On 10/19/07, Andrew Patterson <andrewpatto at gmail.com> wrote: > > > Templates are the main means of constraint on archetypes - > Specialisations are mainly > > about adding attributes. > > Sam, surely those attributes are available by virtue of the fact that the > parent > archetype says nothing about them. Something in an archetype can never > 'add' > an attribute. All archetypes can do is constrain. And the specialised > archetype > can never remove a constraint of the parent surely? > > For example, an observation archetype that says nothing about the > 'State' attribute > imposes no constraints on that attribute. A specialisation of the > archetype could > impose extra constraints on 'State', but can't add the attribute in. I > mean, there is > either a 'state' attribute there in the RM or not - the archetype > can't add attributes. > > Of course this all leads to a much more interesting theoretical question - > aside > from the immediate syntactic differences, what exactly is the difference > between > a template and a specialisation?
Andrew, this is indeed a very interesting question. It seems to me that all the constraints done in templates can be done with archetypes. The 'artificial' divide between templates and archetypes are probably to do with their different intended uses. Archetypes are semantically coherent and are supposed to be shared between systems. Templates are, on the other hand, created to meet local specific requirements, therefore not supposed to be shared across sites. But the line of distinct seems to be blurred. How local is a local requirement and thus justify the use of a template? Can one start with a template for local use, and later convert the template into an archetype for shared use? Also if all constraints can be expressed using the AOM semantics (which is already very generic and powerful), we perhaps could re-use the same object model to represent template constraints, which would facilitate the conversion between archetypes and templates. Cheers, Rong Andrew > _______________________________________________ > openEHR-technical mailing list > openEHR-technical at openehr.org > http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.openehr.org/mailman/private/openehr-technical_lists.openehr.org/attachments/20071019/4afe3105/attachment.html>
