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Re: Subjects as Literals

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Wed, 30 Jun 2010 15:31:17 -0400
Message-ID: <4C2B9B85.4090707@openlinksw.com>
To: David Booth <david@dbooth.org>
CC: nathan@webr3.org, Pat Hayes <phayes@ihmc.us>, Toby Inkster <tai@g5n.co.uk>, Dan Brickley <danbri@danbri.org>, Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>
David Booth wrote:
> On Wed, 2010-06-30 at 14:30 -0400, Kingsley Idehen wrote:
>> Nathan wrote:
>>> Pat Hayes wrote:
> [ . . . ]
>>> Surely all of the subjects as literals arguments can be countered with 
>>> 'walk round it', and further good practise could be aided by a few 
>>> simple notes on best practise for linked data etc.
>> IMHO an emphatic NO.
>> RDF is about constructing structured descriptions where "Subjects" have 
>> Identifiers in the form of Name References (which may or many resolve to 
>> Structured Representations of Referents carried or borne by Descriptor 
>> Docs/Resources). An "Identifier" != Literal.
>> If you are in a situation where you can't or don't want to mint an HTTP 
>> based Name, simply use a URN, it does the job.
> Can you explain *why* you think literals should not be permitted as
> subjects?  The rationale you have given above sounds like it is saying
> that literals should not be subjects because RDF does not permit
> literals to be subjects.  
> IMHO, RDF should allow "anyone to say anything about anything" -- not
> "anyone to say anything about anything . . . except a literal".
> However, if you see some specific harm in permitting statements about
> literals, please tell us what that harm would be.
Harm isn't of the "breaks anything variety". It just adds ambiguity to 
the process of producing structured descriptions within Web realm.

I could flip this around and ask: what makes a pure URN or other 
identification schemes (that may or may not resolve to anything) 

I am of the assumption that we are seeking globally unambiguous names 
(which may or may not resolve) re. Web of Linked Data aspect of Semantic 
Web continuum.

RDBMS engines support literal identifiers, and the consequences are:

1. Distributed RDBMS tedium -- due to object ambiguity across 
Qualifier/Schema/Database, Owner, and actual Object Name (Tables, Views, 
Procedures) names
2. Security problems -- users are Identified using literals instead of 
proper identifiers (as demonstrated by FOAF+SSL [3]  WebIDs you can 
provide blockers to socially engineered RDBMS vulnerability via 
verifiable identity + data access policies).


1. http://en.wikipedia.org/wiki/Identifier
2. http://en.wikipedia.org/wiki/Unique_identifier
3. http://esw.w3.org/Foaf%2Bssl



Kingsley Idehen	      
President & CEO 
OpenLink Software     
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen 
Received on Wednesday, 30 June 2010 19:32:01 UTC

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