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Re: URI Comparisons: RFC 2616 vs. RDF

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Mon, 17 Jan 2011 11:08:37 -0500
Message-ID: <4D346985.7030903@openlinksw.com>
To: Martin Hepp <martin.hepp@ebusiness-unibw.org>
CC: public-lod@w3.org
On 1/17/11 10:51 AM, Martin Hepp wrote:
> Dear all:
>
> RFC 2616 [1, section 3.2.3] says that
>
> "When comparing two URIs to decide if they match or not, a client  
> SHOULD use a case-sensitive octet-by-octet comparison of the entire
>    URIs, with these exceptions:
>
>       - A port that is empty or not given is equivalent to the default
>         port for that URI-reference;
>       - Comparisons of host names MUST be case-insensitive;
>       - Comparisons of scheme names MUST be case-insensitive;
>       - An empty abs_path is equivalent to an abs_path of "/".
>
>    Characters other than those in the "reserved" and "unsafe" sets (see
>    RFC 2396 [42]) are equivalent to their ""%" HEX HEX" encoding.
>
>    For example, the following three URIs are equivalent:
>
>       http://abc.com:80/~smith/home.html
>       http://ABC.com/%7Esmith/home.html
>       http://ABC.com:/%7esmith/home.html
> "
>
> Does this also hold for identifying RDF resources

Yes, where an RDF resource is a Data Container at an Address (URL). 
Thus, equivalent results for de-referencing a URL en route to accessing 
data.

No, when "resource" also implies an Entity (Data Item or Data Object) 
that is assigned a Name via URI.

The examples above strike me as URLs. Of course,  cURL could indicate 
otherwise, but for now (via my visual senses) they appear to be URLs 
(resource addresses).

>
> a) in theory and
> b) in practice (e.g. in popular triplestores)?
>
> I did not test it yet, but I assume that not all implementations would 
> treat
>
>    http://purl.org/NET/c4dm/event.owl#Event
>    HTTP://purl.org/NET/c4dm/event.owl#Event
>    http://PURL.org/NET/c4dm/event.owl#Event
>    http://purl.org:80/NET/c4dm/event.owl#Event
>
> as the same class.
>
> Any facts or opinions?

See my comments above.

Kingsley

>
> Best
>
> Martin
>
>
> [1] http://www.ietf.org/rfc/rfc2616.txt
>
> --------------------------------------------------------
> martin hepp
> e-business & web science research group
> universitaet der bundeswehr muenchen
>
> e-mail:  hepp@ebusiness-unibw.org
> phone:   +49-(0)89-6004-4217
> fax:     +49-(0)89-6004-4620
> www:     http://www.unibw.de/ebusiness/ (group)
>          http://www.heppnetz.de/ (personal)
> skype:   mfhepp
> twitter: mfhepp
>
>
>


-- 

Regards,

Kingsley Idehen	
President&  CEO
OpenLink Software
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
Received on Monday, 17 January 2011 16:09:19 UTC

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