A Cost Effective Cache Consistency Method for Mobile Clients in Wireless Environment.
ABSTRACT When a mobile client disconnects for a prolonged time which exceeds the window size of the server’s invalidation reports ,
the mobile client’s cache is discarded even if most of data are still valid. In this paper, we propose an efficient cache
consistency method called CCI(Cost-based Cache Invalidation) for mobile clients, which takes into account not only the disconnection
time but also the update frequencies at a server.
Full-textDOI: · Available from: Sungwon Jung, Apr 12, 2014
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ABSTRACT: Data broadcasting is an efficient data dissemination method in a wireless client–server system. A data server broadcasts data items periodically, and mobile clients cache data items to save communication bandwidth, resource usage, and data access time. The server also broadcasts invalidation reports (IRs) to maintain the consistency between server data and the clients’ cached data. Most existing cache invalidation policies in a wireless environment based on IRs simply purge the entire cache after a client has been disconnected long enough to miss a certain number (window size) of IRs. We present a cache invalidation scheme that provides better cache reusability and better data access time after a long disconnection. Our scheme attempts to increase cache reusability by respecting update rates at a server, broadcast intervals, the communication bandwidth, and data sizes, as well as disconnection time. Simulation results show that the increased cache reusability of our scheme can improve the data access time after a long disconnection.Data & Knowledge Engineering 11/2007; DOI:10.1016/j.datak.2007.03.010 · 1.49 Impact Factor
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ABSTRACT: Broadcast is widely accepted as an efficient technique for disseminating data to a large number of mobile clients over a single or multiple channels. Due to the limited uplink bandwidth from mobile clients to server, conventional concurrency control methods cannot be directly applied. There has been many researches on concurrency control methods for wireless broadcast environments. However, they are mostly for read-only transactions or do not consider exploiting cache. They also suffer from the repetitive aborts and restarts of mobile transactions when the access patterns of mobile transactions are skewed. In this paper, we propose a new optimistic concurrency control method suitable for mobile broadcast environments. To prevent the repetitive aborts and restarts of mobile transactions, we propose a random back-off technique. To exploit the cache on mobile clients, our method keeps the read data set of mobile transactions and prefetches those data items when the mobile transactions are restarted. As other existing optimistic concurrency control methods for mobile broadcast environments does, it works for both read-only and update transactions. Read-only transactions are validated and locally committed without using any uplink bandwidth. Update transactions are validated with forward and backward validation, and committed after final validation consuming a small amount of uplink bandwidth. Our performance analysis shows that it significantly decreases uplink and downlink bandwidth usage compared to other existing methods.Journal of Systems and Software 12/2009; DOI:10.1016/j.jss.2009.06.053 · 1.25 Impact Factor
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ABSTRACT: Data Caching improves data availability among the mobile nodes (MNs) that are connected together through unreliable wireless links. The MNs are often updating the cached data due to its dynamism. The query access rate of cached data is varied based on neighbor nodes requirements. The caching nodes must ensure the staleness of data with source. This paper proposes the novel Cluster Based Update (CBU) algorithm to avoid the stale data in caching nodes. The network is partitioning into non overlapping clusters and Cluster Head (CH) is selected based on weighting factor. The CH maintains Global Cache Index (GCI) that consist information about its cluster members and neighbor CHs. The CH maintains the query access entry for cached data in its cluster members. The source also sends data update rate to CH. Thus consistency is maintained based on data update and its query access rate through CHs. The simulation results shown that proposed algorithm reduces the latency, overhead than existing approach by increasing nodes and speed respectively.