Behind the façade: Bringing interoperability and agility to legacy systems

By Chris Royle

FHIRworks Series: The barriers for sharing documentation and data in healthcare are breaking down, helped by standardization, digital technologies and collaboration. In this blog series Chris Royle, Interoperability Specialist for DXC Healthcare, will focus on the use of HL7 FHIR in the real-world, and how it can be used to drive further adoption and innovation in Healthcare.

Bringing interoperability to legacy healthcare systems is often regarded as, at the very least, challenging. But with the help of a façade pattern, it doesn’t have to be. In fact, one of the design patterns I find most useful is the facade pattern. This pattern can be used in many situations.

What is a façade?

The Oxford Dictionary defines a façade as “the principal front of a building that faces onto a street or open space” or “a deceptive outward appearance”.

Let’s consider the first definition. Throughout the ages, humans have built beautiful architecture — the Gothic, the Baroque and the Art Deco of the 1930s (to name just a few). Although the architecture is beautiful, the buildings themselves may be crumbling, given their age. One way to restore life into these living pieces of art is to keep the façade and change the underlying building structure to make it usable again. A prime example of this around the world is the repurposing of old warehouses and factories into modern apartments. The outside of the building remains the same, but on the inside it is new and has an open plan.

Now, let’s think about the second definition — a deceptive outward appearance. In Venice, an annual carnival, the “Carnevale di Venezia”, is held, where Venetians use masks to cover their faces and hide their true selves.

What does a façade have to do with interoperability?

The latest standard in health interoperability is HL7 Fast Healthcare Interoperability Resources (FHIR), which is a new method of providing access to data and enabling access to this data for mobile development. If you are building a new health system today, you can take advantage of this standard and allow developers easier access to your data. That’s all well and good, but many healthcare organisations have numerous legacy systems that hold crucial data.

In these scenarios, we need to think about how to best deploy FHIR resources on top of current systems without having to start from scratch. This is where the façade concept fits in. Creating a façade on top of existing systems allows FHIR resources to interoperate with the business environment. In this way, the FHIR façade can be the “deceptive outward appearance” where we can expose FHIR resources, but populated by traditional HL7 v2 messaging or existing Simple Object Access Protocol (SOAP) services, or even direct database access. This can be done without affecting the underlying back-end systems. Such a capability is very important because we need to keep these systems of record running while enabling better and more open methods of accessing data, as well as improving data interoperability.

How would this pattern work in a real-world example?

Consider a mobile application that allows a user to change some patient details. In the past, we might have created a web service or required the mobile app developers to understand HL7 v2 A31 messages and ask them to deliver that to an integration engine over a TCP/IP port.

Now, using a façade pattern, we can create a FHIR patient resource linked to the HL7 v2.x A31 message. This means that the app developer doesn’t need to understand the nuances of an HL7 v2.x message, but at the same time there’s assurance that the data is validated with the comprehensive set of rules applied by the system of record. It’s great for app developers as they work with technologies they understand (JavaScript Object Notation [JSON] and XML over HTTP), and safe for the healthcare organisation, since all the checks are performed before updating the data.

HL7 FHIR as a standard simplifies implementation and allows data to be opened up so that applications can gain access to the data they need in a way that developers can consume. That’s what makes a façade such a useful design pattern for implementing FHIR on existing systems without having to rethink the interoperability landscape.

As you look for ways to make the most of your data and leverage new capabilities in your current system, consider the use of a façade pattern in your current integration landscape and how it might fit into your broader digital landscape.

For more information on how DXC can extend interoperability through our Open Health Connect platform – visit   

Chris Royle is an interoperability specialist with DXC Healthcare and Life Sciences, Australia and New Zealand with a focus on healthcare interoperability. He has more than 20 years of experience in healthcare technology and interoperability, bringing his knowledge to resolve our customers’ integration challenges now and into the future.


  1. […] systems may have upward of a dozen different EHRs, the other major theme of the conference is interoperability. My focus groups and interviews tell me that, when vendors say this word to healthcare technology […]

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