Data Integration Strategy for Database Grids Based on P2P Framework

The differences between the data integration of a dynamic database grid （DBG） and that of a distributed database system are analyzed, and three kinds of data integration strategies are given on the background of DBG based on Peer to Peer （P2P） framework, including the centralized data integration （CDI） strategy, the distributed data integration （DDI） strategy and the filter-based data integration （FDDI） strategy. CDI calls all the database grid services （DGSs） at a single node, DDI disperses the DGSs to multiple nodes, while FDDI schedules the data integration nodes based on filtering the keywords returned from DGSs. The performance of these three integration strategies are compared with and analyzed by simulation experiments. FDDI is more evident for filtering the keywords with data redundancy increasing. Through the reduction of large amount of data transportation, it effectively shortens the executing time for the task and improves its efficiency.     

Activity sequence modes for Web services and verifications

Behavior requirement expression and its satisfiability verification for composite Web services is one of the ongoing issues in service computing.In this paper,the concept of behavior specifications based on activity sequence is proposed to express one kind of behavioral requirements for composite Web services.Its basic element is activity sequence.The method to express such behavioral requirements by behavioral modes is presented.Five behavioral modes used in this method are adopted.Through mapping modes to Labeled Transition Systems(LTSs),these modes are encoded with exact operation semantics.Then,the sufficient and necessary conditions as well as the checking algorithm for satisfiability of behavioral modes are given.Finally,an example analysis is presented.The result indicates that the behavioral requirements based on activity sequence are more suitable for the case of composite Web service than those based on activity or scenario.The behavioral modes expressions are concise and the satisfiability checking is effective by the given algorithm.     

Research of virtual experiment based on flex and XML

In this paper, the design of a virtual experiment system based on Flex and XML is described. The system adopts three-layer architecture and it is composed of four modules. Flex is used to design user interface, and XML is used as data format between layers or modules. Data services are used to store or retrieve the information of experiment components or experiment scenes. Principles for the design of simulation engine and simulation scheduler are discussed. The design of the simulation engine for "Digital Logic" course is described in detail. The system has been implemented in the experiment teaching of Digital Logic. Teaching results and the feedback from students demonstrate that the virtual experiment system can improve the effects of experiment teaching and arouse the learning interests of students.     

Worst-Input Mutation Approach to Web Services Vulnerability Testing Based on SOAP Messages

The growing popularity and application of Web services have led to increased attention regarding the vulnerability of software based on these services. Vulnerability testing examines the trustworthiness and reduces the security risks of software systems. This paper proposes a worst-input mutation approach for testing Web service vulnerability based on Simple Object Access Protocol （SOAP） messages. Based on characteristics of SOAP messages, the proposed approach uses the farthest neighbor concept to guide generation of the test suite. The corresponding automatic test case generation algorithm, namely, the Test Case generation based on the Farthest Neighbor （TCFN）, is also presented. The method involves partitioning the input domain into sub-domains according to the number and type of SOAP message parameters in the TCFN, selecting the candidate test case whose distance is the farthest from all executed test cases, and applying it to test the Web service. We also implement and describe a prototype Web service vulnerability testing tool. The tool was applied to the testing of Web services on the Internet. The experimental results show that the proposed approach can find more vulnerability faults than other related approaches.     

Electromechanical dynamics analysis and simulation on rollforming equipment with both sides variable cross-section

Electromechanical dynamics analysis and simulation on a rollforming equipment with both sides variable cross-section are discussed in this study.The system includes mechanical parts and electro-magnetism parts, and it is a strongly coupled electromechanical system.Based on a virtual work principle and given power,generalized forces of this system are obtained.By using Lagrange-Maxwell equations, a model of electromechanical dynamics is established.Differential equations of two-phase winding on d-q axis are obtained by Park transformation, which comes from three-phase winding equations on the A-B-C axis.This system is solved with the 4th order Runge-Kutta’ s method, and discrete solutions of all variables are obtained.Finally, by using Matlab language, the system is simulated.The results show that the proposed method works very well.     

Application of intelligent control theory in AC servo system

An AC servo system based on neuron control theory is presented. Experimental results show that the neural control mode doesn't need the Precise model of the system, therefore, it has many advantages, such as simple design and high response performance. The simulation research of the AC servo system which is non-linear, time-varied.based on neuro-fuzzy controller is done. The results of the simulation show that the performances of the system are considerably improved and it is one of the novel pathways to realize intelligent control of servo system.     

Efficient and reproducible folding simulations of the Trp-cage protein with multiscale molecular dynamics

Folding simulations are often time-consuming or highly sensitive to the initial conformation of the simulation even for mini protein like the Trp-cage. Here, we present a multiscale molecular dynamics method which appears to be both efficient and insensitive to the starting conformation based on the testing results from the Trp-cage protein. In this method the simulated system is simultaneously mod- eled on atoms and coarse-grained particles with incremental coarsening levels. The dynamics of coarse-grained particles are adapted to the recent trajectories of finer-grained particles instead of fixed and parameterized energy functions as used in previous coarse-grained models. In addition, the compositions of coarse-grained particles are allowed to be updated automatically based on the coherence during its history. Starting from the fully extended conformation and other several different conformations of the Trp-cage protein, our method successfully finds out the native-like conformations of the Trp-cage protein in the largest cluster of the trajectories in all of the eight performed simulations within at most 10 ns simulation time. The results show that approaches based on multiscale modeling are promising for ab initio protein structure prediction.     

