Vol. 21 · No. 4

Grid technology has evolved over the past several years to provide the services and infrastructure needed for building ``virtual'' systems and organizations. With this Grid based infrastructure that provides for using and managing widely distributed computing and data resources in the science environment, there is now an opportunity to provide a standard, large-scale, computing, data, instrument, and collaboration environment for science that spans many different projects, institutions, and countries. We argue that Grid technology provides an excellent basis for the creation of the integrated environments that can combine the resources needed to support the large-scale science projects located at multiple laboratories and universities. We also present some science case studies that indicate that a paradigm shift in the process of science will come about as a result of Grids providing transparent and secure access to advanced and integrated information and technologies infrastructure: powerful computing systems, large-scale data archives, scientific instruments, and collaboration tools. These changes will be in the form of Grid based services that can be integrated with the user's work environment, and that enable uniform and highly capable access to these computers, data, and instruments, regardless of the location or exact nature of these resources. These services will integrate transient-use resources like computing systems, scientific instruments, and data caches (e.g., as they are needed to perform a simulation or analyze data from a single experiment); persistent-use resources, such as databases, data catalogues, and archives; and collaborators, whose involvement will continue for the lifetime of a project or longer. While we largely address large-scale science requirements in this paper, Grids, particularly when combined with Web Services, will address a broad spectrum of science scenarios, both large and small scale, as well as various commercial and cultural cyberinfrastructure applications.

This paper began its life as an unpublished technical review citeanalysis of the proposed Open Grid Services Architecture (OGSA) as described in the papers, ``The Physiology of the Grid'' citefoster by Ian Foster, Carl Kesselman, Jeffrey Nick and Steven Tuecke, and ``The Grid Service Specification (Draft 2/15/02) citeogsi'' by Foster, Kesselman, Tuecke and Karl Czajkowski, Jeffrey Frey and Steve Graham. However, much has changed since the publication of the original documents. The architecture has evolved substantially and the vast majority of our initial concerns have been addressed. In this paper we will describe the evolution of the specification from its original form to the current draft of 10/4/02 authored by S. Tuecke, K. Czajkowski, J. Frey, S. Graham, C. Kesselman, and P. Vanderbilt, which is now the central component of the Global Grid Forum Open Grid Service Infrastructure (OGSI) working group which is co-chaired by Steven Tuecke and David Snelling.

This paper describes our Desktop Grid Environment Enabler (DEGREE), a set of Web Services that provides advanced capabilities for grid computing. DEGREE services are based both on the Globus Toolkit and the Grid Resource Broker, a grid portal developed at the University of Lecce. Trusted users can develop innovative, grid-aware applications that seamlessly access computational resources and services exploiting our Web Services independently of platform and programming language.

When data mining and knowledge discovery techniques must be used to analyze large amounts of data, high-performance parallel and distributed computers can help to provide better computational performance and, as a consequence, deeper and more meaningful results. Recently grids, composed of large-scale, geographically distributed platforms working together, have emerged as effective architectures for high-performance decentralized computation. It is natural to consider grids as tools for distributed data-intensive applications such as data mining, but the underlying patterns of computation and data movement in such applications are different from those of more conventional high-performance computation. These differences require a different kind of grid, or at least a grid with significantly different emphases. This paper discusses the main issues, requirements, and design approaches for the implementation of grid-based knowledge discovery systems. Furthermore, some prospects and promising research directions in datacentric and knowledge-discovery oriented grids are outlined.

We extend the service abstraction in the Open Grid Services Architecture citeogsa for Quality of Service (QoS) properties. The realization of QoS often requires mechanisms such as advance or on-demand reservation of resources, varying in type and implementation, and independently controlled and monitored. Foster et al. propose the GARA citeFostKessl99 architecture. The GARA library provides a restricted representation scheme for encoding resource properties and the associated monitoring of Service Level Agreements (SLAs). Our focus is on the application layer, whereby a given service may indicate the QoS properties it can offer, or where a service may search for other services based on particular QoS properties.

In the field of biodiversity informatics a wide range of diverse databases and tools already exists. The challenge is to integrate such resources in order to support scientists wishing to explore complex problems of relevance to biodiversity, and to create new resources where necessary. In this paper we outline the relevance of biodiversity informatics requirements to the future development of the GRID, identifying the main issues that need to be addressed in this area. We present GRAB (GRid And Biodiversity), which is a prototype demonstrator illustrating how one particular biodiversity-related task, namely bioclimatic modelling, can be supported in a Globus-based environment. We also describe a much larger-scale GRID application project that is just commencing (BiodiversityWorld) in which a flexible problem-solving environment is to be built for full-scale investigations by scientists working in a number of biodiversity research areas.

For several years, UNICORE and Globus have co-existed as approaches to exploiting what has become known as the ``Grid''. Both offer many services beneficial for creating and using production Grids. A cooperative approach, providing interoperability between Globus and UNICORE, would result in an advanced set of Grid services that gain strength from each other. This paper outlines some of these parallels and differences as they relate to the development of an interoperability layer between UNICORE and Globus. Given the increasing ubiquity of Globus, what emerges is the desire for a hybridised facility that utilises the UNICORE work-flow management of complex, multi-site tasks, but that can run on either UNICORE- or Globus-enabled resources. The technical challenge in achieving this, addressed in this paper, consists of mapping resource descriptions from both grid environments to an abstract format appropriate to work-flow preparation, and then the instantiation of work-flow tasks on the target systems. Other issues such as reconciling disparate security models and file transfer support are also addressed.

In this paper, we consider static scheduling techniques for heterogeneous systems, such as clusters and grids. We successively deal with minimum makespan scheduling, divisible load scheduling and steady-state scheduling. Finally, we discuss the limitations of static scheduling approaches.