Grahame and Jobst and I (and, I am sure, also Thomas) agree that there is "benefit in commonly agreed semantics". The thesis that has served as the central pillar of this blog since its inception, however, is that after 14 years of development effort, and after so many failures, we should finally accept that the RIM is not able to serve as basis for the needed commonly agreed-upon semantics.
HL7 Watch and others have provided considerable documentation that the RIM is both counter-intuitive and unnecessarily complex; that it is thus difficult to teach and difficult to document (and thus inconsistently documented); and that it is therefore difficult if not impossible to implement.
Moreover, multiple arguments have been provided to demonstrate that, even if it were implemented, the RIM would still not bring about the end which its defenders seek, namely: consistency of semantics. This is because the RIM's own semantics is so counter-intuitive, and thus so inconsistently documented, that its different users will inevitably produce semantically inconsistent implementations, thereby resurrecting the very problems which had led to the conception of the RIM in the first place.
We have learned much in the field of semantics in the 14 RIM years, and what has been learned can now be used as the basis for a better and simpler solution. It is time to start again.
Postscript 4/2/2011, 11:19 AM
So, you keep quoting me, and I keep having to respond ...
In his comment of 4/02/2011 to our "The Rise and Fall of HL7" thread, Graham Grieve argues that, in spite of all the objections advanced by Elliot Muir and in the comments above, there is value in HL7 V3 nonetheless -- because the RIM provides a 'semantic standard', and "the future of HL7 isn't about syntax or technology, it's about semantics."
ummm no. I argued that there is value in a commonly agreed set of semantics. Elliot, if you look closely, didn't mention the need for it, and so that's what I was addressing. I didn't mention the RIM. But omission is not as clear as commission huh?
I do believe that the future of HL7 is semantics, not platform technologies. Well, duh. There's no need for HL7 to invent syntaxes and network protocols these days.
Is the RIM the future? I don't know yet.
I think that the primary debate should be about design by constraint. Tom (who commented in the other thread) did openEHR, which is totally different to v3 and also exactly the same (and also much better and not nearly so good!). The reference model is both more and less abstract than the HL7 RIM, but the methodology is the same: design by constraint.
First, we should figure out what kind of methodology can deliver consistent semantics where we need it, while allowing seamless customisation for particular use cases, where it is needed, without creating an engineering nightmare (one sequelae of that is that it should be usable in multiple architectures without building of extensive custom software stacks). Once we have that, then we can figure out what are the useful properties of an ontology that supports it.
However my view is that no current approach meets such a criteria. We have some candidates on the floor now, and they have the rather useful property of being concrete and usable. v3, and openEHR are the primary ones I know about in health. I work with them both, and they both have strengths and weaknesses. The primary weakness of both is that you have to be steeped in them to understand how to leverage them. But once you are - you can leverage them well. Both v3 and openEHR.Only in the final paragraph does Graham address my specific arguments concerning what so many now see as the dire state of HL7 V3:
To address your concerns directly. The RIM is trying to do a complex thing. So it's hardly a surprise that it's complex. You've been critical of it, but your criticisms have either been rather fractional, or marginal given the RIM's intended use. What's the alternative?Not sure what 'fractional' means when applied to criticism. I can well understand that many of the criticisms on this blog will seem 'marginal' to some of those who are caught up in the attempt to use and maintain the HL7 standards. On HL7's FAQ page, we find an odd entry headed "HL7's Mission", which reads as follows:
HL7 provides standards for interoperability that improve care delivery, optimize workflow, reduce ambiguity and enhance knowledge transfer among all of our stakeholders, including healthcare providers, government agencies, the vendor community, fellow SDOs and patients. In all of our processes we exhibit timeliness, scientific rigor and technical expertise without compromising transparency, accountability, practicality, or our willingness to put the needs of our stakeholders first.It is evident to those, such as myself, who are viewing HL7's processes -- for example as illustrated by some of the more untamed contributions to the HL7 Vocabulary forum -- from the outside, that they exhibit a marked shortfall in timeliness, scientific rigor, transparency, accountability, and practicality. Why is this so? In part, surely, because of those marginal issues -- such as the inconsistency and counter-intuitive nature of the RIM -- which I have been attempting to draw attention to on this blog.
And what is the alternative?
I hope to address this question in more detail in a later post. But for the moment:
- First, recognize that the RIM rests on a series of rather simple confusions (for example between a disease and its diagnosis, between an action and its documentation, between an entity in reality and information about that entity in some record).
- Second, replace the RIM backbone hierarchy with an ontology that is not subject to these confusions, for example in the way that this is done in the Ontology for General Medical Science, which is based in turn on Basic Formal Ontology.
- Third, study the principles of Referent Tracking.
Postscript April 4, 2011: On Grahame Grieve's Comment on "The Fall of the RIM"
I respond, here, to some of the remarks in Grahame Grieve's Comment of April 4 (reproduced in full below):
It may be, as you say, that the RIM confuses reality and information about reality. (Actually, I think you're confused. Reality is not a RIM - or even ontology - based existence. It may be that the RIM confuses information about reality and information about information about reality). But it's real hard for implementers to differentiate these things - so being strict about the difference actually makes things worse.Grahame and I are addressing here what philosophers call the "use-mention confusion", as illustrated for example in: "Swimming is healthy and has two vowels" or "Our system is able to extract tumors from the patient database in 0.005 seconds". It is true that this confusion is common in many computer-related fields. But surely the goal, in message standardization, is to ensure accuracy of communication.
And it may also be that the RIM and the underlying terminologies (including ones that HL7 doesn't define) are not good at distinguishing instance and class, and defining which instance is intended efficiently - I agree with that.
