Concurrency and Computation:Practice and Experience: Published Papers for 2007

Concurrency and Computation: Practice and Experience

Published Papers for 2007

Journal Vision

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Papers under review through 2007

Editorial Board

2007 Volume 19 Articles

CPE1058:The Parallel Image Processing Environment (PIPE): automated parallelization of satellite data analyses

Author(s):James J. Simpson,Timothy J. McIntire,Jared S. Berg,Yueh Lung (Ben) Tsou
Digital Image Analysis Laboratory (DIAL), Scripps Institution of Oceanography, La Jolla, CA 92093-0237, U.S.A.,
http://dx.doi.org/10.1002/cpe.1058
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Abstract: A Beowulf-type cluster can: (1) mitigate many issues associated with the analysis of large, complex remotely sensed data sets; (2) shorten the response time of operational agencies to crisis-management situations; and (3) expedite the reanalysis of large archives of satellite data. Whereas most Beowulf-type designs support modeling applications, the Parallel Image Processing Environment (PIPE) addresses the unique requirements of remote sensing applications. PIPE has four hierarchical layers: hardware, operating system, middleware and applications. Rocks, a middleware sublayer, manages the cluster. DIAL-developed interprocess communication and control daemons form the second middleware sublayer. They encapsulate user-defined applications and thereby support automated, user-transparent parallelization of satellite data analyses, implemented in the applications layer using generalized constructs. The daemons also monitor resource (computational and I/O) utilization on a node/thread basis, a feature not supported by other generally available monitoring utilities. The application support libraries are fully extensible, facilitate the reuse of modular and commonly used software functions in new applications and thereby reduce both the cost and time to implement new applications. Two applications (signal analysis, image classification) show PIPE's versatility and performance characteristics. PIPE is intrinsically scalable, reliable and can be incrementally implemented. A comparison with other embarrassingly parallel systems is also provided. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1059:Performance and effectiveness trade-off for checkpointing in fault-tolerant distributed systems

Author(s):Panagiotis Katsaros,Lefteris Angelis,Constantine Lazos
Department of Informatics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece,
http://dx.doi.org/10.1002/cpe.1059
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Abstract: Checkpointing has a crucial impact on systems' performance and fault-tolerance effectiveness: excessive checkpointing results in performance degradation, while deficient checkpointing incurs expensive recovery. In distributed systems with independent checkpoint activities there is no easy way to determine checkpoint frequencies optimizing response-time and fault-tolerance costs at the same time. The purpose of this paper is to investigate the potentialities of a statistical decision-making procedure. We adopt a simulation-based approach for obtaining performance metrics that are afterwards used for determining a trade-off between checkpoint interval reductions and efficiency in performance. Statistical methodology including experimental design, regression analysis and optimization provides us with the framework for comparing configurations, which use possibly different fault-tolerance mechanisms (replication-based or message-logging-based). Systematic research also allows us to take into account additional design factors, such as load balancing. The method is described in terms of a standardized object replication model (OMG FT-CORBA), but it could also be applied in other (e.g. process-based) computational models. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1073:Parallel four-dimensional Haralick texture analysis for disk-resident image datasets

Author(s):Brent Woods,Bradley Clymer,Johannes Heverhagen,Michael Knopp,Joel Saltz,Tahsin Kurc
Department of Electrical and Computer Engineering, Ohio State University, Columbus, OH 43210, U.S.A.,Department of Radiology, Ohio State University, Columbus, OH 43210, U.S.A.,Department of Biomedical Informatics, Ohio State University, Columbus, OH 43210, U.S.A.,
http://dx.doi.org/10.1002/cpe.1073
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Abstract: Texture analysis is one possible method of detecting features in biomedical images. During texture analysis, texture-related information is found by examining local variations in image brightness. Four-dimensional (4D) Haralick texture analysis is a method that extracts local variations along space and time dimensions and represents them as a collection of 14 statistical parameters. However, application of the 4D Haralick method on large time-dependent image datasets is hindered by data retrieval, computation, and memory requirements. This paper describes a parallel implementation using a distributed component-based framework of 4D Haralick texture analysis on PC clusters. The experimental performance results show that good performance can be achieved for this application via combined use of task- and data-parallelism. In addition, we show that our 4D texture analysis implementation can be used to classify imaged tissues. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1086:Grid benchmarking: vision, challenges, and current status

Author(s):Marios D. Dikaiakos
Department of Computer Science, University of Cyprus, 1678 Nicosia, Cyprus
http://dx.doi.org/10.1002/cpe.1086
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Abstract: Grid benchmarking is an important and challenging topic of Grid computing research. In this paper, we present an overview of the key challenges that need to be addressed for the integration of benchmarking practices, techniques, and tools in emerging Grid computing infrastructures. We discuss the problems of performance representation, measurement, and interpretation in the context of Grid benchmarking, and propose the use of ontologies for organizing and describing benchmarking metrics. Finally, we present a survey of ongoing research efforts that develop benchmarks and benchmarking tools for the Grid. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1106:An optimization approach for decentralized QoS-based scheduling based on utility and pricing in Grid computing

Author(s):Li Chunlin,Li Layuan
Department of Computer Science, Wuhan University of Technology, Wuhan 430063, People's Republic of China,
http://dx.doi.org/10.1002/cpe.1106
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Abstract: This paper presents an optimization approach for decentralized Quality of Service (QoS)-based scheduling based on utility and pricing in Grid computing. The paper assumes that the quality dimensions can be easily formulated as utility functions to express quality preferences for each task agent. The utility values are calculated by the user-supplied utility function that can be formulated with the task parameters. The QoS constraint Grid resource scheduling problem is formulated into a utility optimization problem. The QoS-based Grid resource scheduling optimization is decomposed into two subproblems by applying the Lagrangian method. In the Grid, a Grid task agent acts as a consumer paying for the Grid resource and the resource providers receive profits from task agents. A pricing-based QoS scheduling algorithm is used to perform optimally decentralized QoS-based resource scheduling. The experiments investigate the effect of the QoS metrics on the global utility and compare the performance of the proposed algorithm with other economical Grid resource scheduling algorithms. Copyright 2006 John Wiley Sons, Ltd.

CPE1042:The importance of locality in the visualization of large datasets

Author(s):J. M. Brooke,J. Marsh,S. Pettifer,L. S. Sastry
School of Computer Science, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.,CCLRC, Rutherford Appleton Laboratory, Didcot, Oxon, U.K.
http://dx.doi.org/10.1002/cpe.1042
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Abstract: Many scientific phenomena in large high-resolution datasets such as the U.K. Ocean Circulation and Advanced Modelling (OCCAM) ocean model are better discovered through visualization than by algorithmic analysis: it is often more straightforward to see a feature than it is to characterize it numerically. Using traditional rendering techniques, the size of modern datasets presents a challenge for even high-end graphical supercomputers, and the cost of such hardware limits its availability for day-to-day analysis. We present an architecture that brings visual analysis to the desktop by exploiting consumer-grade graphics hardware in order to provide initial interactive exploration and Web services to enable finer-grained analysis and interoperability with traditional visualization tools. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1043:Applying the Grid to 3D capture technology

Author(s):Lewis Mackenzie,Paul Cockshott,Viktor Yarmolenko,Ewan Borland,Paul Graham,Kostas Kavoussanakis
Department of Computing Science, 17 Lilybank Gardens, University of Glasgow, Glasgow G12 8QQ, U.K.,Edinburgh Parallel Computing Center, The University of Edinburgh, James Clerk Maxwell Building, Mayfield Road, Edinburgh EH9 3JZ, U.K.,
http://dx.doi.org/10.1002/cpe.1043
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Abstract: The PGPGrid project aims to parallelize the process of extracting range data from an experimental 3D scanner using the Grid as a vehicle for accessing necessary resources. The application is potentially highly parallel but has some unusual features such as rapid spawning of processes in real time and a dynamic inter-process network topology. These characteristics are such as to require enhancement of the usual task migration capabilities of the Globus toolkit. The present paper initially discusses attempts to estimate the real parallelizability of the scanner application. It then describes a new Java application programming interface, based on Milner's -calculus, which could be used to extend Globus in a manner capable of supporting systems with this kind of dynamic parallel structure. The location of processing resources for the -calculus is done using a Web-services-based resource locator. The article also describes the pipeline of processing from initial stereo photogrametry to the final production of animation models. A key step in this is the conformation of animators models to the data obtained by the real-time scanner. Algorithmic innovations in this process are described. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1044:Catalyzer: a novel tool for integrating, managing and publishing heterogeneous bioscience data

Author(s):F. W. Howell,R. C. Cannon,N. H. Goddard
Institute for Adaptive and Neural Computation, Informatics, University of Edinburgh, 5 Forrest Hill, Edinburgh EH1 2QL, U.K.,
http://dx.doi.org/10.1002/cpe.1044
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Abstract: The integrative ambitions of systems biology and neuroinformatics-to construct working models of the machinery of living cells and brains-will flounder unless researchers have access to the huge amounts of diverse experimental data being collected. However, the vast majority of bioscience research data that is gathered is never made available to other researchers, partly for the want of an adequate software for annotating experimental data, and partly for social reasons (researchers are rarely rewarded for publishing the actual data sets-just for journal articles summarizing findings). Catalyzer ad hoc

CPE1045:e-Science and artificial neural networks in cancer management

Author(s):S. D. Dolgobrodov,R. Marshall,P. Moore,R. Bittern,R. J. C. Steele,A. Cuschieri
School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, U.K.,Department of Surgery and Molecular Oncology, The University of Dundee, Dundee DD1 9SY, U.K.,Scuola Superiore S'Anna di Studi Universitari e di Perfezionamento, Piazza dei Martiri della Libertá n. 33, 56127 Pisa, Italy
http://dx.doi.org/10.1002/cpe.1045
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Abstract: We describe the origins of this project, its aims and its relevance to e-Science research. Particle physicists at the University of Manchester with experience of artificial neural networks (ANNs) have collaborated with clinicians at the University of Dundee to produce an ANN that is intended to predict survival rates and to indicate management profiles for cancer patients. Comparisons are made between typical data handling problems in particle physics and health care. The problems associated with data procurement, namely reliability and censoring are described, together with a discussion of how these problems were addressed. The inputs to the ANN and its decision output are discussed. The reliability of the ANN is assessed quantitatively. The prototype secure Web-based interface, which allows clinicians to input new patient data to the central node at the University of Manchester and to obtain prognoses from anywhere in the world is presented. For each topic, the e-Science relevance is described and underlined. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1046:Optimization of integrated Earth System Model components using Grid-enabled data management and computation

