描述动态体系结构的关键在于如何刻画软件的动态行为.基于高阶多型π演算理论,提出了动态体系结构描述语言D-ADL(dynamic architecture description language).在D-ADL中,构件、连接件和体系结构风格被模型化为高阶多型π演算中的抽象(abstraction)类型,系统行为被模型化为进程(process),构件和连接件的交互点则被模型化为通道(channel).为方便系统变更逻辑的编写、修改和理解,D-ADL将动态行为从计算行为中分离出来,显式、集中地表达.由于动态行为可形式化为高阶π演算进程,其结果因此能够被预先推导.在D-ADL规约框架下,给出了将π演算的行为模拟和等价理论用于系统联机演化和体系结构模型求精的规则.实际案例说明了D-ADL的应用.
A dynamic architecture description must provide a dynamic behavior specification of software system. Based on the high-order multi-type π calculus theory, a dynamic architecture description language D-ADL is proposed. In D-ADL, components, connectors, and architecture are modeled as the 'Abstraction' type of high-order π calculus; system behavior is modeled as the 'Process'; and the interaction point between component and connector is modeled as the 'Channel'. D-ADL separates the dynamic behavior expressed in an explicit way from the computation behavior, which is helpful to edit and understand the changing logic in system. The result of the dynamic behavior can be beforehand deduced because this behavior is formalized as the high-order 'Process'. On the basis of D-ADL specification, rules about applying the theory of behavior equivalence and behavior simulation in π calculus to online evolution and architecture refinement are proposed. How D-ADL can be used is illustrated through a case study.