CCM中应用服务器的研究与实现

传统的构件模型依赖于特定平台的底层服务，重用程度较低。本文遵循CCM3．0规范，深入阐述了CORBA分布构件模型的基本原理及其实现方案，并将底层服务与业务逻辑分离，降低了应用开发的复杂度，并达到了二进制代码级的重用，实现了服务端程序的跨平台与可维护。     

The Self-Serv environment for Web services composition

Self-Serv aims to enable the declarative composition of new services from existing ones, the multiattribute dynamic selection of services within a composition, and peer-to-peer orchestration of composite service executions. Self-Serv adopts the principle that every service, whether elementary or composite, should provide a programmatic interface based on SOAP and the Web Service Definition Language. This does not exclude the possibility of integrating legacy applications, such as those written in CORBA, into the service's business logic. To integrate such applications, however, first requires the development of appropriate adapters. The paper considers how the mechanism for composing services in Self-Serv is based on two major concepts: the composite service and the service container.     

Business Object Modeling, Validation, and Mediation for Integrating Heterogeneous Application Systems

When different business organizations come together to conduct a joint business in a virtual enterprise environment, their application systems need to have a convenient way to specify the services needed from other systems and to transfer data needed by these services. The transferred data needs to be validated and, in some cases, mediated to meet the constraints and data representation requirements of both the source and target application systems. Ideally, the validation and mediation tasks should be done outside of the legacy application systems so that these systems do not have to be modified. In this work, the Business Object Documents (BODs) introduced by the Open Applications Group (OAG) are used for specifying business operations and transferring data among application systems. We use an active object model to model BODs. The model captures not only the data attributes and methods associated with these business objects, but also events and rules for specifying and triggering the enforcement of attribute constraints and inter-attribute constraints and the activation of data mediation operations. The conceptual models of these BODs with their added semantics are used to generate entity classes, converters and skeletal programs needed for enforcing constraints and for converting data. These generated object classes and software components in Java constitute the platform-independent adapters through which heterogeneous application systems inter-operate over CORBA and RMI communication infrastructures. A distributed approach to data validation and mediation is used. It allows the generated code for validation and mediation to be distributed and processed at different sites, thus avoiding the potential network bottleneck of a centralized approach to the validation and mediation of business object documents.     

A survey of evolutionary and embryogenic approaches to autonomic networking

The term “autonomic networking” refers to network-level software systems capable of self-management, according to the principles outlined by the Autonomic Computing initiative. Autonomicity is widely recognized as a crucial property to harness the growing complexity of current networked systems.In this paper, we present a review of state-of-the-art techniques for the automated creation and evolution of software, with application to network-level functionalities. The main focus of the survey are biologically-inspired bottom-up approaches, in which complexity is grown from interactions among simpler units. First, we review evolutionary computation, highlighting aspects that apply to the automatic optimization of computer programs in online, dynamic environments. Then, we review chemical computing, discussing its suitability as execution model for autonomic software undergoing self-optimization by code rewriting. Last, we survey approaches inspired by embryology, in which artificial entities undergo a developmental process. The overview is completed by an outlook into the major technical challenges for the application of the surveyed techniques to autonomic systems.     

Java与C/C++的结合

JNI是JDK提供的本地编程接口,它允许Java代码操作其他语言编写的应用程序和库,但调用本地方法的同时也带来了安全问题.CORBA是一个分布式的、面向对象的应用架构规范,它允许对象在异构的、分布式的环境中透明传输,从而也能实现Java与C/C＋ ＋的互操作.本文比较了JNI和CORBA两种方法的优缺点,并将CORBA应用在一个J2EE架构下的项目中,解决了项目中Java与C/C＋ ＋的交互问题.     

