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Re: comments on Web Architecture First Edition

From: Pat Hayes <phayes@ihmc.us>
Date: Fri, 7 May 2004 23:25:20 -0500
Message-Id: <p06001f37bcc1d310eaca@[10.0.100.76]>
To: "Roy T. Fielding" <fielding@gbiv.com>
Cc: public-webarch-comments@w3.org, w3c-rdfcore-wg@w3.org
>I have no doubt that there exists some inconsistent use of terms
>within the webarch document.  However, the way to fix them is to
>point to the individual inconsistencies using factual statements.

My point is not that there are clear inconsistencies. It is that

(1) the terminology is ambiguous and its intended meaning is unclear, 
and could easily be made clearer by giving some short non-circular 
explanations (I am unable to offer suggestions for wording precisely 
because I do not know what meaning is intended.)

(2) I can think of two distinct alternative systems of meanings, each 
of which is largely coherent; but

(3) on either of these readings, some parts of the document do not 
seem to make sense. The parts in question differ according to which 
reading one adopts, so again until the intended meaning is clarified 
I am unable to offer concrete suggestions for rewording better than I 
already have done.

>I have no respect for arguments that are based on taking single
>examples out of context and making claims that they somehow define
>the entire space in exclusion of all other potential examples.

I use the examples in the document only as presumed guides as to the 
intended meaning. If these examples are misleading, or nontypical, 
perhaps you could provide more typical examples as a guide to the 
reader?

>
>>The key distinction here is identifying the thing - what Tim calls 
>>"name" -  versus identifying the location - "address"; a difference 
>>which is made vivid when the thing moves to a different address. 
>>OK, good point, one worth making in an architectural context: but 
>>not what I am talking about. I am talking about 'names' (not in 
>>Tims sense) which have got NOTHING WHATEVER TO DO with addresses of 
>>any kind, which are entirely removed from any architectural or 
>>computational sense of 'naming' at all, and which are not 
>>'identifiers' in the same sense (because they cannot in general be 
>>"dereferenced" in the sense that Tim is talking about): the kind of 
>>names and naming that were around in human society ever since apes 
>>started grunting to indicate things in the external world, the kind 
>>of names that pre-dated the computer by several dozen millennia. 
>>Just FORGET about computers and networks and architecture and the 
>>entire WWWeb for a second, if you can, and just think of LANGUAGE 
>>and REFERENCE. How WORDS refer. That is what I am trying to talk 
>>about. That is what the Sweb semantics is an idealization of. It 
>>has got almost NOTHING directly to do with networks.
>
>Sometimes, yes.  I fail to see why the EXAMPLES

(I apologize for the exasperated tone of that message - which , to 
emphasize, was addressed to Dan Connolly, and reflected in part the 
legacy of several extended F2F discussions of these matters -  and 
its use of UPPER CASE. I will try to restore the dialog to a more 
even tone in what follows.)

>  that are provided in
>the document are somehow DEFINITIVE for the entire space of resources,
>or that the document must give equal weight to all examples of resources
>and their interconnectedness.

Look, please. I really, really do not know what this space is 
supposed to be. I am struggling to understand what it is that y'all 
mean by this word "resource". What else can I do, but take the 
examples given as intended to be explanatory? I am sure that you have 
a clear idea in your mind as to what you mean by this term, but it is 
not yet clear to me. Surely its not asking too much for you to give 
enough examples, or some words of explanation, to indicate what the 
range is that you intend your terminology to have?

>You are simply assuming "for all" in cases
>where no such assumption should be made,

Well then please can you give me some way to know when I can make 
such assumptions, or what the intended boundaries of this 'for all' 
are supposed to be? You give no definitions, so I have to rely on 
induction and interpretation and guesswork.

