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 > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.openehr.org/mailman/private/openehr-technical_lists.openehr.org/attachments/20071108/e29a87c7/attachment.html>
