Active Rule Processing in Mobile Environment

• Main Authors: Ho, Shih-Hsun, 何世勳
• Other Authors: Wu Shiow-Yang
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/29986031328802451929

碩士 === 國立東華大學 === 資訊工程研究所 === 85 === For effective and adaptive information access in mobile environment, we investigate the feasibility of applying active database concept as a foundation for mobile information systems. Mobile environment is characterized by the resource limited nature of mobile hosts as well as the dynamically changing environment. To overcome availability, latency, bandwidth, and other resource restrictions, we design an active rule processing algorithm which can execute efficiently and correctly in mobile environment. The design is based on a cross analysis of mobile network and active database rule processing semantics. The principle strategies and design approach are the identification of execution modes, execution phases, as well as intelligent caching and prefetching of data. A combination of static analysis and dynamic analysis is used for predicative caching. The static analysis method employs a technique to generate view definition from rules and profile. Dynamic analysis is intended to be used for adapting view definition and materialization strategies. The effectiveness of our approach is evaluated by both an analytical model and simulation. Experimentation results indicate that the performance of mobile information systems can be significantly improved when the cache size is large enough to hold all data that are designated for prefetching. When the cache size is not large enough to hold all designated data, proper cache replacement strategies can still result in considerable performance improvement.