| The limited wireless communication bandwidth in a mobile computing environment requires caching frequently accessed data in a mobile client's local memory to reduce the bandwidth required and to improve performance over wireless communication channels. To make cached data consistent, the server periodically broadcasts an invalidation report to all mobile clients in its cell so that each can invalidate obsolete data items from its cache. Since a mobile client has very limited battery power, it disconnects from the communication channel frequently to save energy. If a mobile client has a long disconnection period, it may discard its entire cache because it misses invalidation reports. In this thesis, we present four new hybrid cache invalidation schemes, namely, the HSB scheme, HABSB scheme, CHDO scheme, and SCHDO scheme. In these schemes the stateful server is applied to store the caching information of each registered mobile client in its cell to allow for long disconnections. However, the server periodically broadcasts an invalidation report similar to a stateless server. (Abstract shortened by UMI.). |
