Re: LRDD Update (Resource Descriptor Discovery) and Proposed Changes

Williams, Stuart (HP Labs, Bristol) wrote:
> Xiashou, 
>
>   
>> -----Original Message-----
>> From: Xiaoshu Wang [mailto:wangxiao@musc.edu] 
>> Sent: 01 July 2009 13:52
>>     
>
> <snip/>
>
>   
>>>> Then, this comes back to the definition of Information Resource, with a 
>>>> URN, wouldn't IR be the set of all URL's referent?
>>>>     
>>>>         
>>> By Fieldings writings a resource is modelled as a function from time to 
>>> [(sets of equivalent awww:representations) OR (URI)].
>>>   
>>>       
>> By no means to disrespect Fieldings, do we have to take someone's past 
>> writing as a bible that we should never change?  If that, how can we 
>> ever advance? 
>>     
>
> You propose IR as ".. The set of all URL's referents". This makes no sense to me. In your view are those referent things resources or representations - it is not clear from what you write.
>
> I invoke the model written about in REST and I think mostly accepted in the community... which I happen to like and find it makes sense to me. 
>
> You take umbrage...
>   
Nope.  I did not.  My wording my imply that I suggested Fielding's model 
is wrong.  This is not the case.  I am simply questioning the approach 
that you are using.  What Fielding has done is simply explain what is 
working.  It is not the reverse that the Web runs because of his 
interpretation.  What I am doing is just the same.  I am trying to find 
an interpretation that gives me a peace of mind and makes my daily job 
easier.

I couldn't careless about the existence of "information resource" or 
not.  I am simply trying to offer a comfort to those who think so.   If 
there is any umbrage, there is the one at TAG's demand for me to judge 
if "x is IR" or not.  My life before that is easy but it no longer is 
after that.

>>>> If we have not taken 
>>>> IR as *representation*, would this (the duality of URI as name and 
>>>> locator) be the cause? 
>>>>     
>>>>         
>>> But... we have *not* taken "IR as *representation*"....
>>>
>>> Just think of the web as a great big machine that answers 
>>>       
>> (amongst other things) "get" questions of the form "Please 
>> 'get' me a (current) awww:representation *of* the 'thing' 
>> named with this 'uri'"
>>     
>>> Responses that you might get back are one of following kind 
>>>       
>> (non-exhaustive):
>>     
>>> 	- an awww:representation of the 'thing'
>>> 	- advice that 'thing' has another name (temporary or permanent)
>>> 	- advice that more information *about* requested 
>>>     'thing' *may* be available by asking the 'get question' of a 
>>>     different 'thing'.
>>> 	- advice that the requested 'thing' cannot be found/accessed...
>>> 	- something more catastropic.
>>>   
>>>       
>> That is my view, there is no "information resource".
>>     
>
> Information resources are just those that can have webarch repesentations...
>   
Please, please, define the "can"!  Whose capability?  I told you that 
"I" can give any awww:representation to any resource.  And 200 signals 
*my* capability.  But I cannot speak for anyone-else or anything-else.  
Who or what gives the awww:representation of a web-page?  Is it the web 
page itself that gives it a awww:representation? Or you, or I, he or she?

I do *not* think that a web-page can have an awww:representation by 
itself.  Then, I can only 303 forever.

>>> The point is that in web architecture the 'thing' referred 
>>>       
>> to by the 'uri' in the question, and the 'thing' that the 
>> awww:representation (if any) is an awww:representation of are 
>> supposed to be the *same* 'thing'.
>>     
>>>   
>>>       
>> You have repeatedly assured me that no one has taken the view of 
>> "Resource = Representation".
>>     
>
> Yes... no-one I know of on the TAG... and I would continue to assure you of that...
>
>   
>>  What was this supposed *sameness*?  Define it objectively and clearly.
>>     
>
> I think I'd refer you earlier responses from Pat or Jonathan about the meaning of sameness.
>
> Best I can do is:
>
> ForAll ?u:uri ?r:wa-representation SuchThat http-get(?u:uri) yields ?r:wa-representation,
> Exists ?t:thing SuchThat
> 	?u:uri refers-to ?t:thing, 
> 	?r:wa-representation wa-representationOf ?t:thing .  	
>
> Thing ?t is the same thing t in both clauses that m. That's it!
>   
Then, what criteria to evaluate "wa-representationOf"?  Please, you 
think it says anything?  Just like in a programming language, the 
language itself has an object identity equivalence, same as the 
equivalence of URI comparison by char by char.  All other semantic 
equivalence is delegated to the programmers.  What is did in that is to 
simply delegate it to the Web user to implement the 
"wa-representationOf".  There is no definition. 
> <snip/>
>
>   
>> Don't and don't ever take that view. Communication is simple. 
>>     
>
> I don't!
>
>   
>>  You get a message and judge the truth of the claim.  There isn't 
>> something magic about it.  This is how we humans know the universe.
>>     
>>>> Now, let's go back to Pat's question, how a far away galaxy can be 
>>>> connected to the Web?  Say Orion (let's make it a schemeless URN 
>>>> again).  Then, you chose your information path by selecting your 
>>>> transportation protocol.  When you choose "http", your information 
>>>> resource would be http:Orion, which makes it a URL now.  
>>>>         
>> Wouldn't you know what kind of access that you are getting into?
>>     
>>>>     
>>>>         
>>> Well... you are having to invent here a new construct here 
>>> that the web as it is does not support - the schemeless URN. 
>>> As things stand right now there is no defined relationship 
>>> between the things referenced by URI whose spelling differs 
>>> only in the spelling of the scheme component.
>>>   
>>>       
>> Of course, this is why I am proposing TAG to consider it. It helps solve 
>> many problems.
>>     
>
> Oh well... good luck... I suppose! I think you'd actually have more success in proposing a new scheme that fits with URI architecture as it is (and BTW URI schemes (as they are now) are orthogonal to fragID syntax/semantics). Not that would be without significant impedance.
>   
I am asking TAG to consider.  Sure, we could built a schemeless or other 
named URN. That really doesn't matter to me.  What I want is first, to 
make people aware of the two sense of a HTTP-URI that is currently 
used.  So people won't try to make a quibble by using tricks in natural 
languages.   For instance, I have to stop Jonathan's earlier example 
time and time again, just wanting him to be clear which thing, i.e., a 
representation/referent that his use of "web page" is referring to. 
Otherwise, there is no way the argument can proceed.

