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Re: Uniform access to descriptions

From: Xiaoshu Wang <wangxiao@musc.edu>
Date: Sat, 12 Apr 2008 00:54:40 +0100
Message-ID: <47FFFA40.7080704@musc.edu>
To: Michaeljohn Clement <mj@mjclement.com>
CC: "www-tag@w3.org WG" <www-tag@w3.org>



Michaeljohn Clement wrote:
> Hi Xiaoshu,
>
>   
>> We agree that there are legacy data, yes?  Let's make its URI x, whose
>> owner is Joe.
>> Case 1. Joe is lazy.
>> Then, no LINK, no Conneg. Is this fair?
>> Case 2: Joe is not lazy.
>> (a) Joe makes LINK(x)=metadata.
>> (b) Joes make Conneg(x)=metadata (can easily GET x Accept
>> application/rdf+xml).
>>     
>
> (b) would be wrong, because the metadata is not an alternative 
> variant of the resource identified by x.
>   
Why wrong? First define metadata?  Say _:x _:b _:y.  Is this assertion 
metadata of _:x or _:b or _:y?  You assume it is wrong because of an 
arbitrary definition of metadata. In your proposal, any RDF 
transformation is the metadata of an HTML, they should be put in LINK too. 
> Surely there may be more than one application/rdf+xml resource that 
> might be associated in some way with the resource identified by x, 
> right?  It's impossible to distinguish between these by using conneg.
>   
This is the reason.  Perhaps it is not I who have failed to understand 
the <LINK> problem, it is you who have failed to understand Conneg.
> If the only purpose of the Link: header would be the same as the 
> purpose of the HTML <link rel=alternate>, then surely (b) would be 
> more relevant, but the Link: header can express other relations as 
> is being discussed here, viz "describedBy".
>
> The only way (b) can be correct here is if the result of a GET with 
> Accept: application/rdf+xml is actually just a variant representation 
> of the same resource.
>   
What do you mean *just* a variant?  All representations bound to the 
resource 'x' identifies x.  It may be of different format, different 
language, but they are all talking about the same resource - that is 
what matters. 

Of course, this goes back to my request for TAG to delineates the 
meaning of /representation/ vs. /resource/. Without it, any discussion 
on <LINK> is a waste of time.

Xiaoshu
Received on Friday, 11 April 2008 23:55:23 GMT

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