The Architecture of the World Wide Web, First Edition was just issued as a W3C recommendation. I love that title — it reminds me of Monty Python’s “The Meaning of Life”, volume one.
Interesting bit about URIs in the document. To address the ‘resource as something on the web’ as compared to ‘resource as something that can be discussed on the web’ issue, the document describes a resource thusly:
By design a URI identifies one resource. We do not limit the scope of what might be a resource. The term “resource” is used in a general sense for whatever might be identified by a URI. It is conventional on the hypertext Web to describe Web pages, images, product catalogs, etc. as “resources”?. The distinguishing characteristic of these resources is that all of their essential characteristics can be conveyed in a message. We identify this set as “information resources”.
This document is an example of an information resource. It consists of words and punctuation symbols and graphics and other artifacts that can be encoded, with varying degrees of fidelity, into a sequence of bits. There is nothing about the essential information content of this document that cannot in principle be transfered in a representation.
However, our use of the term resource is intentionally more broad. Other things, such as cars and dogs (and, if you’ve printed this document on physical sheets of paper, the artifact that you are holding in your hand), are resources too. They are not information resources, however, because their essence is not information. Although it is possible to describe a great many things about a car or a dog in a sequence of bits, the sum of those things will invariably be an approximation of the essential character of the resource.
The document then gets into URI collision:
By design, a URI identifies one resource. Using the same URI to directly identify different resources produces a URI collision. Collision often imposes a cost in communication due to the effort required to resolve ambiguities.
Suppose, for example, that one organization makes use of a URI to refer to the movie The Sting, and another organization uses the same URI to refer to a discussion forum about The Sting. To a third party, aware of both organizations, this collision creates confusion about what the URI identifies, undermining the value of the URI. If one wanted to talk about the creation date of the resource identified by the URI, for instance, it would not be clear whether this meant “when the movie was created” or “when the discussion forum about the movie was created.”
Social and technical solutions have been devised to help avoid URI collision. However, the success or failure of these different approaches depends on the extent to which there is consensus in the Internet community on abiding by the defining specifications.