Transparent migration of Java-based mobile agents: Capturing and re-establishing the state of Java programs

In this paper we describe a way to save and restore the state of a running Java program. We achieve this on the language level, without modifying the Java virtual machine, by instrumenting the programmer's original code with a preprocessor. The automatically inserted code saves the runtime information when the program requests state saving and re-establishes the program's runtime state on restart. The current preprocessor prototype is used in a mobile agent scenario to offer transparent agent migration for Java-based mobile agents, but could generally be used to save and re-establish the execution state of any Java program.     

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.     

Mobile agents for World Wide Web distributed database access

The popularity of the Web as a universal access mechanism for network information has created the need for developing Web-based DBMS client/server applications. However, the current commercial applet-based approaches for accessing database systems offer limited flexibility, scalability, and robustness. We propose a new framework for Web-based distributed access to database systems based on Java-based mobile agents. The framework supports lightweight, portable, and autonomous clients as well as operation on slow or expensive networks. The implementation of the framework using the aglet workbench shows that its performance is comparable to, and in some case outperforms, the current approach. In fact, in wireless and dial-up environments and for average size transactions, a client/agent/server adaptation of the framework provides a performance improvement of approximately a factor of ten. For the fixed network, the gains are about 40 percent and 30 percent, respectively. We expect our framework to perform even better when deployed using different implementation platforms as indicated by our preliminary results from an implementation based on Voyager     

基于XML的异构环境的Mobile Agents架构

移动Agent技术是集软件Agent技术、移动代码技术、分布式对象技术于一体的技术.移动Agent的编程语言限制了Agent平台的执行环境.然而由于java虚拟机的出现,Java的程序可以不需重新编译,就进行迁移.但是java的移动代理也需要架设平台上有java虚拟机的环境.为了实现一个真正的异构环境的系统,使用基于XML的移动Agent架构,即使用基于XML的移动Agent代码、使用UDDI技术来为Agent注册和查询、Web Services技术来进行通信.它更容易在异构的系统环境中相互通信和操作并更容易实现和在各种环境中得到运用.     

Java连接数据库SQL Server 2005

Java是全球使用广泛的一门网络编程语言,当今许多系统都是用Java语言进行编写的;SQL Server 2005是Microsoft公司推出的大型数据库系统,现在在一些大中型系统中有着广泛的使用,它的编程接口非常丰富、易用,提供了JDBC编程接口。在基于Java的软件系统中通过加载JDBC驱动和相关jar包,既可以实现在Java编程中连接SQL Server,也可通过连接池来连接SQL Server数据库。     

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。     

An accelerator design for speedup of Java execution in consumer mobile devices

In today’s consumer electronics market, Java has become one of the most important programming languages for the rapid development of mobile applications – spanning from home appliances/controllers, mobile and communication devices, to network-centric applets. However, the demand for high-performance low-power Java-based consumer mobile applications puts forward new challenges to the system design and implementation. This paper analyzes the energy consumption, execution efficiency, and speed issues of Java applications in a typical consumer mobile device environment. By adopting a hardware-assisted approach, we introduce a Java accelerator with a companion Java virtual machine. The accelerator is designed in an asynchronous style, and can be integrated with most existing processors and operating systems. The core architecture, design philosophy, and implementation considerations are presented in detail in this paper.     

基于Java的移动Agent系统研究

移动Ａｇｅｎｔ技术是一门新兴的技术,具有移动性,智能性和异步计算等特点,本文介绍了移动Ａｇｅｎｔ概念,分析了一般的移动Ａｇｅｎｔ系统结构,针对Ｊａｖａ语言的特点,分析了Ｊａｖａ语言开发移动Ａｇｅｎｔ优势和几点技术解决方案。     

MAgNET: mobile agents for networked electronic trading

Electronic commerce technology offers the opportunity to integrate and optimize the global production and distribution supply chain. The computers of the various corporations, located throughout the world, will communicate with each other to determine the availability of components, to place and confirm orders, and to negotiate delivery timescales. We describe MAgNet, a system for networked electronic trading that is based on the Java mobile agent technology, called aglets. Aglets are dispatched by the buyer to the various suppliers, where they negotiate orders and deliveries, returning to the buyer with their best deals for approval. MAgNET handles the deep supply chain, where a supplier may need to contact further suppliers of subcomponents in order to respond to an enquiry. Experimental results demonstrate the feasibility of using the Java aglet technology for electronic commerce     

Java use in mobile information devices: Introducing JTRON

Using Java, next-generation mobile devices can serve as highly functionally distributed systems. The JTRON specification achieves real-time performance in Java-based mobile systems     

Mole – Concepts of a mobile agent system

Due to its salient properties, mobile agent technology has received a rapidly growing attention over the last few years. Many developments of mobile agent systems are under way in both academic and industrial environments. In addition, there are already various efforts to standardize mobile agent facilities and architectures. Mole is the first mobile agent system that has been developed in the Java language. The first version was finished in 1995, and since then Mole has been constantly improved. Mole provides a stable environment for the development and usage of mobile agents in the area of distributed applications. In this paper we describe the basic concepts of a mobile agent system, i.e., mobility, communication and security, discuss different implementation techniques, present the decisions made in Mole and give an overview of the system services implemented in Mole.     

