Data Caching with Incremental Update Propagation in Mobile Computing Environments

Users of mobile computers will soon have online access to a large number of databases via wireless network. Because of limited bandwidth, wireless communication is more expensive than wire communication. This implies that caching of frequently accessed data items will be an important technique that will reduce contention on the narrow bandwidth wireless channel. In this paper, we propose a new cache coherency scheme, named CCS-IUP (cache coherency scheme with incremental update propagation), that allows incremental update and use of derived caches. CCS-IUP is novel in the sense that it tries to avoid invalidating cached data; hence, the number of cache misses may be reduced. Furthermore, in CCS-IUP, the server propagates only relevant fractions (increments) of the modifications that affect the cached data, so that it can significantly reduce the amount of data transmission over the wireless network.