In both e-commerce (EC) and service-oriented computing (SOC) environments, sellers or service providers interact with customers or service clients for services or transactions. From the point view of customers or service clients, the trust status of the seller or service provider is a critical issue to consider, particularly when the seller or service provider is unknown to them. Typically, the trust evaluation is based on the feedback on the service quality provided by customers and clients. Traditionally, the trust evaluation method is based on formulas only. This might be rigid to some complex applications, like SOC. In this paper, we propose a novel integrated trust management framework that is event-driven and rule-based. In this framework, the trust computation is based on formulas. But rules are defined to determine which formula and arguments to use according to the event occurred during the transaction or service. In addition, we also propose some trust evaluation metrics and a formula. A set of empirical studies has been conducted to study the properties of the proposed formula and how to control the trust change trend in both trust increment and decrement cases. The proposed framework is more generic and suitable for different domains and complex trust evaluation systems.