Reverse and Reengineering for Old Systems is Seldom Complete

The chapter describes two different and practical reengineering projects – one for business administration and the other for mobile phone control software – on a textbook level. Underlying are three doctoral dissertations /Cr 00, Ma 05, Mo 09/. As the example projects are completely different, from the application domain on one side and from the structure of the systems to be reengineered on the other, we believe that the experiences we acquired are more than just two examples. The chapter emphasizes that a complete reengineering of a system is rather rare due to pragmatic reasons. Therefore, we have to handle changes, which preserve the value of a big part of the system and at the same time offer the necessary and wanted extensions for improved functionality and quality.