Namespace URI address resources

Paul Prescod paul at
Tue Jun 1 06:34:04 BST 1999

Dan Brickley wrote:
> A string can be 'for' identifying an (abstract or physical) resource
> without any URI-string to resource bindings currently being in effect.

According to RFC 2396, A URI is a sequence of characters with a restricted
syntax that can act as a reference to something that has identity. If the
something doesn't exist then it cannot and is thus not a URI.

> <> for
> example, might be a URI whose purpose is to identify an abstract
> resource which is a set of documents on my server about a specific
> topic. This seems a reasonable use of an identifier. Seems odd to say
> that the string stops being a URI for those periods when no documents
> fall into the appropriate category.

The abstract resource is a list which is current empty. There is no
problem here. In HyTime terms the result of your query is the empty
nodelist. In SQL terms it is an empty recordset. That's not the same as
not referring to *anything* which is what some people are claiming about
namespace URIs.
> In general, I see no problem with a server managing a resource but (at
> some point in time) there being no generally agreed binding from a URI
> to that resource. At other points in time there might be several. 

No, there can be only one resource identified by a URI. It may be a list-y
resource but it is a single resource.

> "string of characters _which_ identify an..." the situation
> would be different. As things stand the definition is about intent, not
> whether the URI does currently identify any resources.

Even so it would be wrong to use an HTTP URL without intent to point to
something which is retrievable by HTTP.

 Paul Prescod  - ISOGEN Consulting Engineer speaking for only himself

"Silence," wrote Melville, "is the only Voice of God." The assertion,
like its subject, cuts both ways, negating and affirming, implying both
absence and presence, offering us a choice; it's a line that the Society
of American Atheists could put on its letterhead and the Society of
Friends could silently endorse while waiting to be moved by the spirit
to speak. - Listening for Silence by Mark Slouka, Apr. 1999, Harper's

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