It is always hard to work on code that you did not originally build. It is even harder when the original developers who worked on the code are all gone, there is no documentation, and no one is exactly sure how it is implemented. Unfortunately, this is an all-too-common problem for businesses with legacy software applications. These legacy applications typically have been a driver of revenue and profits for the business for a long time, so they are vital. This means that as the business changes, these legacy applications need to be updated as well. But because of architectural drift and erosion, updating and fixing problems is hard and becoming harder all the time.
Lattix Blog | Software Architecture, DevOps, Systems Engineering