Re: Naive question on redirection.

On Jun 6, 2008, at 2:34 PM, Lee Feigenbaum wrote:

> Alan Ruttenberg wrote:
>> I would think you do know the color. The 302 says the resource can  
>> be found elsewhere for the moment. So it is supposed to be the  
>> same resource. However, once the server stops responding with a  
>> 302 to this address, or the caching information says it is stale,  
>> all bets are off.
>> -Alan
>
> I hope that's not the case. If 302 implies owl:sameAs then I can't  
> make separate statements about two different URLs representing two  
> formats of the same resource (I know I'm messing up the terminology  
> here) accessed via content negotiation.

You already can't make separate statements about negotiated  
representations. At least not on the primary URIs. That's why I don't  
like CN. If you wanted to make a mime type assertion on a resource  
you would need to know that it is a fixed resource - and a get of the  
URI could not return a different format.

> <http://thefigtrees.net/id> a foaf:PerosnalProfileDocument .
>
> 302's based on Accept: headers to either
>
> http://thefigtrees.net/id.n3
> http://thefigtrees.net/id.rdf

That's not how CN is supposed to work. You respond to the request  
with the representation, not with a redirection. The Location header  
is where the resource is. 302 is different.

302 Found
The requested resource resides temporarily under a different URI.  
Since the redirection might be altered on occasion, the client SHOULD  
continue to use the Request-URI for future requests.

Not: you can find a different resource - a fixed resources, which  
happens to have an awww:representation that is the same as the one  
redirected from.

> What if I wanted to include an ex:mimeType triple about the latter  
> ones?

Go ahead. However I don't think 302 is appropriate in that case.  
Respond with the representation to the original request, and put  
these URLs in the Location: header. Then there is no encumbrance.

>
> <http://thefigtrees.net/id.rdf> a foaf:PerosnalProfileDocument ;  
> ex:mimeType "application/rdf+xml" .
>
> Or are you suggesting that this is some strange one-way  
> equivalence? (If X -- 302 --> Y and X p q then Y p q?)

I'm not trying to suggest anything. I'm trying to answer according to  
what the specs say. I'd be happy to be shown to be wrong, either  
because the specs don't mean what I think they do, or because there  
is contradictory information somewhere else, or with an assertion  
that the specs need to be fixed.

-Alan

(don't you just love those "naive" questions?)

> Lee
>
>> On Jun 6, 2008, at 4:57 AM, Phil Archer wrote:
>>>
>>> Suppose I have this triple
>>>
>>> <http://example.org/> ex:colour "red"
>>>
>>> and when I dereference the URI I get a 302 redirect to http:// 
>>> www.example.org/home.asp.
>>>
>>> Do I know what colour http://www.example.org/home.asp is?
>>>
>>> I'm pretty sure the answer's no, but has anyone else grappled  
>>> with the joys of redirects in this way?
>>>
>>> Phil.
>>>
>>> -- 
>>> Phil Archer
>>> Chief Technical Officer,
>>> Family Online Safety Institute
>>> w. http://www.fosi.org/people/philarcher/
>>>
>>>
>>>
>>>

Received on Friday, 6 June 2008 18:54:56 UTC