Not sure how ddl would work in this domain - most db engines accept slightly
different flavours of ddl and I can't see how sending someone some data with
a way of creating tables/fields for that data would help you to semantically
understand it? Even datatypes are not guaranteed to be the same between db
systems and what about object databases? Maybe I don't understand what you
are trying to describe?
Tom Beale has written a lot about why ADL rather than xml or some other
constraint language (see the ADL documentation on the openEHR website). A
lot of effort has gone into this over the years and certainly the decision
wasn't taken lightly or without extensive research. I know that xml was
tried and found to be unworkable.
regards Hugh
________________________________
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Sent: Tuesday, 3 January 2006 10:06 PM
To: [EMAIL PROTECTED]; General Practice [EMAIL PROTECTED] Talk
Subject: Re: GP Requirements - was [GPCG_TALK] Re: The Dreaming
If you sent the sql data definition language along with the data,
and that ddl expressed constraints as
triggers , rules and data type constraints, how different would
that be sending an ADL file along with
some archetype instance data ? Or does the extra little structure
provided by ehr container classes and ehr
base classes really that useful , and are they guaranteed to be
perfect enough to always be backwardly compatible ?
On Tue Jan 3 10:59 , Tim Churches sent:
Richard Hosking wrote:
> I still struggle with this stuff - isnt an archetype
describing
> constraints on the data- ie type, bounds etc? Shouldnt
this be coded
> into the DB? If not where?
No, all those constraints are enforced by the openEHR
kernel/engine (you
know, the bits that aren't available yet) informed by
archetypes
expressed as ADL (archetype definition language) files.
Ultimately, teh openEHr kernel should be built right intot
he underlying
database engine - and that is quite possible with extensible
database
servers such as PostgreSQL - given the right expertise and a
bit of
funding. In the meantime, it can be implemented as a layer
on top of a
database engine eg in C#, Java or Python.
Tim C
> Hugh Leslie wrote:
>
>>
>> An openEHR database schema doesn't contain ANY archetypes
- The data
>> reflects the openEHR reference model, not the archetype
model. If you
>> have
>> to hard code archetypes in a schema then you have not
gained anything at
>> all. The archetypes just describe what the data means.
>>
>>
>>
>>
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