Down to hades and back ? Experiences gained in comprehending a distributed legacy system

Software engineering principles and practices face a lot of challenges. Among them, debugging and comprehending systems is still demanding. Furthermore, comprehending distributed systems, even though there are several papers and approaches to be found in literature, is a challenge of a completely different dimension. This paper describes the experiences gained when trying to comprehend (and debug) a distributed legacy system and it takes a closer look at the different options somebody has in similar situations. It does not propose specific tools or methodologies, but tries to provide guidelines to developers who might be challenged by comparable problems.