W3C home > Mailing lists > Public > public-awwsw@w3.org > April 2008

Re: network endpoints

From: Jonathan Rees <jar@creativecommons.org>
Date: Mon, 28 Apr 2008 20:01:37 -0400
Message-Id: <848E2796-EA6C-4B5B-A5FF-ACB107028CB2@creativecommons.org>
Cc: "public-awwsw@w3.org" <public-awwsw@w3.org>
To: "Booth, David (HP Software - Boston)" <dbooth@hp.com>


On Apr 28, 2008, at 1:13 PM, Booth, David (HP Software - Boston) wrote:
>> From: Jonathan Rees [mailto:jar@creativecommons.org]
>> [ . . . ]
>> So I do not consider this a discussion on the definition of
>> awww:InformationResource. It may be unclear but we are not at liberty
>> to redefine it - it's published.
>
> I think we *need* to redefine it.  The published definition at
> http://www.w3.org/TR/2004/REC-webarch-20041215/#def-information- 
> resource
> is unworkable.  It is: (a) known to be flawed; (b) not how the rest  
> of the document implicitly defines it; and (c) not the actual  
> concept on which the Web architecture is based.

I agree that we need a new definition, and with your reasons. I don't  
agree that we should recycle the same name. I'm having this same  
argument with Alan about whether one ought to attempt a fresh  
definition of information resource...

We could have for example:
	awww:IR-as-explicitly-defined
	awww:IR-as-implicitly-defined
	dbooth:IR-on-which-web-architecture-is-based
or shorter names, or even serial numbers (although those would be  
hard to remember).

>> I consider what we're doing to be
>> (in part) an attempt to articulate the intended semantics and
>> recommended practice around 200 responses.
>
> Right, but I don't see how we can do that without a workable  
> definition of "information resource".

We need to find the right IR-like class, and define some name (URI or  
informal) to denote that class. We could recycle a name that exists,  
but for now I think it's less confusing to just use a different name.
>
> BTW, I just noticed an interesting miscommunication.  I've been  
> using the term awww:InformationResource to refer to the concept of  
> "information resource" that I believe the architecture of the WWW  
> *intended* (basically a function from time and requests to  
> representations) -- *not* how the term is currently defined at
> http://www.w3.org/TR/2004/REC-webarch-20041215/#def-information- 
> resource
> since that definition is erroneous.

Indeed. I have been using awww: generally to mean "in the sense of  
the AWWW document, even if we don't really understand or agree with  
it". But I think I see your point. We have a collision. Shall I  
change the name I'm using, or would you like to change yours?

Generally when I use "information resource" unqualified I am doing my  
best to understand what Tim means by it and/or what AWWW intends to  
mean by it, and I don't mind using a term I don't understand for the  
time being because I'm using it as a probe to find out what others  
think is and isn't "good" with respect to web architecture.

> If we can get back to use cases it would be helpful to me at least,  
> since I'm struggling to figure out what it is that folks are  
> finding difficult to do.  For example, I've offered an n3  
> definition of what can be inferred from a 200 response, but Alan  
> (privately) has complained that the inferred information is  
> tautological, so it seems like he's wanting something different,  
> but I don't know exactly what.  Would it help to look at an example  
> when viewing an IR as a function from time and requests to  
> representations?  We briefly looked at the relationship between  
> these two IRs in W3C's TR space:
>
>   http://www.w3.org/TR/rdf-mt/  (generic)
>   http://www.w3.org/TR/2004/REC-rdf-mt-20040210/ (dated URI)
>
> Would it be helpful to others to see those relationships between  
> those, and the rules that are used to infer them, coded in n3?  If  
> not, can someone suggest a use case example they'd like to see  
> analyzed?

It would be helpful to me to see how you would do it and contrast  
that with how others would do it, since I think your definitions of  
IR are materially different from those of some others in this group.

Here are some of the cases I'm thinking of:

1. I have two URIs X and Y. By varying Accept-Language I learn that I  
can retrieve French and Spanish variants of something via URI X, and  
Spanish and German variants of something via URI Y. The Spanish  
variants retrieved via X and Y are the same. All responses are 200s.

	- Is it possible that X and Y denote the same thing?
	- Is it possible that X and Y do *not* denote the same thing?
	    (assuming that responses are known to be time invariant.)
	- Is it necessary that X and Y do not denote the same thing?

2. Suppose that the values I retrieve (in different languages, say)  
via a URI X say contradictory things - for example, one says that  
Rome is the capital of Italy, and another says that Paris is the  
capital of Italy.

	- Does X denote an information resource, given that the values  
cannot both be representations of the same information?
	- If so, does it denote a "bad" information resource?
	- If not, what does it denote, if anything?
	- Assume unchanging whatever if necessary in order to make these  
questions nontrivial.

3. Suppose I set up a web server responding to requests for some URI  
X as follows:
	- A URI for an IR on the web is chosen at random and a value is  
fetched using that URI
	- The value is returned as the payload of a 200 response
Questions:
	- Does X denote an information resource?
	- If so, what information do its referent's representations represent?
	- If not, what could X's referent be, if it has one? Is it a "bad"  
information resource, or something else?
	- Is the web site behaving within the limits specified by RFC2616  
and/or AWWW?

All these questions can be expressed in RDF. I can come up with more  
cases like this, if you like, but I think you get the idea so let's  
start with these.

Jonathan
Received on Tuesday, 29 April 2008 00:02:13 GMT

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