by Martijn Harthoorn
Simplifier, Forge, and Vonk (the successor of Spark) will be migrated to STU3 before the Madrid WGM in May.
As the tools that we provide to the FHIR community are quite popular and heavily used, we need a very good plan to migrate to STU3. Of course we want to bring you STU3 as soon as possible. But we are not going to drop DSTU2 support just like that. Looking at several of our customers, we expect some companies will remain dependent on DSTU2 for a while. Here’s what we’ll do with our tooling.
Forge has gathered a significant user base. And since Forge is distributed via a ClickOnce installer, we will create a separate side-by-side release for STU3. This means that you will be able to install and run both the current DSTU2 and STU3 Forge releases on the same machine. We will not distribute the STU3 release as an auto-update of the current DSTU2 release; otherwise existing Forge users would no longer be able to manage any DSTU2 profiles. We will announce the STU3 release via the Furore news feed on Simplifier and also on the FHIR chat groups on Zulip.
Forge depends heavily on the FHIR .NET API, which we are currently upgrading to STU3. STU3 brings changes in some of the core resources and datatypes. STU3 also introduces some important changes in the meta data. Therefore DSTU2 and STU3 profiles are not directly interchangeable.
The migration of Simplifier is more complex. In addition to introducing support for STU3, we are also migrating Simplifier to a newer technology stack (ASP.NET core for anyone who’s interested). An additional complication is that Simplifier needs to be able to host both DSTU2 profiles and STU3 profiles at the same time. We will make a strong push towards STU3 after march 20th, but that does not imply that we will abandon DSTU2.
We will make projects on Simplifier FHIR version specific to help you, and our tooling, figure out how and what we should render. Of course, it makes no sense to try and render a DSTU2 profile with a STU3 render engine. It would just fail.
The strategy that we will follow is what we call a graceful fallback strategy. This means that we will move all our internal Simplifier tooling to STU3. And we will move all the rendering logic to STU3. But we will make it possible to still host and even upload DSTU2 profiles. This is not as simple as it may seem. After careful consideration, we decided to implement FHIR validation as a separate step, instead of being tightly integrated as a mandatory step to the import. Currently you are not able to upload DSTU1 or STU3 resources, because the FHIR engine in Simplifier considers it to be invalid input (does not conform to FHIR DSTU2). We are going to change the upload procedure, so that the server will accept invalid FHIR input. And instead of rejecting invalid input, Simplifier will inform you that it is not valid STU3 FHIR.
But this is where our graceful fallback strategy comes into play: we can’t keep everything live for all versions of FHIR. We think it’s not beneficial for the standard either. Whenever you can migrate to STU3, you should. But we will make an effort to do what we can to keep DSTU2 working for you. We keep the existing tool set for DSTU2 alive. And the more we manage to do, the better your DSTU2 experience you will be.
This is our schedule
February 13th – API
We started work on our libraries and packages on NuGet to be as ready as we can for STU3. This includes the model (base resources) parsing and serialization, validation, snapshot generation.
March 20th – FHIR
FHIR STU3 is live.
April 1st – Simplifier
This is not a precise date yet, but around this time we expect our first internal release for BETA STU3 . This is also when we start working on making Simplifier still support DSTU2.
April 17th – Simplifier & Forge
Around this time Simplifier and Forge for will go live with STU3 BETA for the daredevils.
May 6th – Simplifier
Before this date, a week before the Madrid WGM starts, Simplifier and Forge will be battle tested for STU3 and you should be ready to use them.
When something goes live, we’ll tweet about it.
Migration of your profiles
Whether you manage your profiles on Simplifier or on your local disk, migrating structure definitions automatically is no task that can be done without human supervision. But there are several tools in the community to help you. And of course our consultancy team can offer to help you with that too. They have helped a wide range of customers around the globe with migrating their profiles to STU3.