CORBA:全面的分布式对象计算(下)

文章是［１］的续篇,讨论ＯＲＢ和对象适配器（Ｏｂｊｅｃｔ　Ａｄａｐｔｅｒ）对服务对象的管理,及ＯＲＢｓ间的互操作性问题。并指出ＣＯＲＢＡ和ＪａｖａＢｅａｎｓ结合的趋势,最后比较ＣＯＲＢＡ与ＲＭＩ、ＤＣＯＭ的性能。     

对象管理系统

对象管理系统（Ｏｂｊｅｃｔ 　Ｍａｎａｇｅｍｅｎｔ Ｓｙｓｔｅｍ,ＯＭＳ）是集成化软件工程环境的核心和纽带,它以统一的方式管理各种对象（Ｏｂｊｅｃｔ）。文章提出了一种ＯＭＳ模型,即对象－关系－属性（ＯＲＡ）模型,并介绍了相应的对象库结构及其服务设施。     

ObjectARX 2000开发模板的定制

一、概述 ＯｂｊｅｃｔＡＲＸ ２０００是Ａｕｔｏｄｅｓｋ公司针对ＡｕｔｏＣＡＤ ２０００平台上的二次开发而推出的一个开发软件包,他支持面向对象编程,同时也兼容ＡＤＳＣ。ＯｂｊｅｃｔＡＲＸ ２０００的编译环境采用ＶｉｓｕａｌＣ＋＋６．０,使用Ｗｉｎｄｏｗｓ９８／ＮＴ。ＯｂｊｅｃｔＡＲＸ开发模板是为ＯｂｊｅｃｔＡＲＸ应用程序开发者提供的,嵌入在Ｍｉｃｒｏｓｏｆｔ ＶｉｓｕａｌＳｔｕｄｉｏ中用于修改ＯｂｊｅｃｔＡＲＸ项目的工具,主要用于Ｍｉｃｒｏｓｏｆｔ ＶｉｓｕａｌＳｔｕｄｉｏ６.０和ＯｂｊｅｃｔＡＲＸ ２…     

基于ObjectARX的ASI编程技术及应用

本文以ＡｕｔｏＣＡＤＲ１４为开发平台,讨论了基于ＯｂｊｅｃｔＡＲＸ的数据库接口（ＡＳＩ）程序设计方法及在标准件库和ＢＯＭ中的应用。     

CPDM基于CORBA/WEB的PDM

对ＰＤＭ系统产生巨大影响的两种技术──ＣＯＲＢＡ（ＣｏｍｍｏｎＯｂｊｅｃｔＲｅｑｕｉｒｅＢｒｏｋｅｒＡｒｃｈｉｔｅｃｔｕｒｅ）和ＷＥＢ,促使ＰＤＭ迈向新的台阶,ＰＤＭ作为支持并行工程的使能技术,要能够集成不同环境下的应用系统,ＣＯＲＢＡ技术的成熟为实现这一要求提供了一个较好的解决方案。南京新模式软件集成有限公司ＣＰＤＭ就是采用Ｃ＋＋和ＪａｖＳａ语言开发,系统底层基于ＣＯＲＢＡ平台,对于企业外部用户,ＣＰＤＭ将以浏览器作为统一的客户端界面。ＣＰＤＭ作为支持并行工程（ＣＥ）的使能技术,支持异构的计算…     

关于并行FFT算法

关于并行ＦＦＴ算法魏公毅，蔡中善（中国科学院计算中心）ＯＮＰＡＲＡＬＬＥＬＦＦＴＡＬＧＯＲＩＴＨＭＳ￥ＷｅｉＧｏｎｇ－ｙｉ；ＣａｉＺｈｏｎｇ－ｓｈａｎ（ＣｏｍｐｕｔｉｎｇＣｅｎｔｅｒ．ＡｃａｄｅｍｉａＳｉｎｉｃａ）Ａｂｓｔｒａｃｔ：Ｔｈｅｐａｒａｌｌ...     

ODBC与ObjectARX结合开发产品数据管理应用程序

本文首先讨论了 ＡｕｔｏＣＡＤ２０００中 ＯｂｊｅｃｔＡＲＸ ＳＤＫ的特点和编程环境及ＭＦＣ中的ＯＤＢＣ数据库开发方法,然后讨论了将二者结合起来进行 ＡｕｔｏＣＡＤ 二次开发,设计产品数据管理应用程序的方法。在 ＯｂｊｅｃｔＡＲＸ中应用ＭＦＣ,几乎可以利用ＭＦＣ的所有功能和资源,将两者的优点加以综合,大大增强了ＡＲＸ应用程序的功能。     

