[Health-dev] Some thoughts on version-aware records

[Chris Zimmerman]

Hi all,

I am slowly (hey, no complaints! hehe) making my way through the Patient
resource endpoint defined by the FHIR standard. The standard writers
wisely give servers choices on certain points, such as allowing
client-defined ids for records. Some of these choices are somewhat
trivial, but there are other, more systemic choices.

One of the more... interesting choices is the server's handling of
update (and create) requests. For example, say there is a patient record
at /Patient/1, then a client can upload an update to it through a PUT
/Patient/1. Basic REST behavior. However, these records are complex and
robust, and it seems unwise to blindly update the record. Transactional
integrity, information loss, and other issues quickly appear.

The standard leaves this question, quite rightly, to the server. The
standard allows a variety of options (even, if I'm reading it correctly,
not allowing updates at all). However, they do suggest a pattern which
uses version-aware records. I believe there was some previous discussion
on version-aware records. I don't think that tryton/health exposes this
kind of version control (?), although psql does support it through its
timetravel extension. Unless I miss my guess, even limited version
support isn't necessarily a small endeavor.

Any thoughts?

-C