- From: Marc de Graauw <marc@marcdegraauw.com>
- Date: Wed, 12 Sep 2007 23:11:15 +0200
- To: "'Dan Connolly'" <connolly@w3.org>
- Cc: "'David Orchard'" <dorchard@bea.com>, "'www-tag'" <www-tag@w3.org>, "'Rene'" <rene.spronk@ringholm.com>
Dan Connolly: | On Wed, 2007-08-29 at 17:49 +0200, Marc de Graauw wrote: | [...] | > The full formalization is available at: | > http://www.marcdegraauw.com/2007/08/29/axioms-of-versioning/ | | I took a look; it does look coherent, though it might | take a lot of examples to motivate that much detail/complexity. | | I'm mulling it over. I've written a new version of 'Axioms of Versioning' [http://www.marcdegraauw.com/files/axiomsofversioning.html], see point 12 for new stuff. I extended the formalization to get a grasp of the concept of 'Semantic Backward Compatibility' in HL7v3, which I believe is flawed (quote: "Objective of backward model compatibility is that a receiver expecting an 'old' version will not misinterpret content sent from a new version"). It seems to be the reverse of the position of the W3C TAG in 'Extending and Versioning Languages: Terminology', and the position I would defend myself. I notified HL7 of this, and one of our Dutch HL7 representatives told me they were aware of the problem - I don't know whether they will change their definitions or not. Yet the interaction of new senders with old receivers, which HL7 rightly studies, was not sufficiently explored in my post. It turns out that exploration of this notion leads to quite natural definitions of 'may ignore' and 'must understand' semantics. The HL7v3 notion is probably best characterized by the concept of 'partial semantical forward compatibility' in my new Axioms. The concept is also close to, if not the same as, the TAG's 'Partial Understanding'. Regards, Marc www.marcdegraauw.com
Received on Wednesday, 12 September 2007 21:11:32 UTC