Author(s):A. R. Price,G. Xue,A. Yool,D. J. Lunt,P. J. Valdes,T. M. Lenton,J. L. Wason,G. E. Pound,S. J. Cox
Southampton Regional e-Science Centre, University of Southampton, Southampton SO17 1BJ, U.K.,National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, U.K.,School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, U.K.,School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, U.K.,
http://dx.doi.org/10.1002/cpe.1046
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Abstract: In this paper, we present the Grid enabled data management system that has been deployed for the Grid ENabled Integrated Earth system model (GENIE) project. The database system is an augmented version of the Geodise Database Toolbox and provides a repository for scripts, binaries and output data in the GENIE framework. By exploiting the functionality available in the Geodise toolboxes we demonstrate how the database can be employed to tune parameters of coupled GENIE Earth System Model components to improve their match with observational data. A Matlab client provides a common environment for the project Virtual Organization and allows the scripting of bespoke tuning studies that can exploit multiple heterogeneous computational resources. We present the results of a number of tuning exercises performed on GENIE model components using multi-dimensional optimization methods. In particular, we find that it is possible to successfully tune models with up to 30 free parameters using Kriging and Genetic Algorithm methods. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1048:Developing LHCb Grid software: experiences and advances

Author(s):I. Stokes-Rees,A. Tsaregorodtsev,V. Garonne,R. Graciani,M. Sanchez,M. Frank,J. Closier
Department of Particle Physics, University of Oxford, Oxford OX1 3RH, U.K.,Centre de Physique des Particules de Marseille, 163 avenue de Luminy, Case 902, 13288 Marseille cedex 09, France,Departamento de Estructura y Constituyentes de la Materia, Facultat de Fisica, Universidad de Barcelona, Diagonal 647, 08028 Barcelona, Spain,Departamento de Física de Particulas, Facultade de Física, Campus Universitario Sur, E-15782 Santiago de Compostela, Spain,CERN, CH-1211 Genève 23, Switzerland,
http://dx.doi.org/10.1002/cpe.1048
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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.

CPE1049:Supporting scientific discovery processes in Discovery Net

Author(s):Jameel Syed,Moustafa Ghanem,Yike Guo
Imperial College London, South Kensington Campus, 180 Queen's Gate, London SW7 2AZ, U.K.,
http://dx.doi.org/10.1002/cpe.1049
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Abstract: The activity of e‐Science involves making discoveries by analysing data to find new knowledge. Discoveries of value cannot be made by simply performing a pre‐defined set of steps to produce a result. Rather, there is an original, creative aspect to the activity that by its nature cannot be automated. In addition to finding new knowledge, discovery therefore also concerns finding a process to find new knowledge. How discovery processes are modelled is therefore key to effectively practicing e‐Science. We argue that since a discovery process instance serves a similar purpose to a mathematical proof it should have similar properties, namely it allows results to be deterministically reproduced when re‐executed and that intermediate results can be viewed to aid examination and comprehension. We examine the issues involved for software environments used to make discoveries to preserve these properties, and show how they are tackled in the Discovery Net system. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1050:Recycling workflows and services through discovery and reuse

Author(s):Chris Wroe,Carole Goble,Antoon Goderis,Phillip Lord,Simon Miles,Juri Papay,Pinar Alper,Luc Moreau
School of Computer Science, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.,School of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, U.K.,
http://dx.doi.org/10.1002/cpe.1050
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Abstract: Scientific workflows are becoming a valuable tool for scientists to capture and automate e-Science procedures. Their success brings the opportunity to publish, share, reuse and re-purpose this explicitly captured knowledge. Within the Grid project, we have identified key resources that can be shared including complete workflows, fragments of workflows and constituent services. We have examined the alternative ways that these resources can be described by their authors (and subsequent users) and developed a unified descriptive model to support their later discovery. By basing this model on existing standards, we have been able to extend existing Web service and Semantic Web service infrastructure whilst still supporting the specific needs of the e-Scientist. The Grid components enable a workflow life-cycle that extends beyond execution to include the discovery of previous relevant designs, the reuse of those designs and their subsequent publication. Experience with example groups of scientists indicates that this cycle is valuable. The growing number of workflows and services mean more work is needed to support the user in effective ranking of search results and to support the re-purposing process. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1051:Special Issue: Selected Papers from the 2004 U.K. e-Science All Hands Meeting (AHM 2004)

Author(s):D. W. Walker,M. P. Atkinson,I. Sommerville
School of Computer Science, Cardiff University, Cardiff CF24 3AA, U.K.,e-Science Institute, 15 South College Street, Edinburgh EH8 9AA, U.K.,Computing Department, Lancaster University, Lancaster LA1 4WA, U.K.
http://dx.doi.org/10.1002/cpe.1051
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Abstract: No abstract

CPE1061:Special Issue: Parallel and Distributed Systems: Testing and Debugging (PADTAD)

Author(s):Shmuel Ur
IBM Haifa Research Laboratory, Haifa 31905, Israel
http://dx.doi.org/10.1002/cpe.1061
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Abstract: No abstract

CPE1062:Choosing among alternative pasts

Author(s):Marina Biberstein,Eitan Farchi,Shmuel Ur
IBM Haifa Research Laboratory, Haifa University Campus, Haifa 31905, Israel,
http://dx.doi.org/10.1002/cpe.1062
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Abstract: The primary difficulty with testing concurrent programs is their non-determinism, where two executions with the same input can yield different results due to a changed thread schedule (also known as interleaving). This problem is aggravated by the fact that most thread schedulers are almost deterministic, and generate the same interleavings over and over for a given testing environment. The traditional approach to testing concurrent programs is to identify and examine the race conditions. A different solution involves noise-making, which generates different interleavings at runtime, for example, using embedded sleep statements. This paper proposes a totally different technique for generating a rich set of interleavings. In this approach, operations on shared variables are tracked. Every time a shared variable is read, the value to be read is selected from the set of values that were held by this variable during the program execution. The algorithm identifies those values that the variable could hold in some interleaving consistent with the past observed events. Within this subset, the value choice can be random, biased-random, based on coverage, etc. The problem of identifying read values that are consistent with the past observations is far from simple, since past decisions on value selection affect future ones. Our solution is computationally intensive and, therefore, impractical as is. However, insights gained from this solution lead to new heuristics for noise-making. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1063:A method for verifying concurrent Java components based on an analysis of concurrency failures

Author(s):Brad Long,Paul Strooper,Luke Wildman
School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia,
http://dx.doi.org/10.1002/cpe.1063
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Abstract: The Java programming language supports concurrency. Concurrent programs are harder to verify than their sequential counterparts due to their inherent non-determinism and a number of specific concurrency problems, such as interference and deadlock. In previous work, we have developed the ConAn testing tool for the testing of concurrent Java components. ConAn has been found to be effective at testing a large number of components, but there are certain classes of failures that are hard to detect using ConAn. Although a variety of other verification tools and techniques have been proposed for the verification of concurrent software, they each have their strengths and weaknesses. In this paper, we propose a method for verifying concurrent Java components that includes ConAn and complements it with other static and dynamic verification tools and techniques. The proposal is based on an analysis of common concurrency problems and concurrency failures in Java components. As a starting point for determining the concurrency failures in Java components, a Petri-net model of Java concurrency is used. By systematically analysing the model, we come up with a complete classification of concurrency failures. The classification and analysis are then used to determine suitable tools and techniques for detecting each of the failures. Finally, we propose to combine these tools and techniques into a method for verifying concurrent Java components. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1064:MultiRace: efficient on-the-fly data race detection in multithreaded C++ programs

Author(s):Eli Pozniansky,Assaf Schuster
Computer Science Department, Technion-Israel Institute of Technology, Haifa 32000, Israel,
http://dx.doi.org/10.1002/cpe.1064
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Abstract: Data race detection is highly essential for debugging multithreaded programs and assuring their correctness. Nevertheless, there is no single universal technique capable of handling the task efficiently, since the data race detection problem is computationally hard in the general case. Thus, all currently available tools, when applied to some general case program, usually result in excessive false alarms or in a large number of undetected races. Another major drawback of many currently available tools is that they are restricted, for performance reasons, to detection units of fixed size. Thus, they all suffer from the same problem-choosing a small unit might result in missing some of the data races, while choosing a large one might lead to false detection. We present a novel testing tool, called MultiRace, which combines improved versions of Djit and Lockset-two very powerful on-the-fly algorithms for dynamic detection of apparent data races. Both extended algorithms detect races in multithreaded programs that may execute on weak consistency systems, and may use two-way as well as global synchronization primitives. By employing novel technologies, MultiRace adjusts its detection to the native granularity of objects and variables in the program under examination. In order to monitor all accesses to each of the shared locations, MultiRace instruments the C++ source code of the program. It lets the user fine-tune the detection process, but otherwise is completely automatic and transparent. This paper describes the algorithms employed in MultiRace, gives highlights of its implementation issues, and suggests some optimizations. It shows that the overheads imposed by MultiRace are often much smaller (orders of magnitude) than those obtained by other existing tools. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1065:A methodology for early validation of cache coherence protocols based on relational databases

