Thanks, Rong.
On 11/8/07, Rong Chen <rong.acode at gmail.com> wrote: > > On 11/8/07, Randolph Neall <randy.neall at veriquant.com> wrote: > > > > So are you saying that persisted clinical data is never converted to > > conform to newer versions of an achetype, or simply that one is not > > compelled to convert? > > > > New version of an archetype is created when the changes are so significant > that it can't be backwards compatible. In other words, conversion old data > to conform to newer versions of an archetype might not even be possible. > > Quoted from Archetype Principles: > http://www.openehr.org/svn/specification/TAGS/Release-1.0.1/publishing/architecture/am/archetype_principles.pdf > > "Principle 14: There is a means of evolving existing archetypes to > accommodate changing requirements, without invalidating data created with > earlier versions. Since archetypes are used to create data, changes to > archetypes must be regarded as creating a new archetype; i.e. the > identifier of an archetype must incorporate its version. The only types of > change to archetypes that can be made without changing the version are those > which do not invalidate previously created data. Formally, such changes > must not 'narrow' constraints expressed in the existing version." > > /Rong > > > Randolph > > > > > > > > On 11/8/07, Rong Chen <rong.acode at gmail.com > wrote: > > > > > > On 11/8/07, Randolph Neall < randy.neall at veriquant.com> wrote: > > > > > > > > Thomas, thanks for your extended remarks. Your point is one you've > > > > made for a long time, that relational db schemas cannot keep up with the > > > > real world. I'm just wondering if moving the problem out of the > > > > relational > > > > DB and into blobs (persisted objects, I take it) solves the problem you > > > > so > > > > eloquently depict. Yes, it solves the schema problem. I grant you that. > > > > But > > > > you're still left with imperfect and changing models even with blobs. > > > > I've > > > > read the openEHR specs enough to know that when an archetype version > > > > changes, one is obliged to convert all existing records (blobs) to > > > > conform > > > > to the new version, and that, it > > > > > > > > > > That is not true. When an archetype version changes, new data are > > > created/validated by new version of the archetype while old data (blobs or > > > whatever) are still processed by old archetypes. In the root node of the > > > data, there is always information about the archetype (and its version) > > > used > > > to create the data ( LOCATABLE.archetype_details). So there is really > > > no need to convert existing data when archetype changes. Hope this > > > clarifies > > > the matter. > > > > > > Cheers, > > > Rong > > > > > > > _______________________________________________ > > openEHR-technical mailing list > > openEHR-technical at openehr.org > > http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical > > > > > > _______________________________________________ > 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/20071108/395b378e/attachment.html>
