Speaking of the HL7 RIM, is the USAM at
http://aurora.rg.iupui.edu/RIM/
the best reference for someone who wants to encode clinical data with
HL7 3(!)?
If it isn't, what is?
John Gage
Gunther Schadow wrote:
>
> Thomas Beale wrote:
> > GEHR on its own is not an interchange format. The "modern" way to do
> > interchange is using generic mechanisms like CORBA, rather than
> > application level protocols like HL7. CORBA (for example) just
> > serialises whatever structures it finds in memory into a bytestream,
> > according to the rules for the language and the IDL definition for
> > the classes involved. So there is no need to say anything about
> > clinical concepts in the protocol - it's all in the object model
> > (i.e. the class model, i.e. the software - it's all the same thing
> > in OO). HL7 v 2.x has to define clinical concepts in the protocol,
> > because it makes no other assumptions about systems. All one has to
> > do is to build an HL7 interface and stick to the HL7 rules.
>
> Wait, wait, just a moment. You are suggesting that it would be
> favorable to not have clinical concepts represented in the interface
> to a system (a protocol is simply an interface). This goes straight
> against my idea of good system design. Object oriented technology
> allows us to construct system interfaces of ever higher abstractions,
> ever more application (business) oriented and ever less computing-
> technology oriented. This is what computer science did all along:
>
> First systems engineers talked about bits and registers and memory
> units, then about characters and strings, then about tokens and named
> variables, then we distinguished information presentation from
> application level semantics, we built independence from physical
> data base schemas, etc. Now you are saying we should stop right
> here and deal only with a somewhat intermediary logical schema
> and not deal with clinical concepts? No. You are not really
> suggesting it, since GEHR too talks about clinical observations, etc.
>
> In the end, systems want to do clinical business, and communication
> wants to exchange clinically relevant information. I don't say it's
> easy, but wishing application level business logic away from
> inter-system interfaces is not right.
>
> Your points on HL7 version 2 are well taken, but I plead with you
> to keep HL7 v2 out of the discussion. When we compare GEHR with
> HL7 we ought to look at HL7 version 3 only. Whatever you may know
> about HL7 v2 does not apply to HL7 v3. So, please do not even
> mention HL7 v2 any more in this discussion (except if explicitly
> labeled and explained why HL7 v2 is relevant.)
>
> > - because the protocol is defined in terms of its semantic content,
> > there is always the problem of older software not understanding
> > newer messages. This should not in principle happen with CORBA.
>
> This is stated too simply, misleading, and therefore wrong. First
> of all CORBA is not equal to CORBA. (At some point we should start
> using terms and references to models and systems more distinctly.)
> There is CORBA and CORBAmed. CORBA talks about interaction of
> distributed objects. CORBAmed defines application models and
> interfaces using the CORBA infrastructure. CORBA is good stuff.
> CORBAmed defines information models that are designed mostly from
> an information systems perspective rather than from a medical
> information perspective. <SOAPBOX>That's the reason why CORBAmed
> goes pretty fast, but I predict at some point they will get into
> problems tying these many pieces together.</SOAPBOX>
>
> So, if you talk about CORBA here, which do you mean, CORBA plain
> or CORBAmed? It is not true that CORBAmed is free from "semantic
> content" as you suggest to be a good idea here. CORBAmed has
> specific semantic content (that sometimes, however, falls pretty
> short.)
>
> If you talk about CORBA plain, I agree that it is a great
> architecture in which to make medical information systems
> interoperate, but it requires one to add well-defined medical
> semantics to CORBA or otherwise you just communicate "stuff"
> that your systems do not really understand. Thus, the information
> model that encompasses the whole of clinical information is
> of paramount importance. That's what HL7 version 3 is doing.
>
> So, CORBA is to be lauded for it's technical infrastructure,
> but not for it's missing any medically relevant concepts. These
> concepts of our domain have to be added and have to be
> standardized (CORBAmed tries to do just that too.) That's hard
> work, but there is no other way around that work. XML and other
> hyped technologies (like ASN.1, remember it?) all come along with
> great (bold) promises that are never fulfilled -- the technology
> evangelists are like a locust plague: they fall over an application
> domain field that is just about giving crops and eat everything to
> the ground, suggesting to do it all over again, (from the ground
> up so to speak :-) using their new technology. This costs
> so much effort, and leads nowhere. That's why I stick with HL7
> v3 and that's why I refuse to shortcut our application layer
> work to any currently hyped technology.
>
> I consider GEHR to be on a fairly high application layer too,
> defining clinically relevant EMR concepts. My only criticism
> about GEHR is that they build everything on the concept of
> Observation ... often used metaphorically, and sometimes called
> MedicalItem or something. In one part of HL7 version 2 we made
> this same mistake believeing that everything could just be
> represented by an Observation structure (the infamous OBX
> segment.) Yet, we now know that this isn't much better than
> expressing everything in XML: tag-value pairs are technology,
> the medical semantics still needs to be added. And that's our
> paramount job in the medical information standards community.
> Instead of doing our job, some of us always choose to get
> distracted by some hyped technology. This makes it harder.
>
> regards
> -Gunther
>
> --
> Gunther_Schadow-------------------------------http://aurora.rg.iupui.edu
> Regenstrief Institute for Health Care
> 1050 Wishard Blvd., Indianapolis IN 46202, Phone: (317) 630 7960
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