Connectathon 7: A Dummies Guide

As Grahame has said, the planning for the 7th FHIR connectathon to be held at the September Working Group Meeting in Chicago is well under way. This time we’ve got 4 separate tracks (you can check the link for the details), but in this post let’s have a look at track 1 – the Patient track.

This is intended to be a simple track for those new to FHIR – a way to get your feet wet (so to speak) and show just how simple basic interoperability with FHIR really is. You do need to write some code, but given the tools available these days, that’s not hard to do, so the barrier to entry is pretty low (and remember, the FHIR test servers are always available so you can do the basic learning in the privacy of your own home before you come!)

Using FHIR is actually made even easier by using one of the freely available client libraries. There are a number of them, but the 2 most well known are the .net library (from Furore – one of the earliest companies to support FHIR) and a Java one from the HAPI team – who have had a well regarded library for HL7 version 2 for many years.

In this post I’m going to use the .net libraries – but the java one will work just as well – in fact the two libraries (not co-incidentally) share a common approach.

I’d like thank my colleague Peter Jordan from HL7 New Zealand  for the code snippets in this post – I’ve adapted them a bit so I’ll take responsibility for any errors!

You’ll probably want to start with a copy of Visual Studio Express (which is free), so down load the version that suits your purpose (ie whether you’re writing a web or a desktop application).

You’ll need to download the .net FHIR libraries – they are in github, but the easiest way to get them is by using NuGet and searching for the FHIR libraries there. (The github reference has more information including links to documentation and a NuGet reference)

Now, you can create a project in Visual Studio. (btw I’m not an expert in Visual Studio – and as I use a mac it’s a bit fiddly for me to use it so this is not a step by step guide – there are a ton of tutorials on the web so it should be easy to get more detailed instructions if you need them). An alternative you can use is Xamarin which does run on the Mac.

First you need to include references to the c# FHIR libraries (and a couple of others)

using System;
using System.Collections.Generic;
using System.Configuration;
using System.IO;
using Hl7.Fhir.Model;
using Hl7.Fhir.Rest;

In order to use the library, you first instantiate a new FhirClient object, passing in the base URL of the FHIR Server. Then, you can call the required methods on that library which will issue the required REST calls – and throwing exceptions when errors occur.

In the example below, the FhirClient is initialized against the Orion Health ‘Blaze’ server, and the Conformance resource read and saved to a file.

var client = new FhirClient(@"https:/fhir.orionhealth.com/blaze/fhir/");
var confStat = client.Read<Conformance>("metadata");
string TestFile = "c:\temp\" + Guid.NewGuid().ToString() + ".html";
File.WriteAllText(TestFile, confStat.Summary);

So how do you find a patient? Well…

var client = new FhirClient(@"https:/fhir.orionhealth.com/blaze/fhir/");
List<string> searchCriteria = new List<string>();
searchCriteria.Add("name='eve'");
var bundle = client.Search<Patient>(searchCriteria.ToArray());
foreach (ResourceEntry entry in bundle.Entries) {
   // create a Patient Object from the Entry Resource
   Patient patient = (Patient)entry.Resource;
   // ... do something with patient, it's a c# object representing the patient resource ...
}

You want to create a new patient?

var client = new FhirClient(@"https:/fhir.orionhealth.com/blaze/fhir/");
// create new Patient object
Patient newPat = new Patient();

// create identifier list item and add it to the new patient
Uri uri = new Uri("http://nhi.health.nz")
Identifier id = new Identifier { System = uri, Value = "PRP1660", Label = "NHI" };
newPat.Identifier = new List<Identifier>();
newPat.Identifier.Add(id);

// create a human name list item and add it to the new patient
List<string> famName = new List<string>();
famName.Add("Jones");
List<string> givName = new List<string>();
givName.Add("Indianna");
HumanName hn = new HumanName { Family = famName, Given = givName };
newPat.Name = new List<HumanName>();
newPat.Name.Add(hn);

// add DOB and gender
newPat.BirthDate = "1955-12-16";
newPat.Gender = new CodeableConcept { Text = "M" };
client.Create<Patient>(newPat);

So there you have it – that’s half of the scenario done for you! How hard can it be?

See you in Chicago…