Grid Environments (grid + environment)

Distribution by Scientific Domains

Selected Abstracts


Cynthia S. Loftin
ABSTRACT: The model described herein was used to assess effects of the Suwannee River sill (a low earthen dam constructed to impound the Suwannee River within the Okefenokee National Wildlife Refuge to eliminate wildfires) on the hydrologic environment of Okefenokee Swamp, Georgia. Developed with Arc/Info Macro Language routines in the GRID environment, the model distributes water in the swamp landscape using precipitation, inflow, evapotranspiration, outflow, and standing water. Water movement direction and rate are determined by the neighborhood topographic gradient, determined using survey grade Global Positioning Systems technology. Model data include flow rates from USGS monitored gauges, precipitation volumes and water levels measured within the swamp, and estimated evapotranspiration volumes spatially modified by vegetation type. Model output in semi-monthly time steps includes water depth, water surface elevation above mean sea level, and movement direction and volume. Model simulations indicate the sill impoundment affects 18 percent of the swamp during high water conditions when wildfires are scarce and has minimal spatial effect (increasing hydroperiods in less than 5 percent of the swamp) during low water and drought conditions when fire occurrence is high but precipitation and inflow volumes are limited. [source]

Resource discovery and management in computational GRID environments

Alan Bradley
Abstract Corporations are currently using computational GRIDs to improve their operations. Future GRIDs will allow an organization to take advantage of computational GRIDs without having to develop a custom in-house solution. GRID resource providers (GRPs) make resources available on the GRID so that others may subscribe and use these resources. GRPs will allow companies to make use of a range of resources such as processing power or mass storage. However, simply providing resources is not enough to ensure the success of a computational GRID: Access to these resources must be controlled otherwise computational GRIDs will simply evolve to become a victim of their own success, unable to offer a suitable quality of service (QoS) to any user. The task of providing a standard querying mechanism for computational GRID environments (CGE) has already witnessed considerable work from groups such as the Globus project who have delivered the Metacomputing Directory Service (MDS), which provides a means to query devices attached to the GRID. This paper presents a review of existing resource discovery mechanisms within CGE. Copyright © 2005 John Wiley & Sons, Ltd. [source]

A standards-based Grid resource brokering service supporting advance reservations, coallocation, and cross-Grid interoperability

Erik Elmroth
Abstract The problem of Grid-middleware interoperability is addressed by the design and analysis of a feature-rich, standards-based framework for all-to-all cross-middleware job submission. The architecture is designed with focus on generality and flexibility and builds on extensive use, internally and externally, of (proposed) Web and Grid services standards such as WSRF, JSDL, GLUE, and WS-Agreement. The external use provides the foundation for easy integration into specific middlewares, which is performed by the design of a small set of plugins for each middleware. Currently, plugins are provided for integration into Globus Toolkit 4 and NorduGrid/ARC. The internal use of standard formats facilitates customization of the job submission service by replacement of custom components for performing specific well-defined tasks. Most importantly, this enables the easy replacement of resource selection algorithms by algorithms that address the specific needs of a particular Grid environment and job submission scenario. By default, the service implements a decentralized brokering policy, striving to optimize the performance for the individual user by minimizing the response time for each job submitted. The algorithms in our implementation perform resource selection based on performance predictions, and provide support for advance reservations as well as coallocation of multiple resources for coordinated use. The performance of the system is analyzed with focus on overall service throughput (up to over 250 jobs per min) and individual job submission response time (down to under 1,s). Copyright © 2009 John Wiley & Sons, Ltd. [source]

Discovering data sources in a dynamic Grid environment

Jürgen Göres
Abstract The successful adaptation of information integration techniques to the requirements of data Grids is essential for the proliferation of Grid technology. In addition to the well-known problems encountered when integrating heterogeneous sources, the dynamic Grid environment introduces new challenges. This paper discusses the problem of data source discovery, i.e. the selection of the most useful data sources for a given information demand out of a possibly very large set of candidates. We introduce the concept of data source utility and emphasize the pivotal role of semantic correspondences or schema matches for utility. Different variants of concrete utility measures used in an advanced Grid data source registry are presented. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Developing LHCb Grid software: experiences and advances

