A prototype of the CMS Object Oriented Reconstruction and Analysis Framework for the Beam Test Data

CMS software requirements and computing resources will by far exceed those of any existing high energy physics experiment, not only for the complexity of the detector and of the physics task but also for the size of the collaboration and the long time scale. Therefore, software should be developed keeping in mind not only performance but also modularity, flexibility, maintainability, quality assurance and documentation. Object Orientation has been identified as the enabling technology, since it directly addresses this kind of problems. We will report on the development of an Object Oriented Reconstruction and Analysis Framework for the CMS experiment and in particular on a prototype of a complete analysis chain for the CMS test-beam data. The analysis chain consists of three different components: data acquisition, reconstruction and analysis, and interactive analysis tools. In the online part the data, read from the VME, are stored into an Objectivity federated database. Later, using an automatic procedure, the database files are moved from the disk connected to the online computer system to the disks, and eventually tapes, connected to the off-line system. In the reconstruction and analysis step the data are retrieved from the database and an analysis of the detector performances can be carried out. The final step consists in the visualisation of the Histograms ( produced using the LHC++ HISTOO package) and ``Tags'' which have been filled during the previous step. HEP-Explorer tools are used for the visualisation. Commercial as well as freely available class libraries have been used to build the functional prototype. A review of results and performances of the prototype, based on the data collected during the summer 1998, will be presented.