Real-time online multi-player games are becoming increasingly popular due to advances in game design and the proliferation of broadband Internet access. However, fairness remains a major challenge when players over la...
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In this paper, we present a multi-version transaction model, which exploits versions to increase availability in a mobile database environment. Each transaction in our model is either in start, committed or terminated...
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the term "Grid" was coined in the mid 1990s to denote a proposed distributedcomputing infrastructure for advanced science and technology. Due to the large scale of the Grid environment and its rapid expansi...
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ISBN:
(纸本)0780375335
the term "Grid" was coined in the mid 1990s to denote a proposed distributedcomputing infrastructure for advanced science and technology. Due to the large scale of the Grid environment and its rapid expansion, both in resources and networking, it is becoming imperative to provide some kind of management mechanism to enable Grid computing to adapt to the various application requirements in a flexible and automated way. this paper proposes to introduce policy-based management, enhanced by an active network, to cope withthis challenging requirement. Based on the analysis and comparison of three typical Grid architectures, this paper firstly presents a new view of Grid architecture that emphasizes the policy-based Grid management middleware and active network middleware. then, the detailed design of these two middleware is discussed. A case study for controlled and secure massive storage access exemplifies this policy-based active Grid management architecture and shows that an improvement in manageability, automation and flexibility of the Grid system can be achieved.
Over the past decade, mobile computing and wireless communication have become increasingly important drivers of many new computing applications. the field of wireless sensor networks particularly focuses on applicatio...
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ISBN:
(纸本)1581135742
Over the past decade, mobile computing and wireless communication have become increasingly important drivers of many new computing applications. the field of wireless sensor networks particularly focuses on applications involving autonomous use of compute, sensing, and wireless communication devices for both scientific and commercial purposes. this paper examines the research decisions and design tradeoffs that arise when applying wireless peer-to-peer networking techniques in a mobile sensor network designed to support wildlife tracking for biology research. the ZebraNet system includes custom tracking collars (nodes) carried by animals under study across a large, wild area;the collars operate as a peer-to-peer network to deliver logged data back to researchers. the collars include global positioning system (GPS), Flash memory, wireless transceivers, and a small CPU;essentially each node is a small, wireless computing device. Since there is no cellular service or broadcast communication covering the region where animals are studied, ad hoc, peer-to-peer routing is needed. Although numerous ad hoc protocols exist, additional challenges arise because the researchers themselves are mobile and thus there is no fixed base station towards which to aim data. Overall, our goal is to use the least energy, storage, and other resources necessary to maintain a reliable system with a very high 'data homing' success rate. We plan to deploy a 30-node ZebraNet system at the Mpala Research Centre in central Kenya. More broadly, we believe that the domain-centric protocols and energy tradeoffs presented here for ZebraNet will have general applicability in other wireless azld sensor applications.
Real-time online multi-player games are becoming increasingly popular due to advances in game design and the proliferation of broadband Internet access. However, fairness remains a major challenge when players over la...
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ISBN:
(纸本)0769518567
Real-time online multi-player games are becoming increasingly popular due to advances in game design and the proliferation of broadband Internet access. However, fairness remains a major challenge when players over large geographic areas participate in a client-server based game together. the paper proposes a game-independent, network-based service, called Sync-MS, that balances the trade-off between response time and fairness. Sync-MS uses two mechanisms, sync-out and sync-in, to address state update fairness and player action fairness, respectively. Two metrics, ahead and behind, measured against the fair order, are defined to-evaluate Sync-MS's fairness performance. Simulation results show that Sync-MS dramatically improves player action fairness for all players while it slightly increases the average response time for players with shorter network delay to the game server.
the widespread deployment of distributed multimedia services and applications has led to increasing demands in QoS services. In order to deliver QoS to these applications regardless of the presence of QoS mechanisms i...
