Many people involved in FHIR still work with DSTU2 and STU3, and Simplifier is the platform for working with FHIR. Thus making sure, you can keep working with older (draft) versions of FHIR is fundamental to us.
The Simplifier team spent a good amount of time to bring you a complete engine for all FHIR R4 features, while keeping all STU3 features as they are. We are not done yet, but we are very close - here's an update on the latest efforts.
In the previous release of Simplifier, we added the FHIR R4 engine as a beta feature. It allowed you to create an FHIR R4 project and upload R4 resources. It also allowed you to view them using the Simplifier FHIR R4 render engine. What we did not have was a way to generate a snapshot, which is very important to have good insight into changes made in derived profiles with respect to its base profile. With this release we added snapshot generation for FHIR R4: with it, you now have access to the 'diff', 'hybrid', and 'snap' views.
Since Snapshot Generation is a fundamental part of resource validation, once we had it we could also add the FHIR R4 validation engine to Simplifier. Thus, it is now available and it works just as simple STU3 validator: no surprises there.
In all FHIR STU3 projects, you have direct access to the FHIR universe - all resources on Simplifier - just by referencing a canonical URL. This gives a great start experience, but also caused problems. A lot of users re-upload resources from other projects for testing purposes. As a result, you saw places where the wrong StructureDefinition was referenced (a copy instead of the original). When you're working on an official release of your profile or Implementation Guide, you don't want the risk of referencing someone's test resource.
Our original solution was to allow users to register a canonical base to their project, to indicate that they are the official owner of the canonical URL. But this was not perfect. Even here, you see that some teams have a draft project, or a project to design the next release. This is one of the reasons we introduced packages this year: to give you control over what projects (package) and which releases you reference.
For FHIR R4 projects on Simplifier, packages are now the default. That means that we will not understand any canonical reference unless it's in a package that your reference in your project.
The packages feature in Simplifier is going out of beta in the next release. Currently it's still a bit rough around the edges. In the upcoming release, we will make this a more friendly experience. We will then provide you with a default reference to a package containing the official core profiles when you create a project.
We did a lot to improve the performance of the website itself: the performance is close to 100% faster (it serves in half the time)! You should notice the difference.
A few important things are still needed for a full FHIR R4 experience. There is currently no option to save your Implementation Guide as a FHIR R4 ImplementationGuide resource. We will bring this with the next release too.
As you probably know, all FHIR STU3 projects in Simplifier are their own FHIR server: just click on API menu in a project to find out what the API endpoint is.
We don't have a FHIR endpoint for R4 yet - that's still a work in progress. We want to make sure the FHIR server STU3 endpoints are always working. With the next release, I will give you an update on how far along are we with that.