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8th International Workshop on Agents and Peer-to-Peer Computing, AP2PC 2009

作者： Brazier, Frances Ogston, Elth Warnier, Martijn Intelligent Interactive Distributed Systems VU University Amsterdam Netherlands Department of Computer Science University of Warwick United Kingdom

ISBN: (纸本)9783642318085

Complex, intelligent, distributed systems in dynamic environments, such as the power grid need to be designed to adapt autonomously. Self-management, in particular of large scale adaptive systems such as the power grid, is necessarily distributed. Agent and peer-to-peer based decentralized self-management can change the future of energy markets in which the power grid plays a core role. Assuming that both consumers and providers of energy are autonomous systems, represented by software agents or peers capable of self-management, virtual organizations of systems can emerge and adapt when necessary. Communication structures between systems, e.g., hierarchical or clustered organizations, can emerge, organizations between and within which systems can choose to cooperate and coordinate their actions, or compete. Overlay structures (as defined within p2p research) define such adaptive communication structures, multi-agent research provides interaction patterns. Global goals are achieved by local management on the basis of local goals and knowledge. The appropriate delegation of managerial responsibility determines the control structure. Aggregate information differs depending on the position of a system in an organization, the aggregation mechanisms and policies. © 2012 Springer-Verlag.

关键词： Multi agent systems

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Deterministic local algorithms, unique identifiers, and fractional graph colouring

Deterministic local algorithms, unique identifiers, and frac...

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19th International Colloquium on Structural Information and Communication Complexity, SIROCCO 2012

作者： Hasemann, Henning Hirvonen, Juho Rybicki, Joel Suomela, Jukka Institute of Operating Systems and Computer Networks TU Braunschweig Germany Helsinki Institute for Information Technology HIIT Department of Computer Science University of Helsinki Finland

ISBN: (纸本)9783642311031

We show that for any α > 1 there exists a deterministic distributed algorithm that finds a fractional graph colouring of length at most α(Δ + 1) in any graph in one synchronous communication round;here Δ is the maximum degree of the graph. The result is near-tight, as there are graphs in which the optimal solution has length Δ + 1. The result is, of course, too good to be true. The usual definitions of scheduling problems (fractional graph colouring, fractional domatic partition, etc.) in a distributed setting leave a loophole that can be exploited in the design of distributed algorithms: the size of the local output is not bounded. Our algorithm produces an output that seems to be perfectly good by the usual standards but it is impractical, as the schedule of each node consists of a very large number of short periods of activity. More generally, the algorithm shows that when we study distributed algorithms for scheduling problems, we can choose virtually any trade-off between the following three parameters: T, the running time of the algorithm, , the length of the schedule, and κ, the maximum number of periods of activity for a any single node. Here is the objective function of the optimisation problem, while κ captures the "subjective" quality of the solution. If we study, for example, bounded-degree graphs, we can trivially keep T and κ constant, at the cost of a large , or we can keep κ and constant, at the cost of a large T. Our algorithm shows that yet another trade-off is possible: we can keep T and constant at the cost of a large κ. © 2012 Springer-Verlag.

关键词： Costs

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Making cost-based query optimization asymmetry-aware

Making cost-based query optimization asymmetry-aware

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8th International Workshop on Data Management on New Hardware, DaMoN 2012 - In Conjunction with ACM SIGMOD/PODS Conference

作者： Bausch, Daniel Petrov, Ilia Buchmann, Alejandro Technische Universität Darmstadt Department of Computer Science Databases and Distributed Systems Group Hochschulstraße 10 64289 Darmstadt Germany

ISBN: (纸本)9781450314459

The architecture and algorithms of database systems have been built around the properties of existing hardware technologies. Many such elementary design assumptions are 20 - 30 years old. Over the last five years we witness multiple new I/O technologies (e.g. Flash SSDs, NV-Memories) that have the potential of changing these assumptions. Some of the key technological differences to traditional spinning disk storage are: (i) asymmetric read/write performance;(ii) low latencies;(iii) fast random reads;(iv) endurance issues. Cost functions used by traditional database query optimizers are directly influenced by these properties. Most cost functions estimate the cost of algorithms based on metrics such as sequential and random I/O costs besides CPU and memory consumption. These do not account for asymmetry or high random read and inferior random write performance, which represents a significant mismatch. In the present paper we show a new asymmetry-aware cost model for Flash SSDs with adapted cost functions for algorithms such as external sort, hash-join, sequential scan, index scan, etc. It has been implemented in PostgreSQL and tested with TPC-H. Additionally we describe a tool that automatically finds good settings for the base coefficients of cost models. After tuning the configuration of both the original and the asymmetry-aware cost model with that tool, the optimizer with the asymmetry-aware cost model selects faster execution plans for 14 out of the 22 TPC-H queries (the rest being the same or negligibly worse). We achieve an overall performance improvement of 48% on SSD. © 2012 ACM.

