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Some TAG review of "Cool URIs for the Semantic Web"

From: Tim Berners-Lee <timbl@w3.org>
Date: Thu, 20 Sep 2007 09:58:21 +0100
Message-Id: <0B42F1E1-92E3-42CD-B516-D4E71172B7B3@w3.org>
Cc: Technical Architecture Group WG <www-tag@w3.org>
To: Susie Stephens <susie.stephens@gmail.com>

I failed to find my handwritten comments on the physical paper, so I  
will try to remember them.

I am looking at:

https://gnowsis.opendfki.de/repos/gnowsis/papers/2006_11_concepturi/ 
html/cooluris_sweo_note.html

It basically a really valuable document.

1.   "At the same time, web documents have always been addressed with  
Uniform Resource Locators (URLs). URIs and URLs share the same  
syntax, every URL is also a URI. "

The distinction between URLs and URI is not helpful technically.  A  
historical note and relation to the use of "URL" in common parlance  
is reasonable.   This discussion has I suspect prompted the rather  
confused track "What happens if a URI is also a URL?".

  Please dispose of the term URL in the introduction, and use URI  
throughout the rest of the document.

   2.  "On the traditional Web, URIs were used primarily for Web  
documents—to link to them, and to access them in a browser. In short,  
to locate a Web document—hence the term URL (Uniform Resource  
Locator). The notion of resource identity was not so important on the  
traditional Web, a URL simply identifies whatever we see when we type  
it into a browser."

This uses the term URL,  but suggests identity was not important ...  
it was important.
change to maybe:-

"On the traditional Web, URIs were used primarily for Web documents— 
to link to them, and to access them in a browser. In short, to  
identify a Web document, such as  <http://example.com/about> or a  
hypertext anchor within a document such as <http://example.com/ 
about#staff>.  With the Semantic Web, URIs are used more broadly to  
identify not only documents but also arbitrary things such as people,  
proteins and calendar events.

3. (I am happy with th use of "Web document" for the tag's  
"Information Resource". --timbl) (Noah ain't)

4. "Content negotiation [TAG-Alt] is often implemented with a twist:  
Instead of a direct answer, the server redirects to another URL where  
the appropriate version is found"

a)  Content negotiation normally does *not* redirect.  The chosen  
representation is sent back directly.  This is faster.   It is also  
consistent with the (agreed good) practice of having separate URIs  
for the generic and the specific URIs.   The URI of the chosen  
specific URI is sent back in the Content-Location:  header.

Please explicitly recommend the straightforward conneg as she is  
normally practiced, with one round trip instead of two.

5.  For "content of the HTML document" write "an HTML representation  
of the document in English"

6. "By having separate URLs for all versions, this approach allows  
Web authors to link directly to a specific version."
True, and good. Note you don't need to do the extra round trip.  you  
can use the Content-Location header.

7. "On the Semantic Web, URIs identify not just Web documents, but  
also real-world objects like people and cars, and even abstract ideas  
and non-existing things like a mythical unicorn. We call all these  
things resources."

Of course many people would consider the Traditional Web to include  
mailto: links. Suggest:

"On the Semantic Web, http: URIs identify not just Web documents, but  
also real-world objects like people and cars, and even abstract ideas  
and non-existing things like a mythical unicorn. We call all these  
things resources."

8. "Our recommendation is to err on the side of caution: Whenever an  
object of interest is not clearly and obviously a document, then it's  
better to use two distinct URIs, one for the resource and another one  
for the document describing it."

- if there are test cases which you feel might not clearly be an  
Information Resource or not one, then I would like

----------------  This is as far as we got reviewing the document  
together in the TAG face-face meeting  today, FWIW.
Received on Thursday, 20 September 2007 08:58:30 UTC

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