W3C home > Mailing lists > Public > xml-uri@w3.org > May 2000

Re: Namespaces and namespace names: a new synthesis?

From: Tim Berners-Lee <timbl@w3.org>
Date: Mon, 29 May 2000 18:00:53 -0400
Message-ID: <03a001bfc9b9$5c548940$a60a1712@col.w3.org>
To: "Larry Masinter" <masinter@attlabs.att.com>, "John Cowan" <cowan@locke.ccil.org>, <xml-uri@w3.org>

-----Original Message-----
From: Larry Masinter <masinter@attlabs.att.com>
>> 1) Namespaces are resources (they have identity and can be referenced
>> by URIs).
>> 2) Every namespace has a string property called its namespace name.
>It's not clear that the quantifier "every namespace" is finite, but sure,
>I think this is included in the namespec space.
>> 3) A URI which identifies a namespace can be constructed by prepending
>> "data:," to the namespace name.  (The namespace named "foo" has the URI
>> "data:,foo".  The namespace named "http://www.w3.org/2000/xyz" has the
>> URI "data:,http://www.w3.org/2000/xyz".)
>Oh, no! That's nonsense. The only resource a data URI identifies is the
>data contained in the data URI. Trying to say that a data URI can also
>be used to identify a resource is just nonsense. If a namespace is a
>then a URI must be used to identify it.

I completely agree.

>I think it's a silly idea to
>use 'http' URIs to identify resources, since they're already used to
>the resource which is "what's served by this web server when you give it
>this path in the HTTP request".

With this I completely disagree.  This is like saying, ``I think it's a
silly idea to
use ISBNs to identify books, since they're already used to
identify "the object which is "what's served by a library when you give it
this number".

The fact concepts like "The w3C home page" are much more long-lasting
than any set of bits you might have got back from the web on asking
for www.w3.org should be just one reason for understanding that the abstract
resource is a more general concept.

I shouldn't have called it "http:"but "webid" maybe. Sigh.

>Maybe the problem we got into was because all of the W3C recommendations
>use http URLs to identify resources that aren't really served by http

There's an awful lot of that going on. There are all kinds of http: space
things being retreived
perfectly legally from caches and mirrors and things with or without anyone
knowing.   The idea that http: name identifies a location matched neither
the design now the practice.

On the other hand, it is true that manyhttp: resources are transitory, and
many are bound to filenames (by typical web servers) which are difficult to
manage in a persistent way.
But managing a persistent web site is easier than inventing and developing
and supporting a new namespace.

>> 4) Namespace names MUST match the production "URIreference" in RFC 2396,
>> except that the empty string is not a valid namespace name.

That was a mistake, but life is full of them.

>> 5) Namespace names SHOULD match the production "absoluteURI" in RFC 2396.
>I think these are fine.
Received on Monday, 29 May 2000 17:59:37 UTC

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