A mobile agent platform based on tuple space coordination

This paper presents JMAP, a Java-based mobile agents platform. JMAP provides a flexible and efficient agent coordination mechanism and a reliable agent migration mechanism, and supports persistence of agent state and agent security. The unique feature of JMAP is its agent coordination mechanism that exploits the advantages of the extensible markup language (XML) and Linda-like coordination. This XML-based Linda-like coordination mechanism suits the mobility and openness of the Internet application. The XML standard for Internet data representation can guarantee a high degree of interoperability between heterogeneous environments. The design and implementation of key technologies of JMAP are described in this paper. An agent-based application example shows the suitability and the effectiveness of the JMAP. Performance evaluation is made and comparisons with other mobile agent platforms are also made. Meanwhile, some related works are discussed. Finally, some conclusions and remarks are given.     

Coordinating Mobile Agents by the XML-Based Tuple Space

This paper presents Xspace,a programmable coordination paradigm for Internet applications based on mobile agents.The Xspace system fully exploits the advantages of the XML language and Linda-like coordination.It supports XML documents as tuple fields and multiple matching routines implementing different relations among XML documents,including those given by XML query languages,The Xspace uses Java as the implementation language;it is based on object-oriented XMLized tuple spaces to implement a portable and programmable coordination paradigm for mobile agents.The dsign and implementation procedures of Xspace are described in this paper,Experiment and performance evaluation are also made.Finally,some conclusinos and remarks are given.     

Xml dataspaces for the coordination of internet agents

This article presents MARS-X, a programmable coordination architecture for autonomous and mobile Internet agents. In MARS-X, mobile Internet agents coordinate through programmable XML dataspaces, accessed by agents in a Linda-like fashion. Therefore, MARS-X enforces open and uncoupled interactions and, via XML, it offers a high degree of standard interoperability. These properties suit very well the characteristics of both mobile Internet agents and the Internet environment itself. In addition, coordination in MARS-X is made more flexible and secure by the capability of programming the behavior of the XML dataspaces by reaction to the agents' accesses. An application example related to the management of on-line academic courses shows the suitability and effectiveness of the MARS-X architecture.     

Reactive Mobility by Failure: When Fail Means Move

Mobile agent development is mainly supported by Java-based platforms and tools. However, the weak mobility model they use, the lack of adequate support for developing inference and reasoning mechanisms, added to the inherent complexity of building location-aware software, impose strong limitations for developing mobile intelligent agent systems. In this article we present MoviLog, a platform for building Prolog-based mobile agents with a strong mobility model. MoviLog is an extension of JavaLog, an integration of Java and Prolog, that allows us to take advantage of the best features of the programming paradigms they represent. MoviLog agents, called Brainlets, are able to migrate among different Web sites, either proactively or reactively, to use the available knowledge in order to find a solution. The major contribution of MoviLog is its Reactive Mobility by Failure (RMF) mechanism. RMF is a mechanism that acts when an agent needs a resource or service that is not available at the current executing site. RMF uses a distributed multi-agent system to transparently transport the executing agent to the site where the resource/service is available, thus reducing the development effort with respect to the traditional mobile agent approach, while maintaining its advantages.     

MARS: a programmable coordination architecture for mobile agents

Mobile agents offer much promise, but agent mobility and Internet openness make coordination more difficult. Mobile Agent Reactive Spaces (MARS), a Linda-like coordination architecture with programming features, can handle a heterogeneous network while still allowing simple and flexible application design     

JavaLog: a framework-based integration of Java and Prolog for agent-oriented programming

Intelligent agent development has imposed new challenges on the necessary language support. Object-oriented languages have been proposed as an appropriate tool, although logic-oriented languages are more adequate for managing mental attitudes. Multi-paradigm languages supporting encapsulation of actions, hiding of private knowledge and flexible manipulation of knowledge are, certainly, a good alternative for programming agents. However, a unique language to support flexible and efficient development of multi-agent systems confronts with the tradeoffs imposed by expressive power, efficiency and support technology. An alternative to conciliate these tradeoffs is not to think about a single language but an incrementally compatible family of agent-oriented multi-paradigm languages. In this work we present an approach based on object-oriented framework technology for integrating object and logic paradigms in such a way that new language features can be incrementally added to the core language. This core language is based on logic modules integrated as object abstractions in the object paradigm. JavaLog is a materialization of this framework integrating Java and Prolog. This core was extended to provide multi-threading support, mobility and temporal-logic operators to Prolog. MoviLog, the mobile part of the family provides a novel mobility mechanism, reactive mobility by failure, which enables virtual Prolog databases distributed across Web sites.     

基于移动Agent的智能楼宇异构数据库集成设计

提出了一个基于移动Agent的智能楼宇异构数据库集成的框架,通过将数据库记录转换成XML文档形式,以及用Java语言和Aglet平台对移动Agent的设计,为智能楼宇异构数据库的集成提供了一种新方法。     

基于共享空间的移动Agent交互

在移动agent应用环境中,agent并不是孤立地完成任务,它需要经常与其它agent交互并不断地与环境交互。而基于TupleSpace的交互模型已经被证明是最适合于移动agent环境的。该文将基于TupleSpace的交互模型进行智能性扩展,使其不仅具有反应力而且具有推理和学习能力,并将该模型作为移动agent系统中的交互媒体,支持移动agent之间、agent与系统资源间的交互。实际上,该模型松散耦合到移动agent环境,因而不仅支持交互,它还支持任何异质环境中(包括移动agent系统)的安全问题、效率问题及灵活性问题的解决。     

