Bills-FHIR-page

These are my notes on FHIR. As they become mature they will probably migrate to John's page.

FHIR class

March 11, 12 2014 took FHIR class given by HL7 (Floyd taught). The slides from that class are available for download from here

As a summary of the class, I believe that the full semantics of XDS.b can be translated to FHIR. This would mean replacing the ebXML Registry binding with the FHIR binding and replacing the SOAP binding with the combination of FHIR REST and ATOM. I describe it this way because FHIR has its own flavor of REST and ATOM. (a comment, not a criticism).

The class was quite overwhelming in the same way that drinking from a fire hose is overwhelming.

What follows below are my notes from the class. I will continue to add to this page as I discover more things that I learned (see fire hose).

REST vs Transactions

FHIR has transactions and it has REST. Here I mean REST in the form of direct addressing of individual objects like DocumentEntry and SubmissionSet (XDS terms).

On the direct addressing side, one can submit a single object, say DocumentReference, assigning it a permanent ID or allowing the server to assign the ID. To submit allowing the server to assign the ID you would POST the single DocumentReference object to

    http://server.com/xds/DocumentReference

where

http://server.com/xds

defines the server and service supporting FHIR (yes, I made them up). The FHIR server would reply giving status (HTTP status) and giving you the permanent address of the object in a HTTP header:

    Location: http://server.com/xds/DocumentReference/1002/_history/1

where 1002 is the assigned ID (server controlled) and the _history/1 indicates that this is the first version of this object. The object can be retrieved with a GET to

    http://server.com/xds/DocumentReference/1002

which will return the most recent version.

This shows the most simple submit/retrieve operation on what we would call metadata. Beware, FHIR has another definition of metadata and it has nothing in common with what DS calls metadata. More on that later.

The simple submit/retrieve has been done via REST. No transaction was involved. Transactions, like in the traditional database use of the term, implies that multiple object are involved and the operation is performed all or none. I have to layout a lot more detail before I can comment on transactions. This was just a teaser.