[Didier PH Martin]
> 
>  Paul said:
>  > Query parameters are NOT representations of resource. Query parameters
>  > are part of the address for resources. The representation is the thing
>  > that you get when you do a GET or the thing that you PUT or POST.
> 
>  Didier replies:
>  Let's add that there is a one to one relationship between a URL and a
>  resource and a one to one relationship between a resource and a
>  representation. Therefore there is a one to one relationship between a URL
>  and a resource. Let's say also that the representation is the
manifestation
>  of a particular URL.

Let's rather say one to one relationship between a URL __reference__ and a
resource ...

>  So
> 
>  URL <-(1,1)->Resource <- (1,1)-> representation. => URL <- (1,1)->
>  representation.
> 
>  It is easy then to see why for people, concretely a resource is what is
>  referred by a URL and that the resource is the outcome we get when GETting
a
>  resource.
> 
>  In REST, each URL is a different resource.

Well, you can map several URLs to one resource.  My company does that with
its home page.  It's a .org, but it bought up the .com name to prevent users
from automatically typing ".com" and not getting the company.  Both URLS
resolve to the same home page.

A resource is unique. What we get
>  by performing an HTTP GET is a representation of this resource. Therefore
we
>  can say that the representation is some sort of physical (OK, in bits and
>  bytes or encoded with characters) incarnation of an etherized monad named
a
>  resource. People skip the etherized monad and make the direct connection
>  Resource <---> URL (resource being - in that case - what I get with an
HTTP
>  GET). So maybe we can say to make things clear:
> 
>  a) The resource is an abstract entity representing something on the web.
Its
>  a metaphysical monad, an abstarct thing associated to a concrete thing:
the
>  representation.
>  b) A resource may be identified by a URI. More particularly its location
>  represented by a URL and its name by a URN.

Or by any URI (doesn't have to be a URN although it seems sensible to use
URNs that way).

>  c) The outcome of an HTTP GET operation on a particular resource
identified
>  by a particular URI is its representation.
> 
>  However, a resource has not:
>  a) several representations

Sure they can have several representations.  How about GIF vs SVG vs PDF?
How about HTML customized for MS vs NS?  Surely they are representations of
the same resource!

>  b) several URIs.
> 

See above...


Cheers,

Tom P


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