A Study of Distributed Real - Time Active Database Applications

Real-time database systems has been an active research area in recent times. In spite of this, their applicability to speci c applications has not been well studied. We attempt to rectify this shortcoming by studying two applications: 1) cooperative distributed navigation systems and 2) network services database systems. The former is a hard real-time system and the latter a soft/ rm real-time system. Cooperative distributed navigation systems appear in several complex applications such as road following and robot navigation. These systems usually consist of multiple sensor-based agents which work in a distributed and cooperative fashion towards a common goal. These agents are guided by a high level controller which facilitates coordination and cooperation among the agents. Network services databases provide support for the service-providing intelligent network (IN). IN provides services like dialed number services (800 service), personal mobility service, virtual business group service and televoting service. The data and the service logic 3 in this system is distributed. These applications are of particular interest, because, a lot of concepts have been developed by assuming certain characteristics of an application for real-time database systems. For example, it is assumed that transactions have timing constraints, but how those constraints are derived from the application needs is not properly studied. Similarly various other data and transaction characteristics are assumed. In this paper we will study two real-time active database applications in detail. We will discuss their data and transaction characteristics in detail and see if the protocols and features developed in the research have applicability in these applications. In section 2, we will consider the motivations for using a real-time active database for these complex applications. In section 3, we will discuss in detail the cooperative distributed navigation application and in section 4, we will study the network services database application. Then nally in section 5, we will give some concluding remarks.