基于旅行计划图的移动Agent迁移策略研究

移动Agent为完成指定的任务,通常需要移动到多个主机上。迁移策略为移动Agent规划出最佳迁移路径,保证移动Agent正确、高效地完成任务。在分析现有迁移策略的基础上,提出一种基于旅行计划图的迁移策略,该迁移策略能根据当前网络的软硬件环境和其他负载信息,利用服务评估为移动Agent动态地规划出一条最佳迁移路径,充分体现了移动Agent的自主性和反应性。该策略还可避免网络断连、主机故障及服务失效引起的迁移失败。     

基于支持向量机的移动Agent迁移策略

迁移策略为移动Agent规划出最佳迁移路径，保证移动Agent正确、高效地完成任务。文章分析了现有移动Agent系统中采用的几种代表性迁移策略，提出了基于支持向量机的移动Agent迁移策略。模拟实验结果表明，与其它迁移策略相比该策略能够以较大的概率得到最优的结果，从而验证了算法的有效性和可行性。     

分布式检索系统中基于蚁群的移动agent动态迁移算法*

以真实蚁群算法为基础,提出了一种分布式信息检索下的移动agent动态迁移算法。该算法有如下特点：a）Agent能根据当前主机的状态,自主选择下一个负载轻的主机移动;b）Agent能找到一条开销最小的路径移动。仿真结果表明,该算法与固定路由算法相比,性能提高80%以上,并且算法无须依赖集中的迁移模块。蚁群算法分布在各节点中,提高了系统的容错性,具有分布、并行的特点。     

基于旅行图的移动Agent迁移策略

移动Agent为完成用户指定的任务，通常需要移动到多个主机上．迁移策略为移动Agent规划出最佳迁移路径，保证移动Agent正确、高效地完成任务．提出了“旅行图”的概念并给出了基于“旅行图”的3种迁移策略．旅行图能描述移动Agent的移动语义并能刻画运行环境的动态变化．载有“旅行图”的移动Agent感知运行环境的变化，及时反应并自主修改迁移路线，按照预先设定的指标完成任务，充分体现了Agent的反应性和自主性．基于“旅行图”的迁移策略还可避免由网络断连或结点失效导致的迁移失败．     

移动Agent系统中的迁移策略及其关键技术

本对移动Agent技术进行了较详细的论述，在提出了如何利用移动Agent迁移策略的同时，给出了迁移路径的算法，这其中重点阐述了队列管理机制，缓冲管理机制，Java的动态迁移机制。     

一种改进的基于迁移计划图的移动Agent迁移策略*

在分析了现有迁移策略的基础上,提出一种改进的基于迁移计划图的结构化迁移策略。该迁移策略能根据当前网络的软硬件环境及其他负载信息,在满足预算约束条件下考虑服务质量和服务价格等因素,动态地为移动Agent规划出一条最佳迁移路径;该策略还能避免网络断连、主机故障及服务失效引起的迁移失败。     

一种基于移动Agent的迁移路由的研究

目前的移动Agent迁移机制的诸多路由算法对迁移过程的关键特性提及较少。本文在AntNet算法基础上分析了三个重要的特性，即移动Agent找到目标主机成功的概率，在搜寻目标主机过程中根据每个请求产生的Agent的数量，以及每个Agent迁移的跳数。通过分析得出的结论，可以在算法中加入调节参数，来适度调节和控制每个请求产生的Agent数量和每个Agent可以迁移的跳数，来有效地提高迁移成功率，减少网络计算资源的消耗。     

改进的蚁群算法在求解旅行Agent问题中的应用

蚁群算法作为一种新的生物进化算法，具有并行、正反馈和启发式搜索等特点，但它与其它进化算法同样存在易于陷入局部最小点等缺陷。为了克服这些缺陷，介绍了一种改进的蚁群算法来求解旅行Agent问题，解决移动Agent为完成用户指定任务，在不同主机间移动时的迁移策略问题。实验结果表明了算法的可行性。     