But replacing the RIM backbone with something like the ontology you talk about would be a problem because it doesn't have the semantic breadth of the RIM. Whether or not some of the thinking in that ontology is better than what is evident in the RIM or not, it's a 5% coverage replacement. ...If I am right, then the RIM will, sooner or later, have to be abandoned. At that point an alternative will be needed. I have suggested some elements of an alternative. Of these BFO certainly has sufficient semantic breadth to represent any of the types of entity, and to annotate any of the types of information, that are relevant in healthcare. It has also been thoroughly tested in use, especially in biology. Moreover, BFO stands up well along a number of dimensions when compared to the RIM, as is revealingly shown by the Cecil Lynch saga documented here. What BFO lacks is semantic depth -- though with the OGMS work we are beginning to fill this gap. The RIM has this semantic depth because it has been extended in so many different directions by so many for so long. But because the RIM lacks coherence, these extensions typically do not work either, and they certainly do not work well when taken together.
Finally, the real problem with your recommendations for what to do is that there is such a gap between your recommendations and the actual resistance and issues HL7 faces with v3. I continuously get feedback about what is not good about v3. Your prescriptions are something that would make a difference to playing the end-game with v3 - decision support, reasoning systems - but it costs so much to get to the field, that no one even sees the mid-game yet.Again: if I am right, then the RIM will, sooner or later, have to be abandoned -- cost what it will. The groundswell of criticism can be held back for a bit longer, perhaps, through application of the existing strategies used to cow critics into anonymity. But what makes the case of Elliot Muir so interesting is that these strategies, too, are no longer working.
Postscript April 12, 2011
An interesting report on national health reporting standards in Norway contains the claim that:
"Most European countries that make use of HL7 messaging standards for new purposes uses HL7 version 3. This applies in particular [to] Britain, Germany and the Netherlands."
In fact, however, it seems that there is know one in Germany who is using v3 messaging, although CDA is in use in some places. In the UK there is some v3 legacy, but there seems to be no new development; rather, new work is being done within the framework of the 13606-based Logical Reporting Architecture (LRA), which seems (to me at least) to be a much more coherent modelling effort. Netherlands, it is true, is still using v3 messages, though it is not clear that they are actively developing anything new. And outside of those three countries? In Norway, for instance, plans were indeed announced to mandate v3 - solely, it seems, in light of its status as an 'international standard'. But from the above-cited report it seems that Norway has pulled back from the brink. In the rest of Europe it is CDA that is being used, or 13606 or LRA.
In a comment by Rene Spronk (provided in full below), the question is raised as to HL7 Watch's view of openEHR in light of the fact that the latter has certain similarities with HL7. openEHR, too, I believe, has need of a more sophisticated upper ontology-based approach: it is thus far marked by a lop-sided focus on information models at the expense of representations of reality of the sort which ontology can provide. But there are leading figures in openEHR who would agree with this diagnosis, and I remain optimistic that openEHR - and similar ventures under the CEN-13606 heading - will take the steps needed to rectify problems in this regard. The HL7 community, unfortunately, which is currently advancing the RIM as an 'upper ontology' in the context of its new 'Services-Aware Interoperability Framework’ or SAIF, still gives no evidence of having understood what a well-designed ontology might look like, and what such an ontology is able to achieve. As addressed at length already elsewhere in this blog the RIM has fatal shortcomings not only because it contravenes the very basic rules of information modelling, but also because its backbone taxonomy of Act, Entity and Role is too narrow to allow serious ontological work.
openEHR and similar approaches differ from HL7 v3, too, in that they can be critiqued as can any other ordinary object-oriented reference model approach, precisely because they conform to industry practices. This is not true of HL7 v3.
Referring to an earlier link posted by Rik Smithies listing 22 known software implementations based on the RIM, Rene argues that
This is just the tip of the iceberg in terms of known organizations that voluntarily embrace the RIM as either a persistence model or a in-memory business layer model. This is mainly done for research, public health and DSS purposes, although we've also seen implementations to support classic on line transaction processing applications. ... Calling the RIM "fallen" when at the same time it is increasingly being embraced as an internal model in all sorts of applications - your call, but curious to say the least.
One of the earliest posts on this blog, dated November 25, 2005 is entitled "Misleading Claims regarding HL7 V3" and concerns a 'white paper', edited by Rene, and containing a claim to the effect that "Significant V3 national implementations exist in many countries, e.g. in the UK (the English NHS), the Netherlands, Canada, Mexico, Germany and Croatia." Already at that time there were considerable grounds for scepticism concerning such claims. Now however we have a better view. In the UK, for example, we can see that at least one part of the reason for the massive failure of the Connecting for Health program was precisely that the use of HL7 v3 was imposed upon its designers.
Use of HL7 v3 messaging is, certainly, widespread within the community to which Rene belongs. But it is questionable whether this is a large community. And it is still more questionable whether the members of this community are exuding confidence that they are riding the wave of the future.
Postscript August 3, 2012
Postscript August 3, 2012
See now also Graham's "Design by Constraint – not as useful as people think" (published on April 30, 2011) on
"Implementation Disasters":
The inevitable outcome of wide scale adoption of [the Design by Constraint] technique is chaos. Different implementors want to live at different points on the general <-> specific curve, and there’s a variety of options to attempt to externalise costs from one implementor to another.
There’s various approaches to handling this. You can be like HL7: put your head in the sand, claim that it all works (in other words, externalise the costs), and then be real confused about why your brilliant idea isn’t actually solving all the problems in the world. ...
