Re: Naive question on redirection.

On Jun 6, 2008, at 3:11 PM, Lee Feigenbaum wrote:

> I should have prefaced my comments by saying that I've never dug  
> deeply into this, and have just tried to learn from what I've heard  
> and seen from others. So I'm speaking from a position of inexperience.
>
> Alan Ruttenberg wrote:
>
>>> <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.
>
> I got my example from the recent SWEO publication, "Cool URIs for  
> the Semantic Web". Please see:
>
> http://www.w3.org/TR/cooluris/#conneg
>
> is that example incorrect?

This one, I presume.
> Content negotation is often implemented with a twist: Instead of a  
> direct answer, the server redirects to another URL where the  
> appropriate representation is found:
>
> HTTP/1.1 302 Found
> Location: http://www.example.com/people/alice.en.html
> The redirect is indicated by a special Status Code, here 302 Found.  
> The client would now send another HTTP request to the new URL. By  
> having separate URLs for different representations, this approach  
> allows Web authors to link directly to a specific representation.
>
>

It looks incorrect to me. But what do I know? I just read the specs.

Also incorrect: One doesn't link to (awww) representations, one links  
to resources.

They also say:

> Note that the URI of this representation is passed back in the  
> Content-Location header, this is not required but a recommended  
> good practice
>
>
I'd say in your case it would be required ;-)

-Alan


(You are in a maze of twisty passages, all alike.)

>
> Lee
>
>> 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 20:10:03 UTC