Digital transformation

Use your Legacy application for a long time

August 3, 2021 - 5 minutes reading time
Article by François Zielemans

Rising maintenance costs, dissatisfied users and poor integration with new technology – once an application or system reaches the limits of its shelf life, but you can't just say goodbye to it, you are facing a 'legacy challenge'. Don't worry: with one of the following 3 scenarios, your aging application can likely still be used for a long time.

‘Legacy software’ exists when the functionality, ease of use, technology and methods used have deteriorated to unacceptable levels. Think of customers or users you can no longer serve properly, security issues, changes that are slow and costly to implement, or problematic integration with other modern systems and cloud platforms. It is time for renewal!

Three renewal scenarios

If a niche is too small for standard software or if there is a demonstrable financial benefit to be gained by deploying customization, it can be useful to (continue to) invest in custom applications. There are 3 different scenarios to future-proof your legacy application.

1. Modern portals

In application development, most of the development time goes to the ‘business logic’ layer and the user interface that overlays it (the screens that the users of the application see). In a legacy application, these are often outdated and no longer in line with the expectations of a new generation of users. Access for external target groups, such as customers and business partners, can also be an obstacle for an outdated legacy application.

On the other hand: after having used the existing application for years, internal 'power users' often like to have many fields and functions on one screen, something that is only possible to a limited extent with a web application. At the same time, after years of continued development of the existing system, this layer is also the most costly to replace.

A popular approach to extending the lifecycle of a legacy application, is to add new screens through one or more modern web portals that run in the browser. An additional advantage is that the legacy application can continue to communicate with other legacy applications. A 'hybrid scenario' is therefore also very popular: it is often a win-win, both for the users and in terms of the (limited) investment required.


  • New look & feel, and better user experience
  • Serving new external target groups with a limited investment
  • Maintain integration with other legacy systems


  • Some limitations of the old technology remain
  • Limited innovations in business logic and workflows
  • Possible additional licensing costs, due to an increasing number of technologies

2. Renew everything, except the database

In the previous option, new screens were added via one or more portals. As a result, the impact on the legacy application is limited, but all existing functional limitations remain in place. In the second option, everything is renewed except the database. All screens and the entire business logic (insofar as the database allows, think 'stored procedures') are converted into a full-fledged web application.

The innovation in business logic brings many new possibilities: better integration with chain partners, a larger number of connected devices (for example IoT integration) and a good connection with developments in the field of data analytics (such as machine learning). However, it is also a much more expensive scenario: after all, work is not only done on the legacy system; also the linked (legacy) systems are carefully examined. And you're still stuck with that 'old' database.

But there is hope: the days when databases from Oracle, Progress or IBM were much more reliable, or better, than others, are far behind us. Now that most databases are 'mature' and developments follow each other in such quick succession, organizations will rarely opt for this approach and will rather go for scenario 1 or 3.


  • Automate new insights about business models and processes
  • Additional possibilities of new technologies for the business logic and screens
  • No data migration required
  • Suitable when multiple legacy applications share a single database


  • The renewed application is bound to the (im)possibilities of the existing database
  • Less obvious due to the large current offering of mature database solutions

3. Complete renewal

Whereas the renewals in scenarios 1 and 2 are still limited, in scenario 3 the brakes go completely off. In the case of complete renewal, all layers of the application are replaced. Not everything in the renewed application needs to be 100 percent new. After all, it still must fit into the existing IT landscape.

In scenario 3, there are no more technological constraints, and full attention can be given to making the new application future-ready, both from a business point of view and technically. It is the perfect opportunity to incorporate your organization's vision of the future into the application, so that it will still fit the business strategy five years from now.

In addition to more freedom in the design of the application, scenario 3 also gives you plenty of room to scrutinize the way the application is developed, tested, deployed, monitored and hosted. More recent concepts such as Agile Scrum, automated testing, continuous integration & rollout of new versions, and scripting of hosting environments, are much more suited to a rapidly changing environment than traditional methods and techniques.


  • The sky is the limit
  • The right time to redesign business models and business processes
  • Completely new technology stack


  • The most expensive scenario
  • Risk of 'old wine in new bottles', unless the business really dares to look ahead
  • Requires new team composition to get the most out of the investment.

Which scenario you choose depends on the wishes of the organization. After all, it knows better than anyone else the customer's needs, its own strengths, and the weaknesses of the competition. Whichever option is the best in your case: with the right scenario you will certainly enjoy your renewed legacy application for years to come.

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