Heath Frankel wrote: >Dear Sam, etal, > >I wonder if the specialised schema approach for archetypes is one that >openEHR should encourage. Not so much discourage the investigation but at >least indicate to those who are going down this route that previous work by >Ocean and DSTC has indicated that the approach is not workable in a dual >layer model approach. Perhaps the more useful task is to find a suitable >schema for ADL if this has not already been done for which archetype >definitions can be validated against, not instances. > > an XML-schema for the Archetype Object Model will be available very soon, initially probably as a hand-built one, but with the X-openEHR specification converter, we will be able to generate schemas for the entire RM and AM from that.
>Perhaps it should be encouraged to use some existing schema's such as OWL >but again this is representing the archetype definition not the archetype >instance. > > OWL I think is still research in this area; it has very weak leaf level semantics (which are known by the OWL community); we are working with the experts including prof Alan Rector and Rahil Qamar at University of Manchester to understand better how to "do archetypes in OWL". >Perhaps, the DSTC approach to represent archetypes using XML with a XML >schema for the Archetype Model should be endorsed by openEHR if this is the >preferred approach so people don't waste their time and develop a >proliferation of approaches which are likely to be incompatible or at least >require translation. > > this is indeed the intended view, although I have recently come to the realisation that archetypes (or more properly openEHR templates - particular aggregations of archetypes) can be used to generate XML-schemas as well as XML-instance; the former would be usable as message definitions, for those who love messages. This would actually provide, for the first time, a single source development framework for software, schemas, screen definitions, and messages - all obeying coherent, consistent reference model, archetypes, templates and teminologies. >What would be better use of peoples time would be the investigation of an >archetype instance validating parser that uses the XML document representing >the archetype definition similar to an XML validating parser uses xml schema >(which is also an XML document). > > this is indeed one thing that is needed; personaly, I would do it by reading in the archetype and the data from XML form into a DOM-tree and jst using the kernel to do the work. >The reason we need to have an XML document represent the archetype is >because of the dual layer model approach where the XML schema is used at the >reference model level and an xml instance can't have two associated schemas >for validation for each level. However, from my understanding (which is >limited), this is not an issue in some of these other schema systems like >Schematron and RelaxNG, so it might be useful for people to investigate >these if they really want to represent archetypes as XML schema's but >knowing that traditional parsers and XML tools will not support this due to >the dual layer model approach. > > I also have suspicions that these other schema types might in fact be better for our purposes than XML-schema, and I hope others might be able to provide expert input on this. - thomas - If you have any questions about using this list, please send a message to d.lloyd at openehr.org