基于任务权重蚁群算法在Agent迁移中的应用

针对移动Agent在路径迁移的问题,提出了基于Agent任务权重的改进蚁群算法。该方法是将Agent任务权重的思想应用到蚁群路径信息素的更新当中,使任务权重较大的Agent有权去更新所经过的路径上的信息素,从而提高该算法的全局搜索能力。实验结果表明,相比现有的Agent迁移中路径选择的蚁群算法,提出的改进蚁群算法,在提高该算法的搜索全局最优解的能力的基础上,能更好地提高多任务的Agent系统的运行效率。     

.Net平台上Agent移动的实现技术研究

移动Agent是一个能在异构网络中自主地从一台主机迁移到另一台主机,并可与其他Agent或资源交互的程序。移动性是移动Agent区别于其他软件的重要特性之一,要实现移动Agent平台或者开发移动Agent的相关应用,首先需要解决代码移动这个关键问题。在研究了．Net平台上序列化、网络编程、多线程等相关技术后。本文提出了实现Agent移动性的解决方案并给出了实现的方法。该特性的实现为．Net平台上开发移动Agent应用奠定了基础。     

移动Agent在网格中的路径优化算法研究

用移动Agent作为访问网格服务的任务载体,代表服务或者应用程序在各种网格服务间智能地移动,能充分发挥移动Agent的优势,达到提高效率、减少开销的目的.因为网格环境具有自己的特点,因此提出了动态市场旅行商问题（TSP）模型来充分描述移动Agent在网格环境中行为方式,以及移动Agent在该模型中的路径优化算法,这对于指导不同类型移动Agent在网格中的路径选择是很有实用价值的.     

WSN中改进蚁群算法求解移动代理问题*

关于求解无线传感器网络中移动代理迁移路径问题,在蚁群系统基础上对蚁群算法进行改进,使算法更适用于无线传感器网络环境。从大量初始化路径中选出部分最优路径留下信息素,而且考虑节点的剩余能量,从而引导蚂蚁选择不同的路径;同时,针对无线传感器网络节点通信能力有限的特点,为了避免无效路径的产生引入变异操作。理论分析和仿真实验表明,改进后的蚁群算法增强了算法的全局搜索能力并有效求解无线传感器网络移动代理迁移路径问题。     

一种改进的移动Agent通信算法

如何实现远程Agent通信的位置透明性，保证消息不会因为目标Agent迁移而丢失，一直是移动Agent通信所面临的难题，在现有的很多移动Agent系统中都没有得到解决，作者在Mogent系统中提出的通信算法初步实现了通信的位置透明和可靠的消息传输，该文在原有处的基础上提出了一种改进的适于多种迁移和通信模式的移动Agent通信算法，进一步减少了Agent的地址注册开销和迁移受到的限制，并给出了一种避免地址欺骗攻击的解决方案。     

Reliable Communication for Highly Mobile Agents

The provision of a reliable communication infrastructure for mobile agents is still an open research issue. The challenge to reliability we address in this work does not come from the possibility of faults, but rather from the mere presence of mobility, which complicates the problem of ensuring the delivery of information even in a fault-free network. For instance, the asynchronous nature of message passing and agent migration may cause situations where messages forever chase a mobile agent that moves frequently from one host to another. Current solutions rely on conventional technologies that either do not provide a solution for the aforementioned problem, because they were not designed with mobility in mind, or enforce continuous connectivity with the message source, which in many cases defeats the very purpose of using mobile agents.In this paper, we propose an algorithm that guarantees delivery to highly mobile agents using a technique similar to a distributed snapshot. A number of enhancements to this basic idea are discussed, which limit the scope of message delivery by allowing dynamic creation of the connectivity graph. Notably, the very structure of our algorithm makes it amenable not only to guarantee message delivery to a specific mobile agent, but also to provide multicast communication to a group of agents, which constitutes another open problem in research on mobile agents. After presenting our algorithm and its properties, we discuss its implementability by analyzing the requirements on the underlying mobile agent platform, and argue about its applicability.     

