基于构件的数据流软件可靠性模型

基于构件的数据流软件由输入数据激活的构件确定程序执行路径，其可靠性受输入数据分布特性的影响，难以采用基于状态或基于路径等传统模型进行评测。提出一个结合构件执行频度和操作剖面的可靠性模型，其从分析数据流程序结构入手，通过定义组合节点，将程序表示成多级层次结构的形式。根据构件间数据流和控制流关系，确定实际激活的构件，计算其执行频度，并将操作剖面沿着数据流向本层和下层构件传递。利用基于深度优先的递归算法思想，按照相反顺序，逐层估算各级组合节点的可靠性，最后获得整个软件的实际可靠性。应用实例表明，模型能有效地佑算基于构件数据流软件的实际可靠性，反映输入接口有效数据就绪状态及分布特性。

Software Reliability Model for Component-based Dataflow Software

Duc to the mechanism that component based dataflow software has its execution path determined by components activated by data fed into input interfaces,its software reliability can be influenced by distribution of input data,and is thus difficult to evaluate using traditional models such as statcbased or path-wise ones. A reliability model combining frectuency statistics and operational profile was put forward in this paper. Starting from analysis of dataflow software structure, programs were denoted as multi-layer structure by introduction of composite node. On the basis of data and control flow relations,activated components and their execution probability were estimated. The operational profile was transferred along the direction of data flow to components on the same or a lower layer. By means of depth-first rule, reliability of composite nodes on all levels was evaluated in opposite order until the actual reliability of the whole software was obtained. A case study shows that the model can effectively evaluate actual reliability of component based data flow software, reflecting ready state of effective data in input interfaces and data distribution attributes.