Abstract: In recent years, the component-based development pattern is becoming increasingly popular with developers. Generally, a software system is made up of multiple components. The trustworthiness of software systems depends on the trustworthiness of every component. This paper will try to study the trustworthiness of systems from the component view. Firstly, all components in the system are divided into the critical and non-critical ones according to their importance, and a weight value is assigned to each component. For every basic construction between components, the trustworthiness metric model of the subsystem is proposed by composing the trustworthiness of components. Secondly, we prove that these metric models satisfy the metric criteria, such as monotonicity, non-negativity, acceleration, sensitivity, and substitution. Furthermore, the trustworthiness metric model of the whole system is shown based on the trustworthiness metric model of the subsystem. Finally, an algorithm is designed to compute the trustworthiness metric of the whole system. An example is shown to verify the reasonability of the metric model.

Key words: component, trustworthiness of software, measurement of software, quality of software