Online Steering of HEP Grid Applications

Online steering and visualization of scientific applications is a wellestablished method for accelerating research and saving resources. However, for Grid environments no appropriate, secure online steering tools exist. As a part of the HEPCG (High Energy Physics Community Grid) project we are developing the online steering system RMOST for Grid applications, which is specifically targeted towards HEP applications used for the ATLAS experiment at the LHC. RMOST is fully integrated into the ATLAS software, i.e., the Athena framework and the ROOT toolkit used for visualization; users just have to extend the job description files. The steering system is based on a layered architecture with well defined, application independent interfaces. In this paper, we will focus on the communication layer, which implements solutions for the two most important requirements in a Grid environment: (1) a user-friendly way of finding the running job, and (2) a mechanism to enable a secure communication, even across firewalls or private IP networks.