iGrid: Interactive Grid

Grid computing is traditionally applied for batch jobs in the scientific and academic computing. This is also the case at WLCG, the global computing infrastructure providing the production and analysis environments for the LHC experiments at CERN. In this paper we envision the next generation Grid computing systems to support High Energy Physics (HEP) online sessions. We refine a resource management framework for enabling on-demand private virtual clusters on the AliEn Grid middleware and run applications on an online computing environment. We describe the software components distributed among the submission node and the site front-end and execution nodes. Our experiment evaluates the scalability of the agents deployed at the execution nodes and measures the performance of PROOF - the de-facto standard software for HEP data analysis - on our Grid environment rather than on a local cluster. Because PROOF generates time-sensitive I/O and requires to handle potentially thousands of network connections, we describe a multiplexed I/O approach as the ideal solution for scalable and high-performing proxy services.