Ensuring Database Availability in Dynamically Changing
Mobile Computing Environment
Aamir Rasheed
Department of Computer Technology, Monash University
900 Dandenong Road, East Caulfield Victoria 3145, Australia.
AamirR@broncho.ct.monash.edu.au
Arkady Zaslavsky
Department of Computer Technology, Monash University
900 Dandenong Road, East Caulfield Victoria 3145, Australia.
A.Zaslavsky@monash.edu.au
Abstract
Wireless communication technologies and emerging mobile computing have made it possible for users to carry on their work non-stop regardless of location, time and presence of network connections. This tendency has given rise to new and challenging prob
ms related to mobility, namely, frequent connections/disconnections, and possible non-availability of mobile workstations. This paper summarises the effects of regular non-availability of mobile workstations on different transaction management models.
tential extensions to these models are discussed where appropriate. The replication of data is considered as one of the more practical solutions to solve the problem of non-availability of mobile workstations. The concept of twin-transactions is propos
to support synchronisation of database replicas between stationary and mobile workstations and to also replicate/emulate the transaction processing flow while a mobile workstation is unavailable. Full concurrency control is not possible as a conflict
solution graph cannot be generated due to the non-availability of transactions executing
on a disconnected mobile workstation. A transaction management model to achieve some sustainable success ratio is proposed and discussed.
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