A significant quality factor reliability is an important requirement for all software systems. Reliability analysis and evaluation for a system is necessary for the success of these systems. This paper proposes a fault metric called use case fault metric (UCFM) for object-oriented systems using use case diagram and is built on the theory of Fault Tree Analysis (FTA). The goal is to address an important issue of measuring reliability of object-oriented systems during initial stages of software development. This goal is achieved by extending the model-driven software development process with the concept of Fault Tree Analysis (FTA). The Fault Tree analysis is performed in bottom-up way to compute quantitatively the proposed metric called UCFM. The proposed approach transforms the use case in an equivalent Fault Tree. This FTA is used to compute a metric that quantifies the probability of occurrence of faults in different use cases. The UCFM value is computed at use case, use case diagram and system level. The proposed metric is validated theoretically using measurement theory and practically using Kaner’s framework.

质量因素的可靠性是所有软件系统的重要要求。系统的可靠性分析和评估对于这些系统的成功是必需的。本文使用用例图为面向对象的系统提出了一种称为用例故障量度（UCFM）的故障量度，并建立在故障树分析（FTA）理论的基础上。目的是解决在软件开发的初始阶段测量面向对象系统的可靠性的重要问题。通过使用故障树分析（FTA）的概念扩展模型驱动的软件开发过程来实现此目标。故障树分析以自下而上的方式进行，以定量计算所提议的度量标准UCFM。所提出的方法将用例转换为等效的故障树。此FTA用于计算度量标准，该度量标准量化了不同用例中故障发生的可能性。UCFM值是在用例，用例图和系统级别计算的。所提出的度量在理论上使用测量理论进行了验证，并在实际中使用了Kaner框架进行了验证。