An increasing number of distributed applications are currently being constructed as sets of connected components and dynamically deployed in wide area networks using frameworks such as CORBA, .NET, and Web Services. Such dynamic deployments enable applications to flexibly adapt to changes in client QoS requirements and network properties, but introduce a consistency problem because of replicated components. Ideally, the frameworks deploying the applications should ensure that the application consistency requirements are satisfied, even though the requirements can range from weak to strong and dynamically change at run-time. Thus, a key challenge is to design a flexible cache coherence protocol that uses application-specific information while still being application-neutral.

This paper describes Flecc, an application-neutral cache coherence protocol used by a component-based framework (Partitionable Services Framework) to satisfy the consistency requirements of deployed applications. Flecc allows applications to specify appropriate consistency and granularity levels and define complex synchronization decisions as simple functions. We demonstrate the benefits of our cache coherence protocol by analyzing the behavior of a component-based application modeling an airline reservation system.