Open, distributed systems face the challenge to maintain an appropriate operation performance even in the presence of bad behaving or malicious agents. A promising mechanism to counter the resulting negative impact of...
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the centrality metrics such as Closeness and Betweenness in Online Social Network (OSN) determine how much end-to-end delay and queue-load of a node can have as a source or as a destination through Social Routing. Exp...
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ISBN:
(纸本)9783319399096;9783319399102
the centrality metrics such as Closeness and Betweenness in Online Social Network (OSN) determine how much end-to-end delay and queue-load of a node can have as a source or as a destination through Social Routing. Experimentally, we find that nodes with high Out-Closeness centrality in OSN suffer from high end-to-end delay as a target, but not as a source. We show that the cause of this end-to-end delay is that most nodes with high Out-Closeness centrality have low In-Closeness centrality. Moreover, we show that the increase in the local In-Degree centrality will increase the global In-Closeness centrality. We also find that the promised level to increase the In-Closeness centrality of a node is its Friends of Friends-Of-Friends (Level-3). An agent-based Model for Social Routing is proposed and a set of large-scale Google+ Graphs are used. A simulation study is also completed by propagating a set of requests in different societies with different routing schemes and diverse queue disciplines, in order to compare the average end-to-end delays from the source and target perspectives.
this paper focuses on minimizing jointly data storage and networking costs in a distributed cloud storage environment. We present two new efficient algorithms to place encrypted data chunks and enhance data availabili...
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ISBN:
(纸本)9783319295824;9783319295817
this paper focuses on minimizing jointly data storage and networking costs in a distributed cloud storage environment. We present two new efficient algorithms to place encrypted data chunks and enhance data availability when guaranteeing a minimum cost of storage and communication in the same time. the proposed underlying solutions, based on linear programming approach lead to an exact formulation with convergence times feasible for small and medium network sizes. A new polynomial time algorithm is presented and shown to scale to much larger network sizes. Performance assessment results, using simulations, show the scalability and cost-efficiency of the proposed distributed cloud storage solutions.
the Integrated Video conference System of State Grid hosts many video conference applications. It is an important office assistant system, comprises a massive number of discrete components. In order to meet the growin...
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ISBN:
(纸本)9781509051540
the Integrated Video conference System of State Grid hosts many video conference applications. It is an important office assistant system, comprises a massive number of discrete components. In order to meet the growing demands and expectations of customers, stability and reliability of the system need to be further enhanced. In this paper, we study the system architecture, maintenance routine, system capacity, etc., and propose a hierarchical conference control strategy based on the conference Management System. the proposing strategy can improve the reliability and efficiency of large scale video conferences via a conference assistant mode, which can guarantee unity of command and achieve hierarchical maintenance.
Matrix multiplication is one of the most widely used computational kernels in scientific computing and machine learning. Using dedicated circuit for matrix multiplication can reduce the computational time and energy c...
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ISBN:
(纸本)9781509011445
Matrix multiplication is one of the most widely used computational kernels in scientific computing and machine learning. Using dedicated circuit for matrix multiplication can reduce the computational time and energy consumption. Traditional matrix multipliers always adopt linear array architecture, which works inefficiently when the size of matrix sub-block is much smaller than the array length. Using short array structure can improve the computational efficiency at the cost of occupying more memory bandwidth. In this paper, we present a workload sensitive dynamic scaling matrix multiplier structure, which can dynamically adjust the array length according to the matrix size. We build a prototype system on a Xilinx Zynq XC7Z045 FPGA. the result shows that compared with a fixed array architecture our design achieves much better performance and needs less memory bandwidth.
We focus on the vertex-centric (VC) model introduced in Pregel, a Google system for distributed graph processing. In particular, we consider two popular implementations of the VC model: Apache Giraph and GraphChi. the...
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ISBN:
(纸本)9781509028467
We focus on the vertex-centric (VC) model introduced in Pregel, a Google system for distributed graph processing. In particular, we consider two popular implementations of the VC model: Apache Giraph and GraphChi. the first is a VC system for cluster computing, while the second is a VC system for a single PC. Apache Giraph became very popular after careful engineering by Facebook researchers in 2012 to scale the computation of PageRank to a trillion-edge graph of user interactions using 200 machines. On the other hand, GraphChi became popular, around the same time in 2012, as it made possible to perform intensive graph computations in a single PC, in just under 59 minutes, whereas the distributed systems were taking 400 minutes using a cluster of about 1,000 computers (as reported also by MIT Technology Review). Since then, new versions of Apache Giraph and GraphChi have been released, where new ideas and optimizations have been implemented. therefore, it is time to validate again the claims made four years ago. In this work, we embark in this validation. We consider three cornerstone graph problems: computing PageRank, shortest-paths, and weakly-connected-components. Based on current experiments, we conclude that in the present, even for a moderate number of simple machines, Apache Giraph outperforms GraphChi for all the algorithms and datasets tested. this is in contrast to the claims of the GraphChi authors in 2012.
Heterogeneous data and various system that manage data in organization can be one of the difficult factor to manage data and application. SOA proposed several years ago boast an open standard based on loosely coupled ...
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ISBN:
(纸本)9781509041398
Heterogeneous data and various system that manage data in organization can be one of the difficult factor to manage data and application. SOA proposed several years ago boast an open standard based on loosely coupled architecture for better integrating application in distributed and heterogeneous environment. ESB is introduced as infrastructure for SOA service connection and message exchange that can mediates different environment to be managed. Web service as a technology drive the application to use data by requesting via network. this condition is the background to do research on designing Enterprise Service Bus Architecture to support multi-tenant client and provider. this research results the model of ESB and implement it design to be an application that can provide the organization to integrated heterogeneous data and various systems.
Any information system using encryption tends to have its own key management infrastructure. In practice, we find a separate key management systems dedicated to application encryption, or database encryption, or file ...
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ISBN:
(纸本)9781509029143
Any information system using encryption tends to have its own key management infrastructure. In practice, we find a separate key management systems dedicated to application encryption, or database encryption, or file encryption etc. this emergent needs to several key management systems and multiple cryptographic algorithms are resolved by the new Key Management Interoperability Protocol (KMIP). this work specifies how the Key Management Interoperability Protocol (KMIP) can be included in Transport Layer Security (TLS) protocol in order to provide additional security features, flexibility, interoperability and authentication specially in distributed systems like Cloud computing. Till now, authentication in TLS is limited to digital certificate and Kerberos. In this paper, we use the Key Management Interoperability Protocol to make an additional authentication option for TLS and we reduce handshake latency to 0-RTT for repeated handshakes and 1-RTT for full handshakes. We specify also the KMIP-TLS extension and its formal validation with AVISPA tool.
Information and communication technology witnesses a raise of open, distributed systems that consist of various heterogeneous elements. Within such an environment, individual elements have to efficiently fulfil their ...
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In content-centric networking, the schemes of in-network caching can affect the performance of the whole network. Existing schemes lack of the global view, which results in inefficient caches. In this paper, we aim to...
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ISBN:
(纸本)9781467399913
In content-centric networking, the schemes of in-network caching can affect the performance of the whole network. Existing schemes lack of the global view, which results in inefficient caches. In this paper, we aim to analyze the real-time distribution of contents among caches from multiple perspectives. this paper proposes TCBRP, a scheme that analyzes caching tendency of various contents in reverse path, based on centrality of nodes, popularity of contents and replacement rate of nodes, to cache in-network contents. this scheme also has decent scalability and can be expended conveniently. the experimental results reflect that TCBRP report savings in average hops and balance cache hit rate, compared with BetwRep and LCE.
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