A Query Routing Approach Based on Users’ Satisfaction for Resource Discovery in Service-Oriented Networks

Service oriented networks are distributed computing infrastructures that provide widely distributed resources. These networks are dynamic and their size and complexity continue to increase and allow to users a ubiquitous access to available resources and services. Therefore, efficient query routing approaches in large and highly distributed service oriented networks are required and need to be adaptive in order to cope with a dynamically changing environment. In this paper, a query routing approach based on mobile agents and random walks with a reinforcement learning technique is presented. By enhancing random walks with a reinforcement learning mechanism centered on users’ satisfaction, this approach allows dynamic and self-adaptive location of required resources. Peers incorporate knowledge from past and present queries which will be used during next searches by mobile agents to select their next hops. This approach is analyzed through two query routing techniques using the network simulator ns2.     

MAWS: A platform-independent framework for mobile agents using Web services

This paper proposes a framework for a multiplatform mobile agent system based on Web services. The framework includes a mobile agent factory, the mobile agents, and the host Web services. The mobile agents are created at the factory, migrate between Web services-enabled hosts, and execute at the destination hosts through invocation by XML-RPC. The transfer of mobile agents is accomplished through the employment of SOAP attachments where service handlers are used at the source and destination hosts to attach and detach agent files, respectively. The framework was implemented using the Java Web Service Developer Pack (JWSDP) and tested on 20 Linux and Windows hosts within a Wide Area Network (WAN). The system worked seamlessly on all designated hosts (proving interoperability) while comparing well in terms of throughput to three well-known mobile agent systems, namely, Voyager, Aglets, and Concordia. This paper demonstrates how the proposed system can interoperate with existing systems and serve as a model for interoperability among them. The paper also illustrates how the mobile agent can be secured against confidentiality and integrity attacks during transport and suggests ways for protecting it from malicious hosts as well as guarding hosts from malicious agents.     

一个基于Java的Mobile Agent安全体系结构模型

与早期分布式计算的范例比较Mobile Agent变得日益流行,但是阻碍其广泛应用的主要原因是与移动代码相伴而来的安全问题.这就要求Mobile agent系统提供一种机制,来完成对服务器资源的访问控制以及保证通信的安全性,并对Mobile Agent自身的进行保护.文章提出了一个基于Java的安全体系结构模型,该模型通过创建资源代理来实现安全策略,为基于Java的Mobile Agent系统提供了一个统一的安全服务接口.     

一个基于CORBA和移动智能体的分布式网箱集成框架

文中分析了当前主流网管系统在体系结构上的缺陷,阐述了分布对象技术（CORBA）与移动智能体技术各自在网管领域的应用方法与优势。结合这些优势,给出了一个基于CORBA和移动智能体的分布式网管集成框架,并进一步通过实验模拟证实了其可行性。     

Integrate software agents and CORBA in computational grid

This paper presents an Agent-based Computational Grid (ACG), which applies the concept of CORBA and agent to computational grid. The ACG system is used to implement a uniform higher level management of the computing resources and services on the Grid, and provide users with a consistent and transparent interface for accessing such services. In ACG grid, grid services are implemented by CORBA or by grid agent. Grid agents and CORBA objects will interact with each other to achieve user's service request. Our solution is the creation of a bridge between the CORBA and grid agents. The solution provides with the opportunity of considering an agent as a CORBA service and accessing CORBA services even from a grid agent. Thus, in AGC grid, existing legacy systems can be easily exploited as grid services. In this paper, firstly, the features of ACG grid are described, and then the design and implementation are given. Finally, some conclusions are given.     

服务Agent的设计与实现

将Web服务与Agent相结合代表了Web技术的发展方向之一。服务Agent能够管理一组密切相关的Web服务,并智能化地向外界提供综合的、集成的服务功能。服务Agent的能力建立在内部定义的一组规划基础上。在BDIAgent的基础上,本文提出了一种服务Agent的结构定义;提出了基于目标规划的语义模型和基于ECA规则规划的语法模型,用以进行基于事件驱动的规划选择和执行;实现了支持服务Agent建模的可视化工具;最后介绍一个应用实例。     

MobiPADS: a reflective middleware for context-aware mobile computing

Traditionally, middleware technologies, such as CORBA, Java RMI, and Microsoft's DCOM, have provided a set of distributed computing services that essentially abstract the underlying network services to a monolithic "black box." In a mobile operating environment, the fundamental assumption of middleware abstracting a unified distributed service for all types of applications operating over a static network infrastructure is no longer valid. In particular, mobile applications are not able to leverage the benefits of adaptive computing to optimize its computation based on current contextual situations. In this paper, we introduce the Mobile Platform for Actively Deployable Service (MobiPADS) system. MobiPADS is designed to support context-aware processing by providing an executing platform to enable active service deployment and reconfiguration of the service composition in response to environments of varying contexts. Unlike most mobile middleware, MobiPADS supports dynamic adaptation at both the middleware and application layers to provide flexible configuration of resources to optimize the operations of mobile applications. Within the MobiPADS system, services (known as mobilets) are configured as chained service objects to provide augmented services to the underlying mobile applications so as to alleviate the adverse conditions of a wireless environment.     

