This paper defines and evaluates a hierarchical distributed data structure, distributed digest trie, supporting range queries in P2P systems. Providing efficient support for these queries is currently a challenging research issue in the P2P field, as classical approaches based on distributed hash ta

Service Oriented Architecture (SOA) and Grid computing are very hot research topics, nowadays. While Grid computing is aimed at sharing dynamically heterogeneous resources, SOAs is a meta-architectural style that enable business flexibility in an interoperable way. There is a growing consensus that SOA(s) and Grid(s) might be beneficial to each other. In Grid-based SOAs a central role is played by tools for the publishing/discovering of services (resources).

This paper describes the study conducted to design and evaluate a two-level on-line scheduler to dynamically schedule a stream of sequential and multi-threaded batch jobs on large scale grids, made up of interconnected clusters of heterogeneous machines. The scheduler aims to schedule arriving jobs respecting their computational and deadline requirements, and optimizing the utilization of hardware resources as well as software resources.

Autonomic management can be used to improve the QoS provided by parallel/distributed applications. We discuss behavioural skeletons introduced in earlier work: rather than relying on programmer ability to design "from scratch" efficient autonomic policies, we encapsulate general autonomic controller features into algorithmic skeletons. Then we leave to the programmer the duty of specifying the parameters needed to specialise the skeletons to the needs of the particular application at hand. This results in the programmer having the ability to fast prototype and tune distributed/parallel applications with non-trivial autonomic management capabilities. We discuss how behavioural skeletons have been implemented in the framework of GCM (the grid component model developed within the CoreGRID NoE and currently being implemented within the GridCOMP STREP project). We present results evaluating the overhead introduced by autonomic management activities as well as the overall behaviour of the skeletons. We also present results achieved with a long running application subject to autonomic management and dynamically adapting to changing features of the target architecture. Overall the results demonstrate both the feasibility of implementing autonomic control via behavioural skeletons and the effectiveness of our sample behavioural skeletons in managing the "functional replication" pattern(s).

Bioinformatics is one of the key application of this century. The attention received by all the current media is astonishing and both academics and industries are carrying on researches in many fields related to computational methods applied to life sciences. In this paper we present some results obtained within an Italian funded research project called ESCOGITARE. We present the design and implementation of a grid-based architecture for scientific workflow management that, differently from others, allows the dynamic discovery of existing Web services in combination to ad-hoc developed ones. The paper presents the main features of current scientific workflow management systems. Using a real-world case study (taken by the agricultural research domain), we show how we overcome the limitations of current approaches.

Component-based grid applications have complex deployment models. Performance-sensitive decisions should be taken by automatic tools. Such tools must match developer knowledge on component performance with QoS requirements on the applications, in order to find deployment plans that satisfy a service level agreement (SLA). This paper presents a steady state performance model that can be employed to reason about and automatically map stream-based component programs

Summary form only given. There has been a lot of water pass under the bridge since the term grid computing was introduced by Foster and Kesselman in the middle of 90s. Since then the grid concept has evolved, losing its initial high-performance computing flavor. Currently there is an increasing number of researchers that looks at the grid as "A fully distributed, dynamically reconfigurable, scalable and autonomous infrastructure to provide location independent, pervasive, reliable, secure and efficient access to a coordinated set of services encapsulating and virtualizing resources (computing power, storage, instruments, data, etc.) in order to generate knowledge". This grid definition is the outcome of an internal brainstorming exercise conducted recently in the CoreGrid (http://www.coregrid.net/) Executive Committee. Moreover, several researchers envision that economics principle will guide in the future the development of grid-aware applications: an open market of services and resources will become available to the developer, who will choose to use computing time and software solutions from different vendors, sold at different prices, with different performance and QoS. In this light the great majority of complex software applications will, in the mid-long term, be dynamically built by composing services which will be available in an open market of services and resources. In this sense, the grid might be conceived as a world-wide cyber-utility populated by self-* cooperating services which interact as in a complex and gigantic software ecosystem. This will lead to a new style of application development based on software services, which will in turn need the expansion of existing practice regarding service location, standardization, semantics of services, certification, and others. After an introduction on the current European strategies on grid technologies, and on the most recent 1ST FP6 funded European projects, this talk presents the outcome of a group of independent experts convened by the European Commission with the objective to draw visions of the future for European grids, and in particular about possible evolutions of GRTDs towards service oriented knowledge utilities

Abstract The Grid and its related technologies enable large‐scale sharing of resources of various types. We envision that in the near future applications will be completely built in a bottom‐up fashion using software components deployed on various locations and interconnected to form a workflow graph. In this paper, we make some proposals on the design of a component search service, enabling users to locate the components they need to deploy an application. Copyright © 2005 John Wiley & Sons, Ltd.

