Chinese Journal of Computers   Full Text
Title	Data Prefetching to Support Real-time Transactions Processing in Mobile Environments
Authors	LI Guo-Hui1) YANG Bing1) CHEN Hui1) DU Jian-Qiang2)
Address	1)(School of Computer Science & Technology, Huazhong University of Science & Technology, Wuhan 430074) 2)(School of Computer, Jiangxi University of Traditional Chinese Medicine, Nanchang 330006)
Year	2008
Issue	No.10(1841—1847)
Abstract &   Background	Abstract With the rapid advances in mobile computing technology, there is an increasing demand for processing real-time transactions in mobile environments. Due to the intrinsic limitations of a mobile environment, there can be long time latency for a data access. Sometimes the data can even be unavailable due to the network disconnection. Data prefetching is an approach to this problem. However, most of the previous studies in data prefetching don’t consider the timeliness for data objects and deadlines of transactions. Therefore they are inefficient for supporting mobile real-time transaction processing. This paper proposes a data prefetching strategy to support real-time transaction processing in a mobile data broadcast environment. Each data object is assigned a prefetching value determined by its changeability, access frequency. For the data objects with bigger prefetching values, by further considering the priorities of the transactions which access the data objects and the validity intervals for these data objects, the authors determine whether these data objects are actually prefetched. Extensive simulation experiments are conducted and show that when using the proposed data prefetching strategy, more mobile real-time transactions can meet their deadlines. Keywords data prefetching; mobile real-time transaction; cache invalidation; prefetching schemes Background The work in this paper is supported by the National Science Foundation of China under grant No.60873030, the National High-Tech Research and Development Plan of China under grant No.2007AA01Z300. The research projects aim to get some efficient methods to support real-time transaction processing in mobile distributed computing environments. Till now authors have analyzed environmental factors that have direct impacts on the distributed and mobile real-time transaction processing. A relative timing correctness criterion and the strategy to implement it have been investigated. Based on the checkpoint-based transaction execution model that may benefit transactions to satisfy their timing constraints, a distributed cooperative real-time transaction model for a kind of distributed real-time database applications is proposed. Considering the undependable and asymmetric wireless communication channel and the limited power capacity, a data broadcast strategy to support mobile real-time transaction processing is under consideration. This paper focuses on data prefetching to support real-time transaction in mobile environment.