Tom, Now I know why HL7 has so much trouble. -- "just basic god practice.
" Shouldn't god be capitalized? I think HL7 needs to pay Tom a consulting
fee - for all the advice.
W. Ed Hammond, Ph.D.
Director, Duke Center for Health Informatics
Thomas Beale
<thomas.beale at oce
aninformatics.com To
> openehr-technical at openehr.org
Sent by: cc
openehr-technical
-bounces at openehr. Subject
org Re: More on ISO 21090 complexity
11/18/2010 06:38
AM
Please respond to
For openEHR
technical
discussions
<openehr-technica
l at openehr.org>
On 18/11/2010 06:51, Vincent McCauley wrote:
>From the point of view of a clinical datatype implementer who has to
write
actual code, the ISO dataypes provide a level of detail
that is both required and sufficient. They are definitely not
"simple" in
their definition but are mostly "simple"
in terms of concept representation.
The atom at one time looked "simple" and remains so in concept,
though in
fact having considerable underlying complexity.
The level of detail required depends on your use case which seems to
be a
major contributor to your divergence of opnion.
I see this as one of the major problems of HL7 actually. It seems to think
that everything should be driven by use cases. This is not the case. The
general drive in all engineering and software development is to have layers
of highly reusable elements that work in all situations. Thus the design
concept of 'Integer' and 'String' in a programming language is not specific
to any particular used. Neither should the concept of 'codedtext',
'ordinal' or 'physical quantity'. The idea that a set of such data types
should be built not just for messaging, but apparently with features for
other more specific use cases is plain wrong. It is not good modelling.
Contextual (i.e. use-case specific) features should always be added in
specific classes / locations in models dealing with those specific use
cases.
The openEHR data types are designed like that - it is just basic god
practice. They can be (and are) used in messaging, storage, GUI, business
logic. Context specific features are modelled and coded where they are
relevant, not integrated into what would otherwise be completely generic
data types.
Not understanding this basic modelling practice has lead HL7 to produce
models that are very far from being easily implementable or reusable -
which is a real pity.
- thomas
_______________________________________________
openEHR-technical mailing list
openEHR-technical at openehr.org
http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical
