Design strategies and a flexible, adaptable middleware architecture for resource-limited, evolving systems. Mobile computing environments are characterized by heterogeneity systems consisting of different device types, operating systems, network interfaces, and communication protocols. Such heterogeneity calls for middleware that can adapt to different execution contexts, hide heterogeneity from applications, and transparently and dynamically switch between network and sensor technologies.

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... ionally, middleware for context-aware systems must keep a context model (a model of their environment), taking into account several aspects of the environment. The more complex and heterogeneous an execution environment is, the more complicated its underlying context model. Moreover, because systems can evolve, context management must also support model evolution without restarting, reconfiguring, or redeploying applications and services. We describe a context management middleware that can efficiently handle context despite the execution environment's heterogeneity and evolution. It uses context meta-information to improve a context-aware system's overall performance. Heterogeneous environments In pervasive environments, heterogeneity has hardware, software, and network aspects. Hardware heterogeneity refers to the presence of different computing devices, such as desktop computers, palmtops, and mobile phones. This type of heterogeneity demands middleware infrastructures that are deployable on servers, workstations, and portable mobile devices. Software heterogeneity means the environment is executing different operating systems and applications, requiring software interoperability and the adoption of context models that address specific application requirements. Network heterogeneity means that network interconnections among the system's devices don't