支持QoS的IIOP的设计和实现

随着网络技术和中间件技术的发展,许多分布式应用（如多媒体,实时应用）要求支持多种QoS,如端到端的延迟、丢失率等。QoS与中间件平台的集成自然成了人们研究的焦点。当前流行的面向对象的中间件,如CORBA,DCOM和Java/RM1,在这一方面还不成熟。GIOP／IIOP是异种ORB在TCP／IP网络上互操作的基础,因而支持QoS的IIOP是支持QoS的CORBA的基础。本文首先简要介绍了IP的QoS模型和Windows2000中的QoS技术。在此基础上,详细讨论了支持了QoS的IIOP的设计和实现。     

J2EE平台中分布式事务互操作的研究与实现

RMI-IIOP协议扩展了J2EE应用服务嚣的应用领域。符合CORBAIDL规范的非Java语言编写的CORBA客户端可以通过IIOP协议与J2EE应用组件之间实现互操作。在分布式事务环境中,CORBA客户端通过IIOP协议调用应用服务嚣上的EJB组件时,应用服务嚣需要保证客户端的CORBA调用能正确到达EJB组件,并且事务上下文在客户端和服务器之间能够有效传播。本文基于应用服务嚣的JMX体系结构,设计了一个支持事务互操作的服务框架,实现了事务环境下基于IIOP协议对EJB的调用。它具有较好的灵活性和可重配性。并已经在中科院软件所研制的OnceAS应用服务嚣中得到了实现。     

基于Oracle 8i的CORBA应用研究

以Oracle 8i的Aurora ORB为例，着重探讨了基于Oracle 8i的CORBA应用的特点，如基于会话的IIOP、安全机制等，描述了如何开发CORBA应用，并给出实例。     

基于CORBA的主动信息分布技术研究

在分析了传统的信息发布技术后,提出了一种基于CORBA的主动信息发布技术。该技术以CORBA的通知服务为信息传送基础,以ORB,IIOP为网络信息传输协议,具有跨平台、跨网络的主动信息发布能力,可进行服务质量（QoS）控制,适用于网上主动信息发布系统（AIPS）的构造。并给出了以该技术为基础的AIPS的体系结构。     

支持ATM传输协议的CORBA设计和实现

研究第二代实时CORBA使其适应于性能敏感的实时分布应用系统的集成开发是面向对象分布软件技术的一个研究热点，该文介绍了作者设计和实现的一个集成了ATM传输协议的CORBA－QTAO。文中介绍了支持ATM传输协议和多协议连接的ORB结构以及GIOP在ATM上的映射ATMIOP和GIOP的扩充协议QGIOP的设计和实现，也简要介绍了支持ATM的高级通信环境EACE的设计和实现。     

基于CORBA的B／S模式的实时信息分布技术

本文提出了一种基于CORBA的B／S模式下的实时信息发布技术及实时信息发布系统的体系结构。该技术以CORBA提供的事件,ORB以及IIOP等来实现实时信息的网上传送，以CORBA提供的跨平台对象互操作能力和Browser的对象嵌入技术实现实时信息的一致性的表达，并描述了这个融合CORBA和Browser/Server模式优点的应用系统的体系结构。     

基于CORBA的B/S模式的实时信息发布技术

本文提出了一种基于COBB的B/S模式下的实时信息发布技术及实时信息发布系统的体系结构。该技术以CORBA提供的事件服务、ORB以及IIOP等来实现实时信息的网上传送,以CORBA提供的跨平台对象互操作能力和Browser的对象嵌入技术实现实时信息的一致性的表达。并描述了这个融合CORBA和Browser/Server模式优点的应用系统的体系结构。     

CORBA防火墙安全技术研究

传统防火墙通过保护网络入口点防止未授权的访问，这并不适用于CORBA在Internet上使用的IIOP协议，因此OMG提出CORBA防火墙安全性，旨在提供控制IIOP透过防火墙通信的标准方式，允许外部有控制地访问CORBA对象。文章介绍了CORBA分布式系统及防火墙，CORBA防火墙相对于传统防火墙的特殊问题，详细阐述了CORBA系统中的解决方案，对TCP防火墙、SOCKS防火墙，GIOP代理防火墙的运行机制进行了分析。     

