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Re: Resources and URIs

From: Roy T. Fielding <fielding@apache.org>
Date: Tue, 29 Apr 2003 00:28:43 -0700
Cc: uri@w3.org
To: Dan Brickley <danbri@w3.org>
Message-Id: <351D4B18-7A14-11D7-BEFE-000393753936@apache.org>

> http://www.apache.org/~fielding/uri/rev-2002/ 
> rfc2396bis.html#rfc.section.1.1
> [[
> Identifier
>
>     An identifier is an object that carries identifying data. It is not
> necessary for the identifier to define what is being identified; it is  
> only
> necessary for the identifier to provide sufficient data to distinguish
> what is being identified from all other things within the scope of its  
> use.
> A URI is an identifier object consisting of a sequence of characters  
> that
> matches the restricted syntax defined by this specification.
> ]]
>
> I am concerned by the 'within the scope of its use' qualifier. Could  
> you
> give 2 or 3 examples of such usage scopes? Can the state/content of  
> these
> scopes change, making something into an 'identifier' or making it  
> 'mere data'
> depending on context. I find this a very slippery concept to thing  
> about
> without examples.

I mean that if there are only 10 things that can be identified by the
system, then the identifier only needs to distinguish one from the other
nine.  In other words, it isn't necessary for an identifier to have
global scope within a context that only has local scope.  The reason  
that
was included is because I need to add some text about global scope to
the section on schemes.  Maybe it should say "from all other things
within the scope of the system"?

> My specific proposal is that the phrase "within the scope of its use"  
> be
> dropped. Without more detail, it adds only mystique. And we've plenty  
> of
> that already...

I was trying to avoid the rathole of claiming that something can be
distinguished from all things when the set of all things is infinite.

> re "A resource is a source of supply or support within the context of  
> a given system."
> ...is that wording as intended, or in progress. The terms "supply" and  
> "source of"
> seem to do the same work.

It comes from several dictionary definitions of "resource".
Consider the difference between a source of information and a
sink of information (e.g., in HTTP, a process that accepts POST
on a URI but not GET).  I found it difficult to think of that as
a supply, and yet they are clearly resources in the sense that
the system makes use of them to achieve a purpose.  *shrug*

....Roy
Received on Tuesday, 29 April 2003 03:47:20 GMT

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