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Re: A certain difficulty

From: David Megginson <david@megginson.com>
Date: Sat, 26 Feb 2000 09:46:39 -0500 (EST)
Message-ID: <14519.59215.591548.36113@localhost.localdomain>
To: xml-dev@xml.org, www-rdf-interest@w3.org
Len Bullard writes:

 > But why not just exchange the serialized objects?  IOW, is RDF doing 
 > something I can't do with Java, C++, etc.?  I have this uncomfortable 
 > feeling RDF ends up being MID0.1:  what we were doing before they 
 > told us not to do an object-oriented programming language.  Oh well...

If there were a single programming language used everywhere and it had
a single, standard serialization format, that might work, but there's
not and it won't.  Besides, a looser coupling is somewhat beneficial,
so that different recipients can re-instantiate the serialized objects 
in different ways.  I like to explain it to people like this:

  Data Model <-> Object Model <-> Interchange Model

The level of abstraction increases as you move from left to right.

 > > RDF is suboptimal for this, but it gets a lot of things right
 > > (i.e. extensibility) and there doesn't seem to be another
 > > reasonable candidate out there yet.
 > 
 > See last question.  It seems we keep coming back through this time 
 > loop of development:  markup to wrap named property values, then 
 > more markup to define the names of the names of the property values, 
 > then more markup to define the relationships among the names of the 
 > names of the property values.  Jeez.  No wonder HTML became popular. :-)

There are several things you can be referring to here, and I'm not
sure which you mean (schemas?).  Anyway, I'm not interested in all of
that semantic-discovery stuff; all I want is a standard way to
serialize objects:

  <Person global-id="http://www.people.org/ids/12345">
    <name>David Megginson</name>
    <nationality>CA</nationality>
    <parent global-ref="http://www.people.org/ids/54321"/>
  </Person>
   
  <Person global-id="http://www.people.org/ids/54321">
    <name>Marylil Megginson</name>
    <nationality>CA</nationality>
  </Person>

When I receive stuff like this, I shouldn't have to start down at the
DOM or SAX level; it should be possible for an API to give me this:

  Object [http://www.people.org/ids/12345]
    attribute:    name="David Megginson"
    attribute:    nationality="CA"
    relationship: parent=http://people.org/ids/54321

  Object [http://www.people.org/ids/54321]
    attribute:    name="Marylil Megginson"
    attribute:    nationality="CA"

No schemas ... no extra markup to say what names mean ... just a
higher layer of abstract above the XML elements-attributes-characters
data model, so that I can hire Java or C++ or Perl programmers who
have no XML knowledge and have them work on information-exchange
projects.  I took a stab at creating such an API with DATAX

  http://www.megginson.com/DATAX/

and although that needs work, I think it's close to what a
data-exchange API should look like.
   
Yes, RDF already lets me do all of this; I claim that it's suboptimal
only because it tries to do too much more (and thus, scares people
away).


All the best,


David

-- 
David Megginson                 david@megginson.com
           http://www.megginson.com/
Received on Saturday, 26 February 2000 09:47:07 GMT

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