An extensible and lightweight architecture for adaptive server applications

Server applications augmented with behavioral adaptation logic can react to environmental changes, creating self‐managing server applications with improved quality of service at runtime. However, developing adaptive server applications is challenging due to the complexity of the underlying server technologies and highly dynamic application environments. This paper presents an architecture framework, the Adaptive Server Framework (ASF), to facilitate the development of adaptive behavior for legacy server applications. ASF provides a clear separation between the implementation of adaptive behavior and the business logic of the server application. This means a server application can be extended with programmable adaptive features through the definition and implementation of control components defined in ASF. Furthermore, ASF is a lightweight architecture in that it incurs low CPU overhead and memory usage. We demonstrate the effectiveness of ASF through a case study, in which a server application dynamically determines the resolution and quality to scale an image based on the load of the server and network connection speed. The experimental evaluation demonstrates the performance gains possible by adaptive behavior and the low overhead introduced by ASF. Copyright © 2007 John Wiley & Sons, Ltd.     

面向MDA的业务逻辑模型到代码的转换方法研究

业务逻辑自动生成是代码自动生成领域中一个匾待解决的问题。为了解决这个问题,分析了业务逻辑难于生成的原因,在MDA的基础上引入产生式规则的思想,研究PSM模型到代码的转换过程。提出一种基于产生式规则的建模方法对逻辑中业务规则及业务流程进行建横,并基于产生式系统原理,对代码生成器进行设计与实现。基于本方法实现的代码生成器,实现了业务规则及业务流程模型到代码的转换,使目标代码业务逻辑与数据分离,一定程吱上解决了业务逻辑代码自动生成问题。     

Performance comparison of CORBA and RMI

Distributed object architectures and Java are important for building modern, scalable, web-enabled applications. This paper is focused on qualitative and quantitative comparison of two distributed object models for use with Java: CORBA and RMI. We compare both models in terms of features, ease of development and performance. We present performance results based on real world scenarios that include single client and multi-client configurations, different data types and data sizes. We evaluate multithreading strategies and analyse code in order to identify the most time-consuming methods. We compare the results and give hints and conclusions. We have found that because of its complexity CORBA is slightly slower than RMI in simple scenarios. On the other hand, CORBA handles multiple simultaneous clients and larger data amounts better and suffers from far lower performance degradation under heavy client load. The article presents a solid basis for making a decision about the underlying distributed object model.     

基于Struts的Web应用开发研究

J2EE用JSP/Servlet/EJB分离网站的显示/业务/数据逻辑,但是这种简单的分离使HTML和Java强耦合在一起,显示逻辑和业务逻辑混淆不清,由此,引入了Struts框架。Struts提供了一个非常好的MVC框架,在Web应用开发中把界面和业务逻辑分离,有利于网页设计者和程序设计者的分工,提高了代码的可重用性和灵活性,便于组件式开发。文中介绍Struts概念和体系结构,阐述了Struts的工作原理,通过程序示例探讨了Struts三个主要功能模块Controller,Model,View之间的内在联系及各自的处理流程,展现了Struts能够更好帮助Java开发者利用J2EE开发大型Web应用的优势。     

面向航天器自动化测试的Web应用框架

随着Web应用系统更多的应用于企业级的关键业务，其复杂度和规模不断增加。因此，仅仅简单的使用Servlet和JSP技术已经不能满足复杂的Web应用开发的需求。解决这些问题的关键就是选择具有优良体系结构的Web应用框架。当前基于J2EE的Web应用框架都实现了MVC模式，提供了业务逻辑和表现逻辑的分离和封装以及各自的标签库，但在可扩展性和可复用性方面还有不足。针对Weh应用的需求，本文基于J2EE平台，以Struts为基础并对其进行了一定的改进和扩展，设计实现了一种新型的Web应用框架——StrutsE（Struts Extended）。该框架封装了Struts的实现细节，降低了开发复杂度，提高了开发效率，     

并发系统中谓词行为图的行为时序逻辑表达

行为时序逻辑(TLA)组合时序逻辑与行为逻辑, 可以对并发系统进行描述与验证, 它引入动作和行为的概念, 使得系统和属性可用它的规约公式表示, 但存在用TLA描述复杂系统时TLA公式复杂且难以理解的不足。类似于状态转移图, 对于并发转移可以用谓词行为图进行图形化表示, 谓词行为图与行为时序逻辑规约具有相同的表达能力。介绍行为时序逻辑的语法、语义及简单推理规则, 用一个简单的实例说明使用谓词行为图去描述并发转移系统的有效性, 并用系统规约的TLA公式对谓词行为图表达能力进行证明, 表明两者具有等价性, 为描述和分析并发转换系统提供了一种可行的方法。     

