The STAR offline framework Original Research Article

The Solenoidal Tracker At RHIC (STAR) is a large acceptance collider detector which started data taking at Brookhaven National Laboratory in summer 2000. STAR has developed a software framework for simulation, reconstruction and analysis in offline production, interactive physics analysis, and online monitoring. It is well matched both to STARʹs present status of transitioning from a Fortran/C++ base to a fully object oriented (OO) base, and to the emerging OO base. This paper presents the results of two years of effort developing a modular C++ framework based on the ROOT package. The framework encompasses both wrapped Fortran components (legacy simulation and reconstruction code) used via IDL-defined data structures, and fully OO components (all physics analysis code) served by a recently developed object model for event data. The framework supports chronologically chained components, which can themselves be composite sub-chains, with components (“makers”) managing “data sets” they have created and are responsible for. Makers and data sets inherit from the TDataSet class which supports their organization into hierarchical structures for management. TDataSet also centralizes almost all system tasks such as data set navigation, I/O, database access, and inter-component communication. This paper will present an overview of this system, now deployed and well exercised in production environments with 10 TBytes real and 3 TBytes simulated data, and in an active physics analysis development program.