基于ObjextARX的ASI编程技术及应用

本文以ＡｕｔｏＣＡＤＲ１４为开发平台，讨论了基于ＯｂｊｅｃｔＡＲＸ的数据库接程序设计方法及在标准库和ＢＯＭ中的应用。     

自适应运筹滤波方法

自适应运筹滤波方法谢承迪（合肥工业大学）ＡＳＴＯＣＨＡＳＴＩＣ－ＰＲＯＧＲＡＭＭＩＮＧＭＥＴＨＯＤＯＦＡＤＡＰＴＩＶＥＦＩＬＴＥＲＩＮＧ￥ＸｉｅＣｈｅｎｇ－ｄｉ（ＨｅｆｅｉＰｏｌｙｔｅｃｈｎｉｃＵｎｉｖｅｒｓｉｔｙ）Ａｂｓｔｒａｃｔ：Ａｎｅｗａｄａｐ...     

VJ＋＋中DAO的使用

１引言 ＤＡＯ（ＤａｔａＡｃｃｅｓｓＯｂｊｅｃｔ）是Ｊｅｔ数据库引擎的程序设计接口, Ｊｅｔ 引擎是 ＭＳ ＡＣＣＥＳＳ的基础,它也作为 ＯＤＢＣ（ＯｐｅｎＤａｔａＢａｓｅ Ｃｏｎｎｅｃｔｉｏｎ）数据源的数据库驱动程序,同时是一种 ＣＯＭ（Ｃｏｍｐｏｎｅｎｔ Ｏｂｊｅｃｔ　 Ｍｏｄｅｌ）组件。在 ＶＪ＋＋中利用ＤＡＯ可以建立Ｊａｖａ与数据库的连接,并实现对数据库的各种操作ｓ。下面结合例子介绍其原理及实现过程。２实例分析 在开发“基于Ｗｅｂ的编译智能计算机辅助教学系统”的过程中,涉及到对编译领域文法的各种操作…     

基于CORBA代理防火墙研究与实现

CORBA是由国际OMG组织提出来的分布式对象系统设计规范，现已在实际工程中得到广泛应用。由于CORBA系统可在Internet环境下运行，因此，如何保证系统运行的安全性是一个必须要解决的重要问题，而防火墙是解决基于网络运行的系统安全性问题的有效手段。讨论了基于CORBA的代理防火墙的处理流程，并详细给出了基于CORBA的代理防火墙的实现技术。这一技术已被应用于已开发的分布式对象系统中。     

Simulation of resource synchronization in a dynamic real‐time distributed computing environment

Today, more and more distributed computer applications are being modeled and constructed using real‐time principles and concepts. In 1989, the Object Management Group (OMG) formed a Real‐Time Special Interest Group (RT SIG) with the goal of extending the Common Object Request Broker Architecture (CORBA) standard to include real‐time specifications. This group's most recent efforts have focused on the requirements of dynamic distributed real‐time systems. One open problem in this area is resource access synchronization for tasks employing dynamic priority scheduling. This paper presents two resource synchronization protocols that the authors have developed which meet the requirements of dynamic distributed real‐time systems as specified by Dynamic Scheduling Real‐Time CORBA (DSRT CORBA). The proposed protocols can be applied to both Earliest Deadline First (EDF) and Least Laxity First (LLF) dynamic scheduling algorithms, allow distributed nested critical sections, and avoid unnecessary runtime overhead. In order to evaluate the performance of the proposed protocols, we analyzed each protocol's schedulability. Since the schedulability of the system is affected by numerous system configuration parameters, we have designed simulation experiments to isolate and illustrate the impact of each individual system parameter. Simulation experiments show the proposed protocols have better performance than one would realize by applying a schema that utilizes dynamic priority ceiling update. Copyright © 2004 John Wiley & Sons, Ltd.     

基于CORBA的分布式多媒体服务的QoS模型

对于分布式多媒体来说,必须保证包括端系统、通讯系统以及网络在内的整个系统的服务质量（QoS）。CORBA提供了一个开放式的分布式对象计算环境,它能使许多普通的网络程序设计自动化,并允许应用在异构环境下无缝链接。文章根据分布式多媒体通讯系统中的层次结构模型（QOS－A）,提出了一种基于CORBA的分布式多媒体模型。     

A new architecture for integration of CORBA and OODB

Object oriented database system (OODB) supports an object oriented data model with the functionality of persistency and transaction semantics. In order to facilitate the use of OODB, the Object Database Management Group (ODMG) defined a standard for object database management systems. On the other hand, the Object Management Group (OMG) defined the Common Object Request Broker Architecture (CORBA), which is an emerging standard of distributed object technology providing the interconnection network between distributed objects. For the sake of matching these two object models, taking the advantages of merging both of them, and building a more sophisticated infrastructure, the integration of CORBA and OODB is currently an urgent and important issue in distributed object systems. Instead of using Object Database Adapter (ODA) suggested by the ODMG, we provide a novel way of reusing the Object Transaction Service (OTS) and wrapping techniques to introduce OODB into CORBA automatically. Through our design, CORBA clients or OODB object implementers do not need to learn any knowledge of each other. In addition, error recovery is also provided to guarantee the consistency of object states. The whole task for integrating CORBA and OODB is done transparently by our proposed preprocessor, which plays an important role in solving problems encountered by ORB and OODB vendors easily     

