Caching of frequently accessed data on the mobile clients can reduce the number of uplink requests, server load and query latency and can increase data availability. As cached data items eventually become invalid due to updates at the server, an invalidation strategy is employed to maintain cache consistency so that no obsolete data would be used to serve queries. The basic cache invalidation strategies make use of periodic invalidation reports (IRs) and updated invalidation reports (UIRs) broadcast by the server. This paper presents a synchronous stateful caching strategy called update report (UR). UR strategy preserves the advantages of IR/UIR strategies and improves on their disadvantages. It reduces the size of IR by filtering out noncached items, handles long disconnection, reduces query latency by broadcasting recently requested items immediately after every UIR, conserves client energy and supports mobility. Simulation results prove that UR yields better performance than IR and UIR strategies.

Energy efficient cache invalidation in a disconnected wireless mobile environment

Caching at mobile client is an important technique for improving the performance in wireless data dissemination It can reduce the number of uplink requests, server load, query latency and can increase the data availability Battery energy and limited bandwidth are two major constraints imposing challenges to the realization of caching at mobile clients A cache invalidation strategy ensures that the data items cached in a mobile client are consistent with those stored on the server In our invalidation scheme, to minimize uplink requests, all recently updated or requested items are broadcast immediately following the invalidation report To further improve the caching performance, prefetching is used Three update report strategies are presented to reduce average access time and minimize the client energy for cache invalidation Simulation experiments show that the LCF strategy dramatically improves the average access time for mobile clients, reduces the number of uplink requests and conserves the client energy

Broadcast Based Cache Invalidation and Prefetching in Mobile Environment

An invalidation tracker system for tracking messages in a caching architecture of a pricing and shopping platform. The caching architecture includes of multiple levels each comprising one or more servers. Invalidation messages are communicated from one level to another to send invalidation messages to all servers in the caching architecture. The system receives data from provider databases to be communicated to the servers in the caching architecture. The system includes a recording module for recording all invalidation messages communicated to the servers in the caching architecture to form a set of sent invalidation messages, an analyzing module for determining the invalidation messages received at each server in the caching architecture and comparing this with the set of sent invalidation messages to identify one or more undelivered invalidation messages, and a reply module for resending the one or more identified undelivered invalidation messages to an appropriate server in the caching architecture.

Method and system for message tracking and checking

Caching at mobile client is an important technique for improving the performance in wireless data dissemination. It can reduce the number of uplink requests, server load, query latency and can increase the data availability. Battery energy and limited bandwidth are two major constraints imposing challenges to the realization of caching at mobile clients. A cache invalidation strategy ensures that the data items cached in a mobile client are consistent with those stored on the server. In our invalidation scheme, to minimize uplink requests, all recently updated or requested items are broadcast immediately following the invalidation report. To further improve the caching performance, prefetching is used. Three update report strategies are presented to reduce average access time and minimize the client energy for cache invalidation. Simulation experiments show that the LCF strategy dramatically improves the average access time for mobile clients, reduces the number of uplink requests and conserves the client energy.

Broadcast based cache invalidation and prefetching in mobile environment

Caching in mobile computing environment has emerged as a potential technique to improve data access performance and availability by reducing the interaction between the client and server. A cache invalidation strategy ensures that cached item at a mobile client has same value as on the origin server. To maintain the cache consistency, the server periodically broadcasts an invalidation report (IR) so that each client can invalidate obsolete data items from its cache. The IR strategy suffers from long query latency, larger tuning time and poor utilization of wireless bandwidth. Using updated invalidation report (UIR), the long query latency can be reduced. This paper presents a caching strategy that preserves the advantages of existing IR and UIR based strategies and improves on their disadvantages. Simulation results prove that our strategy yields better performance than IR and UIR based strategies.

Energy Efficient Cache Invalidation in a Mobile Environment

Asynchronous Cache Invalidation Strategy to Support Read-Only Transaction in Mobile Environments

The stateless-based cache invalidation schemes for wireless environments can be categorized into either asynchronous or synchronous cache invalidation according to the broadcasting way of invalidation report. However, if the asynchronous cache invalidation scheme attempts to support local processing of read-only transaction, a critical problem may occur; the asynchronous invalidation reports provide no guarantee of waiting time for mobile transactions requesting commit. To solve this problem, the server in our approaches broadcasts two kind of messages, asynchronous invalidation report to reduce transaction latency and periodic guide message to avoid the uncertainty of waiting time for the next invalidation report. This paper presents a simulation-based analysis on the performance of the suggesting algorithms. The simulation experiments show that the local processing algorithms of read-only transaction based on asynchronous cache invalidation scheme get better response time than the algorithm based on synchronous cache invalidation scheme.

SungHun Nam

Papers

Asynchronous Cache Invalidation Strategy to Support Read-Only Transaction in Mobile Environments

An efficient cache invalidation scheme for mobile wireless environments