Application experiences with the Globus toolkit.

The Globus grid toolkit is a collection of software components designed to support the development of applications for high-performance distributed computing environments, or ''computational grids'' [14]. The Globus toolkit is an implementation of a ''bag of services'' architecture, which provides application and tool developers not with a monolithic system but rather with a set of stand-alone services. Each Globus component provides a basic service, such as authentication, resource allocation, information, communication, fault detection, and remote data access. Different applications and tools can combine these services in different ways to construct ''grid-enabled'' systems. The Globus toolkit has been used to construct the Globus Ubiquitous Supercomputing Testbed, or GUSTO: a large-scale testbed spanning 20 sites and included over 4000 compute nodes for a total compute power of over 2 TFLOPS. Over the past six months, we and others have used this testbed to conduct a variety of application experiments, including multi-user collaborative environments (tele-immersion), computational steering, distributed supercomputing, and high throughput computing. The goal of this paper is to review what has been learned from these experiments regarding the effectiveness of the toolkit approach. To this end, we describe two of the application experiments in detail, noting what worked well and what worked less well. The two applications are a distributed supercomputing application, SF-Express, in which multiple supercomputers are harnessed to perform large distributed interactive simulations; and a tele-immersion application, CAVERNsoft, in which the focus is on connecting multiple people to a distributed simulated world