Andrew Patterson wrote: >> Experience from classic email - where orders of magnitude more messages are >> processed - tells us that polling an account as a rule takes much less than a >> second, and that it is indeed absolutely acceptable - even preferable. > > Yes, but that's polling one account (or maybe 5 accounts for those > with lots of accounts) using POP.. the actual delivery of the email > to my mailbox is not done with polling but by the sending mail > server pushing it to my account using SMTP.. I think Ross' point was that it > is impractical to poll every medical facility in australia looking > for pertinent results, much the same way I don't poll every > POP server on the internet hunting for my email..
Sure, but my question was "Why is it necessary to poll every path and imaging provider?" Surely there is only a need to poll the much more limited number of providers to who the GP(s) in a practice have actually referred patients/specimens. If a lab forwards a specimen to another lab, then the results would need to be made available at the original lab for collection from that lab's Web service. > I agree though that we should learn from how email has done > things - in particular, in SMTP the sender always takes > responsibility for the delivery of the email - so it will keep > attempting to send messages until it reaches timeout, all the > while informing back to the originator if it is having problems. Why > couldn't a path lab system keep attempting to initiate a connection > to the GP system "web service" every 10 minutes until it successfully > hands off the result?? Surely that would handle the unreliability of > the australian internet without resorting to hub and spoke models? The underlying assumption behind Ross's model, and also in the NeHTA documents, is that GPs aren't up to running 24x7 servers which host Web services. I have several thoughts on that: 1) Web services can be easily implement using packaged software on a standardised Web server at the edge of each practice. That implies that each practice has a fixed IP address (very shortsighted of the broadband-for-health people to have ignored the suggestion that this be a requirement - although yes, I know that dynamic-DNS solutions are possible, but they are complex and often unreliable). 2) 24x7 operation is not required. The GP's Web service only needs to run while the GPs are there at their practice (either physically or virtually). As Andrew points out, automatic retries by the sender until the message is able to be delivered solves the problem of a GP's Web server being switched off for the weekend, doesn't it? 3) Alternatively, other organisations can run web services on behalf of practices, and the practices can poll those Web services. Which is really the model which NEHTA is pushing, I think. The critical thing is that there is complete interoperability between Web services, so that Divisions of GPs, ISPs and entrepreneurs and others can set them up if they wish - remembering that all the content they are handling is encrypted. The more of these, the better, as it removes major points of failure. The Web services specs from NEHTA need to allow for each practice to use more than one Web services provider to represent them on the Web. Thus, there needs to be a primary and a secondary URL specified for every request/referral for delivery of results/reports. The GP's practice polls both the primary and secondary Web service providers, or perhaps polls the secondary provider if the primary provider is down. Clearly there are details to be worked out, and NEHTA needs to do that ASAP if it wants its model to fly. Then it needs to sponsor a consortium of individual Web service providers (not just the current messaging providers) to demonstrate that this model works and to discover all the flaws that no-one anticipated, and to test scalability, reliability and resilience to point failures. All that testing might cost a few million, but NEHTA now has the cash to be able to finance that sort of thing. Commissioning a suitable group to write an open sourced reference implementation of such a Web services server would cost perhaps a few hundred thousand (including documentation and testing) and would kick-start the process and encourage lots of redundancy by allowing Divisns of GP, ISPS, even state health authorities to run Web services, for themselves and on behalf of GPs. Some GP practices may run their own as well. The more Web service providers there are, the better. Then we would have a really sound, reliable, scalable, and open system of health messaging/Web services in which market forces (due to the openness of the infrastructure) quick force the prices down to the lowest sustainable level (which in my view should be very low, particularly when such an approach allows a "RAID" - a redundant array of inexpensive delivery/collection [Web services]. Of course, all of this is still predicated on a pervasive PKI, isn't it? Does NEHTA think that HeSA cuts the mustard in this respect, I wonder? Given that a national provider index is planned in the next three years, a national PKI intimately hooked up to the national provider index makes enormous sense. NEHTA has, from memory, $30-40 million to implement this. So let's have the national health PKI we ought to have had from the outset. How about it, NEHTA? Tim C _______________________________________________ Gpcg_talk mailing list [email protected] http://ozdocit.org/cgi-bin/mailman/listinfo/gpcg_talk
