5.6 Summary

Understanding the legacy system is one of the major challenges involved in modernizing legacy systems. The level of understanding required, the appropriate techniques to apply, and the appropriate models to create depend largely on how the legacy system will be transformed.

The RSS modernization effort, for example, involves a complete architectural transformation requiring both static and dynamic analysis of the legacy system at all levels of abstraction. This required discovering and documenting the relationships between source-level elements in RSS, including call and create- read-update-delete (CRUD) data. The RSS architecture also had to be reconstructed to the degree required to map between program elements in the legacy system and the target architecture.

The RSS modernization effort required transforming the existing but largely uncharacterized legacy system architecture to the target architecture we define in Chapter 12. Chapter 6 discusses architectural representation and its application in legacy system modernization.