Interfacing parallel scientific applications with multiple visualization systems: The CUMULVS approach

As high-performance computer simulation increasingly replaces more expensive and time-consuming conventional alternatives, namely physical prototyping/experimentation, it becomes important to provide mechanisms for interacting with parallel or distributed simulation programs. Such interactive exchanges can close the loop on simulation experiments by providing visualization of intermediate results and then allowing scientists to respond by manipulating the simulation, while it is running. This type of visualization and computation steering feedback system can dramatically shorten the experimental cycle by pruning off experiments that are quickly seen to be undesirable. Further, such interaction can provide enhanced capabilities for what if analyses, even beyond what would be possible in a physical environment. This approach also introduces new forms of collaboration, by allowing multiple remote collaborators to cooperate and interact via the running simulation programs, each person exploring their own view of the data and then sharing their understanding with the group. The CUMULVS (Collaborative User Migration User Library for Visualization and Steering) system is a middleware library infrastructure that allows multiple, potentially remote, scientists to monitor and coordinate control over a parallel simulation program. Using CUMULVS, various front-end viewers can dynamically attach to a simulation to view snapshots of the ongoing computation, or manipulate (steer) parameters of the simulation, and then detach. The snapshots of intermediate data array values can be rendered using a variant of visualization systems, including AVS, Tcl/Tk, and VTK, or as simple text dumps. CUMULVS provides the interfacing between the simulation tasks and the visualization systems, and transparently handles the viewer connection protocols and the data collection required for decomposed or distributed data. CUMULVS also provides mechanisms for developing fault-tolerant applications in heterogeneous distributed computing environments