The operational template (OPT) for blood pressure has only OBSERVATION as its starting point. I have only one OPT that is for a COMPOSITION. I’ll probably use that one for preparing a COMPOSITION.
I just remembered that all my sample OPTs are in my local Nedap folder - they should be familiar 
- I’m using “openEHR-EHR-OBSERVATION.blood_pressure.v2.0.8_opt.json”.
- I’ll use “openEHR-EHR-COMPOSITION.report.v1.0.0_opt.json” next.
I still have to learn about COMPOSITIONS so maybe my modeling is wrong.
Full GraphQL sample can be downloaded from here.
The idea is to have native classes that can be used by developers without requiring them to know anything about openEHR.
Instead of giving them OpenAPI schema and asking them to send data to the CDR, I’m experimenting with simple classes they are used to (SDK). These classes take care of everything openEHR related.
It is similar to EHRbase SDK but one that can be used in “frontend” languages that web developers are used to.