Large Scale Empirical Validation of the Aspect-Oriented Design Hypothesis

纵观技术历史，模块化设计已被证明是处理系统复杂性的有效方法。模块化设计也经常应用于软件密集型系统。然而，软件不同于硬件。具体来说，软件可以通过编程方式影响其他软件，这一事实拓宽了模块化的选择。模块的本质可以用在硬件中不切实际的方式重新定义。面向对象编程（AOP）最近提出了这些重新定义之一。在AOP中，一些被称为“方面”的模块通过从局部效应所属的模块外部对这些关注点进行建模来直接解决某些设计关注点的横切性质。本研究将对AOP提出的设计假设进行大规模的实证验证，并将利用它来推导模块化设计的原则。AOP假设有三个子假设：（1）复杂软件必须处理横切关注点的存在;使用传统的面向过程或面向对象设计，这些横切关注点表现为分散在几个模块中的设计元素，并与这些模块中的其他关注点纠缠在一起;（2）分散和纠缠对设计过程是"坏"的;（3）面向方面的语言如AASPJ所体现的替代组合机制比传统的组合机制更好。AOP的经验验证将由一个名为Sourcer的基础设施来实现，该基础设施是为收集、搜索和分析Internet上可用的大规模开源软件而开发的。更广泛地说，这项研究将调查在开源软件中进行实证研究的方法。

Throughout the history of technology, modular design has proven to be an effective way to deal with system complexity. Modular design is also routinely applied to software-intensive systems. Software, however, is different from hardware. Specifically, the fact that software can programmatically affect other software broadens the options for modularization. The very nature of modules can be redefined in ways that would be impractical in hardware. Aspect-Oriented Programming (AOP) has recently put forth one of those redefinitions. In AOP, some modules called ''aspects'' directly address the crosscutting nature of some design concerns by modeling those concerns from outside the modules to which the local effects belong.This research will conduct a large-scale empirical validation of the design hypothesis put forth by AOP, and will leverage it to derive principles for modular design. The AOP hypothesis has three sub-hypotheses: (1) Complex software must cope with the existence of cross-cutting concerns; using traditional procedure- or object- oriented design, those cross-cutting concerns show up as design elements scattered throughout several modules and tangled with other concerns within those modules; (2) Scattering and tangling are ''bad'' for the design process; (3) The alternative composition mechanisms embodied in an aspect-oriented language like AspectJ are ''''better'''' than the traditional ones. The empirical validation of AOP will be enabled by an infrastructure called Sourcerer, developed for collecting, searching, and analyzing software on the very-large scale of Open Source software available on the Internet. More broadly, this research will investigate methodologies for conducting empirical research in Open Source software.