>and not specifically identifying
>cases where the document does make that assumption and should be fixed.
>
>>[...]
>>>  In particular, in sense (C), but not in sense (D), there is a
>>>  presumption of a computable or effective process which can be applied
>>>  to the identifier to provide access to the entity identified;
>>
>>no, I don't believe there is any such presumption in the webarch
>>document.
>>
>>
>>Oh, surely this assumption is implicit throughout the document. It 
>>says for example that resources are connected by networks, that 
>>they can be accessed and operations performed on them by network 
>>protocols, etc. ; less directly, the idea that resources have a 
>>unique identifier has no rational basis for anything other than 
>>nodes which must be somehow addressed on a network in order to 
>>support transmission protocols.

It does not say any of this clearly and unambiguously, I agree. But 
then it hardly says anything clearly and unambiguously (which is OK 
for this kind of a document, but does mean that readers are obliged 
to interpret). Nevertheless, it seems to clearly convey these ideas 
as somehow recommended or necessary.

>Where does it say that all resources are connected by networks?

The opening sentence
"The World Wide Web is a network-spanning information space of 
resources interconnected by links."
is surely intended to convey the idea of resources being things that 
are linked on a network, is it not? If this is supposed to be read as 
identical in meaning to the paraphrase "the WWW is a network-spanning 
information space of things interconnected by links." then it is 
almost painfully vacuous. Is this the way you mean it to be read??
But more generally, if resources are not connected by networks, what 
have they got to do with the Web, and why is this document talking 
about them?

>Where does it say that all resources can be accessed?

It seems to identify 'access' with 'identify', for example where it says

"A URI must be assigned to a resource in order for agents to be able 
to refer to the resource. It follows that a resource should be 
assigned a URI if a third party might reasonably want to link to it, 
make or refute assertions about it, retrieve or cache a 
representation of it, include all or part of it by reference into 
another representation, annotate it, or perform other operations on 
it."

On the face of it, using the normal meanings of words like 'refer' 
and 'operations', this seems to confuse two different ideas: that of 
describing something, and that of accessing or manipulating it. These 
ideas have got almost nothing to do with one another, so to see them 
mixed together in a listing like this is startling, and when I read 
this I was forced to think about what it could possibly mean. It 
would make sense if one were to identify access with reference, so I 
take it that this is what was intended. If it is not, could this be 
rephrased, so as to make the two senses more separate? [See later for 
more on this text.]

>Where does it say that all resources have a unique identifier?

Sorry about that last one, I phrased it badly. I know the document 
does not say that resources have a unique URI, ie that URIs cannot 
converge in identification; in fact it explicitly denies it. What I 
should have said is that the idea that resources must be identified 
by an unambiguous URI has no rational basis, etc.. As I have 
explained in earlier emails, with examples, it is not necessary to 
have an identifier for something in order to refer to it.

>Those are obvious contradictions with what has been written in
>rfc2396bis, and if they exist in the webarch document then I want to
>know where so that we can fix them.  I don't see them, but at this point
>I've read the document too many times and my eyes tend to glaze over.

Well, I know how that feels :-)

>
>>[...]
>>
>>>  2. Hunting down what is meant by "resource".
>>[...]
>>>  The latter (D) interpretation seems to be insisted upon by the cited
>>  > document <http://gbiv.com/protocols/uri/rev-2002/rfc2396bis.html>
>>>  which reads:
>
>It has been changed since then.

OK, I may be behind the curve, forgive me. I seem to have lost the 
pointer to a more uptodate version.

>
>>  > Which could be paraphrased as "A resource can be anything, and
>>>  everything is a resource".
>>
>>Well, then, it is hard to resist asking the question, why did y'all 
>>feel obliged to (mis)-use a word when there already were perfectly 
>>good words you could have used, such as "entity" or even the 
>>plainer "thing" ? Grice's maxims come into effect at this point in 
>>the reader's mind: they aren't using the ordinary word, so they 
>>must intend a special sense...try to figure out what it is....
>
>Do you really think that those words would be any less likely to be
>misinterpreted?