I. Stokes-Rees
Abstract The LHCb Grid software has been used for two Physics Data Challenges, with the latter producing over 98 TB of data and consuming over 650 processor-years of computing power. This paper discusses the experience of developing a Grid infrastructure, interfacing to an existing Grid (LCG) and traditional computing centres simultaneously, running LHCb experiment software and jobs on the Grid, and the integration of a number of new technologies into the Grid infrastructure. Our experience and utilization of the following core technologies will be discussed: OGSI, XML-RPC, Grid services, LCG middleware and instant messaging. Specific attention will be given to analysing the behaviour of over 100,000 jobs executed through the LCG Grid environment, providing insight into the performance, failure modes and scheduling efficiency over a period of several months for a large computational Grid incorporating over 40 sites and thousands of nodes. © Crown copyright 2006. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd. [source]

Auctioning resources in Grids: model and protocols

D. Grosu
Abstract In this paper, we propose and study an auction model for resource management in Grids. We propose and investigate by simulation three types of auction-based resource-allocation protocols: (i) first-price auction protocol; (ii) Vickrey auction protocol; and (iii) double auction protocol. The goal is to find which of these is best suited to the Grid environment from the users' perspective as well as from the resources' perspective. The results showed that when we consider a mix of risk-averse and risk-neutral users, the first-price auction protocol favors resources while the Vickrey auction protocol favors users. On the other hand, the double auction protocol favors both users and resources. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Learning with an active e-course in the Knowledge Grid environment

Hai Zhuge
Abstract An active e-course is an open, self-representable and self-organizable media mechanism. Its kernel idea is to organize learning materials in a concept space rather than in a page space. The tailored content and flexible structure of the e-courses can be dynamically formed to cater for different learners with different backgrounds, capabilities and expectations, at different times and venues. The active e-course can also assess learners' learning performances and give appropriate suggestions to guide them in further learning. An authoring tool for constructing course ontology and a system prototype have been developed to support an active e-course, enabling a learner-centred, highly interactive and adaptive learning approach. The results of an empirical study show that the system can help enhance the effectiveness and efficiency of learning. Copyright © 2005 John Wiley & Sons, Ltd. [source]

GridBLAST: a Globus-based high-throughput implementation of BLAST in a Grid computing framework

Arun KrishnanArticle first published online: 24 JUN 200
Abstract Improvements in the performance of processors and networks have made it feasible to treat collections of workstations, servers, clusters and supercomputers as integrated computing resources or Grids. However, the very heterogeneity that is the strength of computational and data Grids can also make application development for such an environment extremely difficult. Application development in a Grid computing environment faces significant challenges in the form of problem granularity, latency and bandwidth issues as well as job scheduling. Currently existing Grid technologies limit the development of Grid applications to certain classes, namely, embarrassingly parallel, hierarchical parallelism, work flow and database applications. Of all these classes, embarrassingly parallel applications are the easiest to develop in a Grid computing framework. The work presented here deals with creating a Grid-enabled, high-throughput, standalone version of a bioinformatics application, BLAST, using Globus as the Grid middleware. BLAST is a sequence alignment and search technique that is embarrassingly parallel in nature and thus amenable to adaptation to a Grid environment. A detailed methodology for creating the Grid-enabled application is presented, which can be used as a template for the development of similar applications. The application has been tested on a ,mini-Grid' testbed and the results presented here show that for large problem sizes, a distributed, Grid-enabled version can help in significantly reducing execution times. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Service selection and workflow mapping for Grids: an approach exploiting quality-of-service information

Dimosthenis Kyriazis
Abstract The advent of heterogeneous and distributed environments, such as Grid environments, made feasible the solution to computational-intensive problems in a reliable and cost-effective manner. In parallel, workflows with increased complexity that require specialized systems to deal with them are emerging, so as to carry out more composite and mission-critical applications. In that rationale, quality-of-service (QoS) issues need to be tackled in order to ensure that each application satisfies the corresponding user requirements. Therefore, considering the quality provision aspect as fundamental for enabling Grid applications to become QoS compliant, we present an approach for service selection using QoS criteria. The latter is achieved with a suite of components that allow the different mappings of application workflow processes to Grid services that not only meet the user goals and requirements but also maximize his/her benefit in terms of the offered QoS level. We also demonstrate the operation of the aforementioned suite of components and evaluate its performance and effectiveness using a Grid scenario, based on a 3D image rendering application. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Toward replication in grids for digital libraries with freshness and correctness guarantees