Engineering mobile agent applications via context-dependent coordination

The design and development of Internet applications requiring dynamic and possibly mobile access to Internet resources can take advantage of an approach based on autonomous mobile agents. However, mobility introduces peculiar issues related to the modeling and management of the agents' coordination activities. This paper introduces context-dependent coordination as a framework for the design and development of Internet applications based on mobile agents, and shows how it can be supported by a proper coordination infrastructure. Context-dependent coordination is centered on the notion of programmable coordination media, as the software abstraction via which an agent in an Internet site can access to local resources and coordinate with local agents. Programmability stems from the fact that the behavior of the media can be fully configured to influence agents' coordination activities. This enables local administrators to configure coordination media so as to enact site-dependent coordination policies, and mobile agents to configure the accessed coordination media to obtain an application-dependent behavior of the media themselves. Several application examples shows that exploiting context-dependent coordination promotes a clear separation of concerns in design and development, and can make applications more modular and easier to be maintained. The MARS system is assumed as an exemplar coordination infrastructure to clarify the concepts expressed and to show their actual implementation.     

基于XML文档的图书信息XQuery查询技术

XML与HTML相比在数据管理和格式化组织上具有更大的优越性，XQuery能够有效地查询和处理XMI文档。为了查询网上基于XML文档的图书信息，文章设计了一些统一格式的XML文档作为图书信息的数据源，利用XQuery技术，将XQuery查询程序嵌入实现格式控制的JAVA程序中，JAVA程序可以调用并运行XQuery查询程序，查询的结果保存到一个XML文件中，将查询得到的XML文档转换成需要的格式输出给用户。初步实验证明这种方法是可行的并具有较强的实用性，为实现网上基于XML文档的信息查询提供了技术基础。     

基于Java的移动Agent强迁移技术研究综述

移动Agent强迁移技术已经成为当前移动Agent研究的热点。该文对基于Java语言的移动Agent强迁移技术的若干关键问题进行了归纳和总结，简述了几个典型系统的强迁移实现方法，讨论了这些方法各自的特点。对在Java环境中实现移动Agent强迁移提出了观点和建议。     

Nomad: mobile agent system for an Internet-based auction house

The paper discusses Nomad, a mobile agent system integrated with eAuctionHouse, a next-generation Internet auction server. With the Nomad system, mobile agents travel to the eAuctionHouse site and participate in auctions on the user's behalf. Users can create agents using Java or can automatically generate agents from Nomad's template agent library     

The mobile groups approach for the coordination of mobile agents

We present the concept of mobile groups as a basic mechanism for the reliable coordination of mobile agents. Analogously to traditional group systems, mobile groups also provide message delivery guarantees and virtual synchrony. Furthermore, they make agent mobility not only visible for the group, but also consistently ordered with other group actions (such as crashes, joins, leaves, and other migrations). The mobile groups approach represents a novel mobility support mechanism, which can be used to handle reliability of mobile agents required at both, the application and system level (e.g., for coordinating distributed agents and for reliable agent migration, respectively). In this paper, we discuss the motivations for the mobile groups approach, formally define their properties, and present a membership protocol for such groups. We also discuss some implementation issues and related performance data, and present the advantages of mobile groups against mechanisms commonly employed for the coordination of mobile agents.     

Agents for information retrieval: Issues of mobility and coordination

This paper focuses on agent-based applications for information retrieval on the Web, by specifically analysing mobility and coordination issues. On the one hand, mobile agents well suit the requirements of information retrieval in the new dynamic scenario derived from the Internet. This is due to their capability of moving to the place where the information is stored – therefore saving bandwidth – and to their robustness in the presence of unreliable connections. On the other hand, the search for information by several mobile active agents calls for suitable models to rule the interactions among agents and between agents and execution environments. The paper surveys different coordination approaches and evaluates their impact in information retrieval applications based on mobile agents. The survey outlines the advantages of uncoupled coordination models and points out the suitability of a coordination model based on reactive and programmable tuple spaces: they may increase the safety and the security of the environment while simplifying the task of programming distributed mobile agent applications.     

集成XQuery功能的Xindice数据库

Xindice是一种原生XML数据库,提供了对XML的存储和管理功能.但Xindice只提供了XPath查询语言,不能灵活满足对XML的查询要求.提出了用Java语言实现XQuery的机制,并提出了将其集成到Xindice中的方法,有效地扩充了Xindice的查询功能.     

Scaling up agent coordination strategies

Deploying intelligent agents to do peoples' bidding in environments ranging from Internet marketplaces to Mars has received much attention. Exactly what an agent is and in what sense a computational agent can behave intelligently remain the subject of considerable debate. However, most would agree that coordination, an agent's fundamental capability to decide on its own actions in the context of the activities of other agents around it, is a central concern of intelligent agency. The value of an intelligent agent coordination strategy lies in how well it scales along various dimensions of stress. Understanding the agent population, its task environment, and expectations about its collective behavior are central to mapping the space of potential approaches. The paper discusses agent coordination and dimensions of coordination stress     

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.     

将Java引入TMN的两种方法

介绍了两种将Java应用于TMN的方法：一是将Java引入f参考点，以加强TMN工作站功能的性能；二是将Java引入移动代理，阐述了基于CORBA的移动代理如何增强TMN的管理功能。     

移动代理应用中上下文相关的客观协调

移动代理之间需要进行交互合作才能完成系统任务,每个移动代理也需要与它运行所在的移动代理环境进行交互。文章提出了一种在移动代理应用系统中的上下文相关的客观协调模型,适合移动代理系统中移动代理之间的交互和移动代理与移动代理环境之间的交互,它把全局的耦合交互转变成本地独立的元组空间交互,用可编程的元组空间解决由代理移动引起的上下文相关协调问题,而且环境相关的协调策略和应用相关的协调策略可以集成到可编程的元组空间中。