Second, we need *syntactic* difference to denote the concept that we 
used quite often.  It is a matter of convenience. For instance, we do 
not have to invent the word "red" to mean a particular kind of color.  
We can just do it by how it relate to other colors.  But we do it in 
life because it makes our life easier.  Providing a syntactic construct 
just forces a certain clarity.  You can consider it to be too rigid.  
But so does the grammar in a natural language.  The purpose is to ensure 
the clarity of language use.

>>> Also, whilst I think this is the topic of TAG issue 
>>>       
>> schemeProtocol-49, what a URI refers to and how you access 
>> that 'thing' (if you can) should be regarded as orthogonal. 
>> The HTTP protocol itself can be used with URI from any scheme 
>> - though there are obvious practicalities in setting up the 
>> relevant gateways/proxies.
>>     
>>>   
>>>       
>> Wouldn't my proposal help clarify that? A scheme denotes a path to 
>> acquire "awww:representation" of a resource, denoted by the 
>> schemeless-URI? If we give a default namespace to the scheme 
>> part. 
>>     
>
> *But* that is what the web already is - a machine that obtains wa-representions (where possible) of things (resources) designated by URIs.
>   
>> Then, people can follow their nose to understand what is the protocol, right?  
>> If you take a static view point, then what a schemed URI denotes is the 
>> "information resource". Besides, it also solve the problem between the 
>> equivalence of http-URI and https-URI.
>>     
>
> Hmmm... you may think you have solved it others with deployed systems that depend on the fact that such an equivalence is not stipulated probably see neither a problem or a solution!
>   
Honestly, as a person, I couldn't careless because I, as a web engineer, 
know the intrinsic relation between an HTTP and HTTPS URI.  But handling 
that job to an RDF reasoner and see where kind of problem it may give rise?

>> I am not saying this is currently supported.  That is why I ask TAG to 
>> consider. We do use URI in two senses, one as URN and the other URL. Do 
>> you agree? 
>>     
>
> As a name and as a locator... Yes I see those uses, but the intention of webarchitecture AIUI is that in those case where both usages are possible they are (should be) aligned - what is named is that which is located (ie. that which an obtained representation is a representation *of*).
>   
We go back to full circle.  I think anything can be *of* anything-else.  
If you think otherwise, define your "of"-ness.

I cannot help pleading Wittgenstein's principle -- "Meaning is use."  If 
you think that a term will affect people's engineering practice.  Then, 
please *define* it with objectivity and clarity.

If we really want the web architecture to be pragmatic, as Jonathan has 
said before, I really hope that we can understand how Wittgenstein has 
changed philosophy.  Let's *please* not use these all purpose term to 
convey our criteria because it can be used in all purpose to either 
support or against our criteria.  Let's *please* define pragmatic terms 
so we will not be trapped by our linguistic ambiguity.


