Recovering software requirements from system-user interaction traces

As software systems age, the requirements that motivated their original development get lost. Requirements documentation is unavailable or obsolete. Recapturing these requirements is critical for software reengineering activities. In our CelLEST process we adopt a data-mining approach to this problem and attempt to discover patterns of frequent similar episodes in the sequential run-time traces of the legacy user-interface behavior. These patterns constitute operational models of the application's functional requirements, from the end-user perspective. We have developed an algorithm, IPM, for interaction-pattern discovery. This algorithm discovers patterns that meet a user-specified criterion and is robust to insertion errors, caused by user mistakes or by the availability of alternative scenarios for the same user task. In this paper, we discuss IPM and we evaluate it with a case study.