A Scalable Communication Mechanism in Service Emergence Based on Bio-network

A scalable communication mechanism is proposed for service emergence based on bio-network. Service emergence is a novel model inspired by the characteristics of emergence and self-evolution in biological neuroendocrine and immune system, emergent communication means a group communication of mobile bio-entities. A series of protocol and algorithm are presented within frequently bioentities migration and failure, it includes distribution and parallelization of message propagation method, a token-ring protocol that considerably improves the performance of emergence, and failure detection mechanisms. Experiment results show the desired capability via the proposed solution.     

I-Wander:一种面向非结构化对等网络的Web服务发现方法

针对非结构化对等网络,设计了一种称为I-Wander的Web服务发现方法.将具有相同功能属性的Web服务聚合成社区.查询包在社区间漫游,把漫游过的社区和节点存储起来,构成认识列表.认识列表被逐跳更新,并在查询包相遇时相互交换.查询包在匹配度最高的社区被大量复制扩散,据非功能属性选出最优服务,用于Web服务组合.实验结果表明,服务聚合和认识列表及其交换机制,节省了查询包的探测时间,提高了Web服务查找的效率.     

内容寻址网络的P2P语义Web服务组合系统架构

为了提高语义Web服务组合系统的扩展性、可靠性和稳定性,提出了一种基于P2P的语义Web服务(P2PSWS)组合系统架构.该架构结合了集中式和分布式结构的优点,将统一描述、发现和集成协议的功能分散于本地Web节点、组Web节点和公共Web节点;设计了一种基于内容寻址网络的P2P网络语义Web服务的定位机制,以保证每个共享服务按领域划分,按被所有节点所共享的公共Web节点来注册.原型系统运行表明,该架构有助于克服传统公共Web服务结构上的单一节点失败问题,扩展了P2P系统的能力,有效地实现了基于本体的语义Web服务的组合.     

A Survey of Web Information System and Applications

The fourth international conference on Web information systems and applications （WISA 2007） has received 409 submissions and has accepted 37 papers for publication in this issue. The papers cover broad research areas, including Web mining and data warehouse, Deep Web and Web integration, P2P networks, text processing and information retrieval, as well as Web Services and Web infrastructure. After briefly introducing the WISA conference, the survey outlines the current activities and future trends concerning Web information systems and applications based on the papers accepted for publication.     

A distributed service composition method based on service association

In this paper, a Web service composition architecture based on structured P2P network is proposed. Semantics is used to achieve service accurately matching and user personality customization. Through Web service virtual mapping（WVM） association the fast computing of distributed service composition based on the service function is also implemented. The Web service composition architecture and distributed service composition algorithm proposed in this paper solve a series of existent problems in ser- vice discovery and composition in distributed environment, and provide a service composition result meeting user personality requirement. At the same time, they improve the efficiency of service composition calculation.     

A stable, function-separated hierarchical P2P overlay based on node heterogeneity

Current peer-to-peer (P2P) applications suffer performance degradation from the problems such as load imbalance, topology mismatch between overlay and underlay, and instability caused by node joining and leaving. In this paper, we propose the idea of implementing 2 functions of routing message and maintaining service index on different layers of overlay to deal with the aforementioned problems. Taking Chord as example, we design algorithms for building cluster and overlay and implement function-separated (FUSE) overlay with 2-dimensional address ID space. We further propose an analytic model for describing node’s load for evaluation. Simulation results indicate that, compared with 2-layer Chord-centered overlay in previous researches, this overlay excels in the metrics such as query path length, load, and query delivery ratio. Biography: LI Wenxiang(1979–), male, Lecturer, research direction: P2P computing, mobile computing.     

P2P网络仿真软件设计与实现

P2P网络技术能够为计算机网络用户提供共享,同时有效整合互联网资源,将基于Web网页的互联网应用转变成动态存取、自由交互的海量信息网络。P2P发展将影响整个计算机网络发展和信息获取模式。介绍了P2P网络仿真软件实现功能:可通过大量节点扩大覆盖范围,使多个节点能够分担服务器压力,并将这些数据传送到活跃节点,仿真软件可进行实时网络状态仿真。     

Adaptive Trust Management Framework in P2P Grid Computing

In P2P Grid computing systems, the authorization decision is often tackled by two different trust management methods： policy-based approach, where authorization are built on logical rules and verifiable properties encoded in signed credentials, and reputation-based approach, based on collecting, aggregating and disseminating reputation among the peers. However, the overhead caused by proof of compliance on authorization and the absence of certifying authorities may negate the strong and objective security advantages of policy-based approach, whilst vagueness, complexity and inaccurate characterization caused by reputation evolution may eliminate the quantitative and flexible advantages of reputation-based approach. We propose an adaptive trust management framework, which combines the merit of policy proof and reputation evolution such that authorization is aware of not only the strong and objective security traits, but also the calculability and the availability security traits. Finally, the framework of system is proposed.     

Automatic Web services composition based on SLM

Motivated by the problem of simplifying the manual operation of the composition process, we propose an approach to automatically compose available Web services to fulfill user＇s goal based on the assumption that there are a set of alternative Web services with similar functionality and different QoS properties. A formal model （i.e. semantic links matrix, SLM for short ） is proposed to store semantic links values for the Web services with semantic relationship and QoS of Web services. The SLM provides a search place for a backward-search planning algorithm, at the same time; the QoS criteria make a rational and effective decision among a number of similar Web services. The function and some properties of the algorithm are analyzed. The approach can improve the correctness and flexibility for Web services composition and satisfy the local QoS attribute.