Fuat Akal
Abstract Building digital libraries (DLs) on top of data grids while facilitating data access and minimizing access overheads is challenging. To achieve this, replication in a Grid has to provide dedicated features that are only partly supported by existing Grid environments. First, it must provide transparent and consistent access to distributed data. Second, it must dynamically control the creation and maintenance of replicas. Third, it should allow higher replication granularities, i.e. beyond individual files. Fourth, users should be able to specify their freshness demands, i.e. whether they need most recent data or are satisfied with slightly outdated data. Finally, all these tasks must be performed efficiently. This paper presents an approach that will finally allow one to build a fully integrated and self-managing replication subsystem for data grids that will provide all the above features. Our approach is to start with an accepted replication protocol for database clusters, namely PDBREP, and to adapt it to the grid. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Job completion prediction using case-based reasoning for Grid computing environments

Lilian Noronha Nassif
Abstract One of the main focuses of Grid computing is solving resource-sharing problems in multi-institutional virtual organizations. In such heterogeneous and distributed environments, selecting the best resource to run a job is a complex task. The solutions currently employed still present numerous challenges and one of them is how to let users know when a job will finish. Consequently, reserve in advance remains unavailable. This article presents a new approach, which makes predictions for job execution time in Grid by applying the case-based reasoning paradigm. The work includes the development of a new case retrieval algorithm involving relevance sequence and similarity degree calculations. The prediction model is part of a multi-agent system that selects the best resource of a computational Grid to run a job. Agents representing candidate resources for job execution make predictions in a distributed and parallel manner. The technique presented here can be used in Grid environments at operation time to assist users with batch job submissions. Experimental results validate the prediction accuracy of the proposed mechanisms, and the performance of our case retrieval algorithm. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Incentive-based scheduling in Grid computing

Yanmin Zhu
Abstract With the rapid development of high-speed wide-area networks and powerful yet low-cost computational resources, Grid computing has emerged as an attractive computing paradigm. In typical Grid environments, there are two distinct parties, resource consumers and resource providers. Enabling an effective interaction between the two parties (i.e. scheduling jobs of consumers across the resources of providers) is particularly challenging due to the distributed ownership of Grid resources. In this paper, we propose an incentive-based peer-to-peer (P2P) scheduling for Grid computing, with the goal of building a practical and robust computational economy. The goal is realized by building a computational market supporting fair and healthy competition among consumers and providers. Each participant in the market competes actively and behaves independently for its own benefit. A market is said to be healthy if every player in the market gets sufficient incentive for joining the market. To build the healthy computational market, we propose the P2P scheduling infrastructure, which takes the advantages of P2P networks to efficiently support the scheduling. The proposed incentive-based algorithms are designed for consumers and providers, respectively, to ensure every participant gets sufficient incentive. Simulation results show that our approach is successful in building a healthy and scalable computational economy. Copyright © 2006 John Wiley & Sons, Ltd. [source]

GAUGE: Grid Automation and Generative Environment,

Francisco Hernández
Abstract The Grid has proven to be a successful paradigm for distributed computing. However, constructing applications that exploit all the benefits that the Grid offers is still not optimal for both inexperienced and experienced users. Recent approaches to solving this problem employ a high-level abstract layer to ease the construction of applications for different Grid environments. These approaches help facilitate construction of Grid applications, but they are still tied to specific programming languages or platforms. A new approach is presented in this paper that uses concepts of domain-specific modeling (DSM) to build a high-level abstract layer. With this DSM-based abstract layer, the users are able to create Grid applications without knowledge of specific programming languages or being bound to specific Grid platforms. An additional benefit of DSM provides the capability to generate software artifacts for various Grid environments. This paper presents the Grid Automation and Generative Environment (GAUGE). The goal of GAUGE is to automate the generation of Grid applications to allow inexperienced users to exploit the Grid fully. At the same time, GAUGE provides an open framework in which experienced users can build upon and extend to tailor their applications to particular Grid environments or specific platforms. GAUGE employs domain-specific modeling techniques to accomplish this challenging task. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Enabling interactive and collaborative oil reservoir simulations on the Grid

