Reengineering legacy software products into software product line

Abstract

The idea of Software Product Line (SPL) approach is to manage a family of similar software products in a reuse-based way. Reuse avoids repetitions, which helps reduce development/maintenance effort, shorten time-to-market and improve overall quality of software. A number of open problems must be solved for SPL to have wide-spread impact on software practice. One of them is to understand and manage variability in software artefacts. To migrate from existing software products into SPL, one has to understand how they are similar and how they differ one from another. In current practice, such analysis is done mostly manually, with some help of clone detection tools. We propose higher level of automation, and a sandwich approach that consolidates feature knowledge from top-down domain analysis with bottom-up analysis of code similarities in subject software products. Our proposed method integrates model differencing, clone detection, and information retrieval techniques, which can provide a systematic means to reengineer the legacy software products into SPL based on automatic variability analysis. Once the variability among the different product variants have been recovered and understood, SPL core assets are built to facilitate reuse. In that area, our contribution is in proposing effective strategies for managing variability in core assets. We analyzed benefits and trade-offs involved in strategies based on applying multiple traditional variability techniques, and in applying a uniform variability technique of XML-based Variant Configuration Language (XVCL). Our proposed strategies have been evaluated in an industrial project and a number of lab case studies.