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Managing Legacy Systems (Upgrade, Replace, Rebuild)

Every organisation has systems that help them carry out day-to-day tasks. These systems provide the core structure to the organisation and can include devices like data stores, devices, and even applications. When these systems get outdated and cannot function with newer technology, it is referred to as legacy systems.  

These systems have been used for years, but they are never replaced because the staff is used to them. In addition, the management doesn't want to spend money on something apparently working fine.   

Organisations didn't always understand that relying heavily on these outdated systems can lead to inefficiencies in cost, time, and resources. But now, they are slowly starting to realise the importance of modernisation. In 2019, the global spending on the modernisation of legacy systems reached $1.18 trillion (IDC Tracker). This shows that the world is fast to modernise its components. 

In this article we discuss the importance of managing legacy systems to get the most out of your operations. We will also touch upon the options of upgrading, replacing, and rebuilding your legacy IT infrastructure. 

What are legacy systems 

A legacy system refers to an old or outdated system, software, or technology that organisations continue to use because it is still performing its intended function. They are categorised as legacy systems due to their inability to support new technology and the lack of maintenance. This results in limited growth and impacts the organisation. 

Impact of legacy systems 

According to numerous recent studies, customer experience is considered the main factor of digital transformation. However, although most CIOs consider digital transformation as critical to the continuity of the business, only a small percent consider themselves as highly mature in this area.  

Most organisations do not welcome change. They believe that if it isn't broken, you do not need to fix it. The truth, on the other hand, is quite different. Unbeknownst to IT professionals within the organisations, a legacy system can negatively impact the organisation in the following ways: 

  1. The world is going digital at a fast pace. With mobile usage rates higher than ever, organisations need to be mobile compatible. Legacy systems cannot offer mobile capability, which means that systems can only be accessed at work, resulting in the loss of productivity 
  1. Using outdated software and system can negatively impact customer experience due to the lack of functionality and employees who do not have the right tools to perform their tasks at maximum potential. 
  1. Data privacy is becoming a growing concern, and legacy systems do not have the appropriate safeguards to protect the stored data. As a result, data in legacy systems have a higher propensity for leakage. 
  1. If the system is outdated and prone to data breaches, your brand will lose its reputation and, in turn, their customer base 
  1. People see upgrading or replacing their legacy system as costly. However, owning, supporting, and maintaining a legacy system can cumulate to a much bigger outflow than the one-time expense of replacing or upgrading it. 
  1. Data is growing exponentially, and having scalable technology is paramount for an organisation to function correctly. Legacy systems are incapable of being scaled to meet the growing demand 

Managing legacy systems 

Legacy systems cause many problems, and managing them isn’t easy.  

So, no matter how difficult it may seem to upgrade them, organisations choose to do so because they want better compliance with industry and government rules, enhanced security, and ease of use.  

The exorbitant maintenance costs are also a motivator for managers to modernise their existing processes and systems. But for that, they have to evaluate the following facets: 


Organisations need first to audit their applications and software to evaluate and identify the opportunities to modernise. Next, managers need to assess employee workloads and identify whether modernisation is required to grow the business. 


Organisations need to evaluate infrastructure elements, ROI, and performance rates to assess where newer technologies deliver better outcomes.   


Modernisation can get expensive; it is vital to allocate a budget. This can help you find budget burdens and ways to optimise resources. 


To decide whether or not modernisation is necessary, you need to weigh the benefits and risks of keeping the legacy system against modernisation and see which one has less risk and more reward. 


Determine which new skill sets, training, and processes need to be factored into modernisation costs and timelines. 


Data integrity is essential, which means that the organisation plans to protect the data during and after the modernisation process. In addition, organisations should confirm adherence to governmental and industry compliance regulations in the new environment in the security plan. 

Typical approaches to modernisation  

Depending on the evaluation, there are three different approaches the organisation can take towards modernising its systems. These are as follows: 

  • Replace 

This means decommissioning existing legacy components and replacing them with modern ones. There is a complete overhaul of all existing systems from hardware to software and replacing it with newer technology in this approach. This is done while taking into account new requirements and business processes. You can also opt for the SaaS route, which would be faster, but IT teams need to be prepared for the cloud migration. Therefore, there needs to be a significant amount of planning before implementing this approach. This planning will deal with components and train employees to use the new infrastructure optimally. 

  • Rebuild 

The second approach refers to restructuring the legacy elements into a cloud environment to optimise processes. This is the most expensive way to modernise your business but has shown the best results. This is considered the ideal end state for any business.   

  • Upgrade 

Upgrading your system to the latest version is yet another way to modernise your legacy infrastructure. This approach presupposes that there is a latest version to upgrade to. You also need to check if upgrades from your version are still supported. If upgrading is possible, this is where a single application's components are ported to a new version and, depending on the minimal code changes are made. This means the component will have the same features but better. 

Using APIs to modernise legacy systems 

Mulesoft offers an alternative solution for organisations that want to modernise their IT infrastructures and improve their business processes without risking disruption:  

  • Add a layer of digital experience  

In a recent blog by MuleSoft we read “Modernising legacy stacks with a digital experience layer reduces the risk of bringing new capabilities into the business. This is achieved through cloud-based solutions that build an API layer between the existing legacy applications and user and customer-facing channels. As soon as consuming systems rely on modern APIs, legacy systems can be gradually replaced, and/or existing capabilities can be reused, extended, and composed with new services to meet new business requirements. Utilising an agile approach brings immediate business value”. 

Benefits of modernising legacy systems 

Digital transformation is often painful for organisations that have gotten used to their legacy systems.  

It may be costly for organisations to do a complete overhaul. Still, legacy system modernisation has several benefits, making it well worth the effort. These include: 

Improved security  

It is common to see patch releases for software from developers. This is done to mitigate any risk or vulnerability that may have been identified for the software. Like patches in software, modernising legacy systems can help improve the organisation's IT security with the help of vendor updates. 

Improved performance  

Legacy systems have naturally become slower over the years. This results in more resources used and time taken to complete a task. Modernising your systems can improve efficiency, optimise workplace performance, and improve employee satisfaction. 

Allows new functionality 

Legacy systems are restricted when it comes to supporting new technology. As a result, they have obsolete features and functionalities, resulting in cost and time inefficiencies. With modernisation, your organisations can add new features, offering better functionality and a better experience for your business users. 

Frees up your IT resources 

Modernised systems require less input as opposed to legacy systems. This means that the IT resources used to run a legacy system will be freed, allowing them to concentrate on other business processes. 

Wrapping up 

Modernisation of legacy systems is becoming necessary for organisations looking to excel in today's fast moving world. However, with data growing and the digital paradigm shift in full swing, organisations cannot expect to generate results with outdated legacy systems and software.  

Therefore, there is a solid need to step away from these systems and start using strategies that can help simplify tasks and improve efficiency and agility. 

Other useful links:

Interview: how to get the API-led approach to integration right

MuleSoft Anypoint Platform

5 customer advantages of API-led connectivity

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