Author(s):Mahadevan Subramaniam,Patrick Conway
Computer Science Department, University of Nebraska at Omaha, NE 68182, U.S.A.,Advanced Micro Devices, Sunnyvale, CA 94088, U.S.A.
http://dx.doi.org/10.1002/cpe.1065
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Abstract: A novel, table-driven approach based on relational database technology is proposed for the design and early validation of cache coherence protocols. A protocol is specified as multiple communicating, multi-input, multi-output, finite-state machines each represented by a relational database table. The tables are automatically generated by solving relational calculus constraints specifying the protocol transactions. Early protocol validation prior to an implementation is performed by testing these tables for several protocol properties expressed using relational queries and database integrity constraints. The debugged tables are automatically mapped to a high-level hardware implementation while preserving their correctness. The proposed approach has been deployed at Fujitsu Systems Technology Division for the design of their next-generation multiprocessor and has been highly successful in reducing the overall protocol development time and has discovered several errors early in the design cycle. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1066:An instrumentation technique for online analysis of multithreaded programs

Author(s):Grigore Roşu,Koushik Sen
Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL, U.S.A.,
http://dx.doi.org/10.1002/cpe.1066
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Abstract: This paper presents an automatic code instrumentation technique, based on multithreaded vector clocks, for extracting the causal partial order on relevant state update events from a running multithreaded program. This technique is used in a formal testing environment, not only to detect, but especially to predict safety errors in multithreaded programs. The prediction process consists of rigorously analyzing other potential executions that are consistent with the causal partial order: some of these can be erroneous despite the fact that the particular observed execution was successful. The technique has been implemented as part of a Java program analysis tool. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1067:Distributed desk checking

Author(s):Amiram Hayardeny,Shachar Fienblit,Eitan Farchi
IBM Haifa Research Laboratory, Haifa University Campus, Israel,
http://dx.doi.org/10.1002/cpe.1067
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Abstract: Desk checking is known to be an effective reading technique for early detection of sequential program errors. This paper discusses how to extend desk checking for concurrent and distributed programs. In addition to exponential possible schedules, concurrent and distributed programs have execution states that include more than one process. The new distributed desk-checking technique supports the selection of schedules and execution states to be reviewed. The cross-product functional coverage technique assists in the selection process. Schedule selection guidelines that facilitate early detection and coverage are introduced. It is demonstrated that code inspection can be applied effectively to large industrial applications using the selection mechanism introduced by this technique. Industrial pilots show that distributed desk checking is an effective early error-detection review technique. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1068:Towards a framework and a benchmark for testing tools for multi-threaded programs

Author(s):Yaniv Eytani,Klaus Havelund,Scott D. Stoller,Shmuel Ur
Computer Science Department, University of Haifa, Haifa, Israel,Kestrel Technology, NASA Ames Research Center, Moffett Field, CA 94035-1000, U.S.A.,Computer Science Department, State University of New York at Stony Brook, Stony Brook, NY 11794, U.S.A.,IBM Haifa Research Laboratory, Haifa University Campus, Haifa, Israel
http://dx.doi.org/10.1002/cpe.1068
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Abstract: Multi-threaded code is becoming very common, both on the server side, and very recently for personal computers as well. Consequently, looking for intermittent bugs is a problem that is receiving more and more attention. As there is no silver bullet, research focuses on a variety of partial solutions. We outline a road map for combining the research within the different disciplines of testing multi-threaded programs and for evaluating the quality of this research. We have three main goals. First, to create a benchmark that can be used to evaluate different solutions. Second, to create a framework with open application programming interfaces that enables the combination of techniques in the multi-threading domain. Third, to create a focus for the research in this area around which a community of people who try to solve similar problems with different techniques can congregate. We have started creating such a benchmark and describe the lessons learned in the process. The framework will enable technology developers, for example, developers of race detection algorithms, to concentrate on their components and use other ready made components (e.g. an instrumentor) to create a testing solution. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1103:Parallelization and scalability issues of a multilevel elastohydrodynamic lubrication solver

Author(s):C. E. Goodyer,M. Berzins
Computational PDEs Unit, School of Computing, University of Leeds, Leeds LS2 9JT, U.K.,School of Computing, University of Utah, Salt Lake City, UT 84112, U.S.A.
http://dx.doi.org/10.1002/cpe.1103
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Abstract: The computation of numerical solutions to elastohydrodynamic lubrication problems is only possible on fine meshes by using a combination of multigrid and multilevel techniques. In this paper, we show how the parallelization of both multigrid and multilevel multi-integration for these problems may be accomplished and discuss the scalability of the resulting code. A performance model of the solver is constructed and used to perform an analysis of the results obtained. Results are shown with good speed-ups and excellent scalability for distributed memory architectures and in agreement with the model. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1107:MRMOGA: a new parallel multi-objective evolutionary algorithm based on the use of multiple resolutions

Author(s):Antonio López Jaimes,Carlos A. Coello Coello
CINVESTAV-IPN, Evolutionary Computation Group (EVOCINV), Departamento de Ingeniería Eléctrica, Sección de Computación, Av. IPN No. 2508, D.F. 07360, Mexico,
http://dx.doi.org/10.1002/cpe.1107
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Abstract: In this paper, we introduce MRMOGA (Multiple Resolution Multi-Objective Genetic Algorithm), a new parallel multi-objective evolutionary algorithm which is based on an injection island approach. This approach is characterized by adopting an encoding of solutions which uses a different resolution for each island. This approach allows us to divide the decision variable space into well-defined overlapped regions to achieve an efficient use of multiple processors. Also, this approach guarantees that the processors only generate solutions within their assigned region. In order to assess the performance of our proposed approach, we compare it to a parallel version of an algorithm that is representative of the state-of-the-art in the area, using standard test functions and performance measures reported in the specialized literature. Our results indicate that our proposed approach is a viable alternative to solve multi-objective optimization problems in parallel, particularly when dealing with large search spaces. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1113:Using parallelization and hardware concurrency to improve the performance of a genetic algorithm

Author(s):Vijay Tirumalai,Kenneth G. Ricks,Keith A. Woodbury
Department of Electrical and Computer Engineering, The University of Alabama, Tuscaloosa, AL 35487-0286, U.S.A.,Department of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487-0286, U.S.A.
http://dx.doi.org/10.1002/cpe.1113
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Abstract: Genetic algorithms (GAs) are powerful tools for solving many problems requiring the search of a solution space having both local and global optima. The main drawback for GAs is the long execution time normally required for convergence to a solution. This paper discusses three different techniques that can be applied to GAs to improve overall execution time. A serial software implementation of a GA designed to solve a task scheduling problem is used as the basis for this research. The execution time of this implementation is then improved by exploiting the natural parallelism present in the algorithm using a multiprocessor. Additional performance improvements are provided by implementing the original serial software GA in dedicated reconfigurable hardware using a pipelined architecture. Finally, an advanced hardware implementation is presented in which both pipelining and duplicated hardware modules are used to provide additional concurrency leading to further performance improvements. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1114:Performance of computationally intensive parameter sweep applications on Internet-based Grids of computers: the mapping of molecular potential energy hypersurfaces

Author(s):S. Reyes,C. Muñoz-Caro,A. Niño,R. M. Badia,J. M. Cela
QCyCAR. E. S. Informática. Universidad de Castilla-La Mancha, Paseo de la Universidad 4, 13071 Ciudad Real, Spain,Barcelona Supercomputing Center, Campus Nord UPC, Mòdul D6, Jordi Girona 1-3, 08034 Barcelona, Spain,
http://dx.doi.org/10.1002/cpe.1114
CCPE Title/Author Summary
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Abstract: This work focuses on the use of computational Grids for processing the large set of jobs arising in parameter sweep applications. In particular, we tackle the mapping of molecular potential energy hypersurfaces. For computationally intensive parameter sweep problems, performance models are developed to compare the parallel computation in a multiprocessor system with the computation on an Internet-based Grid of computers. We find that the relative performance of the Grid approach increases with the number of processors, being independent of the number of jobs. The experimental data, obtained using electronic structure calculations, fit the proposed performance expressions accurately. To automate the mapping of potential energy hypersurfaces, an application based on GRID superscalar is developed. It is tested on the prototypical case of the internal dynamics of acetone. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1119:A distributed packed storage for large dense parallel in-core calculations

Author(s):Marc Baboulin,Luc Giraud,Serge Gratton,Julien Langou
CERFACS, 42 avenue Gaspard Coriolis, 31057 Toulouse Cedex, France,ENSEEIHT, 2 rue Camichel, 31071 Toulouse Cedex, France,University of Tennessee, 1122 Volunteer Boulevard, Knoxville, TN 37996-3450, U.S.A.
http://dx.doi.org/10.1002/cpe.1119
CCPE Title/Author Summary
CCPE Metadata
Abstract: In this paper we propose a distributed packed storage format that exploits the symmetry or the triangular structure of a dense matrix. This format stores only half of the matrix while maintaining most of the efficiency compared with a full storage for a wide range of operations. This work has been motivated by the fact that, in contrast to sequential linear algebra libraries (e.g. LAPACK), there is no routine or format that handles packed matrices in the currently available parallel distributed libraries. The proposed algorithms exclusively use the existing ScaLAPACK computational kernels, which proves the generality of the approach, provides easy portability of the code and provides efficient re-use of existing software. The performance results obtained for the Cholesky factorization show that our packed format performs as good as or better than the ScaLAPACK full storage algorithm for a small number of processors. For a larger number of processors, the ScaLAPACK full storage routine performs slightly better until each processor runs out of memory. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1147:Reengineering for Parallelism

Author(s):Berna L. Massingill,Timothy G. Mattson,Beverly A. Sanders
Department of Computer Science, Trinity University, San Antonio, TX, U.S.A.,Microprocessor Technology Laboratory, Intel Corporation, DuPont, WA, U.S.A.,Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL, U.S.A.
http://dx.doi.org/10.1002/cpe.1147
CCPE Title/Author Summary
CCPE Metadata
Abstract: Many parallel programs begin as legacy sequential code that is later reengineered to take advantage of parallel hardware. This paper presents a pattern called Reengineering for Parallelism to help with this task. The new pattern is intended to be used in conjunction with PLPP (Pattern Language for Parallel Programming), described in our book (Mattson TG, Sanders BA, Massingill BL. Patterns for Parallel Programming. Addison-Wesley: Reading, MA, 2004). PLPP contains a structured collection of patterns and embodies a methodology for developing parallel programs in which the programmer starts with a good understanding of the problem, works through a sequence of patterns, and finally ends up with the code. Most of the patterns in PLPP are also applicable when reengineering legacy code, but it is not always clear how to get started. Reengineering for Parallelism provides an alternate point of entry into PLPP and addresses particular issues that arise when dealing with legacy code. Copyright 2006 John Wiley & Sons, Ltd.

