William E Hammond wrote:
>What happens when messaging is used for query. I view messaging as any >interchange between two or more entities. I view pier to pier >communications as messages, and I have found nothing to contradict that. I >would be interested in any references that suggest otherwise. > I don't want to get into any serious debate on the issue (since for many people it is an argument of whether 6 eggs is the same as "half-a-dozen" or not), but one differentiator is that people tend to use the word "message" more when the structure of the messages themselves have been defined - i.e. that is what is being standardised, and nothing is being said about the communicating systems. People talking about peer-peer or other configurations of distributed systems are usually thinking more along the lines of information/service model defintions of the systems, while the messages are not defined explicitly - they come out automatically from the tools, based on the service models, as happens in CORBA, COM, .net, OSF/DCE, XML/SOAP and other such technologies. Some people will call everything that goes between two nodes a "message", which is literally true, but not that useful for explaining what kind of message, or how it was put together, or what rules it obeys. So I tend to use the word to mean communications which have been specified by defining message contents, rather than the semantics of information or services available in systems. So in openEHRor CEN, if there were two nodes sending part of an EHR to each other, and XML/SOAP/WSLD (essentially the web version of Corba or RPC) was being used, I would not explain it to someone as being a message, since there is no need to specify the message, even though in literal terms, a "message" (= string of bytes) is being sent. However, if an EHR node was receiving a pathology result in HL7 form, I would call it a "message". >Why is the definition of messaging important? Messaging is different from >syntax. Whether I use ER7, XML, SOAP or whatever, the trigger events and >message content is what is important and what will be persistent. strongly >agree that messages are different than the EHR. However, I populate much >of my EHR from messages I receive from other components of the health care >institution - lab, radiology, ADT, pharmacy, clinic, etc. > That's true, but it is more than likely that a) a lot of messages are of no interest to the EHR (e.g. they are destined for an orders management, prescription, or admin service) and b) messages which are of interest will not go into the EHR in their message form. They will be validated, sifted, filtered, reformatted into EHR form, have links back and forward to other EHR items added, be classified this way and that, during the process of being added to the EHR. As soon as one starts thinking about what has to happen to turn messages into EHR content, it becomes clearer and clearer that the EHR is nothing like a compendium of messages; for from it - it is a time-based accumulator of EHR information, some of which is sourced from messages, much of which is created by human users of GUI applications. - thomas beale - If you have any questions about using this list, please send a message to d.lloyd at openehr.org