Yes, definitely. The WordNet definition of "resource" has three entries:

resource (as in "assets") n. : available source of wealth; a new or 
reserve supply that can be drawn upon when needed 

resource (as in "asset") n. : a source of aid or support that may be 
drawn upon when needed: "the local library is a valuable resource" 

resource (as in "inventiveness") n. : the ability to deal 
resourcefully with unusual problems; "a man of resource" 

which clearly indicate a particular sense, having to do with sources 
of support or enabling, a sense which is quite remote from anything 
'universal' such as thing or entity.  It lists 'asset' as a more 
general term, and "natural resources" as a more specific one.  I know 
of no usage of "resource" external to the W3C which gives that word 
anything like the scope that you use it with.

I take the general point that any word when used in a technical way 
may have to undergo a shift of meaning: but this just seems like an 
argument for giving a reasonably clear explanation of what its 
intended non-standard meaning is, when it is so used.

>  In any case, entity is typically used to refer to
>an embodiment of some type

Not in general English usage. WordNet again:

"entity (as in "entity") n. : that which is perceived or known or 
inferred to have its own physical existence (living or nonliving)  "

with, notably, no more general or synonymous terms and 21 (!) 
distinct more specific instances. (I think, speaking now as a 
philosopher manque, that 'physical' here is inappropriate, but 
whatever.)

>, and not all "things" are resources,

I am genuinely surprised by this, since I had thought that according 
to the broad interpretation preferred by Dan C and yourself, 
*anything* was a resource. Can you give me an example of a thing that 
is not a resource?

>so both
>examples are more overloaded given what we want to use resources for in
>the SemWeb.
>
>We have already talked about why more of the rationale behind "resource"
>is not in rfc2396bis.  To some extent, I have improved the definition
>since then, as the number of obstructionists have decreased over time.
>However, my recollection was that you could not come up with a definition
>that was any better

Of course I cannot come up with a definition, as I do not know what 
you mean by it. The only way I could offer a single definition would 
be by being telepathic. I tried my best to figure out what you meant 
and I was left with two alternatives, neither of them perfect and 
mutually incompatible. I tried to explain these two, and asked y'all 
if you could make your intentions more clearly known. I don't know 
what more I can do.

The particular thread you are now involved in arose from Dan C. 
claiming ( I think) that my alternatives were not incompatible, a 
position which I firmly disagree with, but which is different from 
the thrust of my comments of the architecture document (though 
obviously related to them.)

>, nor any useful recommendations for better terminology.

Well, I would suggest using a very plain word like "thing" ("entity" 
having been poisoned) if that is really what you intend to mean. If 
that makes some of the sentences seem rather flat and pointless, then 
take that to be a critique of the sentences rather than an 
justification of the use of a fancier word. Or, I have already 
suggested that you could use 'resource' in the very general sense, 
but clearly stated to be so intended, and use "source" for the more 
restricted sense (or Tim B-L's "web resource").

>>Is wood something which can be connected to a network-spanning 
>>information space by a link?
>
>Yes.

What??? I am gobsmacked by this response.  Can you explain or 
elaborate, if only briefly? What would it mean to connect to wood by 
a network link?

I can think of two possible meanings, just.

One is that there could be a representation of something wooden, say 
an image of woodgrain, such as those at 
http://www.rockler.com/ecom7/product_group.cfm?&objectgroup_id=173&catid=47
or an OWL ontology about wood, say. This is not what I meant by a 
link TO wood (but if it is what you mean, then that would help 
clarify a lot of other things in the document.)

Another is that there could be some piece of woodworking machinery, 
say a IIDA profile moulder, hooked up to a network in some kind of 
Web-connected automated woodshop, so that a network signal could 
cause some actual physical wood item to be cut and sanded, and then 
maybe have its surface sensed and a report on it sent back somewhere. 
Is this the kind of thing you mean, what might be called network 
robotics? If so, that isnt what I meant either: that might, at a 
stretch, be said to be a network connection to a particular piece of 
wood (I would dispute this, in fact, but I concede the case needs 
arguing) but it is not a network connection to wood, the generic 
concept of wood.

