Skip to content

Let's Build DevDays US 2020

Jump to bottom
James Agnew edited this page Jun 16, 2020 · 7 revisions

Let's Build - DevDays US 2020

This page contains instructions for the DevDays US 2020 Let's Build session. In this exercise we will take a few key features of the HAPI FHIR JPA Server for a spin.

First, check out the project here: https://github.com/hapifhir/hapi-fhir-jpaserver-starter (or if you already have, perform a git pull to ensure you have the latest code.

You will also need a Java JDK with version 8 or 11 (others may work but we recommend one of these two as they are the focus of our testing). You can get JDK 11 here: https://adoptopenjdk.net/

Finally, you will need Apache Maven. You can get Maven here: https://maven.apache.org/download.cgi

Start the Server Up

Out of the box, HAPI FHIR JPA uses an embedded database called H2. H2 is a nice database for testing things, because it doesn't require you to install anything. We will use it for this session, but if you are building a server that you are going to put real data on you will definitely want to swap this for a production grade database such as Postgresql.

To start the JPA server, issue the following command:

mvn clean jetty:run

You will see some messages in the console while it starts. After a few moments, it should settle down and you'll see a message like this:

[INFO] Started ServerConnector@3f867060{HTTP/1.1,[http/1.1]}{0.0.0.0:8080}
[INFO] Started @17521ms
[INFO] Started Jetty Server

Seeding Some Data

Let's add two patients to our server. First, we'll do a FHIR Update with Client Assigned ID to create a patient with the ID Patient/A. This is a useful feature of FHIR that allows the client to pick the ID assigned to the resource:

{
	"resourceType": "Patient",
	"id": "A",
	"identifier": [ {
		"system": "http://springfieldhospital.edu/patient",
		"value": "3894746"
	} ],
	"name": [ {
		"family": "Simpson",
		"given": [ "Homer", "J" ]
	} ],
	"gender": "male",
	"birthDate": "1956-05-12"
}

Next, let's create a Patient/B

{
	"resourceType": "Patient",
	"id": "B",
	"identifier": [ {
		"system": "http://springfieldhospital.edu/patient",
		"value": "1234567"
	} ],
	"name": [ {
		"family": "Simpson",
		"given": [ "Marge" ]
	} ],
	"gender": "female",
	"birthDate": "1956-10-01"
}

Now, let's create a few Observations. We'll use a FHIR Transaction for this, in order to create several resources at the same time.

{
	"resourceType": "Bundle",
	"type": "transaction",
	"entry": [
		{
			"resource": {
				"resourceType": "Observation",
				"status": "final",
				"code": {
					"coding": [
						{
							"system": "http://loinc.org",
							"code": "789-8",
							"display": "Erythrocytes [#/volume] in Blood by Automated count"
						}
					]
				},
				"subject": {
					"reference": "Patient/A"
				},
				"effectiveDateTime": "2020-06-16T12:00:00-04:00",
				"valueQuantity": {
					"value": 4.12,
					"unit": "10 trillion/L",
					"system": "http://unitsofmeasure.org",
					"code": "10*12/L"
				}
			},
			"request": {
				"method": "POST",
				"url": "Observation"
			}
		},
		{
			"resource": {
				"resourceType": "Observation",
				"status": "final",
				"code": {
					"coding": [
						{
							"system": "http://loinc.org",
							"code": "11557-6",
							"display": "Carbon dioxide in blood"
						}
					]
				},
				"subject": {
					"reference": "Patient/B"
				},
				"valueQuantity": {
					"value": 6.2,
					"unit": "kPa",
					"system": "http://unitsofmeasure.org",
					"code": "kPa"
				}
			},
			"request": {
				"method": "POST",
				"url": "Observation"
			}
		}
	]
}

You may want to add some more data beyond what we are showing here.

Try it out

Let's try a few searches for data. A couple of ideas are here, but you should play around and try others:

Adding Interceptors

Let's start with an easy interceptor: the Request Validating interceptor. You can see documentation for this interceptor here: https://hapifhir.io/hapi-fhir/docs/interceptors/built_in_server_interceptors.html#validation-request-and-response-validation

Adding this interceptor is easy because the JPA Starter project has a configuration option that handles this. In your IDE, open the file hapi.properties and look for the following line:

validation.requests.enabled=false

Change the value to true, and restart your server by hitting Control-C in the terminal window where you started it and then rerunning mvn clean jetty:run.

Your server is now set to validate incoming requests and will reject requests that fail validation. Let's test this out.

{
	"resourceType": "Patient",
	"name": [ {
		"family": "van Houten",
		"given": [ "Milhouse" ]
	} ],
	"gender": "male",
	"age": "12"
}

This request should fail, because we're using an invalid property ("age"). Try correcting this to the more correct "birthDate" element.

Clone this wiki locally