Production grid systems and their programming

Summary form only given. There are a large variety of grid test-beds that can be used for experimental purposes by a small community. However, the number of production grid systems that can be used as a service for a large community is very limited. The current tutorial provides introduction to three of these very few production grid systems. They represent different models and policies of using grid resources and hence understanding and comparing them is an extremely useful exercise to everyone interested in grid technology. The Hungarian ClusterGrid infrastructure connects clusters during the nights and weekends. These clusters are used during the day for educational purposes at the Hungarian universities and polytechnics. Therefore, a unique feature of this grid is the switching mechanism by which the day time and night time working modes are loaded to the computers. In order to manage the system as a production, one, the system is homogeneous, all the machines should install the same grid software package. The second even larger production grid system is the LHC-grid that was developed by CERN to support the Large Hadron Collider experiments. This grid is also homogeneous but it works as a 24-hour service. All the computers in the grid are completely devoted to offer grid services. The LHC-grid is mainly used by physists but in the EGEE project other applications like bio-medical applications are ported and supported on this grid. The third production grid is the NorduGrid which is completely heterogeneous and the resources can join and leave the grid at any time as they need. The NorduGrid was developed to serve the Nordic countries of Europe but now more and more institutions from other countries join this grid due to its large flexibility. Concerning the user view an important question is how to handle this large variety of production grids and other grid test-beds. How to develop applications for such different grid systems and how to port applications among them? A possible answer for these important questions is the use of a grid portal technology. The EU GridLab project developed the GridSphere portal framework that was the basis of developing the P-GRADE grid portal. By the P-GRADE portal, users can develop workflow-like applications including HPC components and can run such workflows on any of the grid systems in a transparent way