Do Legacy Systems dream of Modernization?

Small surges of electricity breathe life into legacy systems far beyond anyone’s expectations. Today, we develop software designed to last about 6–8 years, perhaps stretching to 10–12 in the best-case scenario, yet some legacy monoliths remain active, largely unchanged since the 1980s. What gives these systems their enduring vitality and necessity? Why do software engineers often approach them with trepidation? And how do successful organizations find themselves trapped with outdated technologies that they can neither replace nor adequately maintain?

In the first part of this talk, we explore the nuances and paradoxes of our relationship with legacy systems. We examine why we simultaneously struggle to tolerate legacy code while in the same time being unable to do without it. The second part offers a practical cheat sheet filled with insights for engineers about to embark on, or already navigating, the challenges of a software modernization journey. Finally, we delve into common design patterns that facilitate legacy displacement, drawing on real-life examples to illustrate each approach.