CPE1148:Stabilizing large-scale generalized systems on parallel computers using multithreading and message-passing

Author(s):Peter Benner,Maribel Castillo,Rafael Mayo,Enrique S. Quintana-Ortí,Gregorio Quintana-Ortí
Fakultät für Mathematik, TU-Chemnitz, D-09107 Chemnitz, Germany,Departamento de Ingeniería y Ciencia de Computadores, Universidad Jaume I, 12.071-Castellón, Spain,
http://dx.doi.org/10.1002/cpe.1148
CCPE Title/Author Summary
CCPE Metadata
Abstract: We discuss the parallelization of an efficient algorithm for the partial stabilization of large-scale linear control systems in generalized state-space form. The algorithm is composed of highly parallel iterative schemes that appear in the computation of certain matrix functions. Here we evaluate different approaches to exploit parallelism at two levels, based on threads and processes. Our experimental results on a cluster of symmetric multiprocessors and a CC-NUMA platform show that the efficiency of the matrix operations underlying the iterative schemes carry over to the parallel implementation of the stabilization algorithm. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1152:An analytical study on optimizing the lookup performance of distributed hash table systems under churn

Author(s):Di Wu,Ye Tian,Kam Wing Ng
Department of Computer Science and Engineering, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong,
http://dx.doi.org/10.1002/cpe.1152
CCPE Title/Author Summary
CCPE Metadata
Abstract: The phenomenon of system churn degrades the lookup performance of distributed hash table (DHT) systems greatly. To handle the churn, a number of approaches have been proposed to date. However, there is a lack of theoretical analysis to direct how to make design choices under different churn rates and how to configure their parameters optimally. In this paper, we analytically study three important aspects on optimizing DHT lookup performance under churn, i.e. lookup strategy, lookup parallelism and lookup key replication. Our objective is to build a theoretical basis for designers to make better design choices in the future. We first compare the performance of two representative lookup strategies-recursive routing and iterative routing-and explore the existence of better alternatives. Then we study the effectiveness of lookup parallelism in systems with different churn rates and show how to select the optimal degree of parallelism. Owing to the importance of key replication on lookup performance, we also analyze the reliability of the replicated key under two different replication policies, and show how to perform proper configuration. Besides the analytical study, our results are also validated by simulation, and Kad is taken as a case to show the meaningfulness of our analysis. Copyright © 2007 John Wiley & Sons, Ltd.

CPE1054:Special Issue: Component and Framework Technology in High-Performance and Scientific Computing

Author(s):David E. Bernholdt
Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN, U.S.A.
http://dx.doi.org/10.1002/cpe.1054
CCPE Title/Author Summary
CCPE Metadata
Abstract: No abstract

CPE1120:Cross-organization interoperability experiments of weather and climate models with the Earth System Modeling Framework

Author(s):Shujia Zhou,V. Balaji,Carlos Cruz,Arlindo da Silva,Chris Hill,Erik Kluzek,Shep Smithline,Atanas Trayanov,Weiyu Yang
NASA Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A.,Princeton University, 201 Forrestal Road, Princeton, NJ 08450-6646, U.S.A.,Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, U.S.A.,National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80305, U.S.A.,National Center for Environmental Prediction, 5200 Auth Road, Camp Springs, MD 20746, U.S.A.
http://dx.doi.org/10.1002/cpe.1120
CCPE Title/Author Summary
CCPE Metadata
Abstract: Typical weather and climate models need a software tool to couple sub-scale model components. The high-performance computing requirements and a variety of model interfaces make the development of such a coupling tool very challenging. In this paper, we describe the approach of the Earth System Modeling Framework, in particular its component and coupling mechanism, and present the results of three cross-organization model interoperability experiments. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1121:Towards an architecture for component-oriented parallel programming

Author(s):F. H. Carvalho Junior,R. D. Lins,R. C. Corrêa,G. A. Araújo
Departamento de Computação, Universidade Federal do Ceará, Fortaleza, Brazil,Departamento de Eletrônica e Sistemas, Universidade Federal de Pernambuco, Recife, Brazil,
http://dx.doi.org/10.1002/cpe.1121
CCPE Title/Author Summary
CCPE Metadata
Abstract: The # component model was proposed to meet the growing demands of new complex applications of science and engineering that require productive and efficient use of high-performance computing architectures. This paper presents the principles, intuition, and theories underlying the # component model, and the design of an architecture for programming frameworks that comply to the # component model. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1149:Productivity and performance through components: the ASCI Sweep3D application

Author(s):Young Yoon,James C. Browne,Mathew Crocker,Samit Jain,Nasim Mahmood
Department of Computer Sciences, Taylor Hall 2.124, 1 University Station C0500, Austin, TX 78712-0233, U.S.A.,
http://dx.doi.org/10.1002/cpe.1149
CCPE Title/Author Summary
CCPE Metadata
Abstract: This paper is a case study of the effectiveness of component-oriented development for enhancing both productivity and performance for parallel programs. A process for converting monolithic applications into semantically composable components is described. The supporting software, the P-COM2 compositional compiler, is briefly described. The componentized version of Sweep3D is described. Productivity is illustrated by composing different instances of the Sweep3D code through automated composition of components using P-COM2. These instances, each of which targets improving performance for some execution environment or problem case, are examples of a family of instances which are composable from a modest set of components. It is found that customization of componentized codes by component-level adaptation may yield substantial performance improvement for specific execution environments. We identify and explain some of the benefits of component-oriented development for high-performance parallel systems. Copyright 2006 John Wiley & Sons, Ltd.

CPE1056:This article is a U.S. Government work and is in the public domain in the U.S.A.

Author(s):Torsten Wilde,James A. Kohl
Oak Ridge National Laboratory, Oak Ridge, TN 37831-6016, U.S.A.,
http://dx.doi.org/10.1002/cpe.1056
CCPE Title/Author Summary
CCPE Metadata
Abstract: Component frameworks for high-performance computing (HPC) have special requirements that distinguish them from general component frameworks and other traditional/monolithic codes. HPC component-based applications have a crucial need for correct, high-performance execution across a variety of open-source and proprietary component compositions, potentially incorporating several different programming languages. This paper targets the unique challenges associated with debugging HPC component-based applications in the Common Component Architecture (CCA). We propose to take advantage of the well-defined code separation created by component interfaces or ‘ports’ by logging port method invocations and capturing the corresponding data arguments. This approach makes it possible to find and isolate faulty components, simulate their invocation for specific debugging analyses, check data argument validity and boundaries, and create inputs for black-box testing. Published in 2006 by John Wiley & Sons, Ltd.

CPE1057:Component-based iterative methods for sparse linear systems

Author(s):J. Jones,M. Sosonkina,Y. Saad
Ames Laboratory, Iowa State University, Ames, IA 50011, U.S.A.,Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455, U.S.A.
http://dx.doi.org/10.1002/cpe.1057
CCPE Title/Author Summary
CCPE Metadata
Abstract: Iterative methods play an important role in solving large-scale systems of linear equations that arise in real-world applications. Due to numerous linear system properties that may affect the solution, it is rather difficult for a user to develop a good sparse linear system solver from scratch. Thus, various collections of solution methods are made available to the user. One such software package is SPARSKIT, which is well known in the scientific community. Written in FORTRAN77 and provided with a cumbersome interface, it is considered, however, a legacy code. Our objective is to enable its wider usage in modern applications and to facilitate further SPARSKIT enhancements. Applying a ‘peer-component’ design, we have created a set of SPARSKIT components that: (a) incorporate both original and new iterative methods; (b) are readily extensible with more methods; (c) may be connected to applications in a component framework; and (d) provide access from a variety of programming languages. Tools available from the Common Component Architecture (CCA) Forum enabled our component design of SPARSKIT. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1060:High-speed network and Grid computing for high-end computation: application in geodynamics ensemble simulations

Author(s):S. Zhou,W. Kuang,W. Jiang,P. Gary,J. Palencia,G. Gardner
Northrop Grumman Corporation, 4801 Stonecraft Boulevard, Chantilly, VA 20151, U.S.A.,NASA Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A.,Joint Center for Earth Systems Technology (JCET), University of Maryland at Baltimore County (UMBC), Baltimore, MD 21250, U.S.A.,Pittsburgh Supercomputing Center, Mellon Institute Building, 4400 Fifth Avenue, Pittsburgh, PA 15213, U.S.A.,
http://dx.doi.org/10.1002/cpe.1060
CCPE Title/Author Summary
CCPE Metadata
Abstract: High-speed network and Grid computing have been actively investigated, and their capabilities are being demonstrated. However, their application to high-end scientific computing and modeling is still to be explored. In this paper we discuss the related issues and present our prototype work on applying XCAT3 framework technology to geomagnetic data assimilation development with distributed computers, connected through an up to 10 Gigabit Ethernet network. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1074:Component-oriented application construction for a Web service-based Grid

Author(s):Rainer Schmidt,Siegfried Benkner,Ivona Brandic,Gerhard Engelbrecht
Institute of Scientific Computing, University of Vienna, Nordbergstrasse 15/C/3, 1090 Vienna, Austria,
http://dx.doi.org/10.1002/cpe.1074
CCPE Title/Author Summary
CCPE Metadata
Abstract: We present the architecture and prototype implementation of a component-oriented programming environment for a Web service based computational Grid. As middleware, we utilize the Vienna Grid Environment (VGE), a framework that enables the provision of compute-intensive parallel applications as configurable, QoS-aware Grid services. Our component model follows the Common Component Architecture (CCA) and models application Web services as distributed components. We describe a component framework that integrates VGE services with a component model allowing to express and dynamically manage application and performance meta-data as well as dependencies on the infrastructure or other components. Furthermore, we show how the client programming interface is used to compose Grid applications from abstract application components that are mapped against available Grid services by the component framework at runtime. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1075:A component-based nuclear power plant simulator kernel

