"Grid" computing has emerged as an important new field, distinguished from conventional distributed computing by its focus on large-scale resource sharing, innovative applications, and, in some cases, high-performance orientation. In this article, we define this new field. First, we review the "Grid problem," which we define as flexible, secure, coordinated resource sharing among dynamic collections of individuals, institutions, and resources---what we refer to as virtual organizations. In such settings, we encounter unique authentication, authorization, resource access, resource discovery, and other challenges. It is this class of problem that is addressed by Grid technologies. Next, we present an extensible and open Grid architecture,inwhich protocols, services, application programming interfaces, and software development kits are categorized according to their roles in enabling resource sharing. We describe requirements that we believe any such mechanisms must satisfy and we discuss the importance of defining a compact set of intergrid protocols to enable interoperability among different Grid systems. Finally, we discuss how Grid technologies relate to other contemporary technologies, including enterprise integration, application service provider, storage service provider, and peer-to-peer computing. We maintain that Grid concepts and technologies complement and have much to contribute to these other approaches.

In both e-business and e-science, we often need to integrate services across distributed, heterogeneous, dynamic “virtual organizations ” formed from the disparate resources within a single enterprise and/or from external resource sharing and service provider relationships. This integration can be technically challenging because of the need to achieve various qualities of service when running on top of different native platforms. We present an Open Grid Services Architecture that addresses these challenges. Building on concepts and technologies from the Grid and Web services communities, this architecture defines a uniform exposed service semantics (the Grid service); defines standard mechanisms for creating, naming, and discovering transient Grid service instances; provides location transparency and multiple protocol bindings for service instances; and supports integration with underlying native platform facilities. The Open Grid Services Architecture also defines, in terms of Web Services Description Language (WSDL) interfaces and associated conventions, mechanisms required for creating and composing sophisticated distributed systems, including lifetime management, change management, and notification. Service bindings can support reliable invocation, authentication, authorization, and delegation, if required. Our presentation complements an earlier foundational article, “The Anatomy of the Grid, ” by describing how Grid mechanisms can implement a service-oriented architecture, explaining how Grid functionality can be incorporated into a Web services framework, and illustrating how our architecture can be applied within commercial computing as a basis for distributed system integration—within and across organizational domains. This is a DRAFT document and continues to be revised. The latest version can be found at

Many scientific disciplines are now data and information driven, and new scientific knowledge is often gained by scientists putting together data analysis and knowledge discovery “pipelines”. A related trend is that more and more scientific communities realize the benefits of sharing their data and computational services, and are thus contributing to a distributed data and computational community infrastructure (a.k.a. “the Grid”). However, this infrastructure is only a means to an end and scientists ideally should be bothered little with its existence. The goal is for scientists to focus on development and use of what we call scientific workflows. These are networks of analytical steps that may involve, e.g., database access

A software development system based uponin0/----E30 skeleton technology (ASSIST)i a proposal of a new programmi/ enviammi/ oriiam to the development of parallel and di0 tri0C/3 hiC/3C/0:/EEC90 applii0:/E accordi to auniCfl approach. The mai goals are: hi:0CCP--C programmabiQQ9 and softwareproductiC/Q for complexmulti0PC/PE0:/33 appli0 tipli ipli0P data-iPC/PE0: andi0/fl3C90:/ software; performance portabince across dioss ent platforms,i partims,0 large-scale platforms andgri/Q e#ecti-- reuse of parallel software; e#ciwa evoluti; ofappli30:/CC through versih0 that scaleaccordi9 to theunderlyi: technologiCC The purpose ofthi paperi to show the pri99fl30: of the proposed approachi terms of the programmifl model(successi0 paperswie deal wil theenvi39--0:/ ivi39--0:/flfl# andwiE performance evaluatice0 The features and thecharacteri###3 of the ASSIST programmiC model aredescri3fl accordifl to anoperati:flQ semanti style andusiP examples todrifl the presentati3Q to show the expressi: power and todiP--#-- the research iesear Accordih to ourpreviC9 experi90: i structured parallelprogrammi3C i ASSIST we wi0 to overcome some li0fl3--PE0: of theclassi--fl skeletog approach toi0P--Q/ generalifl and flexi/0:flPP expressiP power ande#ci/CE fori0/3--Qfl0: dynami andi0P--39--0:fl appli39 tipli as well as for complexcombi0flEQ3C of task and dataparalleli:fl A newparadi#/ www.elsevi r.com/locate/parco Parallel Computi0 28 (2002) 1709--1732 qThi work has been supported by the Italian Space Agency: ASI-PQE2000 Project on "Development of Earth Observatis Applit0flP ns by means of Systems and Tools forHiPfl--P--0:Q# anceComputiQ0:Q and by theNatio3fl ResearchCoearc :Agenzi 2000 Project on "DevelopmentEnviPC#3 nt forMulti3E0:3 rm and Multi/0: uageHi0fl9fl--Q0 rmanceAppli/flQ-- ns, Based up...

