Managing Information Flow in ALICE

ALICE is one of the experiments at the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland. The ALICE detector control system is an integrated system collecting 18 different detectors’ controls and general services. Is implemented using the commercial SCADA package PVSS. Information of general interest, such as beam and condition data, and data related to shared plants or systems, are made available to all the subsystems via the distribution capabilities of PVSS. Great care has been taken to build a modular and hierarchical system, limiting the interdependencies of the various subsystems. Accessing remote resources in a PVSS distributed environment is very simple and can be initiated unilaterally. In order to improve the reliability of distributed data and to avoid unforeseen and unwished dependencies, the ALICE DCS group has enforced the centralization of global data required by the subsystems. A tool has been developed to monitor the level of interdependency and to understand the optimal layout of the distributed connections, allowing for an interactive visualization of the distribution topology.