Implementing Distributed Controlled Objects with CORBA

The heart of the control system implementation of the light source ANKA is an object model of devices. It is the Accelerator Control Interface (ACI), a language independent collection of interfaces based on network distributed objects using the CORBA standard. All common accelerator components such as power supplies, vacuum, RF, position and current monitors are defined by means of functions and parameters. The devices are described according to CORBA with the Interface Definition Language (IDL), which presents a language-independent way of defining object interfaces. Each controlled parameter, called device property, is an object by itself, implementing atomic actions such as get/set, increment/decrement, etc. All constants related to a property such as min/max, name, description, etc. are obtained from the property directly by means of remote methods- no direct database access is necessary. Values of the properties are updated asynchronously by means of monitor objects. The ACI is meant to be a standardised interface so that applications and pieces of control systems can be hooked to it from either side. The ACI does not replace existing control system architectures and frameworks but rather tries to use their features in order to be as compatible as possible to those systems. 1