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Legacy System – Legacy Systems in Companies

In most companies IT systems and applications have expanded over the years. They have been optimised for various platforms, programmed in different languages and are connected with each other – in whatever form. The system in question is often a legacy system. This refers to old methodologies, technologies, as well as application programmes, which originate from a previous or outdated computer system. The aim of modernisation is to allow these applications to be used continuously and to make them more flexible.

What is a Legacy System?

It is called a ‘legacy‘ system as previous programmes no longer meet current requirements and they therefore slow down business processes. Mainframe based applications turn into legacy IT, for example in the case of development or operating environments, which are nowadays outdated. These systems have expanded within the company, they were linked with other programmes and have numerous interfaces to additional applications. Therefore, they are not only complex but also business-critical. Many companies feel the pressure to modernise as old applications no longer meet today’s requirements. But legacy IT is inflexible and unwieldy. Due to the numerous links of old systems with business processes, it is a challenge to replace it with new IT. Legacy systems are used beyond their planned end of life to circumvent failure risks or conversion costs, which may occur during replacement of the programmes.

When Does Legacy IT Turn into a Problem?

When talking about digital transformation, then most of the time legacy systems are ignored. They slow down companies as they represent more a mix of in-house developments than a comprehensively thought out tool. They do not advance companies sufficiently as they are spread via several platforms or constitute older or no longer modern bought-in applications, which work with each other, but not in a way which would be ideal for internal processes.

The accounts department works for example with a software solution for controlling, while the production of the invoicing is done using templates in common Office applications. The HR department keeps a digital personnel file using an application purchased for this particular purpose. A digital calendar in the intranet is used for appointments, which is connected with other applications via a Java applet. This IT infrastructure cannot be adjusted to changing requirements as all interfaces would have to be renewed – a time-intensive and costly process. Those who want to implement new business processes or optimise existing processes will have difficulties. Increasing requirements to ever growing data volumes, modern demands on digital security or data protection and efficient data mining are not able to cope with such constructions. In particular Delphi or C++ applications, uncommon today, can hardly be maintained by anybody when the programmers responsible leave the company.

Challenges of a Legacy System and Alternatives

Challenges of a Legacy System

In some industry sectors it is a requirement to keep data for a long time. Here legacy systems cannot simply be switched off as they still contain sensitive and critical information, which have to be accessed in future. Nevertheless, a sophisticated strategy and sound consolidation are necessary. Often those responsible within the organisation do not know where to start when legacy systems need to be deactivated. It may prove difficult to create a plan and implement this comprehensively. In many cases it is most appropriate to first identify all business areas, where an IT modernisation is particularly worthwhile.

If some legacy systems are replaced, the modernisation can quickly pay off as hence financial leeway becomes available for additional change processes. Initially replacements can be implemented in those areas, where an efficient technology creates the biggest added value.

An alternative to legacy IT is also managed services. Although outsourcing of tasks from IT can meet resistance at first, it is worthwhile to consider for which applications a cooperation with an external professional may be helpful. It is not only storage capacity that can be outsourced but also core systems, whose maintenance often occupies staff in-house. In the past, data saved in such applications could not be separated from the programme itself, however nowadays a transfer into an open world of data is possible. Through Managed Services, modernisation can become a continuous process.


Legacy IT exists in almost all companies but one day, earlier applications will no longer be sufficient as they will not meet new requirements, or those responsible can no longer react to changing trends. The systems are often associated with high maintenance costs as they have become complex data packages. A comprehensive new set-up of IT is not always necessary. This would also be very cost intensive. Instead, central applications can be replaced or external IT professionals can be engaged with the support of a part of the software. If a legacy software is equipped with the advantages of a cloud, then this can extend the lifespan of legacy systems. This modern combination of legacy IT and modern solutions is made possible with oneclick™.



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