中文摘要：

以基于服务组合的可信软件为研究对象，重点研究通过组合服务的动态演化机制保障网络化软件的可信性．首先，提出了一个合理性保持的演化操作集，避免复杂的验证过程，使得演化后的组合服务保持结构合理性；在此基础上，通过构造冗余路径的方式给出了一个面向可用性保障的组合服务演化方法；然后，针对组合服务动态演化过程中运行实例的处理，设计了一个组合服务演化中运行实例在线迁移算法，为正确实施演化提供支持；最后，设计实现了一个支持动态演化的组合服务执行引擎，并通过实验验证了所提出方法的有效性．

英文摘要：

This paper is concerned with trustworthy software constructed through service composition and is especially emphasizes guaranteeing the trustworthiness of networked software through dynamic evolution of composite services. First of all, a set of evolution operations preserving soundness of composite services is proposed so as to avoid the complex verification process. Second, a composite service evolution method with availability guarantee is provided, the main idea of which is to create redundant execution path to improve the availability of a composite service. Third, to deal with runtime instances after dynamic composite service evolution, a live instance migration algorithm is designed to support the correct evolution enforcement. Finally, a composite service execution engine supporting dynamic evolution is developed and the effectiveness of the proposed method is showed through a set of experiments.