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In this paper, we consider the problem of how to place redundant sensor nodes in an arbitrary sensor network to establish multi-connectivity. Specifically, after exploring the existing general k-connectivity algorithm, this paper proves that its approximation ratio is upper-bounded by only O(k3α), asymptotically one order of k lower than that presented before. Since establishing k-connectivity is not cost-efficient for many applications, this paper further relaxes k-connectivity to partial k-connectivity and upper-bounds the approximation ratio of partial k-connectivity with O(k4α). [ABSTRACT FROM AUTHOR]

The existing CBD development methods deal with the analysis phase in a superficial manner. Applying such a superficial analysis to cooperative business applications with a number of distributed sub-components makes analysis models be inconsistent with levels and styles, only depending on experiences of the analysts. In this paper, we propose a rule-based analysis method that provides an analysis template for cooperative business applications. This method analyzes the concepts of cooperative business applications by using external events and internal rules that process the events. Employing this method, a huge business application can be developed by a couple of co-analysts who work together in a consistent and systematic manner. This paper also provides an efficient way to apply the rule-based analysis method to UML Component development methods. [ABSTRACT FROM AUTHOR]

Grid computing is the next generation platform that maximizes computing performance of system as using numerous computing resources on computer networks. Grid computing not only shares computing resources but also efficiently utilizes available computing resources. Therefore, grid computing needs resource management policies that handle and manage grid computing resources. This paper reviews existing resource management models based on economic principles such as auction model and commodity market model. This paper proposes an efficient resource management model, which is called the grid resource trade network model, and presents its bidding algorithms for grid users and grid providers. The proposed model reduces idle resources, improves resource utilization, and provides effective resource distribution. Empirical results show usefulness and efficiency of the grid resource trade network model. [ABSTRACT FROM AUTHOR]

This paper focuses on how to model grid resource and locate grid resource using efficient and scaleable protocol under a grid environment. A mathematic model of grid physical resource space and logical resource space is built based concept of virtual organization. Then, a mathematical method based the binary equivalent relation is presented to divide grid physical resource space. Then, this paper proposes the concept of grid resource domain, and introduce a fully decentralized grid resource locating protocol based it from aspects of the overlay network of grid resource domains and query routing protocol among different grid resource domains. On the other hand, in order to propagate query among information nodes within given grid resource domain, this paper presents informed search protocol based bloom filters. Our resource locating protocol can enhance the query success rate and recall rate, and avoid too much unnecessary query messages. [ABSTRACT FROM AUTHOR]

This paper presents a design and development of a data distribution management modeling in computational grid. The modeling focuses on system performance improvement of a satellite cluster management system which uses an inter-federation communication in HLA (High Level Architecture)-compliant grid system. The inter-federation communication allows to execute a complex large-scale cluster management system with distributed satellites and share the dispersed data assets among satellite components collaboratively. In addition, this paper discusses the data distribution management modeling with centralized and decentralized approaches to improve system performance and scalability of satellite cluster management. The analytical and empirical results on the heterogeneous OS-based computational grid show usefulness of data distribution management and inter-federation communication in the satellite cluster management system. [ABSTRACT FROM AUTHOR]

AMS02 science activities collaborated by Southeast university and CERN led by Samuel C.C. Ting are generating the unprecedented volume of data. The existing FTP has caused user to discomfort by delay and data loss according to network status. Therefore, it is necessary to efficiently raise transfer performance and minimize data loss. In this paper, we will introduce a new large file transfer tool based on QoS and multi-stream technology- BBFTP which is used in the AMS02 experiment. Through Monte Carol simulation data transfer experiments between SEU-SOC and ShanDong University node in ChinaGrid, we found the optimal parameters which help to promote BBFTP throughput performance. This paper focuses on related works about performance enhancement of large file transfer, which is critical to the performance of SOC (Science Operation Center). [ABSTRACT FROM AUTHOR]

A grid workflow is regarded as a fundamental service in a grid environment. To design a user friendly end-to-end grid workflow model is generally a challenging task for general users. In this paper, we propose the concept of grid workflow component, which can be created and then reused to construct the grid workflow model dynamically. This paper firstly presents a framework for dynamic grid workflow. Then the grid workflow component model, which consists of a semantic sub-model and a syntactic sub-model, is defined. Next the methodologies for reusing grid workflow component, especially its search strategy and assembling patterns, are discussed in the paper. [ABSTRACT FROM AUTHOR]

