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- R. Karban, N. Kornweibel
ESO, Garching bei Muenchen, Germany
- D.L. Dvorak, M.D. Ingham, D.A. Wagner
JPL, Pasadena, California, USA
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Large telescopes are characterized by a high level of distribution of control-related tasks and will feature diverse data flow patterns and large ranges of sampling frequencies; there will often be no single, fixed server-client relationship between the control tasks. The architecture is also challenged by the task of integrating heterogeneous subsystems which will be delivered by multiple different contractors. Due to the high number of distributed components, the control system needs to effectively detect errors and faults, impede their propagation, and accurately mitigate them in the shortest time possible, enabling the service to be restored. The presented Data-Driven Architecture is based on a decentralized approach with an end-to-end integration of disparate independently-developed software components, using a high-performance standards-based communication middle-ware infrastructure, based on the Data Distribution Service. A set of rules and principles, based on JPL's State Analysis method and architecture, are established to avoid undisciplined component-to-component interactions, where the Control System and System Under Control are clearly separated. State Analysis provides a model-based process for capturing system and software requirements and design, helping reduce the gap between the requirements on software specified by systems engineers and the implementation by software engineers. The method and architecture has been field tested at the Very Large Telescope, where it has been integrated into an operational system with minimal downtime.
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