Mobile Transaction Management in Mobisnap

Abstract

To allow mobile users to continue their work while disconnected, mobile systems usually rely on optimistic replication techniques. In mobile database systems, mobile units cache subsets of the database state and allow disconnected users to perform transactions concurrently. These transactions are later integrated in the master database state. As concurrently performed transactions may conflict, it is usually impossible to determine the result of an update in the mobile unit. Moreover, this model differs from the traditional client/server model due to the fundamental fact that the user will usually not be connected to the system when the results of his transactions are finally determined -therefore, he can not immediately perform adequate alternative actions. In this paper we describe a transaction management system that takes into consideration the above-mentioned characteristics. Transactions are specified as mobile transactional programs, which allows the precise definition of operation semantics and the definition of alternative actions. Support for active user notification is also provided in the system. Finally, the system relies on a reservation mechanism to be able to guarantee the results of transactions in the mobile units.

Global Consistency Management Methods Based on Escrow Approaches in Mobile ad Hoc Networks

“…In [10,11], the authors discussed transaction management approaches based on an escrow method in mobile environments. In [10], the authors assume special types of applications in which the instances of each data item can be partitioned among sites, e.g., mobile users share consumable resources.…”

Availability/Consistency Balancing Replication Model

“…If the commit on the master copy fails, the originating node is informed why it failed. Application-specific semantics are used for conflict resolution in the mobile transaction management system presented in [28].…”

Reservations for Conflict Avoidance in a Mobile Database System

“…A preliminary and incomplete version of Mobisnap was presented elsewhere [18]. Since then, important modifications have been introduced in the system, such as, the introduction of new reservations and the modification of the transaction processing.…”