DECODE: a cooperative environment for reverse-engineering legacy software

While automated program understanders have had some success in partially extracting design information from source code, they are unlikely to be able to completely understand existing real-world legacy systems. To address this problem, we have been developing DECODE, an environment in which programmer and system cooperate to extract object-oriented designs from legacy systems. DECODE consists of three components: an automated program understander that extracts some initial stereotypical object-oriented design elements; a structured notebook that provides the user with a graphical view of the system's understanding and the ability to extend this understanding by linking source code fragments to object-oriented design elements; and a query processor that uses this design information to support conceptual queries about the program's code and design. This paper describes DECODE and our initial successes and failures with using it to reverse engineer several non-trivial COBOL programs.