Re: resources and URIs

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/ Tim Berners-Lee <timbl@w3.org> was heard to say:
| On Thursday, Jul 31, 2003, at 15:46 US/Eastern, Norman Walsh wrote:
|>
|> / Tim Berners-Lee <timbl@w3.org> was heard to say:
|> | As a web user. when I quote you
|> | http://www.galegroup.com/free_resources/poets/poems/kublakhan.htm
|> | What do I expect of this URI when I dereference it?
|> |
|> | 1. - That it is always something *about* stately pleasure domes?
|> | 2. - That it is always the poem "Khubla Khan"?
|> | 3. - That it is always a poem "Khubla Khan", as published in the
|> | Thompson/Gale collection?
|> | 4. - That it is always a particular set of bits?
|> |
|> | The answer is  2 or 3.  That is what we expect to be invariant for
|> the
|> | URI.
|> | That is the basis on which I make hypertext links.
|> | That is the basis upon which URIs are used.
|> |
|> | That is why we say the URI identifies or denotes the poem.
|>
|> Right, so I might say that it is the URI for the poem Khubla Khan, by
|> which I mean the poem as an abstraction, not the document that
|> contains the poem.
|
| Well, think: which do you actually expect to get representations of?

I expect a representation of the poem. The details of the
representation (advertisements, typography, etc. may vary but I'm not
concerned about that.)

|> Does that square with your thinking on httpRange-14?
|
| Yes, if it is (3).

No, I meant the poem not a particular abstraction of the poem.

| Indeed, english does not come with words for the whole web architecture.
| We will have to do that spec-writing thing and nail down some local
| meanings
| for the purposes of the arch doc.

Indeed.

|> I don't see why I can't say that http://norman.walsh.name/ symbolizes
|> me (I grant that it may not be the best choice of identifiers given
|> the ambiguity it introduces, but I can still do it.)
|
| This is called Indirect identification. It is normal, everyone does it.
| One does not have to be ashamed of it.

No, you misunderstood me. I meant literally identify me:

  <http://norman.walsh.name/> <rdf:type> <wn:Person>

Hence my parenthetical remark about it being less than ideal.

| You go one to describe how human beings tend to use terms loosely.
| We can't let that guide us in nailing down some crisp terms for the
| arch doc.

I didn't say it could.

| [...]
|> No matter what we say, some people will want to use identifiers that
|> way. The longer we talk about this, the more convinced I become that
|> the most we can possibly do is to explain why this might be a problem
|> and encourage people to avoid it unless they have good reason.
|
| We are not trying to control how people talk to each other
| at the bus stop.  We are trying to get engineers to write programs
| which interoperate. These are technical specs.

Yes, Tim. I am aware of that.

I just don't get the interoperation angle.

I was thinking yesterday about how I'd write a SemWeb application. I
was imagining how I'd code it up. Somewhere in my application I'd have
a store of RDF triples. Someone would ask the application to do
something and it'd go off looking at its triple store trying to find
the answer.

As it stumbled along, it'd consider each URI that it encountered and
evaluate some sort of isInteresting() function. Some URIs (resources
or properties) would be interesting and the application would ask
itself, what do I know about this thing?

Sometimes it would decide "not enough" and go off looking for more
information. One way it might do that is by doing a GET on the URI to
see if it got back some information. If it got back triples, it'd add
them to the store and move on. If it didn't get back triples, well,
it'd just move on anyway.

No where in that code would I expect to consider the type of URI
(http, urn, ftp), that'd all be lower down in some URI resolver guts.
Also, no where in that code would I ask questions about what I already
knew about the URI.

I can't, for example, imagine writing the code this way:

  uri = nextInterestingURI();
  if (typeOf(uri, Person)) then
     if (hasFragId(uri)) then
        LoadURI(uri);
     else
        # can't be document so can't be loadable
     fi
  else 
    LoadURI(uri);
  fi

But the "http URIs must be documents" axiom suggests that your
application does work this way. Does it?

I keep struggling to understand what I'm not understanding.

                                        Be seeing you,
                                          norm

- -- 
Norman.Walsh@Sun.COM    | It is good to have an end to journey toward;
XML Standards Architect | but it is the journey that matters, in the
Web Tech. and Standards | end.--Ursula K. Le Guin
Sun Microsystems, Inc.  | 
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Received on Friday, 1 August 2003 16:04:13 UTC