Designing a Resource Broker for Heterogeneous Grids

Grids provide uniform access to aggregations of heterogeneous resources and services such as computers, networks and storage owned by multiple organizations. However, such a dynamic environment poses many challenges for application composition and deployment. In this paper, we present the design of the Gridbus Grid resource broker that allows users to create applications and specify different objectives through different interfaces without having to deal with the complexity of Grid infrastructure. We present the unique requirements that motivated our design and discuss how these provide flexibility in extending the functionality of the broker to support different low-level middlewares and user interfaces. We evaluate the broker with different job profiles and Grid middleware and conclude with the lessons learnt from our development experience.Comment: 26 pages, 15 figure

Advanced Timing and Synchronization Methodologies for Digital VLSI Integrated Circuits

This dissertation addresses timing and synchronization methodologies that are critical to the design, analysis and optimization of high-performance, integrated digital VLSI systems. As process sizes shrink and design complexities increase, achieving timing closure for digital VLSI circuits becomes a significant bottleneck in the integrated circuit design flow. Circuit designers are motivated to investigate and employ alternative methods to satisfy the timing and physical design performance targets. Such novel methods for the timing and synchronization of complex circuitry are developed in this dissertation and analyzed for performance and applicability.Mainstream integrated circuit design flow is normally tuned for zero clock skew, edge-triggered circuit design. Non-zero clock skew or multi-phase clock synchronization is seldom used because the lack of design automation tools increases the length and cost of the design cycle. For similar reasons, level-sensitive registers have not become an industry standard despite their superior size, speed and power consumption characteristics compared to conventional edge-triggered flip-flops.In this dissertation, novel design and analysis techniques that fully automate the design and analysis of non-zero clock skew circuits are presented. Clock skew scheduling of both edge-triggered and level-sensitive circuits are investigated in order to exploit maximum circuit performances. The effects of multi-phase clocking on non-zero clock skew, level-sensitive circuits are investigated leading to advanced synchronization methodologies. Improvements in the scalability of the computational timing analysis process with clock skew scheduling are explored through partitioning and parallelization.The integration of the proposed design and analysis methods to the physical design flow of integrated circuits synchronized with a next-generation clocking technology-resonant rotary clocking technology-is also presented. Based on the design and analysis methods presented in this dissertation, a computer-aided design tool for the design of rotary clock synchronized integrated circuits is developed

Flexible distributed computing with volunteered resources

PhDNowadays, computational grids have evolved to a stage where they can comprise many volunteered resources owned by different individual users and/or institutions, such as desktop grids and volunteered computing grids. This brings benefits for large-scale computing, as more resources are available to exploit. On the other hand, the inherent characteristics of the volunteered resources bring some challenges for efficiently exploiting them. For example, jobs may not be able to be executed by some resources, as the computing resources can be heterogeneous. Furthermore, the resources can be volatile as the resource owners usually have the right to decide when and how to donate the idle Central Processing Unit (CPU) cycles of their computers. Therefore, in order to utilise volunteered resources efficiently, this research investigated solutions from different aspects. Firstly, this research proposes a new computational Grid architecture based on Java and Java application migration technologies to provide fundamental support for coping with these challenges. This proposed architecture supports heterogeneous resources, ensuring local activities are not affected by Grid jobs and enabling resources to carry out live and automatic Java application migration. Secondly, this research work proposes some job-scheduling and migration algorithms based on resource availability prediction and/or artificial intelligence techniques. To examine the proposed algorithms, this work includes a series of experiments in both synthetic and practical scenarios and compares the performance of the proposed algorithms with existing ones across a variety of scenarios. According to the critical assessment, each algorithm has its own distinct advantages and performs well when certain conditions are met. In addition, this research analyses the characteristics of resources in terms of the availability pattern of practical volunteer-based grids. The analysis shows that each environment has its own characteristics and each volunteered resource’s availability tends to possess weak correlations across different days and times-of-day.British Telco

Scalable spatially aware media sharing display system

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Page 129 blank.Includes bibliographical references (p. 91-94).The scalable spatially aware media sharing display system provides an efficient and convenient means of harnessing media messaging in global communications. A three- tiered system of input, control, and output creates a medium for communication and data sharing via varied media types for relevant and enhanced contextual experiences. It is built as a platform independent infrastructure for sharing and/or displaying various media types onto a grid of, or singularly placed, target display nodes while accommodating dynamic growth in its support of on-the-fly display node assimilation. The system promotes interfacing flexibility thus allowing multiple devices, extant or yet to be, to connect and fully exploit its capabilities. In addition, the system supports an architecture that can accommodate loosely coupled parallel tasks thus exhibiting the qualities of a dynamic parallel cluster.by Patrick Menard.M.Eng

A Social Cloud for Public eResearch

Abstract—Scientific researchers faced with extremely large computations or the requirement of storing vast quantities of data have come to rely on distributed computational models like cloud computing. However, distributed computation is typically complex and expensive. The Social Cloud for Public eResearch aims to provide researchers with a platform to exploit social networks to reach out to users who would otherwise be unlikely to donate computational time for scientific and other research oriented projects. In this paper we explore the motivations of users to contribute computational time and examine the various ways these motivations can be catered to through established social networks. We specifically look at integrating Facebook and BOINC, and discuss the architecture of the functional system and the novel social engineering algorithms that power it. I

