RE: [xml-dev] Are people really using Identity constraints specified in XML schema?

["Hunsberger, Peter" <Peter.Hunsberger@STJUDE.ORG>]

w3c@drrw.info writes:

> Len,
> 
> This made me smile thinking about stored procedure and 
> print-statement heaven. 
> CAM certainly does not have any lock-in on doing that classic 
> content-merge-output stuff.  It's just another option in that 
> particular camp. 
> 
> 
> The differentiator vis SQL is that CAM can work directly off 
> an input XML instance as its content source.  How that XML 
> get generated or sourced is entirely down to the implementer 
> naturally.
> 
> So - that's one way to use CAM - the other way is as a 
> validation tool. So people can answer the question - does my 
> xml instance here conform to your business rules?  And if not 
> - why not!
> 
> This brings a whole another aspect - where you can publish 
> the CAM template as the yard-stick as it where for creating 
> valid instances.
> 
> In amongst this - you will pretty soon get into wanting to 
> create dictionaries of element and attribute definitions 
> across schemas - not just local definitions. CAM supports 
> this via the <CcontentReference> section of the template - 
> and ability to denote linkage between your instance nodes and 
> central definitions in a registry.
> 
> This then opens up the possiblity to label things in your XML 
> to suit local usage - but actually refer to the standard name 
> and definition in the dictionary - thus indicating they are 
> the same thing in reality.
> 
> So <billAddr> and <billingAddress> and <bToAd> can all be 
> denoted as the same, etc.

Interesting.  So my earlier response to Bruce Cox's "With XML Schema
data typing, followed by Schematron, what would come next to cover the
residue?" query should have included:

"Perhaps a standard for combining validation rules into a hierarchy (ala
CAM?), or some kind
of generalized Ontological approach (ala CAM?)?"

I didn't realize CAM was treading into the Ontology world also.  That
raises the question of relationships to OWL or perhaps why CAM doesn't
use OWL? However, your earlier comments on CAM being human readable
perhaps explain the latter question...

> 
> This also of course works on legacy XML transactions you 
> already have slopping around out there and now could not 
> possibly change persay.  Just define the CAM template against 
> those instances - thereby qualifying the actual usage 
> semantic details.
>