If you meant neither of these, then I am completely lost, and would 
REALLY like some explanation of what you did mean.

>
>>Is wood something on which operations can be performed by means of 
>>network protocols?
>
>Yes. (assuming the network protocols are only one part of an overall system)

Again, can you explain? (What does it even mean to perform operations 
on wood? ie , wood in general, as opposed to a particular piece of 
wood.)

>
>>Is wood something that must have a unique identifying URI? (What 
>>would that claim even MEAN? what could it POSSIBLY mean? )
>
>No.  I have no idea what you are talking about here.

Sorry, forget the 'unique'. Must wood be identified by a URI? (If so, 
do you happen to know it? The URI for wood, I mean, the URI which 
identifies the resource corresponding to the meaning of the English 
word "wood".  Who owns that URI? Who owns that resource?)

>
>>  > The only example given in the document is disturbingly vague at
>>>  precisely this critical point: the resource is the "Oaxaca Weather
>>>  Report". But what KIND of thing is that,
>>
>>It's a resource.
>>
>>
>>AAARGH. WHAT DO YOU MEAN BY "RESOURCE" ???
>>
>>That answer is VACUOUS since you have not said what you mean by 
>>this damnable word. (It does mean NOT mean resource in the ordinary 
>>English sense of "resource". )
>
>Yes, it does, though you seem to have trouble believing it.  Some people
>use the term "resource" to mean people, others to mean "oil", still others
>to mean "land", etc.

Those are all instances of resources, yes. None of them is 
identifiable with the concept of resource itself. But perhaps I am 
being too picky. Onward....

>The one thing that the ordinary English sense of
>the noun "resource" has in common is that a resource is a source of
>supply or support within the context of a given system, whatever that
>system might be.

A source of supply or support (or use), yes. Within a system, no. The 
normal English meaning of "resource" makes no reference to a 'system'.

>  A system like a "hypertext browser" is going to have
>a very different set of resources than a system like a "theorem prover".
>Nevertheless, the things that they operate on can be termed resources,

Fine, OK.  The things they OPERATE ON can be, yes. The things they 
REFER TO are something else altogether.  So the weather report about 
Oaxaca might well be a resource, but the actual weather is not (and 
neither is Oaxaca).  Please keep this distinction clear: that is all 
I am asking you to do, in fact.

But now I have to do a gear shift. Until now, you seemed to be saying 
that "resource" had to be understood in the broadest sense possible, 
and this is what Dan C was arguing in the message I was replying to, 
and is the sense that (partly on Dan's advice) I wrote into the RDF 
semantics, where "resource" just means "anything and everything". Now 
you seem to be saying that "resource" means what the word indeed 
suggests, which is "things that can be operated on via the network" 
or maybe "things that can be of use on the network" or some such. 
That is my C sense, where resources are things that in some (perhaps 
generous) sense can be accessed and operated on by computational 
operations. It is not the broader sense of things in general, the 
entire contents of the universe of discourse, that Dan C (and until 
now, I thought, you) wanted it to mean.  I am VERY happy with the 
narrower interpretation. So, great: resources are things that can be 
operated on by Web applications. If the architecture document could 
clearly indicate that it is meant to be understood as talking about 
the things that applications operate ON, not what they refer TO, it 
would mostly (ie with a small amount of pruning) make perfect sense 
and I am sure would be a valuable document which was in fact about 
what it claims to be about, viz. architecture, rather than semantics.
Some of the language needs to be adjusted to avoid it being 
mistakenly interpreted as saying something much stronger than (I now 
think) it is intended to say.  For example:

"A URI must be assigned to a resource in order for agents to be able 
to refer to the resource. It follows that a resource should be 
assigned a URI if a third party might reasonably want to link to it, 
make or refute assertions about it, retrieve or cache a 
representation of it, include all or part of it by reference into 
another representation, annotate it, or perform other operations on 
it."
-->
"A URI must be assigned to a resource in order for agents to be able 
to perform operations on the resource. It follows that a resource 
should be assigned a URI if a third party might reasonably want to 
link to it, retrieve or cache a representation of it, annotate it, or 
perform other operations on it."

