W3C home > Mailing lists > Public > www-rdf-interest@w3.org > April 2005

Re: SemWeb Non-Starter -- Distributed URI Discovery

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Sun, 10 Apr 2005 20:28:23 +0300
Message-Id: <e5a1093ffeb3af6f0876f237d468655c@nokia.com>
Cc: www-rdf-interest@w3.org, dviner@apache.org
To: "ext Charles McCathieNevile" <charles@sidar.org>


On Apr 10, 2005, at 11:16, ext Charles McCathieNevile wrote:

> On Mon, 04 Apr 2005 15:39:45 +1000, Patrick Stickler 
> <patrick.stickler@nokia.com> wrote:
>
>> This is an interesting solution.  I definitely agree that it would 
>> restrict
>> the URI creator/originator's freedom.  However, what if we just used 
>> another
>> feature of HTTP to handle this?  I'm thinking of the Accept HTTP 
>> header.
>> Here's a snippet from the rfc 
>> (http://www.w3.org/Protocols/rfc2068/rfc2068)
>>  "
>> The Accept request-header field can be used to specify certain media
>>    types which are acceptable for the response. Accept headers can be
>>    used to indicate that the request is specifically limited to a 
>> small
>>    set of desired types, as in the case of a request for an in-line
>>    image.
>> "
>>  I think it should be feasible to issue this sort of request:
>>  GET /food/blah HTTP/1.1
>> Host: example.com
>> Accept: application/rdf+xml
>
> Patrick replied
>>  Not to just jump in and jump out calously, but this has been
>> explored quite a bit for quite some time and content negotiation
>> is simply not the correct mechanism for this.
>>  C.f. the FAQ section of http://swdev.nokia.com/uriqa/URIQA.html ...
>>  Patrick
>
> I'm not so sure. I can see the problem if you see the world through 
> URIQA glasses, but I think outside of that it is not a bad answer.

The problem with this approach is that it does not
work if the resource in question has a "natural"
representation encoded in RDF/XML -- thus this
approach does not provide a sufficiently general
solution.

Consider just this one case:

You have some URI which identifies an RDF graph. One can
use content negotiation to obtain various representations
of that graph in various encodings.

A description *about* that graph is likely not subsumed
by that graph. Yet if you are using conneg to request
different representations of the graph, how do you use
conneg to request a description of the graph?

The graph itself, when serialized as RDF/XML might be
hundreds of megabytes (e.g. WordNet, Cyc, etc.) yet
the description of the graph will likely be quite small.

Content negotation serves a specific and well understood
purpose. Overloading it to do something else (even if you
can hack it to work here and there) is a bad idea.

Regards,

Patrick


>
> cheers
>
> Chaals
>
> -- 
> Charles McCathieNevile                      Fundacion Sidar
> charles@sidar.org   +61 409 134 136    http://www.sidar.org
Received on Sunday, 10 April 2005 17:29:10 GMT

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