Author(s):Manuel Díaz,Daniel Garrido,Sergio Romero,Bartolomé Rubio,Enrique Soler,José M. Troya
Department of Languages and Computer Science, E.T.S., Ingeniería Informática, University of Málaga, Málaga 29071, Spain,
http://dx.doi.org/10.1002/cpe.1075
CCPE Title/Author Summary
CCPE Metadata
Abstract: This paper presents a nuclear power plant simulator kernel based on the high-performance computing-oriented Common Component Architecture (CCA). The approach takes advantage of both the component-based software development and the efficient execution of parallel simulation models. The use of components improves the software life cycle and facilitates the development, maintenance and evolution of the simulator kernel, which can be adapted to different execution scenarios. Data dependencies among simulation models are resolved automatically by means of a novel algorithm, releasing the programmer from this tedious task and, as a result, making the development process easier. This work introduces the main features of the simulator kernel, describing concepts and the model on which it is based. Some preliminary results are shown that anticipate the feasibility and suitability of the proposal. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1076:Performance modeling of component assemblies

Author(s):Nick Trebon,Allen Morris,Jaideep Ray,Sameer Shende,A. D. Malony
Department of Computer Science, University of Oregon, Eugene, OR 97403-1202, U.S.A.,Sandia National Laboratories, Livermore, CA 94551-0969, U.S.A.,
http://dx.doi.org/10.1002/cpe.1076
CCPE Title/Author Summary
CCPE Metadata
Abstract: A parallel component environment places constraints on performance measurement and modeling. For instance, it must be possible to instrument the application without access to the source code. In addition, a component may admit multiple implementations, based on the choice of algorithm, data structure, parallelization strategy, etc., posing the user with the problem of having to choose the ‘correct’ implementation and achieve an optimal (fastest) component assembly. Under the assumption that an empirical performance model exists for each implementation of each component, simply choosing the optimal implementation of each component does not guarantee an optimal component assembly since components interact with each other. An optimal solution may be obtained by evaluating the performance of all of the possible realizations of a component assembly given the components and all of their implementations, but the exponential complexity renders the approach unfeasible as the number of components and their implementations rise. This paper describes a non-intrusive, coarse-grained performance monitoring system that allows the user to gather performance data through the use of proxies. In addition, a simple optimization library that identifies a nearly optimal configuration is proposed. Finally, some experimental results are presented that illustrate the measurement and optimization strategies. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1085:Comparison of frameworks for a next-generation multiphase flow solver, MFIX: a group decision-making exercise

Author(s):A. Gel,S. Pannala,M. Syamlal,T. J. O'Brien,E. S. Gel
Aeolus Research, Inc., Phoenix, AZ 85044, U.S.A.,Computational Mathematics Group, Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A.,U.S. Department of Energy, National Energy Technology Laboratory, Morgantown, WV 26505, U.S.A.,Arizona State University, Department of Industrial Engineering, Tempe, AZ 85287, U.S.A.
http://dx.doi.org/10.1002/cpe.1085
CCPE Title/Author Summary
CCPE Metadata
Abstract: Computational fluid dynamics (CFD) simulations have emerged as a powerful tool for understanding the multiphase flows that occur in a wide range of engineering applications and natural processes. A multiphase CFD code called Multiphase Flow with Interphase eXchanges (MFIX) has been under development at the National Energy Technology Laboratory (NETL) since the 1980s for modeling the multiphase flows that occur in fossil fuel reactors. CFD codes such as MFIX are equipped with a number of numerical algorithms to solve a large set of coupled partial differential equations over three-dimensional grids consisting of hundreds of thousands of cells on parallel computers. Currently the next-generation version of MFIX is under development with the goal of building a multiphase problem-solving environment (PSE) that would facilitate the simple reuse of modern software components by application scientists. Several open-source frameworks were evaluated to identify the best-suited framework for the multiphase PSE. There are many requirements for the multiphase PSE and each of these open-source frameworks offers functionalities that satisfy the requirements to varying extents. Therefore, matching the requirements and the functionalities is not a simple task and requires a systematic and quantitative decision-making procedure. We present a multi-criteria decision-making approach for determining a major system design decision and demonstrate its application on the framework-selection problem. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1109:Design and implementation issues for distributed CCA framework interoperability

Author(s):Madhusudhan Govindaraju,Michael J. Lewis,Kenneth Chiu
Grid Computing Research Laboratory, Department of Computer Science, State University of New York (SUNY), Binghamton, NY 13902, U.S.A.,
http://dx.doi.org/10.1002/cpe.1109
CCPE Title/Author Summary
CCPE Metadata
Abstract: Component frameworks, including those that support the Common Component Architecture (CCA), represent a promising approach to addressing the challenge of building and deploying high-performance scientific applications in Grid environments, one that is being realized, for example, in our LegionCCA and XCAT-C++ frameworks. The next step beyond building independent individual frameworks is making them interoperate. Component-based applications should be able to transparently span multiple disjoint component frameworks with low overhead as compared with the same applications running within a single framework. Interoperable frameworks enable applications to take advantage of more resources, and to better match constituent parts to the underlying resources that best support them. The CCA specification does not prescribe a wire format for inter-component calls in distributed frameworks, thereby promoting considerable flexibility and customization for the framework developer. This approach thus requires an additional specific strategy outside of the CCA to support interoperability between distributed frameworks. Mandating one common wire format, however, risks choosing the wrong format. We discuss in detail five underlying component framework interoperability requirements, and three general approaches to addressing them. We then discuss how the approaches can be applied to meet the requirements, and address the advantages, issues, and implications of doing so. This effectively defines a design space for framework interoperability approaches. We then address the communication interoperability in detail via a single multi-protocol communication library called Proteus, and discuss how we have incorporated it into two distinct distributed framework implementations of the CCA specification: LegionCCA and XCAT-C++. Copyright 2006 John Wiley & Sons, Ltd.

CPE1069:CCLRC Portal infrastructure to support research facilities

Author(s):Asif Akram,Dharmesh Chohan,David Meredith,Rob Allan
e-Science Centre, CCLRC Daresbury Laboratory, Warrington, Cheshire WA4 4AD, U.K.,
http://dx.doi.org/10.1002/cpe.1069
CCPE Title/Author Summary
CCPE Metadata
Abstract: The emergence of portal technology is providing benefits in developing portlet interfaces to applications to meet the current and future requirements of CCLRC facilities support. Portlets can be reused by different projects, e.g. the high-profile Integrative Biology project (with the University of Oxford), and in different Java Specification Request 168 Portlet Specification (JSR 168) compliant portal frameworks. Deployment and maintenance of applications developed as portlets becomes easier and manageable. A community process is already beginning and many portal frameworks come with free-to-use useful portlets. As rendering is carried out in the framework, applications can be easily accessible and internationalized. Portlets are compatible with J2EE, thus providing additional capabilities required in the service-oriented architecture (SOA). We also describe how Web service gateways can be used to provide many of the functionalities encapsulated in a portal server in a way to support Grid applications. Portals used as a rich client can allow users to customize or personalize their user interfaces and even their workflow and application access. CCLRC facilities will be able to leverage the work so far carried out on the National Grid Service (NGS) and e-HTPX portals, as they are fully functional and have received detailed user feedback. This demonstrates the usefulness of providing advanced capabilities for e-Research and having the associated business logic in a SOA loosely coupled from the presentation layer for an Integrated e-Science Environment. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1084:The LEAD Portal: a TeraGrid gateway and application service architecture

Author(s):Marcus Christie,Suresh Marru
Computer Science Department, Indiana University, Bloomington, IN 47405-7104, U.S.A.,
http://dx.doi.org/10.1002/cpe.1084
CCPE Title/Author Summary
CCPE Metadata
Abstract: The Linked Environments for Atmospheric Discovery (LEAD) Portal is a science application portal designed to enable effective use of Grid resources in exploring mesoscale meteorological phenomena. The aim of the LEAD Portal is to provide a more productive interface for doing experimental work by the meteorological research community, as well as bringing weather research to a wider class of users, meaning pre-college students in grades 6-12 and undergraduate college students. In this paper, we give an overview of the LEAD project and the role that LEAD portal is playing in reaching its goals. We then describe the various technologies we are using to bring powerful and complex scientific tools to educational and research users. These technologies-a fine-grained capability based authorization framework, an application service factory toolkit, and a Web services-based workflow execution engine and supporting tools-enable our team to deploy these once inaccessible, stovepipe scientific codes onto a Grid where they can be collectively utilized. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1092:GridASP: an ASP framework for Grid utility computing

Author(s):Hirotaka Ogawa,Satoshi Itoh,Tetsuya Sonoda,Satoshi Sekiguchi
Grid Technology Research Center, AIST, Akihabara Dai Building, 1-18-13 Sotokanda, Chiyoda-ku, Tokyo 101-0021, Japan,
http://dx.doi.org/10.1002/cpe.1092
CCPE Title/Author Summary
CCPE Metadata
Abstract: One of the greatest evolutions brought about by Grid technology is Grid utility computing, which utilizes various kinds of IT resources and applications across multiple organizations and enterprises, and integrates them into a comprehensive and valuable service. Since 2004, we proposed and have been developing the GridASP framework, which realizes Grid-enabled application service providers (ASPs) in order to realize Grid utility computing. GridASP can bind application providers, resource providers, and service providers together and provide application execution services with security and anonymity to enterprise/science users. In this article, we report the conceptual idea of GridASP and the detail of the framework now being developed. Information on GridASP can be found at http://www.gridasp.org. Copyright 2006 John Wiley & Sons, Ltd.

