Re: URI Fragments

[Kingsley Idehen]

Nathan wrote:
Hi Again :)

Last question(s) related to fragments.. if I have:
  http://example.org/something
  http://example.org/something#a

Those are two unique URIs and thus two unique resources (?)
  
My world view (i.e. I don't do Resource and Information Resource lingo):

Careless and dangerous, but accurate.

1. http://example.org/something  -- a resource URI
2. http://example.org/something#a -- a resource URI


Less confusing, assuming you are have a # terminated URI pattern in play:

1. http://example.org/something  -- a resource URL
2. http://example.org/something#a -- a data object URI (if we are talking about 
a commonly used Linked Data pattern, then URL above would be conduit to the EAV 
model based representation of the description of this data object)



And the semantics of a fragment means that
http://example.org/something#a is a secondary resource, where
http://example.org/something is the primary resource (?)
  
Sorta.
Then if I delete a Primary resource, the secondary resources must also
be deleted, true / false (?).
  
Not necessarily, this really depends on the Linked Data pattern you've 
adopted re. generic HTTP URIs. Basically, the pattern you've adopted 
such that  that you to Reference a Data Object and Access a 
Representation of its Description via a single URI.

Here are some examples, which may seem like over kill but some are
interesting and generally I *feel* rules like this should be either
always true, or always false, never varying.

examples:
if I remove a database table, then all it's rows also no longer exist.
if I remove London then the Tower of London also no longer exists.
if somebody removes me, then my arms also no longer exist.
if I remove test.html then test.html#whatever no longer exists.
if I remove test.rdf then test.rdf#this no longer exists
if I remove http://www.w3.org/People/Berners-Lee/card then
http://www.w3.org/People/Berners-Lee/card#i no longer exists.
  
No, you've lost access to description of:  
<http://www.w3.org/People/Berners-Lee/card#i>, of course it still exists 
:-)
conversely:
if I remove a row, the table still exists
if I remove the Tower of London, London still exists
if you remove my arms, I still exists and I'll find another way to type.
if I remove test.html#whatever test.html still exists
if I remove test.rdf#this, test.rdf still exists
if I remove http://www.w3.org/People/Berners-Lee/card#i then
http://www.w3.org/People/Berners-Lee/card still exists.
  
How do you remove: <http://www.w3.org/People/Berners-Lee/card#i> ? Let's 
say you take it out of <http://www.w3.org/People/Berners-Lee/card>, then 
for agents that seek description of 
<http://www.w3.org/People/Berners-Lee/card#i> via aforementioned URL, 
you get nothing. Nothing stops the 
<http://www.w3.org/People/Berners-Lee/card#i> description existing in my 
linked data space :-)
If the above is true (secondary resource must also be deleted on removal
of primary resource),
Not true .
 then I should never use a fragment Identifier to
refer to a non-virtual object (i.e. "me" a Person) - because I can't be
deleted by simply removing a resource. (?)
  
Best to think about the issue of "Identifier" as absolutely distinct 
from "Representation".

Links:

1. 
http://www.cs.cmu.edu/afs/cs.cmu.edu/user/clamen/OODBMS/Manifesto/htManifesto/node4.html 
-- might come in handy re. Identifier matters .


Kingsley
Regards!

Nathan


  


--

Regards,

Kingsley Idehen	      
President & CEO 
OpenLink Software     
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
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