基于J2EE技术的Web应用

J2EE和DotNet框架是实现Web应用的两个极具竞争力的开发平台。J2EE技术在大型应用系统的研发过程中有重要的意义,合理的分层、采用恰当的设计模式可起到解耦和降低系统复杂度的目的。struts、hibernate、spring三个框架及中间件的结合使用实现了业务逻辑与控制逻辑的有效分离,提高了层次结构的清晰度和复用的粒度,降低了开发代价和维护代价,同时保证了软件的质量使其更具有鲁棒性和可维护性。     

EJB核心技术分析及其应用

EJB是J2EE体系结构的组件,它主要为J2EE应用程序提供业务逻辑,并与其他服务器端J2EE组件交互,业务逻辑认为与其他服务器端J2EE组件交互的特性取决于J2EE应用程序。本文以医疗管理信息系绞放计为研究背景,探讨EJB用于开发和部署商业应用程序的分布式细件模型,而这些商业应用程序通常是高度可伸缩的、事务性的和多用户安全的。     

互操作性和部件标准化接口CORBA/DCOM

本文讨论了在网络计算环境下异构分布应用的复杂性，基于部件系统的优点及部件互操作性的重要性。介绍了解决互操作性的接口技术方案的基本概念及当前两种主流标准化接口ＣＯＲＢＡ与ＤＣＯＭ的原理及结构。最后评点了国内研究中应注意的问题。     

基于WebKit浏览器的中间件系统架构

基于浏览器来构建中间件系统模型,可以使业务系统的应用部署更加灵活方便,同时也带来应用系统开发难度的降低。基于WebKit浏览器,通过增加平台访问的JavaScript接口,使应用系统构建在统一的脚本语言基础上,新的应用代码不需要编译就可以控制整个系统的行为和逻辑,是中间件应用系统模型的较好解决方案。     

基于CORBA的分布实时对象计算技术研究

随着网络化的日益普及,现有计算机系统面临着复杂和难以集成的问题．以ＣＯＲＢＡ为主流技术的分布对象计算技术简单有效地降低了非实时应用的复杂度和集成难度．但是,现有的ＣＯＲＢＡ规范无法支持分布实时环境,因此,有必要研究基于ＣＯＲＢＡ的分布实时对象计算技术．本文分析了现有ＣＯＲＢＡ的规范的实时特性缺陷,以作者设计的基于ＣＯＲＢＡ的分布实时对象软件ＯＲＢａｓｅ为例,介绍了基于ＣＯＲＢＡ的分布实时对象计算的     

基于Struts与JDO的J2EE企业应用系统架构

现有的利用JSP,Servlet和EJB开发基于J2EE企业应用系统存在着重用业务逻辑困难、开发维护效率低等缺陷。因此文中介绍了基于Struts和JDO的J2EE企业应用系统架构,此架构结合了Struts和JDO的优点,提高了开发效率,同时提高了系统的可维护性和可扩充性。Struts提供了一个优秀的MVC框架,分解商业逻辑、控制逻辑和表现逻辑的代码,提高了代码的可重用性和灵活性,便于组件式开发;JDO提供了面向对象的持久数据存储,弥补了EJB对面向对象编程的不足,提供了完全的面向对象支持。     

基于J2EE的交互式工作流管理系统

针对目前工作流系统在描述能力、跨平台能力和交互性上的不足,该文提出了一个基于J2EE技术的交互式工作流管理系统,系统使用分层描述的方法将复杂的业务过程分解为多个简单的业务过程,通过事件驱动机制来实现分解后的过程间的交互,可以完成与原来复杂过程相同的业务逻辑。实际应用表明,该系统在提高描述能力、降低建模复杂性、增强模型间交互能力及跨平台能力方面都有较明显优点。