PERFORMANCE EVALUATION OF CACHE INVALIDATION STRATEGY FOR LOCATION AND TIME DEPENDENT DATA IN MOBILE ENVIRONMENT

Abstract

Caching can reduce the bandwidth requirement in a wireless computing environment and can minimize the energy consumption of wireless portable computers. Cache invalidation is a mechanism which decides whether the cache content is valid or not. Cache invalidation techniques can be categorized in to two depending on the data involved: time dependent caching and location dependent caching. In time dependent caching to facilitate mobile clients in ascertaining the validity of their cache content, servers periodically broadcast cache invalidation reports that contain information about the updated data. In location dependent caching the server will give information about the region for which the data is valid. This region information is used for cache invalidation. Many applications such as traffic control system and weather information system use data that changes both with location and time. When the cached content is both time and location dependent then spatio temporal cache invalidation is used. In this dissertation a spatio temporal invalidation scheme has been developed by using a combination of "Caching Efficiency Based" method for location dependent invalidation and "Selective Dual Report Cache Invalidation" method for temporal invalidation. The performance of this invalidation scheme has evaluated and optimal broadcast report interval has determined. The system runs on windows xp environment with PIII 866 MHz processor and 128 MB RAM. The language used for code development is