Protecting Mobile Web-Commerce Agents with Smartcards

Mobile agents add a new communication paradigm to traditional network communication mechanisms. So far, the pervasiveness of publicly available mobile agent platforms is not given. Offering a seamless integration of mobile agents into the WWW is crucial for the success of mobile agents. One of the growing fields of interest in the Web is the area of electronic commerce. Mobile Web-commerce agents could play a prominent role in future electronic commerce scenarios, if the malicious host problem could be solved. Our paper describes the integration of mobile agents into the Web and the use of Java cards to allow mobile agents to store and securely transport data. This is achieved by allowing the agents to carry encrypted code parts which can only be decrypted by the Java card attached to the target host of the next migration.     

油气工程师助手（PDA）移动代理平台的研究与实现

移动计算被认为是对未来最有影响的四大技术方向之一,它使得计算机或其他信息设备在没有与固定的物理连接设备相连的情况下能够传输数据,将有用、准确、及时的信息能提供给在任何时间、任何地点需要它的任何用户。而移动代理是唯一能满足移动计算全部要求的体系框架。为了更好地支持便携式设备上Microsoft的WinCE平台的移动计算,设计了一个基于C＋＋的支持Windows操作系统的企业用移动代理系统——WinMAS,首次提出了基于编译性语言上的新移动代理迁移机制——利用RPC的序列化和远线程插入机制。     

Ant-based survivable routing in dynamic WDM networks with shared backup paths

In this paper, we consider the problem of survivable routing in dynamic WDM networks with single link failure model. Our work mainly concerns in how to dynamically determine a protection cycle (i.e., two link-disjoint paths between a node pair) to establish a dependable lightpath with backup paths sharing. This problem is identified as NP-complete, thus a heuristic for finding near optimal solution with reasonable computation time is usually preferred. Inspired from the principle of ant colony optimization, we propose in this paper an ant-based mobile agents algorithm for this problem with improved blocking performance. To enable the new ant-based algorithm, we propose to use on each network node both a routing table that contains a set of feasible protection cycles between source destination nodes and also a pheromone table for mobile agents. By keeping a suitable number of mobile agents in a network to continually and proactively update the routing tables based on the current network congestion state, the routing solution of a connection request can be obtained with a reasonable computation time. Extensive simulation results upon the ns-2 network simulator and two typical network topologies show that our new algorithm can achieve a significantly lower blocking probability than the promising algorithm for dynamic lightpath protection proposed in [11] with a comparable computation complexity.     

一种基于指向路径分次删剪的移动Agent通信算法

在移动agent环境下，agent的移动为应用程序的开发提供了更灵活的通信处理方式，但也同时对通信算法的设计提出了许多挑战，其中最突出的就是由于消息传输和agent移动之间的异步性而造成的通信不可靠问题。针对目前解决该问题的各种机制和算法的不足之处，该文提出了一种新的agent通信算法——S—COMP，它综合采用了Home寻址、途经节点转发、指向路径分次删剪和集中同步等手段，能够适应具有不同移动和通信特点的agent的通信需要，在确保消息传输可靠性的同时兼顾了效率和适应性。     

GCS-MA: A group communication system for mobile agents

Reliable messaging is a key component necessary for mobile agent systems. Current researches focus on reliable one-to-one message delivery to mobile agents. But how to implement a group communication system for mobile agents remains an open issue, which is a powerful block that facilitates the development of fault-tolerant mobile agent systems. In this paper, we propose a group communication system for mobile agents (GCS-MA), which includes totally ordered multicast and membership management functions. We divide a group of mobile agents into several agent clusters, and each agent cluster consists of all mobile agents residing in the same sub-network and is managed by a special module, named coordinator. Then, all coordinators form a ring-based overlay for interchanging messages between clusters. We present a token-based algorithm, an intra-cluster messaging algorithm and an inter-cluster migration algorithm to achieve atomicity and total ordering properties of multicast messages, by building a membership protocol on top of the clustering and failure detection mechanisms. Performance issues of the proposed system have been analysed through simulations. We also describe the application of the proposed system in the context of the service cooperation middleware (SCM) project.