1. FHIR and Relational Databases
Robert Worden
Open Mapping Software Ltd

2. TOPICS Making FHIR servers from Relational Databases
FHIR Transform Engine (FTE)
FTE with HAPI Server Engine
FTE and FHIR Mapping Language

3. Relational Databases and FHIR
Most healthcare data is held in relational databases (more than 80%?)
For interoperability, we need to access those data in FHIR
Need to make FHIR servers from existing relational databases
This requires bi-directional transforms, and efficient search – in situ

4. Three Types of Transform are Needed
From To
Purpose
Relational data
FHIR
Get data out
Get data in
RESTful search string
Efficient SQL query
Get data out efficiently
This has been implemented for one example
(PAS database => Server for Patient Resource),
using the FHIR Transform Engine

5. Building Transforms with the FHIR Transform Engine (FTE)
Eclipse-based mapping design toolset
Automatically capture the data structure (e.g. XML, RDBMS)
Automatically capture FHIR resource profiles
Graphically Map from the data structure to FHIR
Tools generate transforms, in both directions
Automated test; fast iterative map/test/map cycle
Does all kinds of transform (e.g. flat => nested)
Escape to Java code when needed

6. Mapping a Database to FHIR Resources
FHIR bundle class model
Whole database
Patient Resource
Tables
Columns
In Patients
table
Green nodes
are mapped
Mapped to
Database record
or column
Fields in
Patient Resource
There is no short cut to doing this analysis

7. Testing Mappings (V2 to FHIR)
Summary
test scores
Result of
V2 to FHIR
transform
ABA = V2 to FHIR to V2
round-trip
AB = V2 to FHIR
transform
All test
Result files
Mappings being tested
Example files used in this test
A, B = codes for test files

8. HAPI and FHIR Transform Engine
HAPI provides a highly capable FHIR Server Engine
But HAPI does not interface FHIR resources to existing relational databases
FTE does
FTE is being integrated with HAPI
This is the best way to make any relational database into a FHIR server
Supports many searches without coding

9. FHIR Servers: HAPI/FTE/RDB
Client A
Server B
User Interface
User Interface
FHIR
Transform
Engine
HAPI
Server
Engine
FHIR
Transform
Engine
Business
Logic
FHIR
Business
Logic
Relational
Database
Relational
Database

10. Efficient RESTful Search
Many different searches may be supported for each resource (see examplefrom HL7 FHIR site)
FTE + HAPI can support these searches:
Do not need to code each type of search
Uses efficient database retrievals
Supports chained reference searches across resources
Any search is possible if the DBMS stores the required information in the resources
HAPI search calls are auto-converted to an SQL query, through FTE mappings
DBMS uses indexes for fast retrieval

11. FHIR Mapping Language FHIR Mapping Language (FML) is part of STU3
Defines transforms from declarative mappings (e.g. X => FHIR, FHIR => X)
FML and FTE are different styles of mapping language
But they are compatible:
Can now generate FML mappings from FTE mappings
Round trips are possible
FTE can act as a graphical editor for FML mappings
FTE and FML are convergent, not competing
Gives choice of mapping development tools, choice of runtime engine