>>>> If we have one URN, I believe all these problems will be gone.  Sure, we 
>>>> can make URI to keep its duality.  But in the latter case, we must be 
>>>> aware which sense we are using when we make a statement.  We should not 
>>>> try to cure one linguistic confusion with another because that only 
>>>> gives rise to new problem while still not settling the old one.
>>>>     
>>>>         
>>> IIUC, you have:
>>>
>>> 	//en.wikipedia.org/wiki/Magna_Carta (or possibly 
>>>       
>> Mogna_Carta) is a 'URN' 
>>     
>>> 		which names 
>>> 			the Magna Carta (a conceptual work with 
>>>       
>> a small number of original transcriptions on vellum)
>>     
>>> 	http:////en.wikipedia.org/wiki/Magna_Carta (or possibly 
>>>       
>> http:Mogna_Carta) is a 'URL'
>>     
>>> 		which names
>>> 			a wikipedia page *about* the Magna Carta.
>>>
>>> In this scheme, what 'URN' do I use for the wikipedia page 
>>>       
>> so that I can write a page *about* it (and so on)?
>>     
>>>   
>>>       
>> You want to propose an http://ftp://http://... .
>>     
>
> No!!! I am asking you what you would propose. I'd leave things as they are!
>   
Then that is what I propose, if we want to make the syntax of URI 
syntactically complete.  Say if you are given a URI in the form of 
"http://http://URN".  Then, from the default scheme URI, say 
"http://example.com/scheme/http", where you will find that currently 
HTTP protocol only supports one level of scheme-recursion. Meaning: the 
thing still exists (if you ask the meaning of this letter word, I will 
refer you to Quine) but currently there is no implementation.  That is, 
you cannot write a *page* about it.  Please note, the *page* that you 
are referring, w.r. to http://URN, is not the same kind of *page* w.r. 
to URN.  If you only want to write the-web page but not the meta-web 
page, you write it in say: http://URN2, where you make an assertion to 
say "URN2 = http://URN1".  Isn't it right and clear?

>> Sure.  I don't think 
>> my proposal is theoretically against that. ou have to define how the 
>> inner scheme is grounded on.   In other words, you have to construct a 
>> meta-Web to do that.  But do you think that it is practically useful?  I 
>> think Godel has told us there is no system that can be self-complete. We 
>> have to stop our recursion somewhere.  Otherwise, we will go nowhere.
>>     
>>> I don't think that we need such rigidity. We just need to 
>>> be careful about what it is that is being named, and some 
>>> named things contain information about other named things.
>>>   
>>>       
>> Sure.  I am all for that.  Then, think about IR/httpRange-14, is it 
>> rigid or not?
>>     
>
> It is very flexible - it does not lock in any rigid syntactic relationship between things whose names have similar but slightly different names. Descriptive information about a thing could be anywhere on the web.
>   
Really?  Flexible to whom?  Then, why you said that I cannot 200 back 
http://example.com/aperson, which denote a person????
>>  
>>     
>>>> I *sincerely* wish that when we define our engineering terms, we can 
>>>> follow Wittgenstein's version of "meaning is use".  A *definition* must 
>>>> be distinguished from a *description*.  The former is aimed at clear 
>>>> usage while the latter comprehension.  If we define a vocabulary X, and 
>>>> no one can tell X from not-X, X must be treated as its subsuming 
>>>> concept.  This is my logical argument for the word "descriptor/metadata" 
>>>> etc. because their definitions make them semantically equivalent to 
>>>> "resource".  Then, it offers no more therapeutic (in Wittgenstein's 
>>>> term) value than what we already have, except making it worse.
>>>>     
>>>>         
>>> I think that you are overreading what people are saying. 
>>> Most people AFAICT, are comfortable with the notions that 
>>> resources can described other resources and will speak of the 
>>> former as being metadata about the latter. One doesn't then 
>>> have to get into meta-'x',  meta-meta-'x' .... One just has 
>>> 'x' and some 'x's have things to say about other 'x's.
>>>   
>>>       
>> Did I?  I am not against people using the word "meta-data".  I am 
>> against people trying to propose a standard approach based on that 
>> word.  I don't care what the word is.  What I care is how I can tell one 
>> thing from the other.  I am engineers.  
>>     
>
> Ok... so the engineering problem is:
>
> 	"Given a name 'u' for a thing 't' how do I find descriptions of 't' as opposed to awww:representations of 't'"
>   
I got lost.  Dereference U, what-else?

Or you mean find t's description without getting any t's representation? 
Then, should I say more?

>> All works is in essence a bunch 
>> of "if elese".  If my "if" always return one result, what is the 
>> "else"?  
>>     
>
> skw parser failure!
>
>   
>> And someone told me that there is an "else".
>>
>> (As a history, I remember when I first heard RDF back in 2000, it was 
>> called a metadata framework.  I guess there is a reason for 
>> that TAG no longer use that.)
>>     
>
> I doubt it. 
Seriously?  See the 1999 version of RDF at 
http://www.w3.org/TR/1999/PR-rdf-schema-19990303/.

> There is also a 'D' in the middle of RDF. RDF lets you make statement about 'things', but one of the problems is completely the reverse - I want to find what is said (and by whom) about some 'thing'. 
 From where?  From the Web, you (1) dereference it or (2) 
google/yahoo/bing etc.
> The natural operation of the web enable you find what a 'thing' has to say of 'itself' in the form of awww:representations (if of course it is of a kind that can do that).
>   
I am not sure what it has to do with the LRDD proposal?  What LRDD 
recommends is: in addition to wrap your information into the 
HTTP-entity, you need to make two wraps -- one descriptive/metadata and 
the other (non-)descriptive/data -- and place the former in LINK while 
the latter in Entity.  I told them now I have trouble making two 
separate wraps.  I want them to be clear on what I should put in the 
Link bucket and what Entity? I am perhaps the numbest people in the 
world.  But so far, no one has been able to demonstrate his or her acute 
sense to me yet. 

Xiaoshu

Received on Wednesday, 1 July 2009 15:39:36 UTC