A Department of Labor (DOL) legacy system with a desktop-only graphical user interface (GUI) needed a web-based GUI. By careful inspection of the code and experimentation, a deep "spike" solution was created that allows a small fraction of the system to be implemented with a web-based system utilizing in-situ business rules and stored procedures. This spike is the basis of planned broadening to provide a practical means of rewriting the entire legacy system, thus de-risking the whole project.
The existing technology was ancient and nearly undocumented. In order to have a functioning spike, a complete and valid environment would have to be duplicated. Because the data was potentially subject to litigation and sensitive, we would have to work entirely with artificially created data.
After installing a DB2 instance and extensive study of the stored procedures, we were able to interface to the database with a simple Python program that implemented a web service interface, thus allowing a simple but possibility-expanding, browser-based demo.
The spike solution dramatically reshaped the DOL's acquisition plan, including cost estimates, by proving that an API-encapsulation approach could work and be expanded at minimal risk.