As Grid technology evolves it is becoming evident that the inclusion of mobile devices in a Grid environment will benefit both the Grid and mobile network communities. Many mobile devices, however, have limits on their computational resources that make it difficult to achieve this goal. The goal of this paper is to investigate how well the most limited wireless devices can make use of grid security services. This paper describes a novel security approach on fast mobile grid services based on current mobile web services platform environment using XML signcryption mechanism. [ABSTRACT FROM AUTHOR]

Running workloads in a grid environment is often a challenging problem due the scale of the environment, and to the resource partitioning based on various sharing strategies. A resource may be taken down during a job execution, be improperly setup or just fail job execution. Such elements have to be taken in account whenever targeting a grid environment for execution. In this paper we explore these issues on a real grid, Grid3, by means of a specific workload, the BLAST workload, and a specific scheduling framework, GRUBER - an architecture and toolkit for resource usage service level agreement (SLA) specification and enforcement. The paper provides extensive experimental results. We address in high detail the performance of different site selection strategies of GRUBER and the overall performance in scheduling workloads in Grid3 with workload sizes ranging from 10 to 10,000 jobs. [ABSTRACT FROM AUTHOR]

This paper illustrates a GIS (Geographic Information Systems) application integration framework, which utilizes GIS Grid services (GGS) to enable large-scale resource sharing and better reusing of legacy systems. Considering the fundamental requirements of GGS, a design with sophisticated interfaces which enables explicit state semantics is proposed as a major contribution of this study. In addition, a prototype system of GGS based on legacy systems and web services is developed. Furthermore, the implementations are evaluated in a grid service selector environment proposed in another paper of this project. [ABSTRACT FROM AUTHOR]

To improve system scalability and restrain cheat, which are two important aspects in resource sharing gird environment, a dynamic-role based access control framework is proposed in this paper. This framework imports trust model, proposes "conversion parameter" and dynamic-role to resolve the problems of access control across multi domains. Simulation results show that it can realize access control easily, prohibit malicious behavior of entities, and improve the scalability of the system. An implementation is also shown in this paper. [ABSTRACT FROM AUTHOR]

The dynamics of Grid calls for flexible and adaptive workflow systems. This paper integrates Web Services and intelligent resource allocation mechanism (through Agent technologies) to Grid Services Workflow System embedded with Coloured Petri Nets (CPNs). The cooperation of Agents and CPNs enhances the adaptability of the framework. We discuss how Web Services can be located and the services provided by them can be invoked. We also discuss how the Agents and Web Services can co-exist to create highly flexible and dynamic Grid Services Workflow System. Finally this paper shows how our framework can be used to achieve adaptability from process, resource and task perspectives through an example of airline ticket service system. [ABSTRACT FROM AUTHOR]

In this paper we propose a mobile-agent-based web service composition (MAWSC) model for the dynamic web service composition (WSC). As compared with the traditional WSC models, our model avoids bottleneck of data transfer by peer-to-peer approach. As it achieves the composition without a centralized control, there is no center needed and every WSC portal can offer services for a large quantity of clients. In MAWSC model, WSC client inputs the specification and the initial parameters through WSC portal; then, system creates mobile agents to achieve the task and return the final results back to the client. In this paper, we define "planning" to specify the logic actions of mobile agent so as to execute the WSC automatically. And we also give the process mapping rules to convert the specification of WSC to the planning, and the behavior matching algorithms to map the planning to the physical behaviors of agents. [ABSTRACT FROM AUTHOR]

Web-Based Instruction(WBI) system offers many advantages to those seeking to advance their education using internet. And WBI system embodied according to traditional process until present. But, this process has inefficiency in system development and gives trouble of operation and administration after development. Therefore, It needs induction of component based development in Web-Based instruction system. In this paper, I implement web-courseware system by component composition in middleware system. For this application, I embody component by Enterprise Java Beans(EJB) and use Prism-MW architecture at the composition method, a middleware platform intended to support software architecture-based development. In this result, I show in application possibility of component based development in Web-Based instruction system as to construct whole score processing system through composition of each component. [ABSTRACT FROM AUTHOR]

