PDQm using FHIR Subscription as Async API to XCPD/XCA

In the last article, he discussed the basic process for using PDQm and MHD as the XCPD / XCA programming interface. This is the classic purpose of current IHE profiles.

But the truth of the XCA community is that

You probably have hundreds of learning communities.
Some of these communities will be fast, others slow.
Some churches will be denied and will not answer.
In fact, the time between buyers demanding the PDQm discovery request and getting all the results from all the communities can be a few minutes. Yes, a few minutes. This long time between silent GET (query) and response is not unusual. The usual REST API for ordinary http is not waiting for a long time.

One solution is to make sure that all of your customer’s applications are waiting for a long time before giving up and assuming the response / initiative infrastructure fails. How long does it take to wait? This amount can be completed anywhere, for example, CapabilityStatement in the responder or in a service directory.

This is not a user friendly though. You can get a program for buyers waiting a few minutes, but it’s likely that someone will be waiting for a long time. It is possible to convert any result if it is available to the buyer. I’m not sure what it looks like. The flow of results also requires a program design for consumers who expect liquid results. That said, they do not expect a full http response before they see what they have … this is not a friendly solution.

In addition, within minutes, the gateway responder should have a lock flag dealing with important resources in intermediate programs.

Some of these problems are http RESTful, but most of them are common problems that exist even in the classic XCPD / XCA world with SOAP.

FHIR has an out-of-the-box solution … Subscribe … With subscription, the buyer creates a resource subscription with a standard subscription that matches the PDQm query performed. The customer will let them know the same data for the subscription.

The standard status of using a subscription is registration to receive new data that other people may create in the future. In case of use I describe here an asynchronous mechanism for a number of transactions (XCPD). In both cases, making a subscription is a trigger to begin exploring the background of XCPD. Once the XCPD discovery completes, the subscription is unavailable. Therefore, the end of the subscription is different from the usual subscription usage status.

I worked with a developer who implemented it as an internal application interface compatible with the electronic switching system (Sequoia Network). There are more than 100 partners, and some partners need a few minutes to respond. The result is a more sensitive behavior of the application, in this case the web interface. In fact, the total response time is faster from start to finish, because critical processing is usually done during waiting, rather than processing money after all network interactions. So I won twice!

It seems more busy, what is … but wait between spaces. The best thing about this method is that “new results: Ping 1234” occurs once for each selected patient to be found and occurs when the match is available. So, the program of using partner games can be very fast. After that, the buyer can do something right, z. B. Show results in moderation. In contrast to the classic solution that prevents buyers from knowing anything until he knows everything.

Note that I used web sockets here, which requires the client to ask for every notification. There are other types of subscriptions that can return to the data. I did not try it and I did not see it.

Below is the font of UML graphics that can be used at https://websequencediagrams.com
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PDQm Subscription Title – XCA

Consumer Co
Participation in the initiative
participant answer

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