用Petri网描述CORBA事件服务

CORBA为构建大规模分布式应用程序提供了一套公共对象服务规范．本文利用Petri网模型可表现系统分布、并发、异步等特性来描述CORBA事件服务，不仅能反映CORBA事件服务的静态行为，也反映其动态行为，为CORBA事件服务建立了形式化的模型．     

分布式计算环境中的事务管理──采用Interposition技术实现CORBA事务服务的初探

CORBA的一个重要的服务是OMG定义面向对象的事务服务（OTS）,它是对分布事务进行处理的。由于事务处理的重要性,OTS本应该作为ORB的一部分来提高事务处理应用的效率。基于上述考虑,OMG在OTS中提出了interposition技术,文章在方法论的基础上探讨如何采用该技术实现OTS。     

分布式计算环境中的事务管理——采用InterPostition技术实现CORBA事务服务的初探

CORBA的一个重要的服务是OMG定义面向对象的事务服务（OTS）,它是对分布事务进行处理的,由于事务处理的重要性,OTS本应该作为ORB的一部分来提高事务处理应用的效率,基于上述考虑,OMG在OTS中提出了interposition技术,文章在方法论的基础上探讨如何采用该技术实现OTS。     

Integrating Java and CORBA: a programmer's perspective

The introduction of Java's proprietary remote method invocation (RMI) with version 1.1 of the Java Development Kit simplified the challenging task of developing distributed object-based systems. RMI provides convenient integration with Java; however, it lacks interoperability with other languages. The Object Management Group's Common Object Request Broker Architecture (CORBA), on the other hand, is a platform- and language-neutral specification for developing distributed object systems. CORBA provides services not covered by RMI, such as managing transactional safety and persistency. We use a small chat room application to describe how a programmer can combine Java RMI's ease of use with CORBA's language neutrality. We start with an implementation based on a set of distributed objects using RMI. We then adapt the example to CORBA or, more specifically, the RMI-over-IIOP (Internet inter-ORB protocol) specification developed by Sun and IBM     

Resource access control for dynamic priority distributed real-time systems

Many of today’s complex computer applications are being modeled and constructed using the principles inherent to real-time distributed object systems. In response to this demand, the Object Management Group’s (OMG) Real-Time Special Interest Group (RT SIG) has worked to extend the Common Object Request Broker Architecture (CORBA) standard to include real-time specifications. This group’s most recent efforts focus on the requirements of dynamic distributed real-time systems. One open problem in this area is resource access synchronization for tasks employing dynamic priority scheduling. This paper presents two resource synchronization protocols that meet the requirements of dynamic distributed real-time systems as specified by Dynamic Scheduling Real-Time CORBA 2.0 (DSRT CORBA). The proposed protocols can be applied to both Earliest Deadline First (EDF) and Least Laxity First (LLF) dynamic scheduling algorithms, allow distributed nested critical sections, and avoid unnecessary runtime overhead. These protocols are based on (i) distributed resource preclaiming that allocates resources in the message-based distributed system for deadlock prevention, (ii) distributed priority inheritance that bounds local and remote priority inversion, and (iii) distributed preemption ceilings that delimit the priority inversion time further. Chen Zhang is an Assistant Professor of Computer Information Systems at Bryant University. He received his M.S. and Ph.D. in Computer Science from the University of Alabama in 2000 and 2002, a B.S. from Tsinghua University, Beijing, China. Dr. Zhang’s primary research interests fall into the areas of distributed systems and telecommunications. He is a member of ACM, IEEE and DSI. David Cordes is a Professor of Computer Science at the University of Alabama; he has also served as Department Head since 1997. He received his Ph.D. in Computer Science from Louisiana State University in 1988, an M.S. in Computer Science from Purdue University in 1984, and a B.S. in Computer Science from the University of Arkansas in 1982. Dr. Cordes’s primary research interests fall into the areas of software engineering and systems. He is a member of ACM and a Senior Member of IEEE.     

永久对象服务的研究和实现

结合对象管理组制定的永久对象服务标准，利用框架技术，针对多种对象类型和存储机制，介绍一种实现存储、恢复永久属性重构对象机制的通用办法，以满足现实世界中对象模型的要求。主要讨论框架的特点，在ＣＯＲＢＡ环境下永久对象服务的实现及对永久对象服务标准的理解。