Implementing a scalable context-aware middleware

Recent advances in portable client devices are enabling new scenarios where mobile users assume to continuously access to various services, such as email, printing, and social computing applications, by opportunistically exploiting any computing resource and any wireless connectivity possibility encountered during their roam. That requirement calls for suitable context-aware middlewares capable of retrieving and using context data to personalize service provisioning. However, existing solutions still exhibit very limited support for context data management and distribution, especially in wide-scale and highly heterogeneous systems. The paper proposes a novel context-aware middleware to achieve scalability in context data dissemination. The primary design guideline is to reduce context data traffic by using a hierarchical distributed architecture and pervasive physical/logical caching techniques. To validate our design choices, we exploited our context-aware middleware to realize an advertisements service and a service discovery facility in our university campus. Obtained performance results demonstrate that our solution positively affects system scalability and average context dissemination time.