Recent peer-to-peer (P2P) systems are characterized by decentralized control, large scale and extreme dynamism of their operating environment. As such, they can be seen as instances of complex adaptive systems (CAS) t...
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ISBN:
(纸本)0769515851
Recent peer-to-peer (P2P) systems are characterized by decentralized control, large scale and extreme dynamism of their operating environment. As such, they can be seen as instances of complex adaptive systems (CAS) typically found in biological and social sciences. In this paper we describe Anthill, a framework to support the design, implementation and evaluation of P2P applications based on ideas such as multi-agent and evolutionary programming borrowed from CAS. An Anthill system consists of a dynamic network of peer nodes;societies of adaptive agents travel through this network, interacting with nodes and cooperating with other agents in order to solve complex problems. Anthill can be used to construct different classes of P2P services that exhibit resilience, adaptation and self-organization properties. We also describe preliminary, experiences with Anthill in implementing a file sharing application.
In this paper, we present a new method of timestamping messages and events in synchronous computations that capture the order relationship with vectors of size less than or equal to the size of the vertex cover of the...
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ISBN:
(纸本)0769515851
In this paper, we present a new method of timestamping messages and events in synchronous computations that capture the order relationship with vectors of size less than or equal to the size of the vertex cover of the communication topology of the system. Our method is fundamentally different from that of Fidge and Mattern's technique. The timestamps in our method do not use one component per process but still guarantee that the order relationship is captured accurately. Our algorithm is online and only requires piggybacking of timestamps on program messages. It is applicable to all programs that either use programming languages based on synchronous communication such as CSP, or use synchronous remote procedure calls.
Finding information in a peer-to-peer system currently requires either a costly and vulnerable central index, or flooding the network with queries. In this paper we introduce the concept of Routing Indices (RIs), whic...
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ISBN:
(纸本)0769515851
Finding information in a peer-to-peer system currently requires either a costly and vulnerable central index, or flooding the network with queries. In this paper we introduce the concept of Routing Indices (RIs), which allow nodes to forward queries to neighbors that are more likely to have answers. If a node cannot answer a query, it forwards the query to a subset of its neighbors, based on its local RI, rather than by selecting neighbors at random or by flooding the network, by forwarding the query to all neighbors. We present three RI schemes: the compound, the hop-count, and the exponential routing indices. We evaluate their performance via simulations, and find that RIs can improve performance by one or two orders of magnitude vs. a flooding-based system, and by zip to 100% vs. a random forwarding system. We also discuss the tradeoffs between the different RI schemes and highlight the effects of key design variables on system performance.
Just like Remote Procedure Call (RPC) turned out to be a very effective OS abstraction in building client-server applications over LANs, Type-based Publish-Subscribe (TPS) can be viewed as a high-level candidate abstr...
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ISBN:
(纸本)0769515851
Just like Remote Procedure Call (RPC) turned out to be a very effective OS abstraction in building client-server applications over LANs, Type-based Publish-Subscribe (TPS) can be viewed as a high-level candidate abstraction for building Peer-to-Peer (P2P) applications over WANs. This paper relates our preliminary, though positive, experience of implementing and using TPS over JXTA, which can be viewed as the P2P counterpart to sockets. We show that, at least for P2P applications with the Java type model, TPS provides a high-level programming support that ensures type safety and encapsulation, without hampering the decoupled nature of these applications. Furthermore, the loss of flexibility (inherent to the use of any high level abstraction) and the performance overhead, are negligible with respect to the simplicity gained by using TPS.
This paper presents in detail an efficient and provably correct algorithm for database replication over partition able networks. Our algorithm avoids the need for end-to-end acknowledgements for each action while supp...
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ISBN:
(纸本)0769515851
This paper presents in detail an efficient and provably correct algorithm for database replication over partition able networks. Our algorithm avoids the need for end-to-end acknowledgements for each action while supporting network partitions and merges and allowing dynamic instantiation of new replicas. One round of end-to-end acknowledgments is required only upon a membership change event such as a network partition. New actions may be introduced to the system at any point, not only while in a primary component. We show how performance can be further improved for applications that allow relaxation of consistency requirements. We provide experimental results that demonstrate the efficiency of our approach.
