Blog_Lead (25)
Olly Shaw Scale Principal

Tech Focus Mon 8th April, 2024

Heritage services: What they are and why we love them

At Equal Experts, we help our customers get the best value from their technology capabilities. This can be through digital transformation and the creation of new digital services to maximise business value. It can also involve nurturing and extracting value from existing services.

We define “Heritage” services as those with a high cost of business change. While the cost of change is high, they are typically of high value and importance to the business. Indeed in many cases, these services were the foundation of the business!

Classification of heritage services

The right classification of a software service has broad consequences:

  • What is an appropriate operating model?
  • What build and run capabilities are needed?
  • What are the ways to extract value?
  • What are the options for improvement?

To help contextualise these problems, we classify services as heritage or digital.

  • Heritage Services: Custom software services and/or self-hosted COTS with a low demand for change and a high cost of change. Crucial for extracting business value.
  • Digital Services: Custom software services with a variable demand for change and a low cost of change. Vital for exploring and expanding business value.

We classify heritage and digital services in terms of cost of change, rather than the traditional dimensions of age, technology stack, or hosting mechanism (cloud vs on-prem). We’ve seen decades-old services with a low cost of change, and months-old services using modern technologies with a prohibitive cost of change.

Our other axis is “demand for business change”. This is the demand for features which seek to explore and expand business value. Digital services and heritage services differ here:

  • Digital services can support high feature demand, and if their cost of change remains low for the long term, they can also handle low feature demand cost-effectively (we call this maintenance mode)
  • Heritage services can only handle low feature demand, due to their high cost of change. Supporting high feature demand in heritage services isn’t viable due to the high cost of change.

The exact capabilities for release frequency will vary from organisation to organisation. Broadly we’d consider a digital service to be able to support multiple releases a day – while heritage services may only support one release or fewer per week.

Why is the cost of change high in heritage services?

It’s time-consuming to change heritage services, due to the aggregation of multiple factors involved in a new release:

  • Risk – As these heritage services are at the organisation’s core, they carry an intrinsic high risk. Their larger scope and interconnected architecture increases the blast radius for any problems. As they are also released infrequently, they also carry an accumulation of risk.
  • Organisational effort – Finally, the organisational effort around a heritage system slows down the ability to release frequently. For well-meaning and understandable reasons, there is often a large bureaucracy with these services.
  • Development time – Changing heritage services is a high-cost activity. If it’s custom-built, it might be in an unfamiliar language, or the code might be unadaptable and inflexible. If it’s a COTS, it might have limited endpoints to extract value from
  • Testing time – Heritage services will often require high levels of manual testing alongside slow end-to-end automation. Digital services will have high levels of fast-running meaningful tests.
  • Rollout and Rollback pathways – Heritage services often have their release process designed to support a Big Bang event. Due to a coupled architecture and hosting strategies, they cannot utilise red/green progressive deployments. For similar reasons, the rollback of these services is also unavailable.

How do we make the most of our heritage?

Now we’ve defined what heritage services are, we need to know how to make the best use of them. In some upcoming content we’ll explore different heritage topics:

  • Dual Operating Model – We’ll discuss how heritage and digital services require different operating models.
  • Making the most of heritage – We’ll discuss how to make the most of your heritage services and extract the most value from the venerable services.
  • Creating a heritage platform – We’ll describe creating a heritage platform, this effort is usually combined with a migration from an on-prem data centre.
  • Rearchitect and don’t create tomorrow’s heritage – We’ll talk about how to migrate from a heritage system to a place where high feature demand can be fulfilled