W3C home > Mailing lists > Public > public-xg-webid@w3.org > December 2011

Re: Redirects continued -- was: Problem with certificate on home-grown WebID

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Wed, 21 Dec 2011 12:13:58 -0500
Message-ID: <4EF213D6.7020507@openlinksw.com>
To: public-xg-webid@w3.org
On 12/21/11 11:19 AM, Henry Story wrote:
> On 21 Dec 2011, at 16:57, Pierre-Antoine Champin wrote:
>> Hi,
>> I had the same misunderstanding as Sebastian, creating WebID
>>   http://champin.net/pa
>> I now created
>>   http://champin.net/#pa
>> (which I too prefer, btw).
>> But that one does not work with foafssl.org :-(
> That's because at present it does not have redirection implemented and you resource redirects
> $ curl -i  http://champin.net/
> HTTP/1.0 302 Found
> Server: BaseHTTP/0.3 Python/2.5.2
> Date: Wed, 21 Dec 2011 16:15:10 GMT
> Location: http://liris.cnrs.fr/~pchampin/
> Content-type: text/html
> Vary: Host

But this is an implementation flaw. You are supposed to de-reference 
URIs. You shouldn't assume the level of indirection between a URI and an 
actual Resource.  Just de-reference the URI leaving HTTP do the REST.

>> I attach the result page. It says
>>   The WebId Profile must be parseable Content and transformable to an
>>   RDF graph
> yep, if I were to be serious about redirects I'd have to change that to say: we don't work with
> redirects....

Come on!

> Since we are looking for use case for webids that redirect, let me ask you: why did you find
> it important to have your webid redirect?

Please talk about URIs. The publisher of a URI is the one that 
determines how it resolves. That isn't for any user agent to decide. 
Speak HTTP that's it.

> Henry
>> but RDF Validator is happy with it:
>> http://www.w3.org/RDF/Validator/ARPServlet?URI=http%3A%2F%2Fchampin.net%2F&PARSE=Parse+URI%3A+&TRIPLES_AND_GRAPH=PRINT_TRIPLES&FORMAT=PNG_EMBED
>> and it is recognized by https://auth.fcns.eu/
>>   pa
>> On 12/21/2011 02:30 PM, Henry Story wrote:
>>> On 21 Dec 2011, at 14:05, Sebastian Trüg wrote:
>>>> On 12/21/2011 11:19 AM, Henry Story wrote:
>>>>> On 21 Dec 2011, at 09:55, Sebastian Trüg wrote:
>>>>>> Attached you find the result from https://foafssl.org/test/WebId. To be
>>>>>> honest I am not sure if it succeeded or not, the output confuses me. :/
>>>>> yes, the output of this test suite is not as well finished as the previous
>>>>> one. And there is a bug there, I'll fix.
>>>>> Ok, so you are using a WebID that redirects. I would suggest against it for
>>>>> two reasons:
>>>>> -1. It increases the verification time for the verifier: the verifier has
>>>>>    to potentially do 2 HTTP connections, and in any case it has to do back
>>>>>    and forth
>>>>> -2 It is possible that some implementations don't support redirect, as it is
>>>>>    one of these less obvious features of the web. As soon as you add complexity
>>>>>    you add ways things can go wrong, and your identity is perhaps important
>>>>>    enough for you not to want these things to go wrong
>>>>>    (In this case my implementation does not support it. But I can add it)
>>>>> -3 We believe we have worked out the security characteristics of redirects,
>>>>>    but they are less obvious than the simple GET and will require more work,
>>>>>    so we have no language in the spec at present covering those - it's undefined
>>>>>    one might say. In any case they confuse Peter Williams, and risk confusing
>>>>>    military grade security people a lot more. So if you want to log in to higher
>>>>>    security sites you may find redirects create confusion with those people
>>>>>    implementing them. This comes up in ISSUE-64
>>>>>    http://www.w3.org/2005/Incubator/webid/track/issues/64
>>>>> Does that make sense?
>>>> Well, yes. However, I am confused. You directed me to the site which I
>>>> took this setup from.
>>> http://www.w3.org/TR/2008/NOTE-swbp-vocab-pub-20080828/
>>> Yes, it is true that the "Best Practice Recipes for Publishing RDF Vocabularies"
>>> covers two cases one of which uses a redirect. The redirect is as we mentioned
>>> may require us to think things through in a bit more detail, though I don't think
>>> it is a big issue.
>>>> Also you mentioned that it would be nicer to have
>>>> web ids like http://www.trueg.de/sebastian instead of something like
>>>> http://www.trueg.de/sebastian/foaf[#me].
>>>> So which is it? :)
>>> I think I mentioned WebIDs like
>>> http://www.trueg.de/sebastian#me
>>> rather than
>>> http://www.trueg.de/sebastian.rdf#me
>>> not
>>> http://www.trueg.de/sebastian
>>> with a redirect.
>>> I think there is a pragmatic consideration in favour of the # one to do with reduction
>>> in communication costs.
>>> But you are right that this would do well to be more clearly specified in the
>>> spec.
>>>>>    So having said that there are a number of redirect types,
>>>>> http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
>>>>> 	300 Multiple Choices
>>>>> 	301 Moved Permanently
>>>>> 	302 Found  // we can ignore this one
>>>>> 	303 See Other
>>>>> 	304 Not Modified
>>>>> 	305 Use Proxy
>>>>> 	307 Temporary Redirect
>>>>> and one needs to consider which of these have what types of security implications, if any.
>>>>> Perhaps there is not much more to do here than to just think it though. But if we want to
>>>>> help implementors implement the WebId protocol so that you get a consistent experience between
>>>>> each verification service, and so that you are not left out in the cold inexplicably
>>>>> some places and not others, then we need to work this out. As you see it is easier and more
>>>>> efficient to stick to #urls.
>>>>> The question is if there are any good rason for non #urls in our authentication use case.
>>>> Only the prettyness of the URL which should be irrelevant in the end
>>>> since the point is to not show it to the user, right.
>>> yes, that alone would not make for a very good reason. Perhaps there are others. It would
>>> be good to collect them.
>>>> I simply followed your advise, or maybe misunderstood your advise...
>>> No you are doing well :-) You're helping us think about this issue 2^6 here. It's an important
>>> one.
>>> Henry
>>>> Cheers,
>>>> Sebastian
>>>>> Henry
>>>>>> Cheers,
>>>>>> Sebastian
>>>>>> On 12/20/2011 10:44 PM, Henry Story wrote:
>>>>>>> Ok, I have updated the server to the new scala version.
>>>>>>> I hope it remains up until you read this e-mail. I am still working on the details
>>>>>>> of how to release it. But if it is still up please let me know if it works now
>>>>>>> with your key.
>>>>>>> Henry
>>>>>>> [snip]
>>>>> Social Web Architect
>>>>> http://bblfish.net/
>>> Social Web Architect
>>> http://bblfish.net/
>> <WebId.html>
> Social Web Architect
> http://bblfish.net/



Kingsley Idehen	
Founder&  CEO
OpenLink Software
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Received on Wednesday, 21 December 2011 17:14:25 UTC

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