基于增强现实技术的移动LBS系统的设计与实现

基于位置服务发展迅速,利用增强现实技术开发LBS系统,对人机界面与GIS服务整合具有重要的理论和现实意义。在此基础上,设计一个空间信息服务的构建与发布机制,利用智能终端配备的传感装置,在Android平台手持设备下扩展增强现实功能,融合真实场景和虚拟信息,搭建远程Web服务器完成数据交互,得到整体基于Web服务的LBS原型系统。     

移动对等直播流媒体系统的服务质量保证机制研究

随着移动网络及移动智能终端的发展和日益普及,移动对等(P2P)网络流媒体方面的研究已成为当前的热点。然而,P2P流媒体的移动化面临两大问题,一是流媒体的差异化服务,二是终端移动过程中的服务质量保证。针对终端的差异性,本文提出了自适应多码率服务的思想,在一个P2P节目流拓扑中,发布多个子流,用户根据自己的网络状况和能力,缓冲全部或者部分子流,并根据网络环境的变化,动态地改变自身缓冲和播放的流,为邻居节点提供差异化的服务;同时提出了一种跨域移动服务质量保证机制,包括数据预缓存、数据暂存等策略。实验证明上述方法能有效提高移动对等直播流媒体系统的服务质量。     

构件化移动agent创建方法研究

分析了Client/Server中C/S结构与B/S结构,指出两种结构都不适用于移动agent。提出了一种构件化移动agent创建方法。采用程序变换技术,将移动agent体系结构分为本体体系结构和虚拟体系结构。本体体系结构表达移动agent实现特性,虚拟体系结构表达移动agent接口特性。最后,文章给出了一个移动agent体系结构,表明该文提出的创建方法在实践上确实可行、有效,较好地解决了上述结构的不足。     

Experiences in developing mobile applications using the Apricot Agent Platform

The trend of increasing mobile services has set a new challenge for service providers: how to develop more advanced and user-friendly, context-aware and personalized mobile services for the users. Apricot Agent Platform is an agent-based software platform designed for developing context-aware and personalized mobile services. Apricot Agent Platform supports the development of user-friendly mobile services by providing tools for combining various mobile and Internet-based services. Apricot agent architecture consists of an agent platform, agents and agent containers. For the developers of mobile services, it provides built-in functionality and communication mechanism. Furthermore, this paper describes four demonstrators that are built up on the Apricot Agent Platform to evaluate the usability and efficiency of the platform in the processes of building mobile services. The outcome of the evaluation indicates relatively promising results and the further target for development is revealed.     

基于增强现实技术的移动LBS系统的设计与实现

基于位置服务发展迅速。利用增强现实技术开发LBS系统．对人机界面与GIS服务整合具有重要的理论和现实意义。在此基础上,设计一个空间信息服务的构建与发布机制．利用智能终端配备的传感装置,在Android平台手持设备下扩展增强现实功能．融合真实场景和虚拟信息,搭建远程Web服务器完成数据交互,得到整体基于Web服务的LBS原型系统。     

Distributed directory service and message routing for mobile agents

Research about networks and agents has identified the need for a layer that provides a uniform protocol to communicate with fixed and mobile agents. In order to preserve the compatibility with existing infrastructures, proposed solutions have involved a “home agent”, which forwards messages to a mobile entity. The mechanism of a home agent puts a burden on the infrastructure, which may hamper the scalability of the approach, in particular, in massively distributed systems, such as the amorphous computer or the ubiquitous/pervasive computing environment. Free from any compatibility constraint, we have designed an algorithm to route messages to mobile agents that does not require any fixed location. The algorithm has two different facets: a distributed directory service that maintains distributed information about the location of a mobile agent, and a message router that uses the directory service to deliver messages to a mobile agent. Two properties of the algorithm were established. Safety ensures that messages are delivered to the agent they were aimed at, whereas liveness guarantees that messages eventually get delivered. A mechanical proof of the properties was carried out using the proof assistant Coq.     

Stochastic modeling and analysis of hybrid mobility in reconfigurable distributed virtual machines

Virtualization provides a vehicle to manage the available resources and enhance their utilization in network computing. System dynamics requires virtual machines be distributed and reconfigurable. To construct reconfigurable distributed virtual machines, service migration moves the runtime services among physical servers when necessary. By incorporating the mobile agent technology, distributed virtual machines can improve their resource utilization and service availability significantly. This paper focuses on finding the optimal migration policies for service and agent migrations for high throughput in reconfigurable distributed virtual machines. We analyze three issues of this decision problem: migration candidate determination, migration timing and destination server selection. The service migration timing and destination server selection are formulated by two optimization models. We derive the optimal migration policy for distributed and heterogenous systems based on stochastic optimization theories. Renewal processes are applied to model the dynamics of migration. We solve the agent migration problem by dynamic programming and extend the optimal service migration decision by considering the interplay of the hybrid mobility. We verify the accuracy of our migration decision policy in simulations.     

多主体系统中基于本体论的服务相容匹配机制

利用本体论的表示能力,提出了基于本体论的主体服务匹配机制;通过自定义的领域概念化语言,描述领域概念集合以及概念的分类体系,在此基础上完成对主体服务的描述.以概念相容度为依据,提出主体服务语义相容度的概念,给出了主体服务匹配的策略和算法,并通过一个例子描述了主体服务的匹配过程,讨论了其相关的实现环境.