Workflow management in the assembly of CMS ECAL Original Research Article

As with all experiments in the LHC era, the Compact Muon Solenoid (CMS) detectors will be constituted of a very large number of constituent parts. Typically, each major detector may be constructed out of over a million precision parts and will be produced and assembled during the next decade by specialised centres distributed world-wide. Each constituent part of each detector must be accurately measured and tested locally prior to its ultimate assembly and integration in the experimental area at CERN. Much of the information collected during this phase will be needed not only to construct the detector, but for its calibration, to facilitate accurate simulation of its performance and to assist in its lifetime maintenance. The CRISTAL system is a prototype being developed to monitor and control the production and assembly process of the CMS Electromagnetic Calorimeter (ECAL). The software will be generic in design and hence reusable for other CMS detector groups. This paper discusses the distributed computing problems and design issues posed by this project. The overall software design architecture is described together with the main technology aspects of linking distributed object oriented databases via CORBA with WWW/Java-based query processing. The paper then concentrates on the design of the workflow management system of CRISTAL.