In a computational grid, collective communication methods are inefficient because of heterogeneous network's features on wide area network. In this paper, we propose the efficient MPI(Message Passing Interface)'s collective communication method in a computational grid on wide area network. The SPPT(Shortest-Path-based Process Tree) algorithm is our proposed algorithm that creates the dynamic-process-tree based on latency information to communicate with each process for efficient collective communication. The experiment shows that the performance of MPI broadcast operation implemented by the SPPT algorithm is higher about 50% and 15% than the Flat-Tree and the HLOT algorithms, respectively, in a grid network which has relatively high latency links. [ABSTRACT FROM AUTHOR]

The structured peer-to-peer system, which is based on the distributed hash table, offers an administration-free and fault-tolerant application-level overlay network. However, a randomly structured overlay can not reflect the heterogeneity of a peer-to-peer system. In this paper, we propose a two-phase approach to exploit the heterogeneity in structured peer-to-peer systems. First, by exploiting the effects of both connections and nodes, we adjust the structure of overlay to reduce the lookup latency. And then a novel load balancing scheme based on lottery scheduling is proposed to balance not only the load but also the movement cost of the load. Our simulation results show that the performance, including query quality from the users' view and load balance from the system's view, can be greatly improved in a heterogeneous environment. [ABSTRACT FROM AUTHOR]

Web spider is a widely used approach to obtain information for search engines. As the size of the Web grows, it becomes a natural choice to parallelize the spider's crawling process. This paper presents a parallel web spider model based on multi-agent system for cooperative information gathering. It uses the dynamic assignment mechanism to wipe off redundant web pages caused by parallelization. Experiments show that the parallel spider is effective to improve the information gathering performance within an acceptable interaction efficiency cost for controlling. This approach provides a novel perspective for the next generation advanced search engine. [ABSTRACT FROM AUTHOR]

AQM is an effective method to improve the performance of end-to-end congestion control. The behavior of various AQM schemes with respect to buffer capacity issues has not been studied in much detail. In this paper, we show the effect of router buffer size on AQM schemes based on queue length and present the reason: the buffer saturation will make the input and output of AQM schemes conflicting. We also propose a saturation compensator which can improve the performance of AQM schemes when routers have small buffer. At last, using PI as an example we propose PI with saturation compensator whose performance is evaluated through NS2 simulations. [ABSTRACT FROM AUTHOR]

Recently, software development method supporting CBD has been adopted widely, and there have been many studies on composition and application of architecture that can effectively use CBD. C2 architecture has been popular because of its composition of message-driven components. However, when you have classified sequence in component and want to use method-call method in server component, modification of component in C2 architecture is inevitable. In this paper, I propose connector interaction method with central message processing. This allows us to use the component without any modification (Plug-and-Play) even when method-call method is in use. More flexible message handling can be achieved by having a parallel composition of components that are free of classified sequence. [ABSTRACT FROM AUTHOR]

This paper describes a methodology for machine-description, intended to help develop processor specific tools in a generic and reusable way. It is based on our work about retargetable compiler for embedded processors and is contributed to Architecture Design Language (ADL). The processor described in our machine-description system is modeled in UML class diagram in 3-layer architecture. The resulting machine-description is reusable for developers to create retargetable compilers. [ABSTRACT FROM AUTHOR]

The proxy cache for streaming media is the important method to economize the resources of the Internet. The cache policies influence the effect for proxy cache. In this paper, based on the client's request rate, cached the video based on segmentation, we proposed that the method for batch, patch and batch patching using dynamic cache. The policies of batch and batch patching using dynamic cache based on segmentation enlarge the width of the batch and patching. It combines dynamic cache based on segmentation with the excellence of patching. Presented that allocation relation between the segmented cache and dynamic cache in the batch and patching, and assured that batch patching using dynamic cache of proxy for streaming media based on segmentation is optimal. [ABSTRACT FROM AUTHOR]

In this paper we first investigate the problem of finding a delay- and degree-bounded maximum sum of nodes ALMT. We proved the problem is NP-hard, and testify its relationship with the well-studied degree-bounded minimum maximum-delay ALMT problem. We proposed a greedy algorithm FindOverlayTree with SRPF heuristic. The simulation results show that our design solution is a valid and cost-effective approach where compared to other three modified classic heuristics under several performance metrics. [ABSTRACT FROM AUTHOR]

