Refactoring a legacy component for reuse in a software product line: a case study

Abstract

Product lines are a promising approach to improve conceptually the productivity of the software development process and thus to reduce both the cost and time of developing and maintaining increasingly complex systems. An important issue in the adoption of the product-line approach is the migration of legacy software components, which have not been designed for reuse, systematically into reusable product-line components. This article describes activities performed to improve systematically the design and implementation of an existing software component in order to reuse it in a software product line. The activities are embedded in the application of Fraunhofer PuLSE TM -DSSA-an approach for defining domain-specific software architectures (DSSA) and product-line architectures. The component under investigation is the so-called Image Memory Handler (IMH), which is used in Ricoh's current products of office appliances such as copier machines, printers, and multi-functional peripherals. It is responsible for controlling memory usage and compressing and decompressing image data. Improvement of both the component's design and implementation are based on a systematic analysis and focused on increasing maintainability and reusability and hence suitability for use in a product line. As a result of the analysis and refactoring activities, the documentation and implementation of the component has been considerably improved as shown by quantitative data collected at the end of the activities. Despite a number of changes to the code, the external behavior of the component has been preserved without significantly affecting the performance. INTRODUCTIONOrganizations developing software face a number of challenges today. In particular, there is a critical need to reduce the cost, effort, and time-to-market of software, but, at the same time, the complexity and size of systems are rapidly increasing and customers are requesting increasingly quality systems tailored to their individual needs [1].A promising approach to improve conceptually the productivity of the software development process and thus to reduce both cost and time of developing and maintaining increasingly complex systems is the notion of software product lines [2]. Product-line software engineering refers to techniques for creating a collection of similar software systems from a shared set of software assets using a common means of production. A software product line is defined as a family of products designed to take advantage of their common aspects and predicted variability [3]. Product-line engineering is based on strategic reuse as opposed to opportunistic reuse, which usually comes into play in single-system development. Strategic reuse means that attributes of software such as generality, modularity, environment independence, and self-descriptiveness are planned and implemented with respect to the predictable benefits concerning customer needs and market trends. In product-line engineering, the overall development life cycle is split into two concurrent phase...

Quality of Merge-Refactorings for Product Lines

“…These approaches mainly provide guidelines and methodologies for identifying features and their related implementation components rather than build tool-supported analysis mechanisms. Some works also report on successful experience in manual re-engineering of legacy systems into featureoriented product lines, e.g., [14].…”

“…Numerous works provide guidelines and methodologies for building product line representations out of legacy systems, e.g., [14,8]. Most of such approaches, however, involve a manual review of code, design and documentation of the system aiming at identifying the set of product line features, as well as the set of components which implement these features.…”

Combining Related Products into Product Lines

“…Several works (e.g., [9,10]) capture guidelines and techniques for manually transforming legacy product line artifacts into SPLE representations. Instead, our goal is to introduce automation into the refactoring process by comparing, matching and merging artifacts to each other.…”

Extending the Reflexion Method for Consolidating Software Variants into Product Lines

“…RE-PLACE is a pure process description and does not delve into concrete program analysis techniques to support the process. Kolb et al described a case study where the framework of PuLSE is used to systematically refactor an existing software component for reuse in an SPL [14,13]. They propose various metrics to measure quality before and after the refactoring.…”