Bunch: A Clustering Tool for the Recovery and Maintenance of Software System Structures

Software systems are typically modi ed in order to extend or change their functionality, improve their performance, port them to di erent platforms, and so on. For developers, it is crucial to understand the structure of a system before attempting to modify it. The structure of a system, however, may not be apparent to new developers, because the design documentation is non-existent or, worse, inconsistent with the implementation. This problem could be alleviated if developers were somehow able to produce high-level system decomposition descriptions from the low-level structures present in the source code. We have developed a clustering tool called Bunch that creates a system decomposition automatically by treating clustering as an optimization problem. This paper describes the extensions made to Bunch in response to feedback we received from users. The most important extension, in terms of the quality of results and execution e ciency, is a feature that enables the integration of designer knowledge about the system structure into an otherwise fully automatic clustering process. We use a case study to show how our new features simpli ed the task of extracting the subsystem structure of a medium size program, while exposing an interesting design aw in the process.