This paper addresses a fundamental problem that arises in data streaming scenarios, namely, today's data mining is ill-equipped to handle data streams effectively, and pays little attention to the network stability and the fast response [36]. To the question, we present a control-theoretic explicit rate (ER) online data mining control algorithm (ODMCA) to regulate the sending rate of mined data, which accounts for the main memory occupancies of terminal nodes. The proposed method uses a distributed proportional integrative plus derivative controller combined with data-mining, where the control parameters can be designed to ensure the stability of the control loop in terms of sending rate of mined data. We further analyze the theoretical aspects of the proposed algorithm, and simulation results show the efficiency of our scheme in terms of high main memory occupancy, fast response of the main memory occupancy as well as of the controlled sending rates. [ABSTRACT FROM AUTHOR]

In e-Science environments, the support for scientific workflows emerges as a key service for managing experiment data and activities, for prototyping computing systems and for orchestrating the runtime system behaviour. Supporting domain specific applications via a common e-Science infrastructure enables knowledge sharing among different applications, and thus can broaden the range of the application and multiply the impact of scientific research. However, most of the existing workflow management systems are driven by the domain specific applications; the applicability to different domains is limited. In this paper, we discuss possible solutions to this problem and present our research in an ongoing project: Virtual Laboratory for e-Science (VL-e). Agent technologies are used to encapsulate the intelligence for problem solving strategies and for workflow orchestration. [ABSTRACT FROM AUTHOR]

This paper describes an integrated architecture for online collaborative multimedia (audio and text) meetings which supports the recording of participants' audio exchanges, automatic metadata generation and logging of users editing interaction and also information derived from the use of group awareness widgets (gesturing) for post-meeting processing and access. We propose a formal model for timestamping generation and manipulation of textual artefacts. Post-meeting processing of the interaction information highlight the usefulness of such histories in terms of tracking information that would be normally lost in usual collaborative editing settings. The potential applications of such automatic interaction history generation range from group interaction quantitative analysis, cooperation modelling, and multimedia meeting mining. [ABSTRACT FROM AUTHOR]

Internet is characterized as a uncontrollable, variable and unpredictable infrastructure, this brings the difficulty of developing, debugging and evaluating network applications. Network emulation system constructs a virtual network environment which has the characteristics of controllable and repeatable network conditions. This makes it possible to predict the correctness and performance of proposed new technology before deploying to Internet. In this paper we present a methodology for predicting the correctness and performance of applications based on the PARNEM, a parallel discrete event network emulator. PARNEM employs a BSP based real-time event scheduling engine, provides flexible interactive mechanism and facilitates legacy network models reuse. PARNEM allows detailed and accurate study of application behavior. [ABSTRACT FROM AUTHOR]

Resource providers and resources users in the computational grid system are composed of the two parties for gaming in fact. A multi-auctioneers prototype system based upon game theory (GT) for grid resource management is designed and implemented in this paper. The prototype system improves throughput of system in high throughput computing. Furthermore it prevents from the fraud actions, which come from dishonest auctioneer's fraud action and user's cahoots fraud action. The prototype system improves the performance and QoS for resource management of computational grid system greatly. [ABSTRACT FROM AUTHOR]

Link failures are common in IP networks. In this paper, we develop a technique for diagnosing link failures in Service Provider or Enterprise IP networks using active measurement.The technique attempts to minimize both the monitoring infrastructure costs as well as the additional traffic due to probe messages. Both the station selection problem and the probe message assignment problem are NP-hard, and we propose approximation algorithms for these problems. We also apply our algorithms to existing ISP networks using topologies inferred by the Rocketfuel tool. The results can be used by ISP operators to trade off between accuracy of diagnosis and monitoring costs. [ABSTRACT FROM AUTHOR]

So far the AIMD (Additive Increase Multiplicative Decrease) mechanism used by the conventional TCP congestion control protocol has been supported nearly by every Internet hosts. However, the conventional TCP has been designed without the theoretic foundations, so as to result in some problems in the long distance high speed network, such as the low bandwidth efficiency and the RTT (Round Trip Time) bias. Based on the flow fluid model, this paper models a scalable TCP congestion control protocol by the continuous differential equation on the RTT timescale, analyzes the condition for stability, and discusses the interrelations among stability, fairness and efficiency, which is aid to guide the design of end-to-end congestion control in the future. [ABSTRACT FROM AUTHOR]

