CORBA-based Common Software for the ALMA project

The Atacama Large Millimeter Array (ALMA) is a joint project between astronomical organizations in Europe and North America. ALMA will consist of at least 64 12-meter antennas operating in the millimeter and sub-millimeter range, with baselines up to 14 km. It will be located at an altitude above 5000m in the Chilean Atacama desert. The ALMA Common Software (ACS) provides a software infrastructure common to all partners and consists of a documented collection of common patterns and of components that implement those patterns. The heart of ACS is an object model based on Distributed Objects (DOs), implemented as CORBA objects. The teams responsible for the control system development use DOs as the basis for components and devices such as an antenna mount control. ACS provides common CORBA-based services such as logging, error and alarm management, configuration database and lifecycle management. A code generator creates a Java Bean for each DO. Programmers can write Java client applications by connecting those Beans with data-manipulation and visualization Beans. ACS is based on the experience gained in the astronomical and particle accelerator domains, and reuses and extends proven concepts and components. Although designed for ALMA, ACS can be used in other new control systems, since it implements proven design patterns using state of the art, stable and reliable technology. This paper presents the architecture of ACS and its status, detailing the object model and major services.