Managing control algorithms with an object-oriented database

Abstract

The Continuous Electron Beam Accelerator Facility (CEBAF) uses the Experimental Physics and Industrial Control System (EPICS) for accelerator control. In EPICS, the atomic element of a control algorithm is a record. Records are grouped together to form generic applications, for example to control a single magnet. The generic applications are then instantiated for each specific item of machine hardware. Instantiated applications are executed on one of the 30 data acquisition and control computers that are used in the control system. There are roughly 125,000 unique, instantiated records at CEBAF, each associated with a specific piece of hardware. Management of these records in a database simplifies the task of application developers by allowing them to concentrate on algorithmic development instead of instantiation details. In addition, it decouples algorithmic development from the specification of operational parameters, allowing responsibility for those parameters to pass to machine operations staff. CEBAF needed an environment to provide support for development of EPICS database management tools. An object-oriented database was chosen for two reasons: higher performance and the ability to smoothly manage objects of different types.