Collaborative Research: CSR-PDOS: Managing OS Extensibilty via Aspect-oriented Programming Technology

开发人员经常以特定的方式扩展大型的基于C的软件系统，包括操作系统、数据库和Web服务器，以满足其性能和功能需求。 许多扩展代表横切关注点，因为它们不适合单个程序模块，而是分散在整个源代码中。 使用常用的工具（特别是diff和patch）来维护和应用这些扩展既耗时又容易出错。此外，在组合多个扩展时确保正确性是具有挑战性的。 这项工作使得横切关注的一部分，基于C的系统架构，利用面向方面的软件开发技术。 具体来说，扩展被捕获为方面，这提供了一种语言支持的方法来表达横切关注点。 这项工作还构建了一组新的工具，用于提取、注入和转换表示为方面的系统扩展。 此外，这项工作开发了静态程序分析技术，有助于从主线代码和扩展的安全组合扩展的语义分离。 为了验证工具的有效性，PI对Linux内核和开放源代码扩展（如提供设备驱动程序隔离和恢复的Nooks系统）进行了案例研究。对于教育界来说，这项工作提供了一种有吸引力的方法来动手学习真实世界的系统。 对于系统软件社区，这项工作提供了更快速和无缝地从想法到设计再到实现新系统级扩展的能力。 最后，对于更广泛的商业开发人员和他们的客户，这项工作提供了一条更灵活的系统软件重用的道路。

Developers often extend large, C-based software systems, including operating systems, databases, and web servers, in an ad-hoc manner to meet their performance and functionality requirements. Many of the extensions represent crosscutting concerns in that they do not fit within a single program module and are scattered throughout the source. Maintaining and applying such extensions with commonly used tools, notably diff and patch, is time consuming and error prone. Furthermore, it is challenging to ensure correctness when composing multiple extensions. This work makes crosscutting concerns part of the architecture of C-based systems by leveraging aspect-oriented software development techniques. Specifically, extensions are captured as aspects, which provide a language-supported methodology for expressing crosscutting concerns. The work also builds a new set of tools that extract, inject, and translate system extensions represented as aspects. Moreover, the work develops static program analysis technology that aids in the semantic separation of extension from mainline code and safe composition of extensions. To validate the tools' effectiveness, the PIs conduct case studies on the Linux kernel and open source extensions such as the Nooks system that provides device driver isolation and recovery. For the educational community, the work offers an attractive approach to hands-on learning about real-world systems. For the system software community, the work offers the ability to more rapidly and seamlessly move from idea to design to implementation for new system-level extensions. Finally, for the broader community of commercial developers and their customers, the work offers a path to more flexible reuse of system software.