关键词： Cost functions

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Towards dependable emergent ensembles of components: The DEECo component model

Towards dependable emergent ensembles of components: The DEE...

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Joint 10th Working IEEE/IFIP Conference on Software Architecture, WICSA 2012 and 6th European Conference on Software, ECSA 2012

作者： Keznikl, Jaroslav Bureš, Tomáš Plášil, František Kit, Michal Department of Distributed and Dependable Systems Faculty of Mathematics and Physics Charles University Prague Czech Republic Institute of Computer Science Academy of Sciences of the Czech Republic Prague Czech Republic

ISBN: (纸本)9780769548272

In the domain of dynamically evolving distributed systems composed of autonomous and (self-) adaptive components, the task of systematically managing the design complexity of their communication and composition is a pressing issue. This stems from the dynamic nature of such systems, where components and their bindings may appear and disappear without anticipation. To address this challenge, we propose employing separation of concerns via a mechanism of dynamic implicit bindings with implicit communication. This way, we strive for dynamically formed, implicitly interacting groups - ensembles - of autonomous components. In this context, we introduce the DEECo component model, where such bindings, as well as the associated communication, are managed in an automated way, enabling transparent handling of the dynamic changes in the system. © 2012 IEEE.

关键词： adaptation dynamic architecture ensemble implicit bindings implicit communication

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Disaster management and profile modelling of IoT objects: Conceptual parameters for interlinked objects in relation to social network analysis

Disaster management and profile modelling of IoT objects: Co...

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2012 4th International Conference on Intelligent Networking and Collaborative systems, INCoS 2012

作者： Zelenkauskaite, Asta Bessis, Nik Sotiriadis, Stelios Asimakopoulou, Eleana Department of Telecommunications Indiana University Bloomington IN United States Distributed and Intelligent Systems Research Group University of Derby Derby United Kingdom Department of Computer Science and Technology University of Bedfordshire Luton United Kingdom

ISBN: (纸本)9780769548081

In recent years, the emergence of ubiquitous and pervasive computing suggests the radical transformation of the Internet to incorporate physical objects. The transformation suggests the enabling of a new form of communication and interaction style that incorporates people, their smart devices and their physical objects through the utilization of distributed sensors spread in the environment. In this study, we propose extending Internet of Things (IoT) by modelling an IoT enabled smart environment as a whole, representing the dynamic communication and interaction among all objects (users, devices, physical objects and sensors). This is by recognizing and categorizing objects' properties in the form of a generic profile. We also reflect this in a disaster management context. That is by identifying which of the parameters of these smart objects are fixed, constant and persistent over time and which parameters are actually change over time, i.e. those characterized by their transient and dynamic nature. Thus, through the process of communication and interaction of the objects, we analyze parameters by demonstrating their static and/or dynamic properties as well as those supporting context-aware variables which are evident in disaster scenarios. To achieve these goals, we designed the persistent or temporal relationships to encompass internal information of smart-objects, along with their characteristics that actually depict their capacity to offer services to users by properties' matchmaking. The interlinked relationships represent a 'social network' providing a terrain of flexible scenarios that would lead to tailored parameters to fit user preferences. To enable communication among them in a dynamic dimension we utilized a distributed topology in which communication could occur indirectly between objects. Finally, we detailed a generic - but equally applicable for disaster management - case scenario in which we used graph theory to demonstrate how embedded intelligenc

关键词： Internet of things

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Interconnectedness of complex systems of internet of things through social network analysis for disaster management

Interconnectedness of complex systems of internet of things ...

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2012 4th International Conference on Intelligent Networking and Collaborative systems, INCoS 2012

ISBN: (纸本)9780769548081

This visionary paper presents the Internet of Things paradigm in terms of interdependent dynamic dimensions of objects and their properties. Given that in its current state Internet of Things (IoT) has been viewed as a paradigm based on hierarchical distribution of objects, evaluation of the dynamic nature of the hierarchical structures faces challenges in its evaluation and analysis. Within this in mind, our focus is on the area of complex social networks and the dynamic social network construction within the context of IoT. This is by highlighting and addressing the tagging issues of the objects to the real-world domain such as in disaster management, these are in relation to their hierarchies and interrelation within the context of social network analysis. Specifically, we suggest to investigate and deepen the understanding of the IoT paradigm through the application of social network analysis as a method for interlinking objects - and thus, propose ways in which IoT could be subsequently interlinked and analyzed through social network analysis approach - which provides possibilities for linking of the objects, while extends it into real-world domain. With this in mind, we present few applications and key characteristics of disaster management and the social networking analysis approach, as well as, foreseen benefits of its application in the IoT domain. © 2012 IEEE.