BTW, if you can confirm that I have this right, I would be willing to 
go through the entire document and suggest minimal changes to the 
text to clarify this meaning, as a top priority (it would take me a 
couple of days). I could edit the HTML directly if that would be 
helpful.

>can be identified by the same system of identification (URI), and over
>the past 10 years I have yet to encounter any other word that can
>express the same sentiment in a reasonable number of characters.

Well, OK, as long as we can be clear about that sentiment. That is my 
C sense, not the D sense. I'll assume that this is the sense 
intended, in the rest of my comments.  But then you cannot reasonably 
expect me to accede to your often-repeated claim that a resource is 
anything with an identity, which is way too inclusive. Which sense do 
you want to use?

>Whether or not all systems can make effective use of all URIs is
>completely irrelevant to whether or not a thing can be a resource
>to one system.

I agree, and I never intended to say otherwise. My complaints have 
been about a different point entirely.

>
>In short, if you feel that "resource" means something other than the
>above in the ordinary English sense, then please feel free to explain
>what your sense of the English IS rather than simply complaining about
>every definition that has ever been proposed.
>
>>There is a real need to explain what you mean when you use words in 
>>an unusual way. This is not just a quibble: until you SAY what you 
>>mean by this highly non-standard usage, the entire document is 
>>literally USELESS.
>>
>>I find it hard to believe that we are even having this 
>>conversation. If the TAG group were a bunch of students in a 
>>high-school English class they would get an F immediately for not 
>>understanding this basic point.
>
>I am surprised that a person working on the semantic web would assume
>that all communities would use the same term in the same way

I don't. I was referring to the apparent refusal to explain the way 
in which the terms were being used by y'all.

>, let alone
>in the way that you claim (but have never actually shown).  I require
>that the terms be defined and used consistently within the scope of
>a given set of specifications, but you reject the definition

No, I have been complaining about the fact there there is no 
definition. "Anything with an identity" is not a definition (and 
apparently is wrong, given what you say above, if I follow you.)

>AND then
>complain that its usage is inconsistent with some imagined definition
>based on the Web examples.  The inconsistency is in your assumption
>that the examples are somehow covering the entire scope of what is
>being described by the Web architecture.

Ok, this is a good point. I think that part of the communication 
problem is that I have no idea what you see as being the scope of Web 
architecture. I can only guess at it from the text you provide. I 
have the sense (from reading your thesis and other documents) that 
you are concerned not to overly restrict the architectural 
description, given the undeniable fact that the growth and 
development of the Web places stress on any attempt to restrict or 
constrain it by describing it in terms of any old, or even present, 
set of categories; and I respect this concern: but I think that in 
trying to avoid being restrictive,.you may have, perhaps 
inadvertently, set the boundaries too wide. Your description tries to 
encompass too much: by tossing naming and reference into the same bag 
as network identification of resources (in your sense given above), 
you have implicitly claimed (or at any rate can be easily read as 
claiming) that referring to things is similar to accessing them or 
performing operations on them; but it isn't.

>  The examples provide a way
>of relating the concepts within the architecture to a familiar set of
>behaviors and interactions within one system based on that architecture.
>If you can think of additional examples that show a wider variety of
>resources, preferably based on real systems rather than potential
>future notions of what you think the SemWeb is about, then
>please send them as your comments.
>
>In fact, your entire tirade is basically taking one sentence,
>reinterpreting a few of the words in a sense that artificially
>bolsters your argument, and then claiming that those reinterpreted
>definitions somehow restrict the semantic web.

That is not fair. I have given a detailed analysis of the text, 
trying as clearly as I know how to explain why parts of it seem to be 
inconsistent with other parts, and offering in some cases alternative 
wordings.

