J. Legatheaux Martins

Integrating synchronous and asynchronous interactions in groupware applications

It is common that, in a long-term asynchronous collaborative activity, groups of users engage in occasional synchronous sessions. In this paper, we discuss the data management requirements for supporting this common work practice. As users interact in different ways in each setting, requirements and solutions often need to be different. We present a data management system that allows to integrate a synchronous session in the context of a long-term asynchronous interaction, using the suitable data sharing techniques in each setting and an automatic mechanism to convert the long sequence of small updates produced in a synchronous session into a large asynchronous contribution. We exemplify the use of our approach with two multi-synchronous applications.

Reservations for Conflict Avoidance in a Mobile Database System

Mobile computing characteristics demand data management systems to support independent operation. However, the execution of updates in a mobile client usually need to be considered tentative because uncoordinated updates that conflict need to be reconciled. In this paper we present a mechanism to independently guarantee that updates can be executed in the server without conflicts. To this end, clients obtain leased reservations upon the database state. Updates are specified as common small PL/SQL programs, dubbed mobile transactions, that execute both in the mobile client and in the server. Using the available reservations, the client transparently verifies that a transaction can be executed in the same way both in the mobile client and in the server, thus leading to the same final result. Mobile transactions may specify conflict detection and resolution rules to be used when transactions cannot be locally guaranteed.

A case study on event dissemination in an active overlay network environment

In this paper, we describe a case study of the design and development of a group-conferencing tool suite, built on top of an overlay network based event dissemination framework, which is extensible via quality of service template plug-ins. We explain, for each of the tools, how the framework built-in conveniences were explored to create simple but effective distributed solutions, backed by the appropriate quality of service templates, whose design we also discuss.

Flexible data storage for mobile computing

In this paper we describe a flexible object storage system aimed at supporting collaborative applications in large-scale environments that include mobile computers. We present an integrated solution to two major problems that arise in such environments: data availability and concurrency control. The first is tackled by the flexible combination of weakly consistent server replication and client caching. The second is tackled through an open object framework that enables easy object development using type specific conflict detection and resolution. This object storage serves as a supporting platform to produce new distributed and mobile collaborative

SUPPORTING MULTI-SYNCHRONOUS GROUPWARE: DATA MANAGEMENT PROBLEMS AND A SOLUTION

It is common that, in a long-term asynchronous collaborative activity, groups of users engage in occasional synchronous sessions. In this paper, we analyze the data management requirements for supporting this common work practice in typical collaborative activities and applications. We call the applications that support such work practice multi-synchronous applications. This analysis shows that, as users interact in different ways in each setting, some applications have different requirements and need to rely on different data sharing techniques in synchronous and asynchronous settings. We present a data management system that allows to integrate a synchronous session in the context of a long-term asynchronous interaction, using the suitable data sharing techniques in each setting and an automatic mechanism to convert the long sequence of small updates produced in a synchronous session into a large asynchronous contribution. We exemplify the use of our approach with two multi-synchronous applications.