Program understanding behavior during corrective maintenance of large-scale software

This paper reports on a software understanding field study of corrective maintenance of large-scale software. Participants were professional software maintenance engineers. The paper reports on the general understanding process, the types of actions programmers preferred during the debugging task, the level of abstraction at which they were working and the role of hypotheses in the debugging strategies they used. The results of the observation are also interpreted in terms of the information needs of these software engineers. We found that programmers work at all levels of abstraction (code, algorithm, application domain) about equally. They frequently switch between levels of abstraction. The programmers' main concerns are with what software does and how this is accomplished, not why software was built a certain way. These questions guide the work process. Information is sought and cross-referenced from a variety of sources from application domain concepts to code-related information, outpacing current maintenance environments' capabilities which are mostly stratified by information source, making cross-referencing difficult.