In the past several years, many scientific applications from various domains have taken advantage of e-science infrastructures that share storage or computational resources such as supercomputers, clusters or PC server farms across multiple organizations. Especially within e-science infrastructures driven by high-performance computing (HPC) such as DEISA, online visualization and computational steering (COVS) has become an important technique to save compute time on shared resources by dynamically steering the parameters of a parallel simulation. This paper argues that future supercomputers in the Petaflop/s performance range with up to 1 million CPUs will create an even stronger demand for seamless computational steering technologies. We discuss upcoming challenges for the development of scalable HPC applications and limits of future storage/IO technologies in the context of next generation e- science infrastructures and outline potential solutions.

Many production Grid infrastructures such as DEISA, EGEE, or TeraGrid have begun to offer services to endusers that include access to computational resources. The major goal of these infrastructures is to facilitate the routine interaction of scientists and their workflows with advanced tools and seamless access to computational resources via Grid middleware systems such as UNICORE, gLite or Globus Toolkits. While UNICORE 5 is used in production Grids since several years, recently an early prototype of the new Web services-based UNICORE 6 became available that will be continuously improved in the next months for its use in production. In absence of a widely accepted framework for visualization and steering, the new UNICORE 6 Grid middleware provides not such a higher level service by default. This motivates this contribution to support e-Scientists in upcoming WS-based UNICORE Grids with visualization and steering techniques. In this paper we present the augmentation of the early standards-based UNICORE 6 prototype with a higher-level service for collaborative online visualization and steering. It describes the seamless integration of this service within UNICORE Grids by retaining the convenient single sign-on feature.

In this showcase we will present live running simulations which are integrated into the Access Grid in a variety of different ways. An example of this is the use of vnc to distribute a desktop on which the simulation is being displayed. Another example is the redirection of the visualization into vic to make 3D animations available over the Access Grid. Other examples that will be explored are the use of SGI's OpenGL VizServer to direct the output of a graphics supercomputer located on the Grid to the AG locations. We will also utilize the ability of the next generation AG software to directly link with visualization toolkits such as vtk, AVS/Express, or COVISE as an integrated part of the Virtual Venue as this functionality has developed by the time of the SC2003 demonstrations. We also demonstrate steering in a collaborative setting using a steering service which is fully compliant with OGSI and with the proposed OGSA architecture. This can be integrated with current Grid middleware (e.g. GT2 and UNICORE) using a specially developed Perl hosting environment, OGSI:Lite.

In order to prepare for the upgrade of the German national scientific network to gigabit capacity in the year 2000, two testbeds have been set up. One of them, the 'Gigabit Testbed West', uses a 2.4 Gbit/s ATM link to connect the Research Centre Julich and the GMD-National Research Center for Information Technology in Sankt Augustin. The testbed is the basis for several application projects, ranging from metacomputing to multimedia. This paper gives an overview of the infrastructure of the testbed and its applications. As an example, the real-time analysis and visualization of functional MRI measurements of the human brain are described in detail.