gViz – Visualization and Steering for the Grid

This paper describes work in the e-Science Core Programme project, gViz, to develop visualization middleware. The focus in this paper is the evolution of our work to Grid-enable IRIS Explorer, a widely used dataflow visualization system from NAG. A crucial feature of IRIS Explorer is the ability to include user-written simulation code as part of the dataflow pipeline, offering the opportunity of computational steering. The evolution has gone through three phases. An early demonstrator showed how, for a specific application, IRIS Explorer could be adapted to launch a simulation on a remote Grid resource, and maintain contact with it to enable steering of control parameters and visualization of results. In the second phase, we extended IRIS Explorer to run in a distributed fashion on the Grid, with different modules in the pipeline able to run on different resources – thus the pipeline spans the Grid. In a final phase, we are developing a computational steering library that allows a flexible coupling of a simulation with a visualization system such as IRIS Explorer. This approach allows the front-end visualization system to connect and disconnect as required from a long running simulation, and takes a service-oriented approach to visualization and steering. In all of the phases we are able to exploit the COVISA collaborative working feature of IRIS Explorer, enabling teams of e-scientists to jointly steer a simulation and visualize the results.