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Re: Do resources have representations?

From: Benja Fallenstein <b.fallenstein@gmx.de>
Date: Mon, 28 Jul 2003 18:46:35 +0200
Message-ID: <3F25536B.3080803@gmx.de>
To: Jon Hanna <jon@spin.ie>
CC: www-rdf-interest@w3.org

Jon Hanna wrote:
>>However, if I pointed my browser to <http://example.org/1434>, I would
>>not consider it correct behavior if my browser opened a HTTP connection
>>to <http://example.net/~foo/bar> and showed me the content that the web
>>server at that address returns -- even if I have proof that these two
>>URIs denote one and the same resource!
> 
> Why not?
> 
> If you know they are the same resource why do you care where the
> representation came from?

Ah, now I think we're getting to the core of the matter. If a browser is 
really allowed to do this, "a URI only denotes a resource" should work 
as a model.

A simple problem with this is: I can make an HTML page and publish it at 
uri1. Additionally I can state (maybe in metadata inside the page) that 
uri1 owl:sameAs <http://www.w3.org/>.

If your browser retrieves this page through HTTP, it can conclude that 
uri1 *really* is owl:sameAs <http://www.w3.org/>. Why? Because the 
person who owns that URI (me) has made a statement to that effect.

Even if everything that I claim about the resource identified by both 
uri1 and <http://www.w3.org/> is in fact not true, that doesn't change 
the fact that the two URIs identify the same resource; as the owner of 
uri1, I can state that axomiatically, which makes it true...

Therefore, following your logic, your browser could serve *anything* I 
put up at uri1 when you ask it for <http://www.w3.org/>. (If 
<http://www.w3.org/> denotes a web page, that's not a problem; I can 
still create another URI to denote the same web page!)


Perhaps this gaping security hole can be fixed. There are more difficult 
cases, though. Assume that the following URI denotes a person:

     http://example.org/~mjk/

This person may have an associated email address, web page, name, age 
and so on.

It's useful then to give only this URI when speaking about the person, 
e.g., "I got this idea from <a href="http://example.org/~mjk/">MJK</a>." 
My user agent could conceivably retrieve the information that 
<http://example.org/~mjk/> is a person with an e-mail address, so when I 
right-click on that link, it could offer me to "Send e-mail to this 
person." Or it could have a "More information about" option which would 
search the Sematic Web and show me a description about the thing defined 
by the URI-- the name, age and so on. Thus, it's useful to link to the 
URI of the person, not the URI of their home page.

OTOH, it could also allow me to retrieve a representation of the person 
through HTTP (simple left click, I guess), which would probably end up 
being that person's home page.

Now, assume that there are other pages about this person on the Web, for 
example a page from their employer, a page on an "I hate these people" 
site, and so on.

When clicking on the link, in the tradition of Web pages I'd still 
expect to be taken to the Web page that the person of the link referred 
me to, not to some other description of the same person.

I think that this is described well by what Peter said-- when I make the 
link in HTML, it not only represents a resource, but also gives a 
particular point of view on that resource (in Peter's terms, an intension).

- Benja
Received on Monday, 28 July 2003 12:48:18 GMT

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