Cache Invalidation and Propagation of Updates in Distributed Caching.

Replication and caching strategies are increasingly being used to improve performance and reduce user perceived delays in distributed environments. A query can be answered much faster by accessing a cached copy than by making a database roundtrip. This setting creates a number of important issues such as maintaining consistency among copies of the same data item. Numerous techniques have been proposed to achieve caching and replication while maintaining consistency among the replicas. A closer investigation of these schemes reveals that no one scheme can be optimal for all environments. In this thesis we look at invalidation protocols for achieving consistency in systems that use distributed caching. We propose heuristics for dynamic adaptation of these protocols for cache consistency. These heuristics aim at propagating invalidations while reducing the cost of data transfer.