关键词： Internet of things

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Financial Option Market Model for Federated Cloud Environments

Financial Option Market Model for Federated Cloud Environmen...

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IEEE International Conference on Utility and Cloud Computing (UCC)

作者： Adel Nadjaran Toosi Ruppa K. Thulasiram Rajkumar Buyya Cloud Computing and Distributed Systems (CLOUDS) Laboratory Department of Computing and Information Systems University of Melbourne Australia Department of Computer Science University of Manitoba Canada

Pay-per-use service by Cloud service providers has attracted customers in the recent past and is still evolving. Since the resources being dealt within Clouds are non-storable and the physical resources need to be replaced very often, pricing the service in a way that would return profit on the initial capital investments to the service providers has been a major issue. Moreover, to maintain Quality of Service (QoS) to customers who reserve the resources in advance and may or may not be using the resources at a future date makes the resources wasted, if not allocated to other on-demand users. Therefore, a need for a mechanism to guarantee the resources to reserved users whenever they need them, while keeping the resources busy all the time is in very high demand. The concept of federation of Cloud service providers has been proposed in the past wherein resources are traded between the providers whenever need arises. We propose a financial option based Cloud resources pricing model to address the above situation. This model allows a provider to hedge the critical and risky situation of reserved users requesting the resources while all the resources have been allocated to other users, by trading (buying or outsourcing) resources from other service providers in the Cloud federation. We show that using financial option based contracts between Cloud providers in a Cloud federation, providers are able to enhance profit and acquire the needed resources at any given time. It would also help creating a trust and goodwill from the clients on the Cloud service providers by less number of QoS violation.

关键词： Contracts Pricing Quality of service Cloud computing Availability Computational modeling Load modeling

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Lecture Notes in computer science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics): Preface

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in computer science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2012年 7201 LNCS卷 V-VI页

作者： Schmitt, Jens B. University of Kaiserslautern Disco - Distributed Computer Systems Lab. Computer Science Department P.O. Box 3049 67663 Kaiserslautern Germany

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E-government and policy simulation in intelligent virtual environments

E-government and policy simulation in intelligent virtual en...

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8th International Conference on Web Information systems and Technologies, WEBIST 2012

作者： Aisopos, Fotis Kardara, Magdalini Senger, Philipp Klinger, Roman Papaoikonomou, Athanasios Tserpes, Konstantinos Gardner, Michael Varvarigou, Theodora Distributed Knowledge and Media Systems Lab. National Technical University of Athens Athens Greece Department of Bioinformatics Fraunhofer SCAI 53754 Sankt Augustin Germany School of Computer Science and Electronic Engineering University of Essex Colchester United Kingdom

ISBN: (纸本)9789898565082

Recently, there has been an increase of interest in the social impact of virtual reality technologies, as virtual worlds experienced an increase of their popularity in various social groups (teenagers, businesses). The growing trend for people to spend more time in suchlike virtual spaces implies a demand for intelligent virtual environments, that could mimic the real world as a simulation and provide functionalities and tools for behaviour analysis and adaptation to user preferences. Within the context of e-government, this paper presents the ongoing project +Spaces, which is developing a range of virtual environment tools. The platform architecture is presented and technical challenges involved in creating intelligent virtual spaces for e-government as well as draft policies to be used in role-playing simulations are discussed.

关键词： Virtual reality

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Preemption-aware Admission Control in a Virtualized Grid Federation

Preemption-aware Admission Control in a Virtualized Grid Fed...

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International Conference on Advanced Information Networking and Applications (AINA)

作者： Mohsen Amini Salehi Bahman Javadi Rajkumar Buyya Cloud Computing and Distributed Systems (CLOUDS) Laboratory Department of Computer Science and Software Engineering University of Melbourne Australia

Many applications in federated Grids have quality-of-service (QoS) constraints such as deadline. Admission control mechanisms assure QoS constraints of the applications by limiting the number of user requests accepted by a resource provider. However, in order to maximize their profit, resource owners are interested in accepting as many requests as possible. In these circumstances, the question that arises is: what is the effective number of requests that can be accepted by a resource provider in a way that the number of accepted external requests is maximized and, at the same time, QoS violations are minimized. In this paper, we answer this question in the context of a virtualized federated Grid environment, where each Grid serves requests from external users along with its local users and requests of local users have preemptive priority over external requests. We apply analytical queuing model to address this question. Additionally, we derive a preemption-aware admission control policy based on the proposed model. Simulation results under realistic working conditions indicate that the proposed policy improves the number of completed external requests (up to 25%). In terms of QoS violations, the 95% confidence interval of the average difference with other policies is between (14.79%, 18.56%).

关键词： Admission control Mathematical model Equations Analytical models Time factors Queueing analysis

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