HL7 FHIR difficult to implement - Misperception or truth?

Recently I am approached by one project team, who stated that it is very difficult to implement HL7 FHIR API with the following two reasons

1) Their system only supports RESTful with JSON

2) They are not familiar with HL7 FHIR

For technical people who has some basic understanding of HL7 FHIR, you must be laughing,  since HL7 FHIR API is using RESTful with JSON, and only difference between HL7 FHIR and other proprietary API is that the format and syntax in HL7 FHIR is standardised

Instead of brushing it aside, and knowing that the system is using Java. So I spent 5 minutes to ask Chatgrp, how to implement client side programme in Java to call HL7 FHIR API

Afterward I spent next few mins to try out and validate in Java IDE (Integrated Development Environment) Eclipse.

Below I briefly described the steps provided by chatgrp

1) Create a Maven project in Eclipse

2) Configure the dependent libraries(HAPI FHIR libraries) in Maven POM

3) Copy and paste the sample code provided by chatgpt into my Java application, and updated the remote FHIR server to FHIR server hosted by Firely (its FHIR server is written in .NET)

Below is the source code of the java application, you can run the application to create patient resource, once it is created, you can check the created resources at Firely Server using this URL - https://server.fire.ly/

package synapxe.fhir.demo;

import java.util.Calendar;

import java.util.Random;

import org.apache.commons.lang3.RandomStringUtils;

import org.hl7.fhir.r4b.model.Bundle;

import org.hl7.fhir.r4b.model.Enumerations;

import org.hl7.fhir.r4b.model.Identifier;

import org.hl7.fhir.r4b.model.Patient;

import ca.uhn.fhir.context.FhirContext;

import ca.uhn.fhir.rest.api.MethodOutcome;

import ca.uhn.fhir.rest.client.api.IGenericClient;

/**

* Sample FHIR Client using HAPI open source library https://github.com/hapifhir/hapi-fhir

*

* @author victorchai

*

*/

public class FHIRClient {

public static void main(String[] args) {

try {

createPatient ();

//searchPatientByName ("HapiVictor");

//deletePatient("cfc18bb8-e1dc-4bab-b4e2-83e1d797034f");

}

catch (Exception ex) {

ex.printStackTrace();

}

}

private static void createPatient() {

// Create a FHIR context for the FHIR version you are using (e.g., R4)

FhirContext ctx = FhirContext.forR4B();

// Create a client to connect to the FHIR server

String serverBaseUrl = "https://server.fire.ly"; // Firely FHIR Server which is implemented in .NET

IGenericClient client = ctx.newRestfulGenericClient(serverBaseUrl);

// Create a Patient resource

Patient patient = new Patient();

Identifier nric = new Identifier();

nric.setSystem("http://fhir.synapxe.sg/Namespace/nric");

String nricDigits = RandomStringUtils.randomNumeric(7).toUpperCase();

nric.setValue("S" +nricDigits + "H");

patient.getIdentifier().add(nric);

patient.addName()

.setFamily("HapiVictor")

.addGiven("John");

patient.setGender(Enumerations.AdministrativeGender.MALE);

Calendar dob= Calendar.getInstance();

Random ran = new Random();

int x = ran.nextInt(10);

dob.set(1970 +x ,Calendar.getInstance().get(Calendar.MONTH), Calendar.getInstance().get(Calendar.DAY_OF_MONTH));

patient.setBirthDate(dob.getTime());

// Send the created patient resource to the server

MethodOutcome outcome = client.create().resource(patient).execute();

// Print the outcome

String patientID = outcome.getId().getIdPart();

System.out.println("Created Patient with ID: " + patientID);

System.out.println("You can access the patient resource at this url - "

+ serverBaseUrl +"/Patient/"+ patientID +"?_format=application/fhir+json");

}

private static void searchPatientByName (String familyName ) {

// Create a FHIR context for the FHIR version you are using (e.g., R4)

FhirContext ctx = FhirContext.forR4B();

// Create a client to connect to the FHIR server

String serverBaseUrl = "https://server.fire.ly"; // Example HAPI FHIR server

IGenericClient client = ctx.newRestfulGenericClient(serverBaseUrl);

Bundle results = client.search()

.forResource(Patient.class)

.where(Patient.FAMILY.matches().value(familyName))

.returnBundle(Bundle.class)

.execute();

System.out.println("Found " + results.getTotal()+ " patients:");

for (Bundle.BundleEntryComponent entry : results.getEntry()) {

Patient patient = (Patient) entry.getResource();

System.out.println("Patient ID:" + patient.getIdElement().getIdPart());

System.out.println("Patient Name:" + patient.getNameFirstRep().getNameAsSingleString());

}

}

private static void deletePatient(String patientID) {

// Create a FHIR context for the FHIR version you are using (e.g., R4)

FhirContext ctx = FhirContext.forR4B();

// Create a client to connect to the FHIR server

String serverBaseUrl = "https://server.fire.ly"; // Example HAPI FHIR server

IGenericClient client = ctx.newRestfulGenericClient(serverBaseUrl);

// Send the patient resource ID to the server

MethodOutcome outcome = client.delete().resourceById("Patient", patientID).execute();

// Print the outcome

System.out.println("Deleted Patient with ID: " + patientID + " with status:" + outcome.getResponseStatusCode()) ;

}

}

Below you can also find the libraries included in  Maven POM.xml which specifies the dependent libraries (again this is also provided by Chatgpt)

<dependencies>

<!-- This dependency includes the core HAPI-FHIR classes -->

<dependency>

<groupId>ca.uhn.hapi.fhir</groupId>

<artifactId>hapi-fhir-base</artifactId>

<version>${hapifhir_version}</version>

</dependency>

<!-- Include the client -->

<dependency>

<groupId>ca.uhn.hapi.fhir</groupId>

<artifactId>hapi-fhir-client</artifactId>

<version>${hapifhir_version}</version>

</dependency>

<!-- At least one "structures" JAR must also be included -->

<dependency>

<groupId>ca.uhn.hapi.fhir</groupId>

<artifactId>hapi-fhir-structures-r4b</artifactId>

<version>${hapifhir_version}</version>

</dependency>

<!--

HAPI-FHIR uses Logback for logging support. The logback library is included

automatically by Maven as a part of the hapi-fhir-base dependency, but you

also need to include a logging library. Logback is used here, but log4j

would also be fine.

-->

<dependency>

<groupId>ch.qos.logback</groupId>

<artifactId>logback-classic</artifactId>

<version>1.2.3</version>

</dependency>

</dependencies>

Btw, there are many many HL7 FHIR open sources libraries available - Java, Net, Python and Javascript, etc, you can find the full list at this URL - https://confluence.hl7.org/.../Open+Source+Implementations

Go explore HL7 FHIR and have fun. Pls msg me if you need have deeper discussion on HL7 FHIR