None of this would matter much if the document were not so important 
and so authoritative, but it is: it will be cited for years to come 
as holy writ, and sentences taken from it will be cited to justify WG 
decisions and to object to proposals, and so on. And so it has (you 
have) a rather unenviable responsibility to make sure that it does 
not say things that are harmful. And it seems to me that at present 
it does, or at any rate can be readily interpreted to be saying them. 
For a major example, it says "A URI must be assigned to a resource in 
order for agents to be able to refer to the resource." which, as I 
have explained, is not true; and in fact is *perniciously* not true, 
in that if it were true then an entire useful technology would be 
impossible (applications which are able to determine referents by 
reasoning).

>I don't believe
>your paper tiger has any bite, and if you took the time to read
>the document without prejudice

I have tried, believe me. I have spent more time than I want to 
recall trying to read it with any interpretation I could imagine so 
as to make it make sense.

>then maybe you could help identify
>the places where the architectural principles are bogus

I have very little to say about the architectural principles, and my 
opinions on them wouldnt be worth much in any case (I did make a lot 
of detailed comments on aspects of the wording in my first long 
email, but have no more to add about those). My worries here are 
almost all to do with the *semantic* implications of the text as it 
is written. Maybe you have no interest in these aspects of the text, 
or did not intend to convey any semantic implications, which is fine: 
but then all I am asking you to do is to clarify this.

>(there are
>a few) or where the prose overstates a practice as being universal
>when it, in fact, is only applicable to one of the systems that
>use the Web.

The only one I'd reiterate is the criticism of the idea that URIs 
must be opaque. The more I think about that, the worse it gets.

>Those are valid and helpful comments.  Claiming that
>you have a special understanding of the English language that differs
>from that used in the document and  invalidates the work we have
>put into describing the Web architecture, is not only unhelpful --
>it is obviously wrong and I have shown you, many times, where your
>claims about the meaning of words are a complete fiction.

I beg to differ on that point, but let us not squabble. I do not 
claim any special understanding of English, but I would claim a 
reasonable mastery of the language and have read most of the major 
dictionaries (I collect them), and I have never intended to 
invalidate anything. While we are being ad hominem, I would venture 
to suggest that if your attitude were less defensive then we might 
make progress a little faster. All I have ever asked for is more 
clarity and less ambiguity, which you have now apparently provided, 
thanks very much.

>>I was not asking about Web architecture; I was asking about the 
>>MEANING of the WORDS you use to describe it. As I said, almost the 
>>entire document makes perfect sense under the reading that you (and 
>>Roy) reject, the one under which it would indeed be a document 
>>describing an architecture, and did not try to simultaneously be a 
>>tract based on an ill-thought-out (and unpublished) 
>>operationalist/pragmatic philosophy of language which apparently is 
>>based on the idea that reference and physical connection are 
>>identical and which assumes that every entity has a unique True 
>>Name. If you really believe this stuff, I think you ought to write 
>>it up and send it to a journal, or at least put it up on a Blog 
>>somewhere where people can comment on it.
>
>Again, I have no idea what you are talking about.  Nobody on the TAG has
>ever assumed that every entity has a unique True Name,

Well, it would be easy to read the text of the 1994 URN proposal in 
that way, but I was being somewhat facetious.

>  though some
>people (myself excluded) would like to require that every name have one
>true interpretation, and most people agree that it is better to use one
>name rather than several different names to refer to the same resource.
>That does not prevent the assignment of multiple names to a resource,
>nor does it ensure that names that have been assigned are used in the
>way that they were intended, but it does state a preference that folks
>should not be intentionally inconsistent in their use of names.
>
>I assume that your comment on an unpublished philosophy of language
>is based on prior messages I sent to you about the background of REST.

In part, but more on various documents. Also please bear in mind that 
comment was a reply to Dan Connolly, not to you personally.

