Dynamic distributed systems like peer-to-peer systems, overlay networks and mobile ad hoc networks must execute their applications using distributed resources and in a decentralized way. The structure (composition and...
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Dynamic distributed systems like peer-to-peer systems, overlay networks and mobile ad hoc networks must execute their applications using distributed resources and in a decentralized way. The structure (composition and topology) of these systems changes frequently due to nodes joining or leaving the network, or due to mobility, faults and networks partitions. distributed algorithms projected to this class of systems must be able to deal with the occurrence of these events and to self-adapt dynamically the application according to changes in its execution environment. In this paper, we propose a dynamic, self-adaptable and intrusion tolerant certificate authority (CA) designed to operate in mobile ad hoc networks. This CA is composed by a set of mobile devices present in the network, which forms a group of servers that supports CA functions. This architecture is based on a dynamic systems model and was conceived to manage changes in the membership of the servers group. This paper introduces an algorithmic base that allows the CA to reconfigure itself, guaranteeing the availability and the inviolability of the certification service.
distributed Network Virtual Environments (NVEs) are becoming more and more popular in today's computing and communications. The scalability of NVEs is an important problem, and faces many challenges. Voronoi-based...
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distributed Network Virtual Environments (NVEs) are becoming more and more popular in today's computing and communications. The scalability of NVEs is an important problem, and faces many challenges. Voronoi-based Overlay Network (VON) has been proposed that promises to maintain the P2P topology in a fully-distributed, low-latency, and message-efficient manner. However, since node heterogeneity in VON does not be considered, communication and message exchange cannot be regulated properly. Additionally, as nodes need to connect to all of their AOI neighbors directly, if there are too many AOI neighbors the transmission size will be too big to transfer in time. Even packet loss can generate in certain some nodes. To these problems, a fully distributed P2P communications architecture for Network Virtual Environments is presented. The architecture calculates optimal AOI-radii according to node ability, and the node crowding may be avoided to a great extent. In constructing multicast tree, node's fan-out is selected based on node's degree in theory which can be calculated by node ability. The child node degrees can be adjusted dynamically in system, and the nodes can balance message load independently based node load. The simulation results show that the algorithm gains a greater improvement on multicast efficiency, and achieves better scalability.
The success of a reputation system depends on accurately calculated reputations that predict the quality of future interactions. In the peer-to-peer (P2P) networks, the scores are distributed by each peer locally or m...
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ISBN:
(纸本)9781424451623;9781424451616
The success of a reputation system depends on accurately calculated reputations that predict the quality of future interactions. In the peer-to-peer (P2P) networks, the scores are distributed by each peer locally or managed by the server/super-nodes. Similar to all other security mechanisms, reputation systems in P2P networks can be under attacks. Some attacks may attempt to exploit the system to its own benefits by deceiving or misleading. This paper focuses on trust model based on both direct and indirect feedbacks. The attacks-defense mechanisms by the trust model with credibility and community context factors are also explored.
Awareness of the activities of other users and also document evolution is an important part of collaborative authoring. We introduce the concept of an editing profile that can be used to maintain and visualise measure...
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Awareness of the activities of other users and also document evolution is an important part of collaborative authoring. We introduce the concept of an editing profile that can be used to maintain and visualise measures of the changes made across a document by different users in both synchronous and asynchronous collaborative editing. It provides a simple means of making users aware of "hot areas" and also who is or has been active in various parts of the document, as well as a quick access point into parts of the document that have been changed. The profile can be adapted to display the most relevant information based on both user preference and situation
Owing to the rapidly growing interests and excitement in distributedcomputing and grid-enabled applications, the facilitating middleware layer has become a center of attention in recent years. At the same time, rapid...
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Owing to the rapidly growing interests and excitement in distributedcomputing and grid-enabled applications, the facilitating middleware layer has become a center of attention in recent years. At the same time, rapid advances in networking technologies such as the resilient packet ring (RPR) have evolved to carry all kinds of information including data, voice, multimedia and now, grid applications. However, little studies have been made to discover the interactions between grid middleware and the network layer. This paper therefore investigates the degree of which grid middleware design takes advantage of the underlying networking resources and features.
Complex Event Processing (CEP) and Mobile Adhoc networks (MANETs) are two technologies that can be used to enable monitoring applications for Emergency and Rescue missions (ER). MANETs are characterized by energy limi...
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Complex Event Processing (CEP) and Mobile Adhoc networks (MANETs) are two technologies that can be used to enable monitoring applications for Emergency and Rescue missions (ER). MANETs are characterized by energy limitations, and in-network processing or distributed CEP is one possible solution. Operator placement mechanism for distributed CEP has a direct impact on energy consumption. Existing operator placement mechanisms focus on static network topologies and are therefore inappropriate for MANETs scenarios. We propose a novel energy efficient decentralized distributed placement mechanism, designed to achieve fast convergence with minimal data transmission cost while achieving a near optimal placement assignment. We compare our decentralized placement mechanism with a centralized approach under different mobility scenarios. Furthermore, we evaluate the distributed CEP under different workload scenarios in order to gain additional insight into different performance characteristics of the system. Finally, we measure the impact of a simple placement replication scheme on the overall system performance in terms of delay and message overhead. Our decentralized placement mechanism achieves up to almost 50% lower message overhead compared to the centralized approach, and it has lower message overhead across different mobility scenarios compared to the centralized approach. The placement replication scheme achieves up to 51% lower delay compared to the decentralized placement mechanism with no replication.
As network data security becoming more and more universalized, distributed Secure Sockets Layer (SSL) reverse proxies are often used in Web systems to offload CPU exhausting SSL operations from Web servers and improve...
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As network data security becoming more and more universalized, distributed Secure Sockets Layer (SSL) reverse proxies are often used in Web systems to offload CPU exhausting SSL operations from Web servers and improve the execution performance of the SSL protocol. The distribution strategy of user requests to the SSL reverse proxies is a significant factor affecting the system's performance in processing SSL operations. Aiming at improving the quality of request distribution decisions, this paper proposes a new approach for SSL reverse proxy load estimation, i.e. the family of algorithms called Load Estimation with Pre-Learning (LEPL), which estimates load using pre-learned machine learning models. Using LEPL, high accuracy of load estimation can be achieved, so that better request distribution decisions can be made. Our experimental results show that by using pre-learning, the SSL reverse proxy system's average response time can be shortened by about 30% - 50%.
In this paper, data structures for reducing redundancy of routing information on the distributed key-value store based on order preserving linear hashing and Skip Graph with the load balancing method are proposed and ...
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ISBN:
(纸本)9798350396386
In this paper, data structures for reducing redundancy of routing information on the distributed key-value store based on order preserving linear hashing and Skip Graph with the load balancing method are proposed and evaluated. In this system, data are divided by order preserving linear hashing and Skip Graph is used for overlay network. For load balancing, by storing many Skip Graph nodes in one physical node, any highest-load Skip Graph can be divided. By this method, load balancing can be done. But the number of Skip Graph nodes becomes very many and redundant routing information exists. But this redundant routing information has regularity. In this paper, two types of data structure for reducing redundant routing elements are proposed. They are tree structure and array structure. By calculating space for them and searching time, the proposed data structures are experimentally evaluated.
Many private BitTorrent communities employ Sharing Ratio Enforcement (SRE) schemes to incentivize users to contribute. It has been demonstrated that communities that adopt SRE are greatly oversupplied, i.e., they have...
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