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ISBN:
(纸本)0780375335
the widespread deployment of distributed multimedia services and applications has led to increasing demands in QoS services. In order to deliver QoS to these applications regardless of the presence of QoS mechanisms in the network, runtime QoS adaptation at the end nodes is essential. In this paper, we present a middleware for adaptive multimedia communication. QMan, an end-to-end QoS management framework, is designed to capitalize on dynamic protocol configurability provided by OCTOPUS dynamic protocol framework (ODPF). the provision of on-the-fly reflection of protocol configurations in ODPF allows QMan to offer a flexible approach in dealing with QoS violations. By using this technique, QMan is able to perform QoS adaptation at a higher level. QMan also provides other QoS management functions: specification, negotiation, mapping, and monitoring. Both QMan and ODPF are independent components of the OCTOPUS middleware.
In this paper, we report the design and implementation of a new JINI/JAVA based multimedia-streaming framework. It is modeled after the OMG A/V stream specification withthe additional support of multipoint-to-multipo...
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ISBN:
(纸本)0780375335
In this paper, we report the design and implementation of a new JINI/JAVA based multimedia-streaming framework. It is modeled after the OMG A/V stream specification withthe additional support of multipoint-to-multipoint stream (MMS). A receiver-based group communication mechanism is also proposed in this framework to extend the semantics of membership management from joining/leaving of individual users to that of groups. In addition, we have designed and implemented a set of interfaces that provides a rather neat and flexible support for intra-group and inter-group stream operations.
distributed denial-of-service (DDoS) attacks have emerged as a major threat to the stability of the Internet. By the very nature of the DDoS attacks, pure preventive and pure reactive approaches are not effective to d...
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distributed denial-of-service (DDoS) attacks have emerged as a major threat to the stability of the Internet. By the very nature of the DDoS attacks, pure preventive and pure reactive approaches are not effective to defend against them. We propose a global defense infrastructure to detect-and-respond to the DDoS attacks. this infrastructure consists of a network of distributed local detection systems (LDSes), which detect attacks and respond to them cooperatively. Because of the current Internet topology, this infrastructure can be very effective even if only a small number of major backbone ISPs participate in this infrastructure by installing fully configured LDSes. Moreover, we propose to use traffic volume anomaly for DDoS attack detection. A fully configured LDS monitors the passing traffic for an abnormally high volume of traffic destined to an IP host. A DDoS attack is confirmed if multiple LDSes have detected such anomalies at the same time. Our simulation studies have demonstrated that the proposed detection algorithms are responsive and effective in curbing DDoS attacks.
Since its birth more than two decades ago, public key cryptography has been recognized as one of the most effective mechanisms for providing fundamental security services including authentication, digital signatures a...
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ISBN:
(纸本)0769518567
Since its birth more than two decades ago, public key cryptography has been recognized as one of the most effective mechanisms for providing fundamental security services including authentication, digital signatures and encryption for dynamic networks. Effective management of keys, or digital certificates holding the keys, is one of the key factors for the successful wide-spread deployment of public key cryptography. the public key infrastructure (PKI ), an infrastructure for managing digital certificates, was introduced for this purpose. the most important component of PKI is the certificate authority (CA), the trusted entity in the system that vouches for the validity of digital certificates. this work describes a framework to provide efficient yet effective distributed CA service for ad hoc wireless networks. We select physically or computationally more secure nodes as MOCAs (MObile Certificate Authority) and use threshold cryptography to distribute the CA's private key among these MOCA nodes. We also provide a protocol for clients to contact MOCAs and get certification services without incurring excessive overhead.
the major prerequisites for successful wireless ad hoc networking are an almost homogeneous distribution of a nontrivial number of nodes and the determination of an almost ideal selective connectivity of the nodes in ...
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the major prerequisites for successful wireless ad hoc networking are an almost homogeneous distribution of a nontrivial number of nodes and the determination of an almost ideal selective connectivity of the nodes in the network. To give a basic characterization of network connectivity, an ad hoc network model based on planar graphs is introduced. According to this underlying mathematical network description, the features of homogeneous connectivity for ad hoc networks are defined. Due to a specific physical layer ratio of wireless capacity utilization, a condition of isolation gives the opportunity to maintain isolated areas in any given ad hoc network distribution. To support identified isolated regions is a main goal of a hybrid transfer network.
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