Tue, 29 May 2007, James Andrewartha wrote:
> > John Elliot wrote:
> > > Effect bearing operations can not really be idempotent.
> >
> > You're confusing idempotent with "has no side-effects".
>
> No, I'm not.
>
> > Idempotent means you get the same result if you perform an
> > operation more than once.
>
> I know what it means.
>
> > In this case the result is there being a resource associated
> > with that URI.
>
> I think your statement there clearly betrays your ignorance.
>
> You don't understand what a "resource" is. If you're going to explain
> how things work to me, I'd appreciate it if you would first go to the
> trouble of understanding them.

http://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm

5.2.1.1 Resources and Resource Identifiers

The key abstraction of information in REST is a resource. Any 
information that can be named can be a resource: a document or image, a 
temporal service (e.g. "today's weather in Los Angeles"), a collection 
of other resources, a non-virtual object (e.g. a person), and so on. In 
other words, any concept that might be the target of an author's 
hypertext reference must fit within the definition of a resource. A 
resource is a conceptual mapping to a set of entities, not the entity 
that corresponds to the mapping at any particular point in time.

More precisely, a resource R is a temporally varying membership function 
MR(t), which for time t maps to a set of entities, or values, which are 
equivalent. The values in the set may be resource representations 
and/or resource identifiers. A resource can map to the empty set, which 
allows references to be made to a concept before any realization of 
that concept exists -- a notion that was foreign to most hypertext 
systems prior to the Web [61]. Some resources are static in the sense 
that, when examined at any time after their creation, they always 
correspond to the same value set. Others have a high degree of variance 
in their value over time. The only thing that is required to be static 
for a resource is the semantics of the mapping, since the semantics is 
what distinguishes one resource from another.







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