基于RapidIO的实时CORBA中间件实现

为了解决CORBA传统传输协议TCP/IP的时延不确定问题,提出了使用基于点对点的包交换RapidIO协议来替代TCP/IP的方法,研究了CORBA的可插拔传输协议框架,从而实现了CORBA报文在RapidIO总线上的传输。测试结果显示,基于RapidIO的CORBA实时性优于基于TCP/IP的CORBA。     

CORBA在J2EE中的集成与实现

本文主要介绍了CORBA技术在J2EE平台中的集成。CORBA技术的工作原理和JavaRMI的结合的必要性,将JavaRMI和CORBA结合起来的关键是IIOP协议。CORBA客户端/RMI服务器和RMI客户端/CORBA服务器的合成方法。最后还介绍了CORBA和EJB合成的好处。     

OCI-based group communication support in CORBA

Group communication is a useful mechanism guaranteeing consistency among replicated objects. The existing approaches do not allow transparent plug-in of group communication protocols into CORBA. They either require modification of CORBA or OS, or provide no room for incorporating group communication transport protocols into CORBA. We thus propose a generic group communication framework that allows transparent plug-in of various group communication protocols with no modification of existing CORBA. We extend the open communications interface (OCI) to support interoperability, reusability of existing group communication, and independency on ORB and OS. We also define the group communication inter-ORB protocol (GCIOP) as a group communication instantiation of the general inter-ORB protocol (GIOP) that encapsulates underlying group communication protocols. The proposed scheme can be exploited for fault-tolerant CORBA (FT CORBA).     

Development of an Ethernet-based equipment integration framework for factory automation

Traditional architectures of factory automation networks possess some shortcomings, such as needing gateways to transform communication data, using multiple different kinds of networks, needing higher maintenance cost, etc. To remedy the shortcomings, a novel Ethernet-based equipment integration framework is proposed in this paper. The proposed framework is qualified to be an equipment (synchronous) control network for the factory automation networking. Also, it conforms to the technical trend of replacing traditional industrial networks with Ethernet. Many technologies, including the master/slave model, Ethernet Switch, real-time operating system kernel, real-time transmission control protocol/Internet protocol application programming interface, and object request broker (ORB), are exploited to develop the framework. Simulation and experimental results for a laboratory-scale factory indicate that the proposed framework can perform well in real-time data transmission, that is, accomplishing the synchronous communication over 10 slave nodes within 1.4 ms. Additionally, the equipment integration framework can be easily integrated with the automation systems in the information-management layer through ORB. Worst-case performance evaluations and timing-parameter setting formulas for the proposed framework are also provided. The work presented here is believed to be a good paradigm for developing Ethernet-based factory automation networks.     

Object request broker: Foundation for distributed simulation

Real-time, human-in-the-loop simulation of air traffic control is naturally distributed across computing platforms because of the need for many input and display devices, the need for computing power, and the need to integrate legacy simulations that run on a variety of platforms. Object orientation has a long history of fruitful application to simulation problems, including real-time simulation. Thus there is great interest in commercial products for distributed object management. We have examined the suitability of object request broker (ORB) technology for simulation control, i.e. applications-as-objects, and for supporting truly object-oriented, distributed, real-time simulation. Our experience with DEC's ORB shows that at present the former is feasible but the latter is probably not; however the available implementations are changing rapidly. ORB technology can also bring the distributed interactive simulation (DIS) protocol of the DoD into an object-oriented framework.     

分布式PACS中ORB自适应并发策略研究

传统CORBA的ORB单个并发模式不能适用于分布式PACS中的复杂应用环境。本文基于对ORB多种并发模式的研究,并结合对PACS应用服务特性的分析,提出了一个适合于分布式PACS的ORB自适应并发策略。该并发策略能够在运行时自适应地选择单线程或多线程的并发模式,基于主动对象构造的协议处理器可以简化多线程并发对象的同步访问机制, 满足了分布式PACS大吞吐量、低响应时间的QoS需求。     

一种实现互操作的分布式集成框架的设计与实现

互操作性问题是分布计算中需要解决的关键问题。这一问题可以通过多种途径加以解决,其中面向对象的集成框架是一种比较好的解决方法。文中首先研究了互操作性的概念,实现主面向对象方法对互操作性的支持机制;在对ＤＣＥ机制和ＣＯＲＢＡ的ＯＲＢ机制比较的基础上,采用面向对象方法和技术,开展了基于Ａｇｅｎｔ的分布客户／服务器集成框架的研究,提出了一种基于Ａｇｅｎｔ的分布式通用框架,以支持客户／服务器应用的开发和实现     

