[kepler-dev] web service actor

[Edward A Lee]

At 12:39 PM 2/26/2004 -0800, Shawn Bowers wrote:
>However, the classic notion of subtyping in programming languages doesn't 
>otherwise pop up much for XML.  One reason is that XML is inherently 
>"distributed."  Gven two schemas from different organizations, just 
>because they have the same structure, or one is a subtype in terms of 
>structure, there is absolutely no guarantee that these schemas have 
>anything to do with each other.  The same is true if we also consider tag 
>names (it may just be coincidence that some of the tag names are the 
>same).  Because the schemas were developed independently, it would also be 
>pretty unusual that even for otherwise identical schemas, that the tag 
>names or structure *would* be the same.

Yes, good point...

However, there might be real potential for subtyping.
Consider for example an XML schema that represents actors
and their interconnection (to pick a random example :-)
and another that extends this with visual annotations (where
on the screen an actor should be rendered, for example).
A tool that used the former type would be unaffected by
the addition of the latter data. In the current state of
affairs, I think that such a tool (if it validates the XML)
would have to reject a model with visual annotations, no?

Edward



------------
Edward A. Lee, Professor
518 Cory Hall, UC Berkeley, Berkeley, CA 94720
phone: 510-642-0455, fax: 510-642-2739
eal at eecs.Berkeley.EDU, http://ptolemy.eecs.berkeley.edu/~eal