SHF: Small: Reverse Engineering Variability Implementations

软件系统中的可变性非常普遍，对于根据用户需求定制系统以及在不同的上下文中灵活使用系统非常重要，而不必为每个上下文中从头开始开发新系统。例如，具有资源约束、高性能优化和最终用户可定制系统的嵌入式系统都可以利用可变性。然而，软件系统中的可变性在(a)重用和(b)开发和维护成本之间产生了根本的紧张关系。一方面，预先规划可变性使系统重用成为可能，并承诺显著减少开发工作、成本和上市时间。另一方面，可变性需要前期投资，并导致长期维护成本，因为变化会产生指数数量的配置，并可能产生复杂的相互作用。特别是如果以一种特别的方式引入并且没有适当地管理，可变性会增加维护成本，使其超过预期的收益。本研究开发并集成了可变性的逆向工程技术，以降低可变性的前期投资，并降低由现有的临时可变性实现的意外复杂性引起的长期维护成本。该项目通过鼓励轻量级和增量实现机制，并为实践中常见的所有临时遗留实现提供迁移机制，包括条件编译（#ifdef）、分支、克隆、文本补丁、命令行参数和插件，重新审视了可变和可重用软件的实现方式。它集成了来自不同社区的研究，包括产品线分析、静态分析、重构、关注点定位和体系结构恢复，以实现逆向工程可变性实现的共同目标。这种集成将允许扩展研究和实践，分析和迁移从核心计算到linux内核大小和复杂性的真实系统的可变性。

Variability in software systems is very common and important to tailorthe system to user needs and to use the system flexibly in differentcontexts without developing a new system from scratch for each context.For example, embedded systems with resource constraints,high-performance optimizations, and end-user customizable systems allexploit variability. However variability in software systems creates afundamental tension between (a) reuse and (b) development andmaintenance costs. On the one hand, planning variability upfront enablessystematic reuse and promises to significantly reduce developmenteffort, costs, and time to market. On the other hand, variabilityrequires an upfront investment and causes long-term maintenance costs,because variations give rise to an exponential number of configurations with potentially intricate interactions. Especially if introduced inan ad-hoc fashion and not managed appropriately, variability canincrease maintenance costs to a level that outweighs the expectedbenefits. This research develops and integrates reverse-engineeringtechniques for variability to lower upfront investments for variabilityand to reduce the costs of long-term maintenance caused by accidentalcomplexity of existing ad-hoc variability implementations.This project revisits how variable and reusable software is implementedby encouraging lightweight and incremental implementation mechanisms andproviding migration mechanisms for all ad-hoc legacy implementationscommon in practice, including conditional compilation (#ifdef),branches, clones, textual patches, command-line parameters, andplug-ins. It integrates research from different communities, includingproduct- line analysis, static analysis, refactoring, concern location,and architecture recovery toward a common goal of reverse engineeringvariability implementations . This integration will allow scalingresearch and practice of analyzing and migrating variability from corecalculi to real-world systems of the size and complexity of the Linuxkernel.