Declarative language design for interactive visualization

We investigate the design of declarative, domain-specific languages for constructing interactive visualizations. By separating specification from execution, declarative languages can simplify development, enable unobtrusive optimization, and support retargeting across platforms. We describe the design of the Protovis specification language and its implementation within an object-oriented, statically-typed programming language (Java). We demonstrate how to support rich visualizations without requiring a toolkit-specific data model and extend Protovis to enable declarative specification of animated transitions. To support cross-platform deployment, we introduce rendering and event-handling infrastructures decoupled from the runtime platform, letting designers retarget visualization specifications (e.g., from desktop to mobile phone) with reduced effort. We also explore optimizations such as runtime compilation of visualization specifications, parallelized execution, and hardware-accelerated rendering. We present benchmark studies measuring the performance gains provided by these optimizations and compare performance to existing Java-based visualization tools, demonstrating scalability improvements exceeding an order of magnitude.     

Toward Automated Support for Transparent Interoperable Queries

Many Object-Oriented Databases (OODBs) use programming languages that predate Java, such as C++, CLOS and Smalltalk. Thus, there is a growing need for interoperating these OODBs with new applications that require Java. Unfortunately, there are few mechanisms that allow software developers to easily integrate Java applications with non-Java OODBs. Although various interoperability mechanisms have been developed over the years, these approaches have some significant drawbacks in practice. They are often difficult to use, provide little, if any, automated support, and produce software that is difficult to engineer and maintain. In this paper, we describe an interoperability approach that allows application developers to seamlessly and transparently access non-Java OODBs from Java applications. We first present JOQL, a Java-based object query language that we are developing. JOQL queries are embedded in Java applications and are used to perform queries over C++-based OODBs. We also describe an accompanying toolset that processes Java programs containing JOQL queries. The toolset produces all the necessary code allowing Java applications to access and manipulate a C++-based OODB. As a result, application developers are free to work in Java without having to concern themselves with the details of interoperating with C++. Finally, we provide some preliminary experimental data that demonstrates our approach incurs a reasonable performance overhead.     

Java安全机制下移动Agent系统的安全性问题

移动Agent作为分布式网络计算的一种新形式,可以降低网络传输量,异步地完成任务。但在复杂的网络环境下,移动Agent对安全性提出了特殊的要求。文中先大致介绍了移动Agent所带来的安全隐患,然后深入地研究了Java语言的安全机制,最后给出了一个安全模型的参考实现,并讨论如何结合Java的安全模型来解决移动Agent的安全性问题。虽然Java的安全模型本身存在一些不完善的地方,但随着其进一步改进,安全模型参考实现也将为移动Agent的应用提供更有力的保障。     

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.     

基于Aglet的网络学习系统

分析了移动Agent在网络学习中应用的原因和优势,阐述了基于IBM Aglet平台实现的一个网络学习系统的模型和关键技术,最后讨论了移动Agent技术在网络学习应用中所要解决的一些问题。     

Integrity protection for Code-on-Demand mobile agents in e-commerce

The mobile agent paradigm has been proposed as a promising solution to facilitate distributed computing over open and heterogeneous networks. Mobility, autonomy, and intelligence are identified as key features of mobile agent systems and enabling characteristics for the next-generation smart electronic commerce on the Internet. However, security-related issues, especially integrity protection in mobile agent technology, still hinder the widespread use of software agents: from the agent's perspective, mobile agent integrity should be protected against attacks from malicious hosts and other agents. In this paper, we present Code-on-Demand (CoD) mobile agents and a corresponding agent integrity protection scheme. Compared to the traditional assumption that mobile agents consist of invariant code parts, we propose the use of dynamically upgradeable agent code, in which new agent function modules can be added and redundant ones can be deleted at runtime. This approach will reduce the weight of agent programs, equip mobile agents with more flexibility, enhance code privacy and help the recoverability of agents after attack. In order to meet the security challenges for agent integrity protection, we propose agent code change authorization protocols and a double integrity verification scheme. Finally, we discuss the Java implementation of CoD mobile agents and integrity protection.     

AgletBlackboard：Aglets系统协同机制的扩充

随着Internet的不断发展，移动Agent技术的应用越来越广泛。实际的应用通常需要由多个移动Agent共同来完成任务，如何组织与协调移动Agent之间的行动带来了对分布式环境中移动Agent之间协同的研究。本文介绍了移动Agent的四种协同模式，并针对Aglets系统中Aglet之间通过直接协同存在的不足．设计实现了基于黑板协同模式的AgletBlackboard，进一步提高了Aglets系统的功能。     

A distributed computing system for magnetic resonance imaging: Java-based processing and binding of XML

Recently we have developed a Java-based heterogeneous distributed computing system for the field of magnetic resonance imaging (MRI). It is a software system for embedding the various image reconstruction algorithms that we have created for handling MRI data sets with sparse sampling distributions. Since these data sets may result from multi-dimensional MRI measurements our system has to control the storage and manipulation of large amounts of data. In this paper we describe how we have employed the extensible markup language (XML) to realize this data handling in a highly structured way. To that end we have used Java packages, recently released by Sun Microsystems, to process XML documents and to compile pieces of XML code into Java classes. We have effectuated a flexible storage and manipulation approach for all kinds of data within the MRI system, such as data describing and containing multi-dimensional MRI measurements, data configuring image reconstruction methods and data representing and visualizing the various services of the system. We have found that the object-oriented approach, possible with the Java programming environment, combined with the XML technology is a convenient way of describing and handling various data streams in heterogeneous distributed computing systems.