Architectural modifications to deployed software

We discuss the nuts and bolts of industrial large-scale software modification projects. These projects become necessary when system owners of deployed systems hit architectural barriers. The mastery of such projects is key to the extension of the best-before date of business-critical software assets. Our discussion comprises the process for problem analysis, pricing and contracting for such projects, design and implementation of tools for code exploration and code modification, as well as details of service delivery. We illustrate these concerns by way of a real-world example where a deployed management information system required an invasive modification to make the system fit for future use. The chosen project is particularly suited for a complete treatise because of its size (just 90,000 LOC), and the nature of the relevant architectural modification (namely, a form of data expansion). We share the lessons that we learned in this and other architectural modification projects.