In this paper, the performance evaluation of an optimal Solution for coordinated cache replacement in Transcoding Proxies is present. We compare the performance over three impacts: impact of cache size, impact of object access frequency, and impact of the number of client classes. The extensive simulation results show that the coordinated cache replacement model greatly improves network performance compared to local replacement models that determine cache replacement candidates from the view of only a single node. Keywords: Web caching, multimedia object, transcoding proxy, cache replacement, performance evaluation, Internet. [ABSTRACT FROM AUTHOR]

Scientific computing requires not only more computational resource, but also large amount of data storage. Therefore the scientific grid integrates the computational grid and data grid to provide sufficient resources for scientific applications. However, most of meta-scheduler only considers the system utilization, e.g. CPU load to optimize the resource allocation. This paper proposed a weighted meta-scheduling algorithm which takes into account of both system load and data grid workload. The experiments show the performance improvement for applications and achieve better load balance by efficient resource scheduling. [ABSTRACT FROM AUTHOR]

In this paper, we compare the performance of some mesh-based applications in a Grid environment using the domain decomposition technique and unbalanced workload strategies. We propose unbalanced distributions in order to overlap computation with remote communications. Results are presented for typical cases in car crashing simulation where finite element schemes are applied in fine mesh. The expected execution time is basically the same when two unbalanced techniques are used, but it is up 34% smaller that the one requires by the classical balanced strategy. We also analyze the influence of the communication pattern on execution times using the Dimemas simulator. Keywords: Domain decomposition, Grid environments. [ABSTRACT FROM AUTHOR]

In the case of desktop grids, a single hardware-determined latency and constant bandwidth between processors cannot be assumed without incurring in unnecessary error. The actual network topology is determined not only by the physical hardware, but also by the instantaneous bandwidth availability for parallel processes to communicate. In this paper we present a novel task assignment scheme which takes the dynamic network topology into consideration along with the traditionally evaluated variables such as processor availability and potential. The method performs increasingly better as the grid size increases. Keywords: task assignment, load distribution, desktop grids. [ABSTRACT FROM AUTHOR]

This paper proposes a framework for transactional Mobile Agent (MA) execution. Mechanisms and algorithms for transactional execution of single MA and multiple MAs are developed. In addition to preserving the basic transaction semantics, the proposed framework also have three desirable features. First, the framework is designed as an additional layer on top of the underlying existing system, so it can be well integrated with the existing systems without having much interference with the existing system functionality. Second, an adaptive commitment model is proposed for transaction MA execution. Third, fault tolerance support is provided to shield MA execution from various failures, so as to increase the commitment rate. The results obtained through experiments show that our framework is effective and efficient. [ABSTRACT FROM AUTHOR]

Challenges revealed in constructing a peer-to-peer (P2P) file system are due to the difficulties of version control.There have appeared no P2P systems, which can solve these problems smoothly. In this paper we show our efforts towards solving the problems by developing a new application, SVCL (a Scalable Version Control Layer in P2P file system), in which version control servers are woven into a peer-to-peer network so that the system will not crash under single node failure. As a result, users can carry out both file updating and reading operations. Experiments have demonstrated the high performance of the proposed system. [ABSTRACT FROM AUTHOR]

Gnutella-like peer-to-peer networks exhibit strong small-world properties and power-law node degree distributions. However, the existing flooding-based query algorithms used in such overlay networks, knowing very little about these inherent natures, scale poorly with inefficient search and heavy traffic load, which is always a challenging problem to solve. In this paper, we eye our viewpoints upon the role of overlay topology in the search performance and propose a novel solution towards scalable and efficient peer-to-peer distributed file sharing, by making better use of such emergent topological properties of these networks. We first, by examining what inspirations can be taken from these properties, provide several helpful guidelines as the design rationale of our solution, and we then propose a new technique for constructing DesirableTopologies and a novel Smart Search algorithm operating on them, as two key components of our solution. To justify the performance gains of our techniques, we also conduct extensive experiments under realistic network conditions and make an all-around comparison with currently well-known systems. [ABSTRACT FROM AUTHOR]

