Distributed objects in action-first experience with the CLEO III data acquisition system

The CLEO III experiment-scheduled to begin data taking in August 1999-includes a 4 layer silicon vertex detector and a novel ring image Cherenkov detector to support particle identification. Drift chambers, EM calorimeters and muon chambers complete the detector assembly. Overall more than half a million electronic channels have to be read out and monitored. With trigger rates up to 1000 Hz the data volume to be handled by the DAQ system exceeds 30 MBytes/s. By the time of Realtime 99 most of the new components of the CLEO III detector will have been installed and the initial commissioning run for the DAQ and trigger system will be completed. We will present the architecture of the CLEO III DAQ system, but special emphasis will be placed on our experience with a large distributed system, with CORBA and Java as well as with objectivity as an event and constants database.