[wsrp][wsia] Re: Proposal for simple properties mechanism based onXForms

Gil,

Thanks for giving this some thought and developing a proposal.  In last week's 
WSIA customization call we also discussed this problem, and after iterating 
over a few alternatives, converged to essentially the same solution as you 
(which gives me additional confidence).  I took an action item to write up and 
publish our proposal, but other tasks in the office kept me too busy and you 
beat me to it.  

Nonetheless, attached is the solution the customization group has been 
discussing, framed as a substitute for the existing property chapter in the 
joint spec (0.4).  I think it is very similar to your idea, with a couple 
of minor differences:

- we did not include the notion of default type bindings.  
- you suggest that getPropertyDescription() should return empty placeholders 
for instance data (i.e., the instance subtree without the leaves).  In our 
proposal, all properties must be explicitly bound, and thus given the set of 
bindings with their XPath references it is possible to automatically construct 
the property tree.  For example, given:
 <model>
  <bind ref="foo" .../>
  <bind ref="bar" .../>
 <model>
The corresponding
 <instance>
  <foo/>
  <bar/>
 </instance>
structure is implied.

I would like to better understand the motivation for your simplicity 
constraints and their relation to the extension items you listed -- are there 
to be three classes of property models?

I have concerns about leaving adherance to the other <bind> attributes to 
extensions.  For example, I question whether it is reasonable to specify that
even a simple Consumer may just ignore a "readonly" constraint placed on a 
property by a Producer.

Are extensions 3 and 4 different from 1 and 2?

Regards,
Tim