W3C home > Mailing lists > Public > www-rdf-interest@w3.org > February 2004

RE: pound sign vs. slash as final URI delimiter

From: Charles McCathieNevile <charles@w3.org>
Date: Mon, 16 Feb 2004 16:03:39 -0500 (EST)
To: Ron Daniel <rdaniel@taxonomystrategies.com>
Cc: "'DuCharme, Bob (LNG-CHO)'" <bob.ducharme@lexisnexis.com>, www-rdf-interest@w3.org
Message-ID: <Pine.LNX.4.55.0402161559100.16928@homer.w3.org>

OK, so my rule of thumb is the opposite...

I don't see any problem with defining my terms so they each have a whole URI,
and then adding a hash fragment:

http://example.org/term1#means
http://example.org/term2#means
http://example.org/term3#means
http://example.org/term4#means
http://example.org/term5#means
http://example.org/term6#means

Since the new RDF specs say that the mening of this is explcitly what you get
when you want the RDF version at that URI, I can easily talk about how badly
http://example.org/term1 explains http://example.org/term1#means for people
reading it (although if I want to talk about some particular fragment of the
document I have to do a bit more work).

There's no reason I can think of for not being able to use
http://example.org/terms? as a namespace - I have done so before, but decided
that I liked the # and its implications better.

Cheers

Chaals

On Mon, 16 Feb 2004, Ron Daniel wrote:

>
>Hi Bob,
>
>My current rule of thumb is to use '/' unless there is some good
>reason not to. But this is not a strongly held belief.
>
>Why do I prefer '/' over '#'?
>1) Fragment IDs imply downloading the source document, then picking through
>   it for the bit you need. For large vocabularies, like many produced by
>   Government agencies, this would be a performance issue.  (Of course,
>   whether something is actually downloaded just because we have used its
>   URL as a namespace ID is another issue.)
>2) There are some people who are vociferous in maintaining that there is a
>   very big difference between a resource and a fragment ID, and that RDF is
>   about describing resources. I am not personally sure of this, but don't
>see
>   much harm in using '/'.
>
>Why I hesitate to categorically state that '/' should be used instead of
>'#'?
>1) Because # should fit a lot better with picking a predicate out of an
>   XML document that specifies the namespace.
>
>I'd appreciate it if people could clarify things.
>
>Ron
>
>> -----Original Message-----
>> From: www-rdf-interest-request@w3.org
>> [mailto:www-rdf-interest-request@w3.org] On Behalf Of
>> DuCharme, Bob (LNG-CHO)
>> Sent: Monday, February 16, 2004 7:15 AM
>> To: www-rdf-interest@w3.org
>> Subject: pound sign vs. slash as final URI delimiter
>>
>>
>> This feels like a beginner question, but after a few searches
>> I can't find
>> any discussion of the issue. Let's say I have a namespace
>> identified by the
>> URI http://www.example.com/pathname. To identify the name foo
>> from that
>> namespace, what are the pros and cons of identifying it with a URI of
>> http://www.example.com/pathname/foo as opposed to
>> http://www.example.com/pathname#foo? The pound sign seems to
>> more clearly
>> indicate "the following is a name from the namespace named up to this
>> point," but I see that most references to Dublin Core names (e.g.
>> http://purl.org/dc/elements/1.1/creator) use the slash.
>>
>> Perhaps the question is better framed without reference to
>> syntax: is it
>> better for a name from a namespace to have it's own complete
>> URI or for it
>> to be referenced using a fragment identifier appended to the
>> URI for its
>> namespace?
>>
>> thanks,
>>
>> Bob
>>
>>
>

Charles McCathieNevile  http://www.w3.org/People/Charles  tel: +61 409 134 136
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Received on Monday, 16 February 2004 16:03:42 UTC

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