518 research outputs found

    A bio-inspired scheduling scheme for wireless sensor networks

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    Author name used in this publication: Chi K. TseAuthor name used in this publication: Francis C. M. LauRefereed conference paper2007-2008 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

    Service-Oriented Ad Hoc Grid Computing

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    Subject of this thesis are the design and implementation of an ad hoc Grid infrastructure. The vision of an ad hoc Grid further evolves conventional service-oriented Grid systems into a more robust, more flexible and more usable environment that is still standards compliant and interoperable with other Grid systems. A lot of work in current Grid middleware systems is focused on providing transparent access to high performance computing (HPC) resources (e.g. clusters) in virtual organizations spanning multiple institutions. The ad hoc Grid vision presented in this thesis exceeds this view in combining classical Grid components with more flexible components and usage models, allowing to form an environment combining dedicated HPC-resources with a large number of personal computers forming a "Desktop Grid". Three examples from medical research, media research and mechanical engineering are presented as application scenarios for a service-oriented ad hoc Grid infrastructure. These sample applications are also used to derive requirements for the runtime environment as well as development tools for such an ad hoc Grid environment. These requirements form the basis for the design and implementation of the Marburg ad hoc Grid Environment (MAGE) and the Grid Development Tools for Eclipse (GDT). MAGE is an implementation of a WSRF-compliant Grid middleware, that satisfies the criteria for an ad hoc Grid middleware presented in the introduction to this thesis. GDT extends the popular Eclipse integrated development environment by components that support application development both for traditional service-oriented Grid middleware systems as well as ad hoc Grid infrastructures such as MAGE. These development tools represent the first fully model driven approach to Grid service development integrated with infrastructure management components in service-oriented Grid computing. This thesis is concluded by a quantitative discussion of the performance overhead imposed by the presented extensions to a service-oriented Grid middleware as well as a discussion of the qualitative improvements gained by the overall solution. The conclusion of this thesis also gives an outlook on future developments and areas for further research. One of these qualitative improvements is "hot deployment" the ability to install and remove Grid services in a running node without interrupt to other active services on the same node. Hot deployment has been introduced as a novelty in service-oriented Grid systems as a result of the research conducted for this thesis. It extends service-oriented Grid computing with a new paradigm, making installation of individual application components a functional aspect of the application. This thesis further explores the idea of using peer-to-peer (P2P networking for Grid computing by combining a general purpose P2P framework with a standard compliant Grid middleware. In previous work the application of P2P systems has been limited to replica location and use of P2P index structures for discovery purposes. The work presented in this thesis also uses P2P networking to realize seamless communication accross network barriers. Even though the web service standards have been designed for the internet, the two-way communication requirement introduced by the WSRF-standards and particularly the notification pattern is not well supported by the web service standards. This defficiency can be answered by mechanisms that are part of such general purpose P2P communication frameworks. Existing security infrastructures for Grid systems focus on protection of data during transmission and access control to individual resources or the overall Grid environment. This thesis focuses on security issues within a single node of a dynamically changing service-oriented Grid environment. To counter the security threads arising from the new capabilities of an ad hoc Grid, a number of novel isolation solutions are presented. These solutions address security issues and isolation on a fine-grained level providing a range of applicable basic mechanisms for isolation, ranging from lightweight system call interposition to complete para-virtualization of the operating systems

    A Bio-Inspired Scheduling Scheme for Wireless Sensor Networks

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    Sensor networks with a large amount of sensor nodes usually have high redundancy in sensing coverage. The network lifetime can be further extended by proper scheduling and putting unnecessary sensor nodes into sleep mode. In this paper a bio-inspired scheduling scheme is proposed. The proposed scheme is a kind of adaptive "selective on-off" scheduling scheme which uses only local information for making scheduling decisions. The scheme is evaluated in terms of target 3-coverage hit-rate, averaged detection delay, and energy consumption per successful target detection. Simulation results show that our proposed scheme can reduce energy consumption by as much as 2/3 when comparing with other generic scheduling schemes while maintaining the detection delay and target hit-rate at a comparable level. Optimization of the network lifetime and other performances is possible by adjusting some parameters.Department of Electronic and Information EngineeringAuthor name used in this publication: Chi K. TseAuthor name used in this publication: Francis C. M. LauRefereed conference pape

