THE ALMA COMMON SOFTWARE, ACS STATUS AND DEVELOPMENTS

The ALMA Common Software (ACS) is a software infrastructure for the development of distributed systems based on the Component/Container paradigm. ACS is being developed primarily for the ALMA collaboration to provide a common and unifying infrastructure used by all partners and across all layers of the system [5]. The usage of ACS extends from high-level applications such as the Observation Preparation Tool that will run on the desk of astronomers, down to the Control Software domain. From a system perspective, ACS provides the implementation of a set of design patterns and services that make the whole ALMA software uniform and maintainable; from the perspective of an ALMA developer, it provides a friendly programming environment in which the complexity of the CORBA middleware and other libraries is hidden and coding is drastically reduced. ACS was presented at ICALEPCS for the first time in 2001 and then in 2003 [1][2]. Since then, the services provided by ACS have been extended and made reliable and scalable. The control system for the ALMA prototype antennas is based on ACS and is routinely used for the technical and scientific evaluation of the antennas [7]. Thanks to the fact that ACS is available under public LGPL licence, the community of users outside ALMA is growing. In particular the control systems of several telescopes are being developed on top of ACS, with the different teams sharing and reusing design concepts and actual software Components. The ACS community has met at a workshop hosted by this conference. This paper presents the status of ACS and the progress over the last two years. Emphasis is placed on describing ACS from the point of view of control system development. More details on specific ACS services and on projects using ACS will be provided by other papers.