Pre-serialization of long running transactions to improve concurrency in mobile environments

Transaction management in different application contexts is still a challenging task. In this paper we propose a novel method in order to improve concurrency of particular kind of transaction, known as long running transactions. Differently from other techniques presented in the literature, we design a sort of hybrid approach between optimistic and pessimistic concurrency models. From one hand, our basic idea consists of handling frequent disconnections or inactivity periods of a generic transaction during its life-cycle and, from the other one, we consider the semantics related to operations produced by transactions. First, our solution avoids an indefinite or long resource locking due to disconnecting (or idle) transactions or a high rate of preventive aborts; eventually, a transaction "semantic compatibility" is exploited in order to increase the concurrency reconcilable operations on the same resources. To these purposes, we have implemented a middleware with the aims of emulating a transactional scheduling, and several experiments have been carried out.