Content rendering and interaction technologies for digital heritage systems

Existing digital heritage systems accommodate a huge amount of digital repository information; however their content rendering and interaction components generally lack the more interesting functionality that allows better interaction with heritage contents. Many digital heritage libraries are simply collections of 2D images with associated metadata and textual content, i.e. little more than museum catalogues presented online. However, over the last few years, largely as a result of EU framework projects, some 3D representation of digital heritage objects are beginning to appear in a digital library context. In the cultural heritage domain, where researchers and museum visitors like to observe cultural objects as closely as possible and to feel their existence and use in the past, giving the user only 2D images along with textual descriptions significantly limits interaction and hence understanding of their heritage. The availability of powerful content rendering technologies, such as 3D authoring tools to create 3D objects and heritage scenes, grid tools for rendering complex 3D scenes, gaming engines to display 3D interactively, and recent advances in motion capture technologies for embodied immersion, allow the development of unique solutions for enhancing user experience and interaction with digital heritage resources and objects giving a higher level of understanding and greater benefit to the community. This thesis describes DISPLAYS (Digital Library Services for Playing with Shared Heritage Resources), which is a novel conceptual framework where five unique services are proposed for digital content: creation, archival, exposition, presentation and interaction services. These services or tools are designed to allow the heritage community to create, interpret, use and explore digital heritage resources organised as an online exhibition (or virtual museum). This thesis presents innovative solutions for two of these services or tools: content creation where a cost effective render grid is proposed; and an interaction service, where a heritage scenario is presented online using a real-time motion capture and digital puppeteer solution for the user to explore through embodied immersive interaction their digital heritage

SCTP - Evaluating, Improving and Extending the Protocol for Broader Deployment

Zugriff auf den Volltext ist gesperrt, neue Version unter DuEPublico-ID 35000 The Stream Control Transmission Protocol (SCTP), originally designed for the transport of signaling messages over IP based telephony signaling networks, is a general transport protocol with features suitable for a variety of applications that can benefit from multihoming, multiple streams, or one of SCTP’s numerous extensions. To date, SCTP has found its way into all kernel implementations of UNIX derivatives and a Windows prototype, but there are still flaws, which have to be identified and corrected. In this thesis, first, a suite of tools consisting of an SCTP simulation and testing environment is provided to lay the groundwork for further studies. Starting from comparing and analyzing kernel implementations, several aspects of the protocol that lead to undesirable behavior are examined. Congestion and flow control that are adopted from the Transmission Control Protocol (TCP), although using the same mechanisms, need a special treatment because of SCTP’s message orientation. The analysis of the SCTP specific characteristics with the help of the simulation will finally result in solutions that lead to a better performance. The deployment of SCTP will be another concern that can be improved by introducing a specific Network Address Translation (NAT) for SCTP.Zugriff auf den Volltext ist gesperrt, neue Version unter DuEPublico-ID 35000 Das Stream Control Transmission Protocol (SCTP) wurde ursprünglich für den Transport von Signalisierungsnachrichten über IP basierte Netze konzipiert. Inzwischen hat es sich jedoch zu einem allgemeinen Transportprotokoll entwickelt, das einzigartige Eigenschaften besitzt. Daher ist es besonders für Anwendungen interessant, die von mehreren Netzwerkadressen pro Verbindung (Multihoming), mehreren unabhängigen Nachrichtenströmen oder einer der zahlreichen Protokollerweiterungen profitieren können. Mittlerweile hat SCTP in die Betriebssystemkerne aller UNIX-Derivate und eines Windows Prototyps Einzug gehalten, aber es gibt noch Mängel, deren Ursachen es zu entdecken und zu korrigieren gilt. In dieser Dissertation wird zunächst eine Reihe von Werkzeugen bereitgestellt, um die Grundlage für weitere Untersuchungen zu schaffen. Ausgehend von der Analyse und dem Vergleich von Implementierungen im Systemkern verschiedener Betriebssysteme werden einige Aspekte des Protokolls untersucht, die zu unerwünschtem Verhalten führen. Die Prinzipien der Überlast- und Flusskontrolle wurden vom stream-orientierten Transmission Control Protocol (TCP) übernommen und benutzen daher dieselben Mechanismen. SCTP als nachrichtenorientiertes Protokoll benötigt jedoch eine diesem Unterschied Rechnung tragende Implementierung der Algorithmen. Die Analyse von SCTP-spezifischen Charakteristika mithilfe der Simulation wird schließlich zu Lösungen führen und zu einer Verbesserung des Durchsatzes. Ein weiteres Anliegen dieser Arbeit ist die Verbreitung von SCTP. Sie kann durch die Einführung einer SCTP-spezifischen Methode zur Umsetzung von Netzwerkadressen (Network Address Translation (NAT)) verbessert werden

The Social Cloud for Public eResearch

Scientific researchers faced with extremely large computations or the requirement of storing vast quantities of data have come to rely on distributed computational models like grid and cloud computing. However, distributed computation is typically complex and expensive. The Social Cloud for Public eResearch aims to provide researchers with a platform to exploit social networks to reach out to users who would otherwise be unlikely to donate computational time for scientific and other research oriented projects. This thesis explores the motivations of users to contribute computational time and examines the various ways these motivations can be catered to through established social networks. We specifically look at integrating Facebook and BOINC, and discuss the architecture of the functional system and the novel social engineering algorithms that power it