Tools for the automation of large distributed control systems

The new LHC experiments at CERN have very large numbers of channels to operate. In order to be able to configure and monitor such large systems, a high degree of parallelism is necessary. The control system is built as a hierarchy of sub-systems distributed over several computers. A toolkit $SMI++, combining two approaches: finite state machines and rule-based programming, allows for the description of the various sub-systems as decentralized deciding entities, reacting in real-time to changes in the system, thus providing for the automation of standard procedures and for the automatic recovery from error conditions in a hierarchical fashion. In this paper we describe the principles and features of SMI++ as well as its integration with an industrial SCADA tool for use by the LHC experiments and we try to show that such tools, can provide a very convenient mechanism for the automation of large scale, high complexity, applications