Simulation and Design of the ALICE Event Builder using the ROOM Method

The Event Builder and Distribution System (EBDS) is a component of the data-acquisition architecture of the ALICE experiment at CERN. The purpose of the EBDS is to dispatch the sub-events originated in the detector front-end electronics to the processors of the Event Filter Farm, where the full events are assembled.<BR>The design method adopted for the EBDS is ROOM (Real-time Object-Oriented Modelling), whose modelling paradigm appears to be well suited to this type of application. The ROOM tool set (ObjecTime Developer) fully supports the method; it allowed us to simulate the behaviour of the system and to progress in the development by gradual refinements. The tool covers all the aspects of the development cycle, including code generation. We have, therefore, been able to produce the EBDS code automatically.<P>We shall describe the process of building the model of the EBDS and of its test environment and the results obtained from the simulation. We shall also review the benefits and obstacles we encountered with ROOM and the ObjecTime tools. We shall finally discuss the performance of the EBDS run-time system.