基于对象请求代理的程序自动开发方法与工具

随着分布式对象技术的日益流行,越来越多的应用程序开始采用基于对象请求代理(object request broker,简称ORB)进行开发.从开发人员角度看,目前这类应用程序在开发过程上仍存在一些不足之处,例如,需要掌握的基本概念较多,ORB产品之间的兼容性不足等.在深入分析了这些问题后,提出了一种改进开发过程的方法,通过代码自动生成,分离特定于ORB产品的代码等技术,尽可能提供对其中开发活动的自动支持.实验结果表明,实现上述方法的支撑工具原型系统可以有效地减少代码编写量,并降低编码出错的概率.     

Wireless Sensor Network transport protocol: A critical review

The transport protocols for Wireless Sensor Network (WSN) play vital role in achieving the high performance together with longevity of the network. The researchers are continuously contributing in developing new transport layer protocols based on different principles and architectures enabling different combinations of technical features. The uniqueness of each new protocol more or less lies in these functional features, which can be commonly classified based on their proficiencies in fulfilling congestion control, reliability support, and prioritization. The performance of these protocols has been evaluated using dissimilar set of experimental/simulation parameters, thus there is no well defined benchmark for experimental/simulation settings. The researchers working in this area have to compare the performance of the new protocol with the existing protocols to prove that new protocol is better. However, one of the major challenges faced by the researchers is investigating the performance of all the existing protocols, which have been tested in different simulation environments. This leads the significance of having a well-defined benchmark for the experimental/simulation settings. If the future researchers simulate their protocols according to a standard set of simulation/experimental settings, the performance of those protocols can be directly compared with each other just using the published simulation results. This article offers a twofold contribution to support researchers working in the area of WSN transport protocol design. First, we extensively review the technical features of existing transport protocols and suggest a generic framework for a WSN transport protocol, which offers a strong groundwork for the new researchers to identify the open research issues. Second we analyse the experimental settings, focused application areas and the addressed performance criteria of existing protocols; thus suggest a benchmark of experimental/simulation settings for evaluating prospective transport protocols.     

Software Architectures for Reducing Priority Inversion and Non-determinism in Real-time Object Request Brokers

There is increasing demand to extend Object RequestBroker (ORB) middleware to support distributed applications withstringent real-time requirements. However, conventional ORB implementations,such as CORBA ORBs, exhibit substantial priority inversion andnon-determinism, which makes them unsuitable for applicationswith deterministic real-time requirements. This paper providestwo contributions to the study and design of real-time ORB middleware.First, it illustrates empirically why conventional ORBs do notyet support real-time quality of service. Second, it evaluatesconnection and concurrency software architectures to identifystrategies that reduce priority inversion and non-determinismin real-time CORBA ORBs. The results presented in this paperdemonstrate the feasibility of using standard OO middleware likeCORBA to support certain types of real-time applications overthe Internet.     

Implementing the CORBA GIOP in a high-performance object request broker environment

The success of the Object Management Group's General Inter-ORB Protocol (GIOP) is leading to the desire to deploy GIOP in an ever-wider range of application areas, many of which are significantly more demanding than traditional areas in terms of performance. The well-known performance limitations of present day GIOP-based object request brokers (ORBs) are therefore increasingly being seen as a problem. To help address this problem, this paper discusses a GIOP implementation which has high performance and quality of service support as explicit goals. The implementation, which is embedded in a research ORB called Gopi, is modular and extensible in nature and includes novel optimization techniques which should be separately portable to other ORB environments. This paper focuses on the message protocol aspects of Gopi's GIOP implementation; higher layer issues such as marshalling and operation demultiplexing are not covered in detail. Figures are provided which position Gopi's GIOP performance against comparable ORBs. The paper also discusses some of the design decisions that have been made in the development of the GIOP protocol in the light of our implementation experience. Received: May 2000 / Accepted: December 2000     

CORBA安全对象系统模型框架研究

CORBA服务规范中描述的安全服务定义了分布式对象系统的通用安全规范 .本文通过对 CORBA安全服务结构的剖析 ,介绍了 CORBA安全对象系统的框架模型 ,分别从安全系统框架的应用层、实现层和管理层三个层次详细描述了 CORBA安全服务实施安全细则和策略的过程 ,为 CORBA安全服务的实现和应用服务器平台安全服务通用框架的设计提供了指导 .