Vector-Field Consistency para Trabalho Cooperativo Vector-Field Consistency for Cooperative Work

Although cooperative work is widely used in a daily basis, nonetheless cooperative work tools are not being used as their potential would suggest. Even though the reasons behind this fact are not completely clear, the truth is that users, sometimes, see current cooperative work tools as a burden to their working activities. To work around this problem, we exploit two concepts: the notion of locality-awareness and the notion of continuous consistency model. The first refers to the ability of a technique to take in consideration the location of users in the making of decisions. The second corresponds to a notion of a mid-term solution between strong and weak consistency, which controls the divergence limits to find the most adequate balancing between availability and consistency. These two notions, when combined enable a powerful technique which bounds divergence limits on a per-user basis depending on the location in the replicated objects. For example, if we take the cooperative work scenario in consideration, we can decide which updates each user is most interested in and which ones he should be unaware of for the moment. This way, we will have an improved experience without compromising the overall application performance. This mixture between the notions of location-awareness and continuous consistency models is exactly what the Vector-Field Consistency (VFC) model does. However this model was designed for the environment of distributed ad-hoc gaming. In this work we propose VFC for Cooperative Work, an adaptation of the original VFC model to the environment of cooperative work, namely document-based cooperative work. This adaptation consisted in the redefinition of the VFC concepts, such as users’ location (pivot), distance between pivots and replicated objects, and consistency zones. The definition of the structure of the document is an essential step to the definition of these concepts. In this work, we first study the state of the art of consistency maintenance in cooperative work tools. Some of the studied techniques were used to create a VFC powered system which is capable of enforcing different divergence limits for each user depending on their location in the replicated object. This model was then specialized for a Latex document, which has a sufficiently rich document structure. Later, the VFC for Cooperative Work model was applied to a Latex editor which was previously enhanced to support totally-consistent cooperation capabilities. Finally, this prototype was used to retrieve results to define the success of this work and the merits and flaws of this model.