Hi Tom >> This is not a difference; it's true of HL7 as well >> > I think people would have a hard time finding it - where is the > reference model from which you can build software?
You can build it from RIM or DMIM's or Messages. Would this be a good choice? I suspect not. But let's be correct here. >>> In HL7, the data are instances of schemas that are >>> progressively refined from the RIM. >>> >> well, it doesn't have to be; and also, you could do this with archetypes >> and/or templates, and it would have some use too. >> > I'm just saying how things work now, so that new people have some hope > of understanding. I doubt if it would have any use with archetypes / > templates though - the subtractive logic based on relational projections > just isn't a part of normal object modelling or openEHR. The "subtractive logic" as you call it, is exactly what cADL is. It's true that it's not part of normal object modelling - and that's a deficiency of normal object modelling. So you invent cADL and Hl7 invents Static Model Diagrams, but they both do the same thing, and in this regard OpenEHR and HL7 do not follow normal object modelling. >> well, I can't speak for "the designers" (I'm spending some time with him >> today on this subject ;-), but archetypes and HL7 models are the same thing. >> I can interconvert between them. The only issues are syntactical differences >> in things that are allowed in each language, and they are minor. Obvious >> conclusion: they are the same thing. >> > That's a somewhat misleading statement. An archetype isn't a new model; > it's a statement about putting together pieces from an existing model. it's not a misleading statement. I am aware that lot's of HL7 people are making misleading statements about HL7 modelling - but they are mislead themselves, and they are generally open to being educated. if I can interconvert, therefore it's true that the 2 formats are presentations of the same concept. ADL is a more natural fit, and I think that in the long term, most people would prefer to develop in the tools that arise out of the ADL constructs. But they are still the same concept So let's all move on: these things are the same concept, there's some engineering differences about how to represent and use the concepts. > Some archetypes and RMIMs are trying to say the same thing however. Is > reliable machine conversion possible? The key point is that while > conversion between the formalisms of some part of an archetype and an > RMIM and vice versa may be possible, conversion between actual real > archetypes and real RMIMs is not the same thing, due to the reference > models involved. agree that automated conversion between reference models is not (yet) possible, and agree that the key difference is in the reference models. This is something we all need to work on. At least we have made major progress with data types. I suggest as an opening gambit regarding how to progress this that the OpenEHR reference model corresponds more closely to the HL7 domain models than to the RIM, and that's the useful point to pursue genuine interoperability. Grahame
