GANGA: a user-Grid interface for Atlas and LHCb

The Gaudi/Athena and Grid Alliance (GANGA) is a front-end for the configuration, submission, monitoring, bookkeeping, output collection, and reporting of computing jobs run on a local batch system or on the grid. In particular, GANGA handles jobs that use applications written for the Gaudi software framework shared by the Atlas and LHCb experiments. GANGA exploits the commonality of Gaudi-based computing jobs, while insulating against grid-, batch- and framework-specific technicalities, to maximize end-user productivity in defining, configuring, and executing jobs. Designed for a python-based component architecture, GANGA has a modular underpinning and is therefore well placed for contributing to, and benefiting from, work in related projects. Its functionality is accessible both from a scriptable command-line interface, for expert users and automated tasks, and through a graphical interface, which simplifies the interaction with GANGA for beginning and c1asual users. This paper presents the GANGA design and implementation, the development of the underlying software bus architecture, and the functionality of the first public GANGA release.