Structural Rd E Ocumentation: a Case Study

terns require a different approach to software documentation than has traditionally been used. In understanding large, evolving software systems, structural redocumentation through reverse engineering plays a key role. Reconstructing and effectively redocumenting the design of existing software systems is even more difficult than initial design. Recognizing abstractions in real-world systems is as crucial as designing adequate abstractions for new ones. This is especially true for legacy software written 10 to 2S years ago, which is often in poor condition because of prolonged, sometimes dramatic More than SO percent of softwareevolution work is devoted to program understanding, a task in which documentation traditionally serves an important role. Yet documentation needs differ significantly for software systems of vastly different scales, say 1,000 lines versus one mill ion lines. Most software documentation is in-the-small, because it typically describes the program at the algorithm and data-structure level. For large legacy systems, understanding the structural aspects of the system’s architecture is more important than understanding any single algorithmic component.