Managing Evolution in Distributed, Heterogeneous Systems

分布式、异构型(DH)软件系统是现代全球化组织运作的关键。像所有的软件一样，随着组织需求的发展，DH系统也面临着进化的压力。调整DH系统以满足安全等领域不断变化的需求是具有挑战性的：以不同语言和在不同平台上进行的协调更改仍然必须保持类型安全，并且不得增加复杂性和/或使维护复杂化。该项目研究了对基于标准的中间件(例如，CORBA)的增强，以支持演化。我们保留并增强了基于IDL的核心中间件的异构性哲学。首先，对用于建模组件体系结构级接口的接口描述语言(IDL)进行了增强，以支持对DH系统的演化更改进行建模。要创建的新信息的更改位置、类型和生命周期都是在IDL级别以面向方面的风格显式建模的。代码生成支持广泛的实现选择，以实现这些架构更改模型。所有实现都是完全可互操作的。最后，变更模型和实现可以“组件化”、打包并添加到现有系统中。像这项研究一样，我们的教育计划也跨越了几个主题领域，包括函数编程、面向对象和体系结构。我们开发了软件演化的实践基础教学方法，比较了在面向对象、高阶多态(包括一元编程)、连接器和方面分离关注点的不同方法。

Distributed, heterogeneous (DH) software systems are critical forthe operation of modern, globalized organizations. Like all software, DH systems come under evolutionarypressure as organizational needs evolve. Adapting DH systems to meet changing needs in areas such as security is challenging:Co-ordinated changes, made in different languages, and on differentplatforms must still preserve type-safety, and must not increasecomplexity and/or complicate maintenance. This project investigates enhancements to standards-based middleware (e.g., CORBA) to support evolution.We preserve and enhance the core IDL-based heterogeneous philosophy of middleware. First, interface-description language (IDL),used to model the architecture-level interfaces of components, is enhanced to supportmodeling of the evolutionary changes made to a DH systems. Locationof changes, types and life-times of new information to be created are all explicitly modeled in an aspect-oriented style at the IDL level. Code generation supportsa wide range of implementation choices torealize these architectural change-models. All implementationsare fully inter-operable. Finally, change-modelsand implementations can be "compononentized", packaged up and added to existing systems. Like this research,our educational plans also spanseveral topics areas, including functional programming,object-orientation, and architecture. We develop practically-grounded pedagogy on software evolution,comparing the varying approaches to separation of concerns inobject-orientation, higher-order polymorphism (includingmonadic programming), connectors, and aspects.