xml-dev - RE: RDF Sample, ICAO Airport Codes

["Didier PH Martin" <martind@netfolder.com>]

Hi David,

In fact, originally RDF was designed to provide metadata about resources.
However, we can say that its rich definition constructs make it a perfect
candidate to data exchange. Or said differently, a way to exchange data base
data. A RDF element or description could be easily associated to a record.

We can then say that RDF provided some interesting side effects  not
necessarily originally intended :-).

In your example you used URLs and more particularly http based URLs, I am
not so sure it is the right kind of URI to uniquely identify a record or
more particularly to uniquely identify a record in an exchange format
between databases. It would be better to employ a location independent or
more simply a protocol agnostic URI for the element's identification.

regards
Didier PH Martin
mailto:martind@netfolder.com
http://www.netfolder.com

-----Original Message-----
From: owner-xml-dev@ic.ac.uk [mailto:owner-xml-dev@ic.ac.uk]On Behalf Of
David Megginson
Sent: Friday, July 30, 1999 1:47 PM
To: xml-dev@ic.ac.uk
Subject: Re: RDF Sample, ICAO Airport Codes


Satya.Rao@chase.com writes:

 > The first line in RDF specification says
 >
 > "The Resource Description Framework (RDF) is a foundation for processing
 > metadata"
 >
 > I thought this is the major use of the RDF. For serializing the
 > entities can't we use XML?

RDF is a layer of abstraction that can be used on top of XML to
provide a better view of serialized objects.

If lots of applications need to process serialized objects, it doesn't
make sense to force them all to do fairly low-level XML handling:
applications for data exchange will usually care about entities
(objects) and their attributes and relationships (properties), not
about elements, attributes, and character data.

By way of illustration, here are the major layers involved in one
particular (imaginary) process:

1. UTF-8 encoding - specifies the actual character encoding used in a
         file.
2. Unicode - specifies the abstract character points available,
         without requiring specific knowledge of the character
         encoding used.
3. XML - specifies a serialized version of a tree with typed nodes,
         without requiring specific knowledge of the characters used.
4. RDF - specifies the interpretation of the tree as a series of
         entities with attributes and relationships, without requiring
         specific knowledge of the elements and attributes used.
5. Application - processes the entities in the abstract, and builds a
         domain-specific object tree.
6. Database - stores the object tree in SQL tables.

If you make the jump straight from #3 to #6 (for example), you'll have
to write and maintain a lot of unnecessary code.


All the best,


David

--
David Megginson                 david@megginson.com
           http://www.megginson.com/

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