Abstract. To better manage the ever increasing complexity of LAM/MPI, we have created a lightweight component architecture for it that is specifically designed for high-performance message passing. This paper describes the basic design of the component architecture, as well as some of the particular component instances that constitute the latest release of LAM/MPI. Performance comparisons against the previous, monolithic, version of LAM/MPI show no performance impact due to the new architecture—in fact, the newest version is slightly faster. The modular and extensible nature of this implementation is intended to make it significantly easier to add new functionality and to conduct new research using LAM/MPI as a development platform. 1

The Internet and the Grid are changing the face of high performance computing. Rather than tightly-coupled SPMD-style components running in a single cluster, on a parallel machine, or even on the Internet programmed in MPI, applications are evolving into sets of collaborating elements scattered across diverse computational elements. These collaborating components may run on different operating systems and hardware platforms and may be written by different organizations in different languages. Complete "applications" are constructed by assembling these components in a plug-and-play fashion. This new vision for high performance computing demands features and characteristics not easily provided by traditional highperformance communications middleware. In response to these needs, we have developed ECho, a high-performance event-delivery middleware that meets the new demands of the Grid environment. ECho provides efficient binary transmission of event data with unique features that support data-type discovery and enterprise-scale application evolution. We present measurements detailing ECho's performance to show that ECho significantly outperforms other systems intended to provide this functionality and provides throughput and latency comparable to the most efficient middleware infrastructures available.

... in non-traditional circumstances where it must interoperate with other applications. For example, online visualization is being used to monitor the progress of applications, and real-world sensors are used as inputs to simulations. Whenever these situations arise, there is a question of what communications infrastructure should be used to link the different components. Traditional HPC-style communications systems such as MPI offer relatively high performance, but are poorly suited for developing these less tightly-coupled cooperating applications. Object-based systems and meta-data formats like XML offer substantial plug-and-play flexibility, but with substantially lower performance. We observe that the flexibility and baseline performance of all these systems is strongly determined by their wire format', or how they represent data for transmission in a heterogeneous environment. We examine the performance implications of different wire formats and present an alternative with significant advantages in terms of both performance and flexibility.

We present an overview of the CCA core specification and CCAFFEINE, a Sandia National Laboratories framework implementation compliant with the draft specification. CCAFFEINE stands for CCA Fast Framework Example In Need of Everything; that is, CCAFFEINE is fast, lightweight, and it aims to provide every "framework service " by using external, portable components instead of integrating all services into a single, heavy framework core. By fast, we mean that the CCAFFEINE glue does not get between components in a way that slows down their interactions. We present the CCAFFEINE solutions to several fundamental problems in the application of component software approaches to the construction of SPMD applications. We demonstrate the integration of components from three

This paper describes Uintah, a component-based visual problem solving environment (PSE) that is designed to specifically address the unique problems of massively parallel computation on terascale computing platforms. Uintah supports the entire life cycle of scientic applications by allowing scientific programmers to quickly and easily develop new techniques, debug new implementations, and apply known algorithms to solve novel problems. Uintah is built on three principles: 1) As much as possible, the complexities of parallel execution should be handled for the scientist, 2) software should be reusable at the component level, and 3) scientists should be able to dynamically steer and visualize their simulation results as the simulation executes. To provide this functionality, Uintah builds upon the best features of the SCIRun PSE and the DoE Common Component Architecture (CCA).

ASSIST (A Software development System based upon Integrated Skeleton Technology) is a programming environment oriented to the development of parallel and distributed high-performance applications according to a unified approach. The language and implementation features of ASSIST are a result of our long-term research in parallel programming models and tools. ASSIST is evolving towards programming environments for high-performance complex enabling platforms, especially Grids. In this paper, we show how ASSIST can act as a valid research vehicle to study, experiment and realize Grid-aware programming environments for high-performance applications. Special emphasis is put on the innovative methodologies, strategies and tools for dynamically adaptive applications, that represent the necessary step for the success of Grid platforms. First we discuss the conceptual framework for Grid-aware programming environments, based upon structured parallel programming and components technology, anticipating how ASSIST possesses the essential features required by