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Re: URIs in @rel and @property...

From: Mark Birbeck <mark.birbeck@webbackplane.com>
Date: Tue, 17 Nov 2009 14:17:11 +0000
Message-ID: <640dd5060911170617v65e5084ay27b33e581b82720e@mail.gmail.com>
To: Niklas Lindström <lindstream@gmail.com>
Cc: Ivan Herman <ivan@w3.org>, Ben Adida <ben@adida.net>, RDFa <public-rdf-in-xhtml-tf@w3.org>
Hi Niklas,

I'm not sure you can call it a "problem". As long as the rules of
interpretation are clear, then authors are free to do what they want
within the context of those rules.

In this particular case, I'd say that if someone defines a
prefix-mapping that matches a URL scheme, then hopefully, they know
what they are doing.

Regards,

Mark

--
Mark Birbeck, webBackplane

mark.birbeck@webBackplane.com

http://webBackplane.com/mark-birbeck

webBackplane is a trading name of Backplane Ltd. (company number
05972288, registered office: 2nd Floor, 69/85 Tabernacle Street,
London, EC2A 4RR)



2009/11/17 Niklas Lindström <lindstream@gmail.com>:
> Another point though. Isn't there a problem if prefixes are declared
> for existing protocols?
>
> When prefixes are declared for e.g.:
>
>    xmlns:http="http://www.w3.org/2006/http#"
>    xmlns:tag="http://example.org/tagging#"
>
> With the proposed rules ("unsafe CURIE or URI"), wouldn't these:
>
>    about="http://example.org/me"
>    resource="tag:example.org,2009:item:1"
>
> be resolved against those prefixes (instead of as-is)?
>
> Best regards,
> Niklas
>
>
> 2009/11/16 Niklas Lindström <lindstream@gmail.com>:
>> Ah, but indeed! Good elephant-hunting Mark! ;) It's quite comforting
>> that RFC 3986 is so precise about these things.
>>
>> (I should have known that -- I now recall reading that very same rule
>> a couple of months ago when investigating the legality of non-escaped
>> colons in URI:s. Only remembered half of it apparently.)
>>
>> Best regards,
>> Niklas
>>
>>
>> 2009/11/16 Ivan Herman <ivan@w3.org>:
>>> Pfew...:-)
>>>
>>> Ivan
>>>
>>> P.S. Mark-the-elephant-hunter:-)
>>>
>>> Mark Birbeck wrote:
>>>> Hi Ivan/Niklas,
>>>>
>>>> 2009/11/16 Ivan Herman <ivan@w3.org>:
>>>>> Hi Niklas,
>>>>>
>>>>> Niklas Lindström wrote:
>>>>>>> So is there an elephant?:-)
>>>>>> I haven't followed this discussion to closely, so I want to check if
>>>>>> this the following is considered:
>>>>>>
>>>>>> This usage will "muddle the waters" in cases when the relative URI:s
>>>>>> contain colon, and there is a prefix with the same name as the leading
>>>>>> part before that, right? Concrete (but contrieved) example:
>>>>>>
>>>>>> Given:
>>>>>>     - base URI: <http://en.wikipedia.org/wiki/>
>>>>>>     - prefix Talk: <http://example.org/schema/talk#>
>>>>>>
>>>>>> When:
>>>>>>     @resource="Talk:Linked_Data"
>>>>>>
>>>>>> Then:
>>>>>>     - URI becomes < http://example.org/schema/talk#Linked_Data>,
>>>>>> instead of <http://en.wikipedia.org/wiki/Talk:Linked_Data>, which is
>>>>>> might be expected?
>>>>>>
>>>>> Hm. You may found the elephant:-)
>>>>>
>>>>> Yes, in this case one would indeed get the example.org URI.
>>>>>
>>>>> The question is: is this use case so strong as to nullify the advantages
>>>>> of using CURIE-s in @about? Indeed, wikipedia uses such URI-s with ':'
>>>>> quite a lot but the user can of course put full URI-s into the value of
>>>>> @about...
>>>>>
>>>>> Thanks!
>>>>
>>>>
>>>> Whoah...slow down. :)
>>>>
>>>> "Talk:Linked_Data" is not a relative path!
>>>>
>>>> Forget prefixes, CURIEs, whatever...even if those things did not
>>>> exist, how would a URI processor know whether "Talk:" is a scheme or
>>>> just part of a relative path?
>>>>
>>>> RFC 3986 [1] addresses this in the following way:
>>>>
>>>>   A path segment that contains a colon character (e.g., "this:that")
>>>> cannot be used as the
>>>>   first segment of a relative-path reference, as it would be mistaken
>>>> for a scheme name.
>>>>   Such a segment must be preceded by a dot-segment (e.g.,
>>>> "./this:that") to make a
>>>>   relative-path reference.
>>>>
>>>> So, if people are using relative paths that contain colons, in the
>>>> wild, then there's a problem, and that problem is completely
>>>> independent of RDFa.
>>>>
>>>> Regards,
>>>>
>>>> Mark
>>>>
>>>> [1] <http://www.ietf.org/rfc/rfc3986.txt>
>>>>
>>>> --
>>>> Mark Birbeck, webBackplane
>>>>
>>>> mark.birbeck@webBackplane.com
>>>>
>>>> http://webBackplane.com/mark-birbeck
>>>>
>>>> webBackplane is a trading name of Backplane Ltd. (company number
>>>> 05972288, registered office: 2nd Floor, 69/85 Tabernacle Street,
>>>> London, EC2A 4RR)
>>>
>>> --
>>>
>>> Ivan Herman, W3C Semantic Web Activity Lead
>>> Home: http://www.w3.org/People/Ivan/
>>> mobile: +31-641044153
>>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>>> FOAF: http://www.ivan-herman.net/foaf.rdf
>>>
>>>
>>
>
Received on Tuesday, 17 November 2009 14:17:46 UTC

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