Real-Time issues in distributed data bases for Real-Time control

Abstract

This paper takes a pragmatic application-oriented view of distributed data bases to be used in Real-Time Process and Manufacturing Control. It acknowledges the strides that have been made in the development of distributed data base techniques in general, but is concerned with the problem of mapping these techniques into the Real-Time Control world. The paper takes the view that distributing data in a control system is not only an essential feature of integrated systems, but indeed is the key to their success or otherwise. However, this distribution of data has characteristics which differentiate it from other areas in which distributed data bases are used — such as air line bookings, etc. The paper discusses the essential nature of these differences and goes on to discuss how distributed data bases have to fit in with the overall control strategy, which in turn calls heavily on the use of integrated communication systems. These latter systems are themselves often based on rapidly emerging standardised systems (primarily for economic reasons), and are increasingly OSI-based. The paper concludes that to be of value, a distributed data base in a real-time control system must be designed from the viewpoint of the user rather than from that of the data base designer!