- From: Harald Tveit Alvestrand <Harald@Alvestrand.no>
- Date: Wed, 01 Sep 1999 07:53:49 +0200
- To: Patrick Schmitz <pschmitz@microsoft.com>, Jack.Lang@ntl.com, Dan Zigmond <djz@corp.webtv.net>, www-tv@w3c.org
- Cc: mav@liberate.com, Dean Blackketter <dean@corp.webtv.net>
At 16:20 31.08.99 -0700, Patrick Schmitz wrote:
>I should have said that more carefully... A URI definition does not
>necessarily imply that there is a document at the location; a URL does. The
>corresponding http: URL may or may not exist, as noted.
actually.....not quite. From RFC 2396:
1.2. URI, URL, and URN
A URI can be further classified as a locator, a name, or both. The
term "Uniform Resource Locator" (URL) refers to the subset of URI
that identify resources via a representation of their primary access
mechanism (e.g., their network "location"), rather than identifying
the resource by name or by some other attribute(s) of that resource.
The term "Uniform Resource Name" (URN) refers to the subset of URI
that are required to remain globally unique and persistent even when
the resource ceases to exist or becomes unavailable.
They both name "resources"; an URL also names at least one access mechanism.
And:
Resource
A resource can be anything that has identity. Familiar
examples include an electronic document, an image, a service
(e.g., "today's weather report for Los Angeles"), and a
collection of other resources. Not all resources are network
"retrievable"; e.g., human beings, corporations, and bound
books in a library can also be considered resources.
The resource is the conceptual mapping to an entity or set of
entities, not necessarily the entity which corresponds to that
mapping at any particular instance in time. Thus, a resource
can remain constant even when its content---the entities to
which it currently corresponds---changes over time, provided
that the conceptual mapping is not changed in the process.
Believe me, the number of emails required to get agreement on that
definition was QUITE horrendous!
Harald A
--
Harald Tveit Alvestrand, Maxware, Norway
Harald.Alvestrand@maxware.no
Received on Wednesday, 1 September 1999 02:15:00 UTC