基于面向对象程序的类动态更新研究

从理论和实际2个方面出发，对面向对象程序动态更新的不同侧面进行研究，提出解决面向对象程序动态更新的方法。引入动态更新事务的概念，既克服了面向对象程序更新只能对类实行一些简单更新的限制，又保证了更新的类型安全性。对于Java程序设计，提出一种可动态更新程序的Java设计方法。实验结果表明，该方法是有效可行的。     

基于FJ的多版本类动态更新演算

针对面向对象软件在动态更新中遇到类型安全问题,定义了一个多版本类的动态更新演算(MCUFJ演算(multi-version class dynamic updamble calculus based on FJ calculus))来描述类动态更新.MCUFJ演算以FJ(featherweight Java)演算为核心,通过增加update操作表示类的动态更新,运用多版本技术使动态更新可以在保持新旧对象共存的情况下完成,讨论了类的数据域和方法进行增加、删除、修改以及类型变化对程序类型安全性的影响,并且指出MCUFJ上类型安全的动态更新需要满足的约束.定义了类的可动态更新限制,并且证明了在该条件下多版本类的动态更新在类型上的安全性.该演算可以用于指导Java语言和面向对象程序语言的类动态更新.     

基于FP_tree的最大频繁项目集增量式更新算法

关联规则的更新是数据挖掘研究的一个重要内容,能否有效地挖掘出动态事务数据库中的最大频繁项目集是衡量一个关联规则更新算法好坏的关键因素。提出基于FP_tree的最大频繁项目集增量式更新(MFIUP)算法,以处理最小支持度和事务数据库同时发生变化之后相应频繁项目集的更新问题,其中事务数据库的变化同时包括增加和减少两种情况,并对其优越性进行了分析和测试。     

动态规划法在设备更新问题中的应用

在日常工作中,经常涉及到设备更新问题,如何求解设备更新问题非常重要。于是阐述了动态规划方法的基本思想,求解设备更新问题的步骤,并用具体实例和程序,说明了动态规划求解设备更新问题的可行性。     

基于频繁模式树的关联规则增量式更新算法

研究了大型事务数据库中关联规则的增量式更新总是，提出了一种基于频繁模式树的关联规则增量式更新算法，以处理最小支持度或事务数据库发生变化后相应关联规则的更新问题，并对其性能进行了分析。     

事务控制的面向服务系统的动态更新协调

就面向服务的分布式系统中多服务动态更新的协调问题,提出基于事务控制的更新协调策略,包括安全更新时机的选择策略、使用2PC(two-phase-commit)协调多服务更新的控制策略.根据更新实施的各步操作时间开销,提出分别采用更新短事务控制基本更新操作(包括创建服务实例、顺序实施运行时状态转换、重定向服务请求和新服务的...     

用于构件动态更新的状态传递方法

研究构件动态更新的关键问题――新旧构件实例间的状态传递。根据类的不同改变方式,提出一种不修改虚拟机的对象动态替换方法,有效地控制改变蔓延,并设计了状态传递算法和实验系统,借助Java虚拟机的类装载机制和反射机制,实现了构件实例间的状态 传递。     

一种基于事务时间分割的关联规则增量式更新方法

文章介绍了一种增量式关联规则更新方法,其核心思想是,将长事务以时间分割,分成一个连续的情节集合,当前情节期间获得的信息,依赖于当前的事务子集以及前面情节期间已经发现的信息。仅使用更新的事务和前面阶段的挖掘结果,增量式地产生频集。用Apriori类算法作为局部过程来产生频集,给出了具体的动态挖掘算法。     

关联规则挖掘中增量式更新算法的研究

关联规则的更新是数据挖掘技术中的一个重要内容,能否有效地挖掘出动态事务数据库中的频繁项目集或关联规则是衡量一个算法好坏的关键因素。该文系统地介绍了关联规则的增量式更新问题,给出或提出了相应的算法,并举例说明了算法的执行过程。     

演绎对象数据库SD-DOOD系统更新的设计与实现

SD-DOOD是一个演绎对象数据库实验系统。论文主要是设计并实现了系统的动态更新数据库功能,文中首先给出了详细的实现更新的算法,进而对算法进行了简单分析,最后通过举例说明了这个功能。系统中采用自底向上和自顶向下相结合的更新方式,增强了系统的安全性。     

Research on dynamic update transaction for Java classes

Dynamic software updating is critical for many systems that must provide continuous service. In addition, the Java language is gaining increasing popularity in developing distributed systems. Most previous works on updating are concerned with safely updating one class every time. It has many limitations on updating classes, such as not allowing deleting methods invoked in other classes. In this paper, the update transaction is purposed to dynamically update the class set, and some of its properties are discussed, such as atomicity, consistency, isolation, and durability (ACID). Then the property of type-safety is proven formally. In order to update without changing the Java Virtual Machine (JVM) and the Java programming language, this paper proposes a new implementation method. The method makes use of the Java class loading mechanism and reflection mechanism. We also present how to design an updatable Java program and a Java updating program. At the end of the paper, an experiment is made for analysis.     

