Andrew po-jung Ho wrote:
>
>
> So - in essense, HL7 was inadequate as an intermediate schema. On the other
> hand, the combination of HL7 and the "interface engine" was a more functional
> "intermediate schema" for your setting.
>
You can view it that way. but it is not quite what I meant. From what I
know, every large scale health care organization in the U.S., at least,
has used interface engine technology, this is not a unique situation.
It was not the failure of HL7 per se, but rather the failure of an
approach that tried to do 100's of one to one transformations that
failed. Even with the best of agreements, enough difference creeps in
that expecting any consistency across all those one to one
transformations is too much to ask. The intermediary provides a single
point for agreement to be mediated by using one transformation per
system. This is pure math, based on the fact that each transformation
looses or changes some of the intended information. The more
transformations you put in the path, the more the end result deviates
from the original.
With enough transformations, the original data has been so 'corrupted'
that any aggregate function becomes hopeless. Our analysis of legacy
system transformations showed that hand tuning (accomplished at the
interface engine) of the transformation (into HL7) based on an intimate
understanding of the source information was necessary. Even at that, we
had to make many changes and legacy system wide sweeps of the infomation
store to 'cleanse' the legacy information itself! I would like to
believe that some magic 'mediators' exist that can do this without human
intervention, but even Renner, et. al. don't support that conclusion.
There is a reason why a very viable market exists in health care for
interface engines and in data wharehousing for 'cleansing' solutions.
The bringing together of multiple viewpoints for single point computer
processing demands it.
My point about scale is this: With a small enough set of records that
a human being can read them all, the 'cleansing' and 'transformation'
takes place inside the human's conscious understanding. It's only when
your record set's get large enough (per an individual's retrieval set)
that you demand on a daily basis a computer to assist with these acts
and that you start to see problems.