Manish Parashar
Abstract Grid-enabled infrastructures and problem-solving environments can significantly increase the scale, cost-effectiveness and utility of scientific simulations, enabling highly accurate simulations that provide in-depth insight into complex phenomena. This paper presents a prototype of such an environment, i.e. an interactive and collaborative problem-solving environment for the formulation, development, deployment and management of oil reservoir and environmental flow simulations in computational Grid environments. The project builds on three independent research efforts: (1) the IPARS oil reservoir and environmental flow simulation framework; (2) the NetSolve Grid engine; and (3) the Discover Grid-based computational collaboratory. Its primary objective is to demonstrate the advantages of an integrated simulation infrastructure towards effectively supporting scientific investigation on the Grid, and to investigate the components and capabilities of such an infrastructure. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Programming and coordinating Grid environments and applications

Cristina Ururahy
Abstract The heterogeneous and dynamic nature of Grid environments place new demands on models and paradigms for parallel programming. In this work we discuss how ALua, a programming system based on a dual programming language model, can help the programmer to develop applications for this environment, monitoring the state of resources and controlling the application so that it adapts to changes in this state. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Parallel programming on a high-performance application-runtime

Wojtek James Goscinski
Abstract High-performance application development remains challenging, particularly for scientists making the transition to a heterogeneous grid environment. In general areas of computing, virtual environments such as Java and .Net have proved to be successful in fostering application development, allowing users to target and compile to a single environment, rather than a range of platforms, instruction sets and libraries. However, existing runtime environments are focused on business and desktop computing and they do not support the necessary high-performance computing (HPC) abstractions required by e-Scientists. Our work is focused on developing an application-runtime that can support these services natively. The result is a new approach to the development of an application-runtime for HPC: the Motor system has been developed by integrating a high-performance communication library directly within a virtual machine. The Motor message passing library is integrated alongside and in cooperation with other runtime libraries and services while retaining a strong message passing performance. As a result, the application developer is provided with a common environment for HPC application development. This environment supports both procedural languages, such as C, and modern object-oriented languages, such as C#. This paper describes the unique Motor architecture, presents its implementation and demonstrates its performance and use. Copyright © 2008 John Wiley & Sons, Ltd. [source]

KDDML-G: a grid-enabled knowledge discovery system

Andrea Romei
Abstract KDDML-G is a middleware language and system for knowledge discovery on the grid. The challenge that motivated the development of a grid-enabled version of the ,standalone' KDDML (Knowledge Discovery in Databases Markup Language) environment was on one side to exploit the parallelism offered by the grid environment, and on the other side to overcome the problem of data immovability, a quite frequent restriction on real-world data collections that has principally a privacy-preserving purpose. The last question is addressed by moving the code and ,mining' the data ,on the place', that is by adapting the computation to the availability and localization of the data. Copyright © 2007 John Wiley & Sons, Ltd. [source]

The Grid Resource Broker workflow engine

M. Cafaro
Abstract Increasingly, complex scientific applications are structured in terms of workflows. These applications are usually computationally and/or data intensive and thus are well suited for execution in grid environments. Distributed, geographically spread computing and storage resources are made available to scientists belonging to virtual organizations sharing resources across multiple administrative domains through established service-level agreements. Grids provide an unprecedented opportunity for distributed workflow execution; indeed, many applications are well beyond the capabilities of a single computer, and partitioning the overall computation on different components whose execution may benefit from runs on different architectures could provide better performances. In this paper we describe the design and implementation of the Grid Resource Broker (GRB) workflow engine. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Dynamic scheduling of network resources with advance reservations in optical grids

Savera Tanwir
Advance reservation of lightpaths in grid environments is necessary to guarantee QoS and reliability. In this paper, we have evaluated and compared several algorithms for dynamic scheduling of lightpaths using a flexible advance reservation model. The main aim is to find the best scheduling policy for a grid network resource manager that improves network utilization and minimizes blocking. The scheduling of lightpaths involves both routing and wavelength assignment. Our simulation results show that minimum-cost adaptive routing where link costs are determined by the current and future usage of the link provides the minimum blocking. For wavelength assignment, we have used a scheme that reduces fragmentation by minimizing unused gaps. We have also analyzed approaches for failure recovery and resource optimization. Copyright © 2008 John Wiley & Sons, Ltd. [source]