Dynamic construction mechanism of a trigger graph on active databases in mobile computing environments

As a result of the rapid development of wireless communications and computer hardware technologies, we can now access various information anywhere using handy terminals. To support the integrative use of data held by mobile hosts in this environment, we proposed the AMDS (Active Mobile Database System) as the kernel system for data management. The behavior definition language of this system, ECA (event-condition-action) rules, has a high description capability that enables users to define complicated behavior. However, the execution of the ECA rules may fall into a chain of unexpected behaviors. In general, a directed graph, called a trigger graph, is used for detecting chains. Since the trigger graph highly depends on network topology, it is difficult to employ the trigger graph in a mobile computing environment. In this paper, we propose a method that reconstructs the trigger graph dynamically to adapt to changes in network topology. Using this mechanism, mobile applications with ECA rules can be used more safely.