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RE: Sample schema extension models

From: Butler, Mark <Mark_Butler@hplb.hpl.hp.com>
Date: Thu, 5 Jun 2003 17:52:07 +0100
Message-ID: <5E13A1874524D411A876006008CD059F066A1D2A@0-mail-1.hpl.hp.com>
To: "'Jason Kinner'" <jason_kinner@dynamicdigitalmedia.com>, www-rdf-dspace@w3.org

Hi team, 

I've been puzzling over the graphs of these three examples all day. I'm not
clear why we need this level of complexity, or what it buys us, apart from
compatibility with Harmony. I don't like inheriting complexity, I think we
should try to avoid it. One of the key ideas of extreme programming is keep
out complexity until you are sure you need it, because it is always easier
to refactor something that is simple than it is to refactor something that
is complex. 

One of the problems is analysing the graphs in itself is quite hard, because
as programmers we are not used to dealing with graphs that much. I prefer to
think of things as tuples in database tables or as data objects. For example
consider if we convert the first graph to data objects (apologies for making
up a new notation here) we get 7 data objects:

urn1
 type: Created
 precedes: urn3
 hasAction: urn2
 hasPatient: hdl:1234/123

urn2
 type: Create
 creates: hdl:1234/123

urn3 
 type: Situation

urn4
 type: Modified
 hasPatient: hdl:1234/123
 preceds: urn5

urn5
 type: Situation

hdl:1234/123;1
 type: Item
 phaseOf: hdl:1234/123
 title: MyExample

hdl:1234/123;2
 type: Item
 phaseOf: hdl:1234/123
 title: Our Example

So we have this strange distinction between Events, Actions and Situations,
but its not clear to me how this helps. For example I think we can easily
use just 4 data objects to do the same thing e.g.

event1
 type: Creation
 precedes: event2
 hasResult: hdl:1234/123;1

event2 
 type: Modification
 follows: event1
 hasPatient: hdl:1234/123;1
 hasResult: hdl:1234/123;2

hdl:1234/123;1
 type: Item
 identity: hdl:1234/123
 version: 1
 title: MyExample

hdl:1234/123;2
 type: Item
 identity: hdl:1234/123
 version: 2
 title: Our Example

where

Modification ISAsubClass Event
Creation ISAsubClass Event

So can anyone explain why we need the additional complexity?

best regards,

Dr Mark H. Butler
Research Scientist                HP Labs Bristol
mark-h_butler@hp.com
Internet: http://www-uk.hpl.hp.com/people/marbut/
Received on Thursday, 5 June 2003 13:17:20 EDT

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