• The KIPS Transactions:PartC
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• v.10C no.3
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• pp.325-334
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• 2003

In stateless server, if an asynchronous cache invalidation scheme attempts to support local processing of read-only transaction in mobile client/sever database systems, a critical problem may occur ; the asynchronous invalidation reports provide no guarantees of waiting time for mobile transactions requesting commit. To solve this problem, the server in our algorithm 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. The asynchronous invalidation report has its own sequence number and the periodic guide message has the sequence number of the most recently broadcast asynchronous invalidation report. A mobile client checks its cache validity by using the sequence numbers of these messages.

• Journal of the Korea Society of Computer and Information
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• v.4 no.3
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• pp.78-92
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• 1999

In mobile computing environments, to efficiently use the narrow bandwidth of wireless networks a mobile host caches the data that are frequently accessed. To guarantee the correctness of the mobile transaction, the data cached in a mobile host must be consistent with the data in a server. This paper proposes a new strategy which maintains cache consistency efficiently when the data cached in a mobile host are inconsistent with the data in a server by the mobility of the mobile host at the asynchronous mobile environment. In this strategy, the size of the invalidation message is relatively small and is independent of the number of data to be invalidated under conditions of variable update rates/patterns. So this strategy uses the narrow bandwidth of wireless networks efficiently and reduces the communication cost.

• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.21-30
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• 2005

In mobile computing environments, a mobile host caches the data to use the narrow bandwidth efficiently and improve the response time. A server periodically broadcasts the update data for maintaining the cache consistency of a mobile host. However, a method for maintaining cache consistency using periodic invalidation report has a problem that defers the commit decision of a mobile transaction to guarantee its serializable execution. In this paper, we propose CCM-AD method that guarantees the serializable execution of a mobile transaction even in the case that it is executed using cached data. As CCM-AD method guarantees the serializable execution of mobile transactions by using the intersection between the data broadcast to mobile host and the data updated at server. Then the CCM-AD method can reduce the delay of commitment decision of a mobile transaction. Also our method can reduce the size of invalidation report.

• The Transactions of the Korea Information Processing Society
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• v.5 no.11
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• pp.2763-2775
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• 1998

In mobile computing environments, to efficiently use the narrow bandwidth of wireless networks a mobile host caches the data that are frequently accessed. But, because the cached data can be inconsistent with the data n a server due to the host mobility and the disconnection from a server, the usefullness of cached data may be losted. The traditional methods emphasize on the cache consistency and assume that broadcasting times are synchronized at all mobile supprot stations. In this paper, we propose a strategy to maintain cache consistency, which resolves the problems that be caused by the migration of mobile host. The proposed strategy has asynchronous broadcasting time and reduces the communication overhead caused by the synchronization. Also, by preventing the unnecessary messages transmitting from the mobile support station to a mobile host, this strategy can reduce the communication cost and use the narrow bandwidth of wireless networks efficiently.

• The KIPS Transactions:PartD
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• v.9D no.6
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• pp.1017-1024
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• 2002

According as mobile computing environment is generalized by development of wireless networking technology and communication device, mobile host uses local cache for extensibility and early response time. and reduction of limited bandwidth. This time, between mobile host and mobile support station cache need consistency interested person of done data accordingly much techniqueses propose. Existent consistency techniques because detection based techniqueses are used mainly and broadcast periodic invalid message considering frequent disconnection. However, these techniqueses increase abort step through increase or delay of transmission message number by accuracy examination of data. Therefore, because mobile host deletes cached data, and extensity are decreased. Techniques that is proposed in this paper did to perform refering update frequency about object that page request or when complete update operation happens to solve these problem. Therefore, have advantage that response is fast because could run write intention declaration or update by update frequency electively asynchronously when update operation consists and abort step decreases. Also, improved extensity running delete or propagation electively according to update frequency about periodic invalid message gone since disconnection.