>I assure you that what you are complaining about above did not originate
>with me and has nothing whatsoever to do with REST or its background.
>Since none of that background appears in this document, I'll just put
>your comments down to an arrogant assumption that you can evaluate my
>work even though you have never seen it

Ive read everything I can get my hands on and have time to read.

>  and do not, in fact, have
>any experience in related fields.  Maybe if you weren't so prejudiced
>against finding any meaningful insight in the webarch document, you
>could find time to comment on what is actually published rather than
>on your assumptions about something you have never seen.

I believe I have already commented on it at some length. This email 
thread results from part of that commentary.

>
>>It is not written with enough precision to know whether it is 
>>consistent or not. It SEEMS to contain inconsistencies, in the 
>>sense that words and phrases  are used apparently with different 
>>and incompatible meanings in different parts of the document. I 
>>have documented this phenomenon in detail.
>
>You documented the phenomenon?  Why don't you simply document the
>instances where usage differs from definition?

What definition? I was forced to invent my own definitions, and I 
gave a detailed analysis of where the document needed altering on 
either reading.

>  The only things you
>highlighted were simple examples used to relate the definitions to
>the real world.  One solution would be to add more examples.
>
>>What you have written is likely to be very useful to people who are 
>>not interested in reference or descriptional semantics. I wish it 
>>were written clearly with that (large) audience in mind. In its 
>>present form, however, the document is not only not helpful, it is 
>>positively harmful, to clarifying the relationship between SW 
>>semantics and Web architecture. I would describe it as corrosive, a 
>>major disaster. I think it, or, more properly, the confusion that 
>>it embodies, fails to clarify, and in places authoritatively 
>>reiterates, has been and continues to be a constant source of 
>>misunderstanding, controversy and potentially bad design decisions, 
>>and that until this mess is cleared away we will never get a 
>>sensible coherent account of the foundations of the semantic web.
>
>That is quite possible.  Not a useful comment, however.  It would
>probably be more coherent if we wrote several different documents,
>as suggested by another commenter, each one with an individual author
>that can maintain consistent use of terminology throughout their
>document.  In the long run, though, I doubt that would help attain
>any sense of consensus, and in any case we barely have enough spare
>time to collaborate on just one document.

Well, I can resonate with that point. Still, other WGs have managed 
to reach consensus on difficult issues.

>
>>  > Trying to home in on your intended meaning by searching the document
>>>  for uses of "resource" gives the following:
>>>
>>
>>>  [[The World Wide Web is a network-spanning information space of
>>
>>>  resources interconnected by links. ]]
>>>
>>>  I take it then that a resource is something that can be connected by a
>>  > link to another resource. I presume also that "link" here means more
>>>  than simply a reference to something,
>>
>>why?
>>
>>
>>Because that is the usual meaning of the words "link" and 
>>"interconnected" . Reference is not in any sense a connection. I 
>>can refer to things that do not exist, or have ceased to exist, or 
>>which might exist but do not yet exist: I cannot be interconnected 
>>to them, by links or anything else. I can refer to things that I 
>>cannot be connected to by virtue of physical limitations, they 
>>being light-years away. I can refer to abstractions such as numbers 
>>or sets, for which it would be logically incoherent to even suggest 
>>that one could be connected in a network sense. I can refer 
>>ambiguously (in fact, I would argue that this is the normal case) 
>>but I cannot be ambiguously connected.  I can refer in one possible 
>>interpretation and refer differently in another, but I do not know 
>>how to get possibly connected in an interpretation. And so on.
>
>That is, of course, a hopeless misinterpretation of the word connected.
>Have you ever seen the BBC series (shown on PBS as well) on the history
>of the world, called "Connections" (James Burke, 1978)?

