System support for robust collaborative applications

Traditional transaction models ensure robustness for distributed applications through the properties of view and failure atomicity. It has generally been felt that such atomicity properties are restrictive for a wide range of application domains; this is particularly true for robust, collaborative applications because such applications have concurrent components that are inherently long-lived and that cooperate. Recent advances in extended transaction models can be exploited to structure long-lived and cooperative computations. Applications can use a combination of such models to achieve the desired degree of robustness; hence, we develop a system which can support a number of flexible transaction models, with correctness criteria that extend or relax serializability. We analyze two concrete CSCW applications-collaborative editor and meeting scheduler. We show how a combination of two extended transaction models, that promote split and cooperating actions, facilitates robust implementations of these collaborative applications. Thus, we conclude that a system that implements multiple transaction models provides flexible support for building robust collaborative applications.