A communication network is a graph in which each node has only local information about the graph and nodes communicate by passing messages along its edges. Here, we consider the geometric communication network where t...
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ISBN:
(纸本)9781450389334
A communication network is a graph in which each node has only local information about the graph and nodes communicate by passing messages along its edges. Here, we consider the geometric communication network where the nodes also occupy points in space and the distance between points is the Euclidean distance. Our goal is to understand the communication cost needed to solve several fundamental geometry problems, including Convex Hull, Diameter, Closest Pair, and approximations of these problems, in the asynchronous CONGEST KT1 model. This extends the 2011 result of Rajsbaum and Urrutia for finding a convex hull of a planar geometric communication network to networks of arbitrary topology.
In the near future, there will be increasingly powerful computers in smart cards, telephones, and other information appliances. This will create a massive infrastructure composed of highly diverse interconnected mobil...
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ISBN:
(纸本)0769515886
In the near future, there will be increasingly powerful computers in smart cards, telephones, and other information appliances. This will create a massive infrastructure composed of highly diverse interconnected mobile entities. In this paper, we present a data-centric approach to storage and querying in such environments. At a first level, we view each entity as a miniature database;at a second level we maintain databases of metadata and services. We describe how information delivery and querying are performed in such architectures.
The on-demand downloading of application code over a wireless network is an emerging paradigm for the distributed environment of mobile computing devices. In this environment, a user must wait while a mobile computing...
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ISBN:
(纸本)0769515851
The on-demand downloading of application code over a wireless network is an emerging paradigm for the distributed environment of mobile computing devices. In this environment, a user must wait while a mobile computing device fetches the application code over the network prior to execution. To reduce this downloading latency, we have developed a download approach based on working sets, and have designed and implemented a working-set generator that defines working sets by focusing on the intervals during which a program refers to functions, variables, and constants, The program invocation times with this approach, simulated using trace information obtained from actual program behaviour on Linux, have been compared with those of all-at-once, page, class, and symbol download approaches. This simulation showed that the working-set approach can reduce the download-execution time compared to that with the four other approaches.
Cloud computing has become the real trend of enterprise IT service model that offers cost-effective and scalable processing. Meanwhile, Software-Defined networking (SDN) is gaining popularity in enterprise networks fo...
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ISBN:
(纸本)9781479962044
Cloud computing has become the real trend of enterprise IT service model that offers cost-effective and scalable processing. Meanwhile, Software-Defined networking (SDN) is gaining popularity in enterprise networks for flexibility in network management service and reduced operational cost. There seems a trend for the two technologies to go hand-in-hand in providing an enterprise's IT services. However, the new challenges brought by the marriage of cloud computing and SDN, particularly the implications on enterprise network security, have not been well understood. This paper sets to address this important problem. We start by examining the security impact, in particular, the impact on DDoS attack defense mechanisms, in an enterprise network where both technologies are adopted. We find that SDN technology can actually help enterprises to defend against DDoS attacks if the defense architecture is designed properly. To that end, we propose a DDoS attack mitigation architecture that integrates a highly programmable network monitoring to enable attack detection and a flexible control structure to allow fast and specific attack reaction. The simulation results show that our architecture can effectively and efficiently address the security challenges brought by the new network paradigm.
By, the use of the ability of dynamic reconfiguration, the flexibility, adaptability, and extensibility of distributed systems are enhanced. flow to treat interactions among components during a dynamic reconfiguration...
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ISBN:
(纸本)0769515851
By, the use of the ability of dynamic reconfiguration, the flexibility, adaptability, and extensibility of distributed systems are enhanced. flow to treat interactions among components during a dynamic reconfiguration is still one of the most crucial problems in this research area. This challenge should be met by middleware design and development. However, the current standard middleware offers little support for dynamic reconfiguration of distributed systems. In this paper, we describe an extended Java RAII that supports efficiently dynamic reconfiguration of distributed systems. This extended Java RAII can automatically monitor and manipulate invocations between components during a dynamic reconfiguration. Moreover, the extended Java RAII can automatically switch invocations from remote to local and vice versa.
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