CPE1093:e-Business applications on the Grid: a toolkit for centralized workload prediction and access

Author(s):Konstantinos Dolkas,Dimosthenis Kyriazis,Andreas Menychtas,Theodora Varvarigou
San Diego Supercomputer Center, University of California at San Diego, La Jolla, CA, U.S.A.,Telecommunications Laboratory, Department of Electrical and Computer Engineering, National Technical University of Athens, 9 Heroon Polytechniou Street, 15773 Zografou Campus, Athens, Greece,
http://dx.doi.org/10.1002/cpe.1093
CCPE Title/Author Summary
CCPE Metadata
Abstract: Enabling e-Business applications on Grid computing has been an important topic of research as the beneficial perspective of Grids lies on solving computational intensive problems by large-scale distributed resources. In this paper we present a toolkit for centralized workload prediction and access, in order to meet the requirements of execution of commercial business processes on Grid infrastructures as well as to take advantage of their cost-effective capability for industrial users. The implementation of centralized workload prediction is achieved with an artificial neural network-available in the toolkit-each time a user completes a job execution. This approach has been adopted and validated within the framework of a GRIA IST project for aspecific industrial application, namely 3D image rendering, which meets the e-Business application's standards. The accuracy of the prediction showed promising results and in combination with the centralized access capability makes e-Business applications feasible on Grids. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1098:Special Issue: Science Gateways-Common Community Interfaces to Grid Resources

Author(s):Nancy Wilkins-Diehr
San Diego Supercomputer Center, University of California at San Diego, La Jolla, CA, U.S.A.
http://dx.doi.org/10.1002/cpe.1098
CCPE Title/Author Summary
CCPE Metadata
Abstract: No abstract

CPE1102:This article is a U.S. Government work and is in the public domain in the U.S.A.

Author(s):John W. Cobb,Al Geist,James A. Kohl,Stephen D. Miller,Peter F. Peterson,Gregory G. Pike,Michael A. Reuter,Tom Swain,Sudharshan S. Vazhkudai,Nithya N. Vijayakumar
Computer Science and Mathematics Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, U.S.A.,Spallation Neutron Source, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, U.S.A.,Department of Computer Science, The University of Tennessee, Knoxville, TN 37996-3450, U.S.A.,Department of Computer Science, Indiana University, Lindley Hall 215, 150 South Woodlawn Avenue, Bloomington, IN 47405-7104, U.S.A.
http://dx.doi.org/10.1002/cpe.1102
CCPE Title/Author Summary
CCPE Metadata
Abstract: The National Science Foundation's Extensible Terascale Facility (ETF), or TeraGrid (http://www.teragrid.org/), is entering its operational phase. An example of an ETF science gateway effort is the Neutron Science TeraGrid Gateway (NSTG). The Oak Ridge National Laboratory (ORNL) resource provider effort (ORNL-RP) now in operation is bridging the gap between a large-scale experimental community and the TeraGrid as a large-scale national cyberinfrastructure. Of particular importance here is the collaboration with the Spallation Neutron Source (SNS) at ORNL. The U.S. Department of Energy's SNS (http://www.sns.gov/) at ORNL will be commissioned in the spring of 2006 as the world's brightest source of neutrons. Neutron science users can run experiments, generate datasets, perform data reduction, analysis, visualize results, collaborate with remotes users, and archive long-term data in repositories with curation services. The ORNL-RP and the SNS data analysis group have spent 18 months developing and exploring user requirements, including the creation of prototypical services such as a facility portal, data, and application execution services. We describe results from these efforts and discuss implications for science gateway creation. Finally, we show incorporation into implementation planning for the NSTG and SNS architectures. The plan is for a primarily portal-based user interaction supported by a service-oriented architecture for functional implementation. Published in 2006 by John Wiley & Sons, Ltd.

CPE1071:HPC-Europa single point of access as a framework for building science gateways

Author(s):Ariel Oleksiak,Alisdair Tullo,Paul Graham,Tomasz Kuczyński,Jarek Nabrzyski,Dawid Szejnfeld,Terry Sloan
Poznań Supercomputing and Networking Center, ul. Noskowskiego 10, 61-704 Poznań, Poland,Edinburgh Parallel Computing Centre, The University of Edinburgh, James Clerk Maxwell Building, Mayfield Road, Edinburgh EH9 3JZ, U.K.,
http://dx.doi.org/10.1002/cpe.1071
CCPE Title/Author Summary
CCPE Metadata
Abstract: One of the goals of the HPC-Europa project is to provide users with a single point of access (SPA) to the resources of HPC centers in Europe. To this end, the HPC-Europa portal is being built to provide transparent, uniform, flexible and intuitive user access to HPC-Europa resources. This portal will hide the underlying complexity and heterogeneity of these resources and the services that provide access to them. Since the computational environment of HPC-Europa is strongly heterogeneous, even in terms of the deployed Grid middleware, we need a mechanism that maps a uniform graphical user interface to the functionality provided by services available in the institutions belonging to the HPC-Europa consortium. In addition, accounting information has to be stored and provided on demand for both limiting resource usage and charging purposes in the HPC-Europa infrastructure. The important goal of the SPA is also to provide the means to support user access to specific applications. This should make access to Grid infrastructures easier for end-users. Both mechanisms (generic and application-specific interfaces), along with additional tools, will combine to provide flexible and efficient software for building science gateways for researchers in various domains. In this paper, we describe the architecture of the SPA, which is based on the GridSphere portal framework. We present a mechanism for enabling end-users to transparently access services available in the HPC-Europa environment. The uniform job submission interface that uses this mechanism and is based on the Job Specification Description Language (JSDL) is presented. The mechanism supporting development of application-specific user interfaces is also described. Finally, we discuss relevant issues and interoperability problems connected with the development of the SPA, in particular those concerning job submission, security and accounting. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1077:Flexibility and user-friendliness of Grid portals: the PROGRESS approach

Author(s):Maciej Bogdanski,Michal Kosiedowski,Cezary Mazurek,Marzena Rabiega,Malgorzata Wolniewicz
Poznan Supercomputing and Networking Center, ul. Noskowskiego 10, 61-704 Poznan, Poland,
http://dx.doi.org/10.1002/cpe.1077
CCPE Title/Author Summary
CCPE Metadata
Abstract: Web portals are one of the possible ways to access the remote computing resources offered by Grid environments. Since the emergence of the first middleware for the Grid, works have been conducted on delivering the functionality of Grid services on the Web. Many interesting Grid portal solutions have been designed help organize remote access to Grid resources and applications from within Web browsers. They are technically advanced and more and more widely used around the world, resulting in feedback from the community. Some of these user comments concern the flexibility and user-friendliness of the developed solutions. In this paper we present how we addressed the need for a flexible and user-friendly Grid portal environment within the PROGRESS project and how our approach facilitates the use of the Grid within Web portals. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1078:The Open Grid Computing Environments collaboration: portlets and services for science gateways

Author(s):Jay Alameda,Marcus Christie,Geoffrey Fox,Joe Futrelle,Dennis Gannon,Mihael Hategan,Gopi Kandaswamy,Gregor von Laszewski,Mehmet A. Nacar,Marlon Pierce,Eric Roberts,Charles Severance,Mary Thomas
National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL 61301, U.S.A.,Department of Computer Science, Indiana University, Bloomington, IN 47404, U.S.A.,Computation Institute, University of Chicago, Chicago, IL 60637, U.S.A.,Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL 60439, U.S.A.,Community Grids Laboratory, Indiana University, Bloomington, IN 47404, U.S.A.,Texas Advanced Computing Center, University of Texas, Austin, TX 78758-4497, U.S.A.,School of Information, University of Michigan, Ann Arbor, MI 48109-1107, U.S.A.,Department of Computer Science, San Diego State University, San Diego, CA 92182, U.S.A.
http://dx.doi.org/10.1002/cpe.1078
CCPE Title/Author Summary
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Abstract: We review the efforts of the Open Grid Computing Environments collaboration. By adopting a general three-tiered architecture based on common standards for portlets and Grid Web services, we can deliver numerous capabilities to science gateways from our diverse constituent efforts. In this paper, we discuss our support for standards-based Grid portlets using the Velocity development environment. Our Grid portlets are based on abstraction layers provided by the Java CoG kit, which hide the differences of different Grid toolkits. Sophisticated services are decoupled from the portal container using Web service strategies. We describe advance information, semantic data, collaboration, and science application services developed by our consortium. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1079:The GridSAT portal: a Grid Web-based portal for solving satisfiability problems using the national cyberinfrastructure

Author(s):Wahid Chrabakh,Rich Wolski
Department of Computer Science, University of California Santa Barbara, Santa Barbara, CA 93117, U.S.A.,
http://dx.doi.org/10.1002/cpe.1079
CCPE Title/Author Summary
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Abstract: http://orca.cs.ucsb.edu/sat_portal

CPE1080:Enabling community access to TeraGrid visualization resources

Author(s):Justin Binns,Jonathan DiCarlo,Joseph A. Insley,Ti Leggett,Cory Lueninghoener,John-Paul Navarro,Michael E. Papka
Computation Institute, The University of Chicago, Research Institute Suite 405, 5640 South Ellis Avenue, Chicago, IL 60637, U.S.A.,
http://dx.doi.org/10.1002/cpe.1080
CCPE Title/Author Summary
CCPE Metadata
Abstract: Visualization is an important part of the data analysis process. Many researchers, however, do not have access to the resources required to do visualization effectively for large datasets. This problem is illustrated through several user scenarios. To remedy this problem, we propose a Visualization Gateway that provides simplified access to such resources to a broad population of users. The current implementation of this gateway is described, including the technology used and the services made available. In particular, a detailed description of a ParaView portlet is included. A proposed design for enabling access to community users is discussed. Technology as well as policy issues that were raised, including security and data management, are covered, as are methods for providing additional services, scaling to include additional resources, and other areas of future development. The paper concludes with a summary of the topics covered. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1081:A AAAA model to support science gateways with community accounts