Yes, of course, and in keeping with the rather facile nature of that 
series, its title is merely a pun. But I will try to take you 
seriously. You are saying, then, that when the architecture document 
uses words like 'connect' and 'interconnected', that this is intended 
to be understood in the broadest possible way, so that an 
'interconnection' between A and B could be something as evanescent as 
the fact that a mention of A reminds someone of B, or that the ideas 
of A and of B might be associated in someone's imagination. Do I have 
that right? Because that is what you seem to be implying here (and 
your dictionary, cited below, has the sense
  5: the process of bringing ideas or events together in memory
         or imagination; "conditioning is a form of learning by
         association" [syn: association, connexion]
being the only one which does not imply some kind of causal 
connection between the things connected.)

But if this is indeed what you mean, what has this got to do with the 
Web, or computational architecture, at all? Why aren't you, in this 
case, making shallow entertainments like James Burke, rather than 
writing authoritative documents about the Web?  And if this is not 
what you mean, what do you mean?

>  For that matter,
>just look it up in any dictionary:
>
>     http://dict.die.net/connection/
>
>I completely reject the notion that "interconnected" implies a physical
>connection of any kind,

To fully capture the English sense one ought indeed to use 'causal' 
rather than 'physical', but with that modification, I would stand by 
my interpretation. Read that definition again: of the 9 senses given, 
the only possible more general sense is number 5, quoted above.

But aside from definition-challenging, surely the use of the 
'connect' word in an architecture document is supposed to connote 
some kind of *architectural* connection? If not, I REALLY do not know 
what the document is supposed to be saying.

>just as I completely reject the notion that a
>hypertext link (a reference that uses a URI

Wrong. A hypertext link is not a REFERENCE that uses a URI. It is a 
LINK that uses a URI, or is made by using a URI (Im genuinely not 
sure of the right way to state this in architectural language, but 
'reference' is semantic language.)  Referring is not an architectural 
or computational concept: it has to do with the meaning of language. 
A reference using a URI is the use of a URI to denote, to refer to, 
something, not the use of a network transfer protocol to fetch 
something. The two may coincide in many cases, but the coincidence is 
just that, not a necessary identity: they are not the same concept. 
If I use the name "Roy T. Fielding" in some plain HTML body text, it 
is a reference to you. If I enclose it in an <a> element with a href 
hyperlink to your website, the reference is unchanged, but the link 
is new.

>) is in any sense a physical
>notion that requires that the referent exists.

I never said it did. We are at cross purposes. However, surely it is 
the case that a (successful, ie not a 404 error) hypertext link does 
require the resource identified by the URL in the link to exist.  (If 
not, how does the GET protocol work, exactly?)

>There is no basis for
>your claims.
>
>>If you do not understand this then I despair of explaining it to 
>>you. Surely it is OBVIOUS that referring to something is not being 
>>connected to it? Do you think you are linked, in the sense implied 
>>by "a network-spanning information space of resources 
>>interconnected by links", to , say Santa Clause, or Nero, or the 
>>great nebula in Andromeda, or to my as yet unborn 
>>great-grand-daughter, or the base of the natural logarithms? Do you 
>>think that simply by mentioning something you are thereby enabled 
>>to perform operations on it, using a kind of network version of 
>>Voodoo?
>
>No.  Nobody here has ever said that all resources are connected to all
>other resources, nor that all resources are accessible by means of
>network protocols, nor that making a reference somehow guarantees
>that operations on it will be successful.

Neither did I say or imply any of this. We seem to be talking 
entirely past each other. My point is not that reference does not 
guarantee the success of performing operations, but that it has 
nothing whatever to do with performing operations. The two sets of 
ideas, of (access and operations) and of (reference and denotation) 
are almost completely unrelated. They shouldn't even be discussed in 
the same document: they have nothing to do with one another.

I think in fact that you might agree with this, if we could bring our 
discussion to a point of mutual understanding. I have no desire to 
interfere with your architectural work or analysis, but please don't 
confuse it with semantics. The Web needs both, and needs to get them 
both more or less right.

Pat Hayes

>
>
>Cheers,
>
>Roy T. Fielding                            <http://roy.gbiv.com/>
>Chief Scientist, Day Software              <http://www.day.com/>


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Received on Saturday, 8 May 2004 00:25:27 EDT

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