On-line software in the HARP experiment

The HARP experiment has collected data in the CERN-PS East Hall during the years 2000-2003. Here we describe the software and hardware architectures of the on-line system, featuring a network-based data acquisition system with the possibility of on-line recording to an object-oriented database. The adoption of a formal object-oriented design methodology very much helped the creation of a consistent architecture in a small amount of time.