Author(s):Von Welch,Jim Barlow,James Basney,Doru Marcusiu,Nancy Wilkins-Diehr
National Center for Supercomputing Applications (NCSA), University of Illinois at Urbana-Champaign, 1205 W. Clark Street, Room 1008, Urbana, IL 61801, U.S.A.,San Diego Supercomputer Center (SDSC), University of California at San Diego, MC 0505, 9500 Gilman Drive, La Jolla, CA 92093-0505, U.S.A.
http://dx.doi.org/10.1002/cpe.1081
CCPE Title/Author Summary
CCPE Metadata
Abstract: Science gateways have emerged as a concept for allowing large numbers of users in communities to easily access high-performance computing resources which previously required a steep learning curve to utilize. In order to reduce the complexity of managing access for these communities, which can often be large and dynamic, the concept of community accounts is being considered. This paper proposes a security model for community accounts, organized by the four As of security: Authentication, Authorization, Auditing and Accounting. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1082:Science gateways to DEISA: user requirements, technologies, and the material sciences and plasma physics gateway

Author(s):Thomas Soddemann
Rechenzentrum der MPG Garching (RZG), IPP, Boltzmann Straße 2, 85748 Garching, Germany
http://dx.doi.org/10.1002/cpe.1082
CCPE Title/Author Summary
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Abstract: DEISA (Distributed European Infrastructure for Supercomputer Applications) is collecting experience with science gateways in different scientific areas and aims at combining all current efforts. This paper describes the development of the DEISA material sciences and plasma physics Web portal application from the view of a project engineer and software architect. It analyzes user requirements, motivates technology choices, and describes the realization of an application that is very similar to the first release candidate. The outlook gives insight into the development steps currently being undertaken towards a release and the planning phase for a future release, as well as the DEISA aims. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1083:Science gateways made easy: the In-VIGO approach

Author(s):Andréa M. Matsunaga,Maurício O. Tsugawa,Sumalatha Adabala,Renato J. Figueiredo,Herman Lam,José A. B. Fortes
Advanced Computing and Information Systems Laboratory (ACIS), Department of Electrical and Computer Engineering, University of Florida, P.O. Box 116200, Gainesville, FL 32611-6200, U.S.A.,
http://dx.doi.org/10.1002/cpe.1083
CCPE Title/Author Summary
CCPE Metadata
Abstract: Science gateways require the easy enabling of legacy scientific applications on computing Grids and the generation of user-friendly interfaces that hide the complexity of the Grid from the user. This paper presents the In-VIGO approach to the creation and management of science gateways. First, we discuss the virtualization of machines, networks and data to facilitate the dynamic creation of secure execution environments that meet application requirements. Then we discuss the virtualization of applications, i.e. the execution on shared resources of multiple isolated application instances with customized behavior, in the context of In-VIGO. A Virtual Application Service (VAS) architecture for automatically generating, customizing, deploying, and using virtual applications as Grid services is then described. Starting with a grammar-based description of the command-line syntax, the automated process generates the VAS description and the VAS implementation (code for application encapsulation and data binding) that is deployed and made available through a Web interface. A VAS can be customized on a per-user basis by restricting the capabilities of the original application or by adding to it features such as parameter sweeping. This is a scalable approach to the integration of scientific applications as services into Grids and can be applied to any tool with an arbitrarily complex command-line syntax. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1087:Special Issue: Autonomous Grid Computing

Author(s):Geoffrey C. Fox,Hai Zhuge
Community Grids Laboratory, School of Informatics, Indiana University, Bloomington, IN 47404, U.S.A.,China Knowledge Grid Research Group, Key Lab of Intelligent Information Processing, Chinese Academy of Sciences, Beijing 100080, People's Republic of China
http://dx.doi.org/10.1002/cpe.1087
CCPE Title/Author Summary
CCPE Metadata
Abstract: No abstract

CPE1088:Multiple states based temporal consistency for dynamic verification of fixed-time constraints in Grid workflow systems

Author(s):Jinjun Chen,Yun Yang
Centre for Information Technology Research, Faculty of Information and Communication Technologies, Swinburne University of Technology, P.O. Box 218, Hawthorn, Melbourne, Victoria 3122, Australia,
http://dx.doi.org/10.1002/cpe.1088
CCPE Title/Author Summary
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Abstract: To verify fixed-time constraints in Grid workflow systems, consistency and inconsistency conditions have been defined in conventional verification work. However, with a view of the run-time uncertainty of activity completion duration, we argue that, although the conventional consistency condition is feasible, the conventional inconsistency condition is too restrictive and covers several different states. These states, which are handled conventionally by the same exception handling, should be handled differently for the purpose of cost saving. Therefore, in this paper, we divide conventional inconsistency into weak consistency, weak inconsistency and strong inconsistency and treat conventional consistency as strong consistency. Correspondingly, we develop some algorithms on how to verify them. Based on this, for weak consistency we present a method on how to adjust it to strong consistency by using mean activity time redundancy and temporal dependency between fixed-time constraints. For weak inconsistency, we analyse briefly why it can be handled by simpler and more cost-saving exception handling while for strong inconsistency, the conventional exception handling remains deployed. The final quantitative evaluation demonstrates that our research can achieve better cost-effectiveness than the conventional work. Copyright 2006 John Wiley & Sons, Ltd.

CPE1089:Topology awareness of overlay P2P networks

Author(s):Habib Rostami,Jafar Habibi
Computer Engineering Department, Sharif University of Technology, Tehran, Iran,
http://dx.doi.org/10.1002/cpe.1089
CCPE Title/Author Summary
CCPE Metadata
Abstract: In overlay networks, the mechanism of a peer randomly joining and leaving a network, causes a topology mismatch between the overlay and the underlying physical topology. This causes a large volume of redundant traffic in the underlying physical network as well as an extra delay in message delivery in the overlay network. Topology mismatch occurs because overlay networks are not aware of their underlying physical networks. In this paper we present a mathematical model for topology awareness of overlay networks (degree of matching between an overlay and its underlying physical network) and the efficiency of message delivery on them. Then we experimentally show that the model is precise in the real world. Also, after determining the computational complexity of the model, we propose an optimization heuristic algorithm to enhance efficiency of message exchange on overlay networks by increasing their topology awareness. Next, we present the results of running the algorithm on different kinds of random graph and show how we can implement the algorithm on peer-to-peer networks; we then simulate the implementation on some unstructured peer-to-peer overlay networks. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1090:Management of real-time streaming data Grid services

Author(s):Geoffrey Fox,Galip Aydin,Hasan Bulut,Harshawardhan Gadgil,Shrideep Pallickara,Marlon Pierce,Wenjun Wu
Community Grids Laboratory, Indiana University, 501 North Morton Street, Suite 224, Bloomington, IN 47404, U.S.A.,
http://dx.doi.org/10.1002/cpe.1090
CCPE Title/Author Summary
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Abstract: We discuss our message-based approach to managing real-time data streams and building higher level services to produce and consume them. Our messaging system acts as a substrate that can be used to provide qualities of service to various streaming applications ranging from audio-video collaboration systems to sensor Grids. The messaging substrates are composed of distributed, hierarchically arranged message broker networks. Services such as filters are deployed along the edges of the network. We discuss the role of management systems for both broker networks and filter services: broker network topologies must be created and maintained, and distributed filters must be arranged in appropriate sequences. These managed broker networks may be applied to a wide range of problems. We discuss applications to audio-video collaboration in some detail and also describe applications to streaming Global Positioning System data streams. These provide specific application filters that can transform and republish message streams to the broker system. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1091:Usage SLA-based scheduling in Grids

Author(s):Catalin L. Dumitrescu,Ioan Raicu,Ian Foster
Department of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology, Mekelweg 4, 2628 CD Delft, The Netherlands,Computer Science Department, The University of Chicago, 5801 South Ellis Avenue, Chicago, IL 60637, U.S.A.,
http://dx.doi.org/10.1002/cpe.1091
CCPE Title/Author Summary
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Abstract: Managing usage service level agreements (uSLAs) within environments that integrate participants and resources spanning multiple physical institutions is a challenging problem. Running workloads in such environments is often a similarly challenging problem owing to the scale of the environment, and to the resource partitioning based on various sharing strategies. Also, a resource may be taken down during a job execution, be improperly set up or fail job execution. Such elements have to be taken into account whenever targeting a Grid environment for problem solving. In this paper we explore uSLA-based scheduling on a real Grid, Grid3, by means of a specific workload (the BLAST workload) and a specific scheduling framework, GRUBER (an architecture and toolkit for resource uSLA specification and enforcement). The paper provides extensive experimental results and comparisons with other scheduling strategies. We also address, in great detail, the performance of different uSLA-based site selection strategies and the overall performance in scheduling workloads over Grid3 with workload sizes ranging from 10 to 10 000 jobs. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1094:Networking scientific resources in the Knowledge Grid environment

Author(s):Hai Zhuge,Lianhong Ding,Xiang Li
China Knowledge Grid Research Group, Key Laboratory of Intelligent Information Processing, Institute of Computing Technology, Chinese Academy of Sciences, 100080 Beijing, People's Republic of China,
http://dx.doi.org/10.1002/cpe.1094
CCPE Title/Author Summary
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Abstract: Scientific documents, research instruments, researchers' abilities and co-operation among researchers are fundamental resources of scientific research. This paper proposes an approach for effectively networking scientific resources by detecting community structures in self-organized social network, discovering interest in information flow, capturing changes of interests over time and analyzing the relationship between peers. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1095:Distribution of mobile agents in vulnerable networks