使用Java编写Oracle触发器的实现

数据库触发器是响应插入、更新和删除等数据库事件而执行的过程。本文详细叙述了Oracle触发器的功能及应用场合,并以一个实例示范用Java创建Oracle9i触发器的全过程。文尾给出了用Java开发不依赖具体数据库的稳固的触发器代码的思路。     

虚拟实验室中用户注册组件的设计与实现

针对基于组件的虚拟实验室中，开发和更新实验组件工作量大的问题，设计并实现了通过用户的参与来扩充实验室功能的方案。综合运用Applet签名技术、Java RMI技术、运行时动态编译技术、Java的反射工具，以及JAXP的更新XML文档技术，实现了用户向虚拟实验系统添加自己构建的实验组件，并通过系统的注册后在Internet上发布的功能，使虚拟实验室易于扩充，参与性更强。     

cwinOSGi:Windows平台下基于C++的OSGi框架设计与实现

OSGi(Open Service Gateway Initiative)服务平台规范定义了一个开放的一般性架构,为网络服务、软件的开发和部署提供一致性的协作环境,其核心是提供一个通用、安全并且可管理的Java框架.OSGi规范本身利用了Java语言的特性,非常适合用Java实现.但其Java实现对系统资源的消耗较大并且运行时依赖Java虚拟机环境(JVM),不适合在系统资源较少和未安装JVM的环境中使用,例如移动设备.本文在分析OSGi框架原理的基础上,提出了一种轻量级的Windows平台下基于C++的OSGi框架实现方案--cwinOSGi,重点解决了组件的打包方式、加载方法、组件间的可见性及动态更新等关键技术问题,实现了OSGi模型的主要功能.实验证明,与OSGi框架的Java实现相比,cwinOSGi的系统资源需求大幅降低,具有更广的适应性.     

Comprehensive aspect weaving for Java

Aspect-oriented programming (AOP) has been successfully applied to application code thanks to techniques such as Java bytecode instrumentation. Unfortunately, with existing AOP frameworks for Java such as AspectJ, aspects cannot be woven into the standard Java class library. This restriction is particularly unfortunate for aspects that would benefit from comprehensive aspect weaving with complete method coverage, such as profiling or debugging aspects. In this article we present MAJOR, a new tool for comprehensive aspect weaving, which ensures that aspects are woven into all classes loaded in a Java Virtual Machine, including those in the standard Java class library. MAJOR includes the pluggable module CARAJillo, which supports efficient access to a complete and customizable calling context representation. We validate our approach with three case studies. Firstly, we weave existing profiling aspects with MAJOR which otherwise would generate incomplete profiles. Secondly, we introduce an aspect for memory leak detection that also benefits from comprehensive weaving. Thirdly, we present an aspect subsuming the functionality of ReCrash, an existing tool based on low-level bytecode instrumentation techniques that generates unit tests to reproduce program failures. Our aspect-based tools are concisely implemented in a few lines of code, and leverage MAJOR and CARAJillo for comprehensive aspect weaving and for efficient access to calling context information.     

基于Java的大规模分布式系统的升级模型

本文分析了大规模分布式系统升级中存在的问题,给出了一种通用性的系统模型,并对模型中的基于BT的文件共享、系统的类动态加载、Java系统更新等关键技术进行了分析,最后总结了该模型的特点。     

Scripting JAX-WS [JavaScript]

This article describes an integration of the ECMAScript programming language commonly known as JavaScript, with an implementation of the Java API for XML Web services (JAX-WS) 2.0. The JAX-WS 2.0 specification - the new version of the for XML-Based RPC (JAX-RPC) defines standard APIs and approaches for building Java-based Web services. As its name implies, JAX-RPC was concerned mostly with how to implement RPC-oriented Web services in Java. JAX-WS expands and improves on the specification in several ways, including tying together and updating its sup port for several base Web services specifications, such as SOAP 1.2; providing a coherent design for using Java annotations to specify Web services metadata; providing support for document-oriented Web services, asynchronous services, and services that use transports other than HTTP; addressing implementation issues surrounding handlers, which are interceptors that provide hooks into message flows between senders and receivers; and describing practices for dealing with versioning in Web services.     

An update calculus for expressing type-safe program updates

The dominant share of software development costs is spent on software maintenance, particularly the process of updating programs in response to changing requirements. Currently, such program changes tend to be performed using text editors, an unreliable method that often causes many errors. In addition to syntax and type errors, logical errors can be easily introduced since text editors cannot guarantee that changes are performed consistently over the whole program. All these errors can cause a correct and perfectly running program to become instantly unusable. It is not surprising that this situation exists because the “text-editor method” reveals a low-level view of programs that fails to reflect the structure of programs.We address this problem by pursuing a programming-language-based approach to program updates. To this end we discuss in this paper the design and requirements of an update language for expressing update programs. We identify as the essential part of any update language a scope update that performs coordinated update of the definition and all uses of a symbol. As the underlying basis for update languages, we define an update calculus for updating lambda calculus programs. We develop a type system for the update calculus that infers the possible type changes that can be caused by an update program. We demonstrate that type-safe update programs that fulfill certain structural constraints preserve the type correctness of lambda terms. The update calculus can serve as a basis for higher-level update languages, such as for Haskell or Java.     

基于JDBC的数据库访问优化策略研究

JDBC是一种用于执行SQL语句的Java API。首先简要分析了JDBC访问数据库的机制,通过剖析访问和操作技术,结合实例,提出了改善数据库访问效率和安全性的优化策略。