A few lessons I have learned (June, '03)

Hi Folks,

Below are a few principles which I hold to be true:

1. Frequently, data endures but the applications which processes the
data comes and goes.

2. Separate everything:

   - separate data from presentation
   - separate data from applications that process the data
   - separate semantic definitions from application code
   - separate hyperlink definitions from data (put hyperlink 
     definitions in a linkbase)

2. Freedom is not "do anything you want".  That is chaos.  Unbridled XML
leads to chaos.  Freedom is brought about through discipline.  Bring
order to instance data by conforming to a design pattern.  

    The RDF Class/Property/Value design pattern seems like a 
    good choice to control the chaos.

3. Minimize exacting requirements on the *form* of instance documents. 
Expect diversity of expression. 

    Corollary: In designing schemas apply liberal quantities 
               of <any> and <all>; minimize use of <sequence>
               and minOccurs="1".

4. Take a step forward to machine understanding of instance data by
documenting how the data relates to other things in the world: How does
the class of data in the instance document relate to other classes of
data? What are the characteristics of the properties?  Answers to these
questions constitute a logical model.  

    OWL seems like a good choice for declaratively expressing 
    logical models. 

I invite your suggestions for deletions/extensions/modifications to this
list. /Roger