In this paper, we design a new routing algorithm using SkipNet and Small-World for peer-to-peer system. The algorithm divides the routing space into two layers, SkipNet layer and Small-World layer. In the SkipNet layer, the routing method using numeric ID is discussed. In the Small-World layer, the routing method using small-world theoretical results is discussed. We also consider the dynamic circumstance-the node's join and departure. The comparison of our algorithm with other algorithms is presented. Our algorithm supports content and path locality, it is very important for security consideration. In our algorithm, a few shortcuts to distant peers are inserted with some probabilities and the average path length is reduced. The preliminary simulation results show that our algorithm is efficient. [ABSTRACT FROM AUTHOR]

In Mobile Ad Hoc Networks the energy conservation problem is a very critical issue since in most cases the nodes are battery-operated. While the energy efficiency can be achieved by routing along the path that requires the lowest total energy consumption and can be solved in polynomial time for unicast communication, it was proved to be NP-complete for the construction of a Minimum-Energy Spanning Tree if the antenna is not unidirectional. Some heuristic solutions have been proposed for this problem, in this paper we present a novel distributed algorithm which effectively exploits the wireless multicast advantage. The analysis results also show that our scheme is economic for energy consumption, and efficient for time and communication complexity. Keywords: MANET, Broadcasting, Energy-efficient Routing. [ABSTRACT FROM AUTHOR]

Ad hoc network is a peer-to-peer grid system. The combination of the Knowledge Grid and ad hoc network could have a great effect on the future interconnection environment. In the existed researches about ad hoc routing protocols, knowledge with trusted requirements is not supported. In this paper, the trust level is used as knowledge for routing. The security rather than shortest path is the primary concern of the method. The performance evaluation via simulations shows that the method is a promising trust routing algorithm for MANETs. The effects of this trust model on DSR route discovery mechanism are analyzed. Results show that our model can improve the performance of DSR route discovery. [ABSTRACT FROM AUTHOR]

Building a topology-aware peer-to-peer overlay network can bring many advantages, such as providing locality-aware connectivity and reducing routing path length. While its benefits on performance have been recognized, an uneven overlay zone distribution has emerged. Recent work has shown that topology-aware neighbor selection during construction can aggravate the unbalance of zone distribution while it reduces routing path length. The imbalance in zone sizes may lead to performance decrease and an unfair load distribution. In this paper, we present an even topology-aware peer-to-peer network based on De Bruijn Graph by developing a dynamic zone-balancing approach. [ABSTRACT FROM AUTHOR]

Peer-to-peer networks can be divided into structured and unstructured based on their overlay topologies. In reality, unstructured p2p networks with superpeers have proved their capacities to support millions of users simultaneously. However, applications deployed on this kind of overlay networks, such as file-sharing, require flooding or gossip-based message routing, which puts more overhead on underlying networks and provides no guarantee on resource discovery. In this paper we propose an overlay adaptation protocol which allows structured superpeer overlay construction from unstructured p2p overlay networks with the potential to leverage the advantages of structured p2p overlay networks such as efficiency, scalability and guaranteed look-up services. The simulation result shows that our protocol can build the structured superpeer overlay with efficiency and scalability. [ABSTRACT FROM AUTHOR]

In P2P systems, every user can release files freely, which makes the large-scale file-sharing feasible. However, with malicious nodes increasing, lots of faked files and deceptive behaviors restrict the development of P2P application. Current P2P trust models can't guarantee the Quality of Service(QoS), and take no consideration for trust decay and cooperative cheat. To address these problems, this paper presents a novel behavior-based P2P trust model. The direct trust and reputation trust are considered, and the time decay function and reputation adjustment factor are provided in the model. Results of simulations show that compared to the current trust models, the proposed model is more efficient and scalable. Keywords: P2P, trust, decay function, QoS. [ABSTRACT FROM AUTHOR]

P2P is a promising technology to construct the underlying supporting layer of a Grid. It is known that contribution from all the peers is vital for the sustainability of a P2P community, but peers are often selfish and unwilling to contribute. In this paper we describe how to construct a fair file-exchanging P2P community. We name this community a P2P file market. Our scheme forces peers to contribute by a micropayment-based incentive mechanism. [ABSTRACT FROM AUTHOR]

