Relation between COS and PD model

[Johannes Koch <jo...@fit.fraunhofer.de>]

Hi,

I wonder what the intended relation between the COS and the PD model is.

Is the COS model the actual data model and the PD classes are only views 
on this data?

Is the PD layer supposed to cache data (for performance issues)?

If data is changed via methods in the PD layer, how are these changes 
propagated to other PD objects? Do we need an observer mechanism for 
data changes?

-- 
Johannes Koch
Fraunhofer Institute for Applied Information Technology FIT
Web Compliance Center
Schloss Birlinghoven, D-53757 Sankt Augustin, Germany
Phone: +49-2241-142628    Fax: +49-2241-142065