Component-oriented software design of Grid applications is commanding growing attention for business and scientific problems. The goal is create applications by assembling together independently developed software components. The components are independently developed, composable, reusable, substitutable software solutions, with clearly defined interface and behaviour.

Today, the development of Grid applications is considered a nightmare, due to lack of grid programming environments, standards, off-the-shelf software components, and so on.

Abstract The last decade has seen a substantial increase in commodity computer and network performance, mainly as a result of faster hardware and more sophisticated software. Nevertheless, there are still problems, in the fields of science, engineering, and business, which cannot be effectively dealt with using the current generation of supercomputers. In fact, due to their size and complexity, these problems are often very numerically and/or data intensive and consequently require a variety ofheterogeneous resources that are not available on a single machine. A number of teams have conducted experimental studies on the cooperative use of geographically distributed resources unified to act as a single powerful computer. This new approach is known by several names, such as metacomputing, scalable computing, global computing, Internet computing, and more recently peer‐to‐peer or Grid computing. The early efforts in Grid computing started as a project to link supercomputing sites, but have now grown far beyond their original intent. In fact, many applications can benefit from the Grid infrastructure, including collaborative engineering, data exploration, high‐throughput computing, and of course distributed supercomputing. Moreover, due to the rapid growth of the Internet and Web, there has been a rising interest in Web‐based distributed computing, and many projects have been started and aim to exploit the Web as an infrastructure for running coarse‐grained distributed and parallel applications. In this context, the Web has the capability to be a platform for parallel and collaborative work as well as a key technology to create a pervasive and ubiquitous Grid‐based infrastructure. This paper aims to present the state‐of‐the‐art of Grid computing and attempts to survey the major international efforts in developing this emerging technology. Copyright © 2002 John Wiley & Sons, Ltd.

The need for realistic simulations of complex systems relevant to the modeling of several modern technologies and environmental phenomena increasingly stimulates the development of advanced computing approaches. Nowadays it is possible to cluster or couple a wide variety of resources including supercomputers, storage systems, data sources, and special classes of devices distributed geographically and use them as a single unified resource, thus forming what is popularly known as a “computational grid” [1,2].

The need to deal with highly complex scientific problems has led some researchers to use geographically distributed computing resources as a single powerful parallel machine. The word metacomputing has been coined to describe this new approach. This paper outlines some experiences in metacomputing carried out on a wide area network. A brief overview is given of the main issues concerning metacomputing, and some experiments in this field are reported. WAMM, the metacomputer visual interface we have developed, is described. Astrophysics is a particularly fruitful field for numerical-intensive computer simulation, because the systems under study, stars and galaxies, are not amenable to controlled laboratory experiments. An astrophysical application of the gravitational n-body problem, developed in conjunction with the Scuola Normale Superiore of Pisa, was used to test WAMM's utility in metacomputer management, and some performance figures related to the case study are given. Work related to WAMM and conclusions are also presented. © 1997 by John Wiley & Sons, Ltd.

Abstract The paper deals with the parallelization of Delaunay triangulation, a widely used space partitioning technique. Two parallel implementations of a three‐dimensional incremental construction algorithm are presented. The first is based on the decomposition of the spatial domain, while the second relies on the master‐slaves approach. Both parallelization strategies are evaluated, stressing practical issues rather than theoretical complexity. We report on the exploitation of two different parallel environments: a tightly coupled distributed memory MIMD architecture and a network of workstations co‐operating under the Linda environment Then, a third hybrid solution is proposed, specifically addressed to the exploitation of higher parallelism. It combines the other two solutions by grouping the processing nodes of the multicomputer into clusters and by exploiting parallelism at two different levels.