The resource discovery algorithms in Peer-to-Peer networks are based on the assumption that reliable resources are provided by each peer. The feather that significantly contributes to the success of many P2P applications is dynamic, anonymity and self-organization. However, they also bring about some malicious nodes to provide untrustworthy and pseudo services. To address this problem, this paper introduces a robust and flexible reputation mechanism in unstructured P2P and presents the heuristicresource discovery algorithm based on reputation-aware to ensure that resource requester can obtain reliable resources and services. This new resource discovery algorithm can effectively suppress the deceptive and fake services of P2P network, improve the reliability and security and decrease network load. [ABSTRACT FROM AUTHOR]

Peer-to-peer systems are distinguished from traditional distributed systems in that nodes join and leave the p2p system at high rates, called churn problem. SChord, a p2p system, is illustrated in this paper, which is constructed on Chord system and aims to handle churn. We analyze the past experimental studies on churn of p2p systems and do some theoretical analysis on the probability distribution of node session time. SChord is based on such analysis which can distinguish nodes of long session time from other p2p nodes and exploit these long session nodes with its special routing algorithm. The simulation shows that SChord has achieved better performance of churn handling than Chord. [ABSTRACT FROM AUTHOR]

This paper focuses on behavior analysis on mobile agents used in network routing. We describe a general agent-based routing model and classify it into two cases based on the reaction of mobile agents to a system failure, namely MWRC (mobile agents with weak reaction capability) and MSRC (mobile agents with strong reaction capability). For each case, we analyze the population distribution (the number of mobile agents) of mobile agents which as an important measure for monitoring the computational resource consumption and network performance. Our analysis reveal theoretical insights into the statistical behaviors of mobile agents and provide useful tools for effectively managing mobile agents in large networks. Keywords: Mobile agents, vulnerable networks, population distribution. [ABSTRACT FROM AUTHOR]

In peer-to-peer (P2P) overlay networks, the mechanism of a peer randomly joining and leaving a network, causes a topology mismatch between the overlay and the underlying physical topology. This causes a large volume of redundant traffic in the underlying physical network as well as an extra delay in message delivery in the overlay network. Topology mismatch occurs because overlay networks are not aware of their underlying physical networks. In this paper we present a mathematical model for topology awareness of overlay networks (degree of matching between an overlay and its underlying physical network) and the efficiency of message delivery on them. We also after determining the computational complexity of the model, propose an optimization heuristic algorithm to increase topology awareness of P2P overlay networks. Then we present the results of running the algorithm on different kinds of random graphs and show, how we can implement the algorithm over P2P networks. [ABSTRACT FROM AUTHOR]

Event-based, Publish/Subscribe, systems are receiving increasingly greater attention as a prevalent approach to decouple various large-scale distributed applications such as Internet wide systems. However, their efficiency is closely tied to the architecture of the underlying notification service, which conveys the event notifications from publishers to subscribers. Peer-to-Peer network topology can offer inherently bounded delivery depth, load sharing and self-organization. In this paper, we present a content-based notification service system over peer-to-peer network topology, and couple it with an efficient filter model and routing algorithms. We also study the performance of our approaches, comparing them with corresponding works. The result shows that our approaches greatly reduce network bandwidth for subscription or filter update propagation, and storage requirement for keeping filter routing information. [ABSTRACT FROM AUTHOR]

In order to deal with free riding in P2P system, incentive mechanism or rating system is presented, and each user rating is computed by itself, which causes that some users exaggerate their ratings. In this paper, three aspects are developed for free riding and for improving service performance in P2P. First of all, it is useful to keep away fake rating that each user rating is calculated by the responders. Secondly, three kinds of user ratings including single user rating and two group ratings are exploited to get better service performance. The last aspect is to provide a service strategy that is adaptive to the responder workload. Finally, the experimental results demonstrate that this strategy can effectively handle the problem of free riding, and especially, group ratings can greatly boost response rate of the whole P2P system. [ABSTRACT FROM AUTHOR]

This paper describes a Global Computing (GC) environment, called XtremWeb-CH (XWCH). XWCH is an improved version of a GC tool called XtremWeb (XW). XWCH tries to enrich XW in order to match P2P concepts: distributed scheduling, distributed communication, development of symmetrical models. Two versions of XWCH were developed. The first, called XWCH-sMs, manages inter-task communications in a centralized way. The second version, called XWCH-p2p, allows a direct communication between "workers". XWCH is evaluated in the case of a real high performance genetic application. [ABSTRACT FROM AUTHOR]