    Distributed Algorithms for Guiding Navigation across a Sensor Network

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    We develop distributed algorithms for self-reconfiguring sensor networks that respond to directing a target through a region. The sensor network models the danger levels sensed across its area and has the ability to adapt to changes. It represents the dangerous areas as obstacles. A protocol that combines the artificial potential field of the sensors with the goal location for the moving object guides the object incrementally across the network to the goal, while maintaining the safest distance to the danger areas. We report on hardware experiments using a physical sensor network consisting of Mote sensors

    Conventional And Cognitive Radio Based Disaster Response Networks, A Comparative Study

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    The need for the deployment of reliable and efficient telecommunication systems in extreme emergency scenarios such as disaster response networks imposes a set of emerging unusual communication and routing challenges and obstacles that questions the performance of existing traditional and commercial telecommunication systems and networks in such scenarios, the revolution of telecommunication and networks industry witnessed the development of enormous telecommunication and networking services and systems that shaped their implementations in various domains of applications , in this paper, we study most of these communication standards in terms of their pros and cons, we also analyze the potentials of these standards in for Disaster Response networks in comparison with Cognitive Radio technology that has distinct capabilities and functionalities that enabled such a technology to be highly applicable for such harsh and unexpected scenario

    Generic Methods for Adaptive Management of Service Level Agreements in Cloud Computing

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    The adoption of cloud computing to build and deliver application services has been nothing less than phenomenal. Service oriented systems are being built using disparate sources composed of web services, replicable datastores, messaging, monitoring and analytics functions and more. Clouds augment these systems with advanced features such as high availability, customer affinity and autoscaling on a fair pay-per-use cost model. The challenge lies in using the utility paradigm of cloud beyond its current exploit. Major trends show that multi-domain synergies are creating added-value service propositions. This raises two questions on autonomic behaviors, which are specifically ad- dressed by this thesis. The first question deals with mechanism design that brings the customer and provider(s) together in the procurement process. The purpose is that considering customer requirements for quality of service and other non functional properties, service dependencies need to be efficiently resolved and legally stipulated. The second question deals with effective management of cloud infrastructures such that commitments to customers are fulfilled and the infrastructure is optimally operated in accordance with provider policies. This thesis finds motivation in Service Level Agreements (SLAs) to answer these questions. The role of SLAs is explored as instruments to build and maintain trust in an economy where services are increasingly interdependent. The thesis takes a wholesome approach and develops generic methods to automate SLA lifecycle management, by identifying and solving relevant research problems. The methods afford adaptiveness in changing business landscape and can be localized through policy based controls. A thematic vision that emerges from this work is that business models, services and the delivery technology are in- dependent concepts that can be finely knitted together by SLAs. Experimental evaluations support the message of this thesis, that exploiting SLAs as foundations for market innovation and infrastructure governance indeed holds win-win opportunities for both cloud customers and cloud providers

    Organising grassroots infrastructure: The (in)visible work of organisational (in)completeness

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    In this article we build on the concept of incompleteness, as recently developed in both organisational and urban studies, to improve our understanding of the collective actions of grassroots organisations in creating and governing critical infrastructures in the changing and resource-scarce contexts of urban informal settlements. Empirically, the article is informed by the case of resident associations providing critical services and infrastructure in informal settlements in Kisumu, Kenya. Findings suggest three organisational processes that grassroots organisations develop for the production and governance of incomplete grassroots infrastructures: shaping a partial organisation but creating the illusion of a formal and complete organisation; crafting critical (and often hidden) material and organisational infrastructures for the subsistence of dormant (but still visible) structures; and moulding nested infrastructure that shelters layers of floating and autonomous groups embedded in communities. In a resource-poor environment, the strategy is to create incompleteness, less organisation and to keep it partial and limited to a minimum of elements. The article also explores the political implications of organisational and infrastructural incompleteness by examining how it leads to efforts to craft loose and ambiguous governmental arrangements, connecting them materially and politically to formal infrastructure systems. These governmental arrangements are shifting and in the making, and therefore also incomplete. The article reveals how grassroots organisations mobilise a wide range of (in)visibility approaches. It concludes by exposing the hidden power of \u27incompleteness\u27 and the potential in hiding certain elements of incompleteness from outsiders, while rendering other elements visible when perceived as useful
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