A Hybrid Cache Cohrency Scheme for Ubiquitous Mobile Clients

We propose a new cache coherency scheme named HCCS(hybrid cache coherency scheme) to facilitate ubiquitous data access of mobile clients. To cope with the limitations of ubiquitous computing environments, it integrates the cache invalidation scheme using broadcast channel into the publish/subscribe-based data synchronization scheme using two-way communication channel. We present novel algorithms and system architecture for the HCCS. By integrating two schemes, the HCCS provides substantial benefits: allows updates on the mobile client which are restricted in the cache invalidation scheme using broadcast channel and disconnected operations, improves the scalability. The HCCS scheme also gives proper support to the short disconnection of mobile clients, dynamically adapts to changes of disconnection period of the mobile clients.