MobiSnap: managing database snapshots in a mobile environment

This paper presents MobiSnap, a research project that aims to support the development of SQL based applications for mobile environments, providing configurable support for data divergence control and connectivity abstractions. One of the project goals is to assist the migration of legacy SQL based applications into these new operational platforms

Mobile transaction management in mobisnap

Lecture Notes in Computer Science, 1884To 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.(undefined

SqlIceCube: Automatic Semantics-Based Reconciliation for Mobile Databases

Optimistic replication lets multiple users update local replicas of shared data independently. These replicas may diverge and must be reconciled. In this paper, we present a general-purpose reconciliation system for mobile transactions. The basic reconciliation engine treats reconciliation as an optimization problem. To direct the search, it relies on semantic information and user intents expressed as relations among mobile transactions. Unlike previous semantics-based reconciliation systems, our system includes a module that automatically infers semantic relations from the code of mobile transactions. Thus, it is possible to use semantics-based reconciliation without incurring the overhead of specifying the semantics of the data types or operations

Coordination and Tailorability Issues in the design of a Generic Large Scale Groupware Platform

Tailorability or adaptability is commonly accepted as a fundamental property of modern and flexible CSCW systems. In order to match the differences in organizational structures, these systems have strong requirements in terms of dynamic reconfiguration and adaptation. This work is concerned with the design and implementation of a tailorable generic distributed system platform for large scale CSCW. We argue in favor of an approach for the tailorability support, focusing different perspectives and emphasis according to different support levels. This approach can help in a better understanding of different structuring levels involved in the support of adaptability. We discuss and ilustrate how these different perspectives are present in the proposed integrated framework and we exemplify the usage of a component model (JavaBeans) as a candidate to build software components for groupware, dealing with the different recognized structuring levels of the tailorability support. Keywords: CSCW/..

Mobisnap: um sistema de bases de dados para ambientes móveis

O Mobisnap é um sistema de base de dados para ambientes móveis. O sistema é baseado numa arquitectura cliente/servidor utilizando replicação optimista. Os clientes mantêm uma cópia parcial dos dados e o sistema combina um mecanismo que evita os conflitos – reservas – com outro que permite a sua resolução – transacções móveis. Estes mecanismos permitem que os clientes mantenham a sua autonomia mesmo em situações de desconexão