Author(s):Wenyu Qu,Masaru Kitsuregawa,Hong Shen,Yingwei Jin
Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan,Graduate School of Information Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan,Department of Computer Science and Engineering, Dalian University of Technology, 2 Linggong Road, Ganjingzi District, Dalian 116024, People's Republic of China
http://dx.doi.org/10.1002/cpe.1095
CCPE Title/Author Summary
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Abstract: Advances in the Internet and the computer industry have created many new application areas for network routing such as Grid computing and also brings new challenges to traditional routing techniques. In this paper we propose a mobile agent-based routing model in vulnerable networks for these applications. To characterize the behaviors of mobile agents and their effects on the network performance, we analyze the population distribution of mobile agents as a measurement of the computational resource consumption. Our analysis reveals theoretical insights into the statistical behaviors of mobile agents and provides useful tools for effectively managing mobile agents in large networks. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1096:P2PGrid: integrating P2P networks into the Grid environment

Author(s):Jiannong Cao,Fred Bojin Liu,Cheng-Zhong Xu
Internet and Mobile Computing Laboratory, Department of Computing, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong,Cluster and Internet Computing Laboratory, Department of Electrical and Computer Engineering, Wayne State University, Detroit, MI 48202, U.S.A.
http://dx.doi.org/10.1002/cpe.1096
CCPE Title/Author Summary
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Abstract: The current Grid architecture suffers from high complexity, inefficiency in leveraging common PC capabilities, and the single point of failure problem originated from Grid's client-server mode of interaction. In this paper, we propose an approach to solve the problems by incorporating peer-to-peer (P2P) networks with the Grid environment. A two-layer integration model is proposed, which consists of a Grid layer and an underlying P2P layer that can be accessed from but is not limited to the Grid layer. A prototype implementation of the model, called P2PGrid, has been developed and experimented with example applications built on the platform. The results show that the complexity for common PCs to participate in the Grid can be greatly reduced, the resource aggregation efficiency has been increased, and the single point of failure problem can be solved by using P2P mode of communication in the Grid environment. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1097:Autonomous semantic link networking model for the Knowledge Grid

Author(s):Hai Zhuge
China Knowledge Grid Research Group, Key Laboratory of Intelligent Information Processing, Institute of Computing Technology, Chinese Academy of Sciences, 100080 Beijing, People's Republic of China
http://dx.doi.org/10.1002/cpe.1097
CCPE Title/Author Summary
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Abstract: A semantic link network (SLN) consists of nodes (entities, features, concepts, schemas or communities) and semantic links between nodes. This paper proposes an autonomous SLN formalism to support intelligent applications on large-scale networks. The formalism integrates the SLN logical reasoning with the SLN analogical reasoning and the SLN inductive reasoning, as well as existing techniques to form an autonomous semantic overly. The SLN logical reasoning mechanism derives implicit semantic relations by a semantic matrix and relevant addition and multiplication operations based on semantic link rules. The SLN analogical reasoning mechanism proposes conjectures on semantic relations based on structural mapping between nodes. The SLN inductive reasoning mechanism derives general semantics from special semantics. The cooperation of diverse reasoning mechanisms enhances the reasoning ability of each, therefore providing a powerful semantic ability for the semantic overlay. The self-organizing diverse scales of the SLN support the intelligent applications of the Knowledge Grid. Copyright © 2006 John Wiley & Sons, Ltd.

CPE1153:Special Issue: Performance Analysis and Enhancements of Wireless Networks

Author(s):Irfan Awan,Geyong Min
Department of Computing, School of Informatics, University of Bradford, Bradford, West Yorkshire BD7 1DP, U.K.,
http://dx.doi.org/10.1002/cpe.1153
CCPE Title/Author Summary
CCPE Metadata
Abstract: No abstract

CPE1163:DS/CDMA throughput of a multi-hop sensor network in a Rayleigh fading underwater acoustic channel

Author(s):Choong Hock Mar,Winston K. G. Seah
NUS Graduate School of Integrative Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576,
http://dx.doi.org/10.1002/cpe.1163
CCPE Title/Author Summary
CCPE Metadata
Abstract: Asynchronous half-duplex Direct-Sequence Code-Division Multiple-Access (DS/CDMA) is a suitable candidate for the MAC protocol design of underwater acoustic (UWA) sensor networks owing to its many attractive features. Our ad-hoc multi-hop network is infrastructureless in that it is without centralized base stations or power control. Hence, we develop an asynchronous distributed half-duplex control protocol to regulate between the transmitting and receiving phases of transmissions. Furthermore, multi-hop communications are very sensitive to the time variability of the received signal strength in the fading channel and the ambient noise dominated by snapping shrimp in harsh underwater environments, because a broken link in the multi-hop path is enough to disrupt communications and initiate new route searches. In our configuration, we use the Ad hoc On-demand Distance Vector (AODV) routing protocol optimized for UWA networks. Empirical studies show that we can model the channel as a slow-varying frequency non-selective Rayleigh fading channel. We theoretically analyze the throughput of our configuration by considering three salient features: the ability of the receiver to demodulate the data, the effect of our control protocol and the effect of disconnections on the generation of routing packets. The throughput under various operating conditions is then examined. It is observed that at optimal node separation, the throughput is improved by a factor of 10. Copyright 2007 John Wiley & Sons, Ltd.

CPE1154:Towards building a conflict-free mobile distributed file system

Author(s):Azzedine Boukerche,Raed A. Al-Shaikh
PARADISE Research Laboratory, SITE, University of Ottawa, 800 King Edward Avenue, Ottawa, Ontario, Canada K1N 6N5,
http://dx.doi.org/10.1002/cpe.1154
CCPE Title/Author Summary
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Abstract: The rising demand for mobile computing has created a need for an improved file system that supports mobile clients. Current file systems with support for mobility provide availability through file replicas that are cached at the client side. However, mobile clients may experience different obstacles with regards to the local cache, such as the limited network bandwidth, the intermittent connection, and serious conflicts when synchronizing back to the server. In this paper, we propose a novel mobile distributed file system design, which provides high availability and reliable storage for files and guarantees that file operations are executed regardless of concurrency and failure issues. The design is intended to fit mobile clients (e.g. PDAs and cell phones) that have limited storage space and cannot store all of the data they need, and yet require access to these data at all times. We adopt a server-side caching in order to guarantee sufficient caching space to all mobile clients, and to ensure the availability of files in the case of clients' failures. We present our algorithm, describe its implementation, simulate its high availability functions, and report on its performance evaluation using a cluster of workstations. Our simulation results indicate clearly that our algorithm exhibits a significant degree of automation and conflict-free mobile file system. Copyright © 2007 John Wiley & Sons, Ltd.

CPE1155:ad-hoc

Author(s):M. K. Denko
University of Guelph, Department of Computing and Information Science, Guelph, Ontario, Canada N1G 2W1
http://dx.doi.org/10.1002/cpe.1155
CCPE Title/Author Summary
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Abstract: he integration of mobile ad-hoc networks (MANETs) with the Internet provides flexible and multi-hop communication capability in hybrid wired and wireless networks. Existing architectures for integrating these networks use Mobile IP and ad-hoc routing protocols with fixed gateways. In this paper, we propose a mobility management scheme based on a mobile gateways (MGs) architecture. We designed a buffering mechanism for micro- and macro-mobility management in hybrid networks. The performance of mobility management with optimized handover (MM-OH), optimized handover with prediction (MM-OHP) and forced handover (MM-FH) are evaluated using simulation. Our simulation results show that a buffering mechanism coupled with the hybrid gateway discovery results in a higher packet delivery ratio for MM-OH and MM-OHP compared with the MM-FH scheme. The MM-OHP scheme has a lower number of handovers compared with the MM-OH scheme. Moreover, the simulation experiments reveal that the speed of the MG has a relatively higher impact on performance than the speed of mobile nodes. Copyright 2007 John Wiley & Sons, Ltd.

CPE1156:Modeling and evaluation of congestion control for different classes of network traffic

Author(s):Lan Wang,Geyong Min,Irfan Awan
Department of Computing, School of Informatics, University of Bradford, Bradford, U.K.,
http://dx.doi.org/10.1002/cpe.1156
CCPE Title/Author Summary
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Abstract: Traffic congestion has become a crucial problem in wireless networks due to its detrimental effects on the end-to-end Quality-of-Service (QoS) of mobile users. This issue has posed various challenges to developing effective congestion control mechanisms and devising new performance evaluation tools. Various congestion control schemes have been proposed to support differentiated QoS. Among these schemes, Active Queue Management (AQM) has been recognized as an effective mechanism to manage downlink buffers in wireless networks. Most existing studies on AQM are based on the use of averaged queue length and the related performance analysis is carried out via software simulation. This paper contributes to the development of an analytical performance model for a finite capacity queuing system subject to AQM and multiple traffic classes based on the instantaneous queue length. Expressions for the aggregated and marginal performance metrics including the mean queuing length, packet loss probability, mean waiting time, system throughput, response time, and utilization are analytically derived. The validity of this new model is demonstrated by comparing the analytical results against those obtained from simulation experiments. The analytical model is then used to investigate the effects of varying thresholds on the aggregated and marginal performance metrics under different combinations of arriving rates for multiple traffic classes. Copyright © 2007 John Wiley & Sons, Ltd.

CPE1158:Distributed communication model in hierarchical Infostation systems

Author(s):M. Tlais,F. Weis
Ambient Computing and Embedded Systems, Institut National de Recherche en Informatique et en Automatique, Rennes, France,University of Rennes 1, Rennes, France
http://dx.doi.org/10.1002/cpe.1158
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Abstract: The Infostations system, small and separated islands of coverage, provides intermittent but very high speed data rates. A new communication model is needed to carry this kind of architecture. Mainly, the discontinuous coverage affects the way data are exchanged between mobile terminals and the network. Moreover, the short time the mobile terminal spends in the coverage area has a direct impact on the network performance. Thus, it is essential to avoid bandwidth wasting due to the overall delay by performing mobility prediction. A new mobility prediction protocol called the Distributed Neighbor Discovery Protocol (DNDP) is proposed. DNDP handles a neighbor graph table that dynamically configures itself according to the terminals' mobility. The simulation shows that the terminals service continuity is significantly improved thanks to DNDP. Copyright © 2007 John Wiley & Sons, Ltd.