Hi Randy, I take your point about there being two threads in this discussion but I think they *are* closely related.
The nub of Tim's argument, if I understand it correctly, is that a two-level model is appropriate but that a three-level model (i.e openEHR specialisations and templates) , allowing for extensions and further local constraint is unnecessary. He argues that the attempt to create single, global 'maximal dataset' archetypes is doomed to failure and that people will simply resort to creating their own models, but I think that is to misunderstand the value of the 'maximal dataset approach' and local templating. This can happen at any level, even within a single hospital system where a locally developed archetype is maximally developed to meet the needs of the local clinical stakeholders, so that it can promote interoperability between these stakeholders. I have been working with medication and allergy archetypes specific to the UK but need exactly the same specialisation and templating principles to satisfy the varying requirements of a very wide group of developers and use cases. It would have been preferable to use the international equivalents but sometimes legacy gets in the way. OTOH I am using these same UK medication archetypes alongside international archetypes as part of a different UK CDR project. For the forseeable future we will be working with this sort of mix and match of local. regional, national and international models. Over time, people will use more of the latter and less of the former as the need to interoperate grows. The maximal dataset approach is really all about being inclusive of the requirements of a groiup of stakeholders who want to maximise interoperability, but recognise that each has legitimate variations or legacy process to support. In this circumstance the archetype is as much about creating a forum where the barriers to interoperability can be discussed and gradually resolved. We need the specialisation and templating layer to smooth this emergent activity, and this is what is difficult to achieve, as I understand it, with UML and XML, at least for now. Ian On 7 April 2013 22:08, Randolph Neall <randy.neall at veriquant.com> wrote: > Hi Thomas, > > I'm surprised that at this advanced stage of openEHR's maturity you'd still > have to defend concepts like these, which are self-evident. Your > architecture, or something closely resembling it, is actually the only path > to (1) computability, (2) shareability, and (3) coherent and maintainable > program code. Ultimately the real enemy is chaos, and that's precisely what > you get unless someone detects and names the universal patterns amidst the > diversity, and structures program code to conform to such patterns. I'm not > clear why this should be controversial. > > This discussion is now dividing into two unrelated branches: (1) the > desirability of consensus around the content of data model, and (2) whether > the model itself, whether widely agreed to or not, should embody a > multi-level abstraction hierarchy permitting code and logic reuse at its > more abstract levels. Both branches, wrongly argued, are a direct invitation > to chaos. From what I understand of it, openEHR is an attempt, in both > regards, to avoid chaos. I can only wish you success against the two > challenges. > > Randy > > > On Sun, Apr 7, 2013 at 8:55 AM, Thomas Beale > <thomas.beale at oceaninformatics.com> wrote: >> >> On 07/04/2013 12:11, Grahame Grieve wrote: >> >> Hi Tom >> >> You ask: >> >> > Is there a better meta-architecture available? >> >> When actually the question at hand appears to be: is it even worth having >> one? >> >> I don't think that this is a question with a technical answer. It's a >> question of what you are trying to achieve. I've written about this here: >> http://www.healthintersections.com.au/?p=820 >> >> >> There is always a meta-architecture. It's just a question of whether >> system builders are conscious of it. If they aren't, then by definition they >> are just doing ad hoc development, with no comprehension of the semantics of >> what they build. >> >> I prefer to have conscious design going on, and make some attempts at >> defining rules for system semantics. Then you know what you can expect the >> system to do or not. >> >> To go back to the question of meta-architecture, let me ask the following >> questions... >> >> 1. is it worth trying to have a publicly agreed (by some community at >> least) information model? I.e. to at least be able to share a 'Quantity', a >> data tree of some kind, a 'clinical statement' and so on? >> => in my view yes. Therefore, define and publish some information >> model. Aka 'reference model' in openEHR. >> >> 2. do we really want to redefine the 'serum sodium', 'heartrate' and >> 'primary diagnosis' data points every time we define some clinical data set? >> => in my view no. Therefore, provide a way to define a library of >> re-usable domain data points and data groups (openEHR version of this: >> archetypes) >> >> 3. do we need a way to define data sets specific to use cases, e.g., the >> contents of messages, documents etc etc? >> => in my view, yes, it seems obvious. Therefore, provide a way to >> define such data sets, using the library of 'standard data points/groups', >> and also the reference model. >> >> and >> >> 4. would we like a way of querying the data based on the library of >> re-usable data items? E.g. is it reasonable to expect to query for 'blood >> sugar' across data-sets created by different applications & sources? >> => in my view yes. To fail on this is not to be able to use the data >> except in some ad hoc brute force sense. >> >> >> You (I don't mean Grahame, I mean anyone ;-) may answer differently, but >> if you don't care about these questions, it means you have a fundamentally >> different view about how to deal with information in complex domains >> requiring information sharing, computation, and ultimately intelligent >> analysis (health is just one such domain). Either you think that the above >> is a 'nice idea' but unachievable, or else that it's irrelevant to real >> needs, or.. something else. >> >> If you think the questions are relevant but have different answers to >> them, it means you believe in a different meta-architecture. >> >> Note that these considerations are actually orthogonal to whether >> standards should be built by agreeing only on messages between systems, or >> how systems are built (the topic of Grahame's blog post). >> >> - thomas >> >> >> >> >> _______________________________________________ >> openEHR-technical mailing list >> openEHR-technical at lists.openehr.org >> >> http://lists.openehr.org/mailman/listinfo/openehr-technical_lists.openehr.org > > > > _______________________________________________ > openEHR-technical mailing list > openEHR-technical at lists.openehr.org > http://lists.openehr.org/mailman/listinfo/openehr-technical_lists.openehr.org -- Dr Ian McNicoll office +44 (0)1536 414 994 fax +44 (0)1536 516317 mobile +44 (0)775 209 7859 skype ianmcnicoll ian.mcnicoll at oceaninformatics.com Clinical Modelling Consultant, Ocean Informatics, UK Director openEHR Foundation www.openehr.org/knowledge Honorary Senior Research Associate, CHIME, UCL SCIMP Working Group, NHS Scotland BCS Primary Health Care www.phcsg.org
