基于自治对象的移动交换中心建模

提出了一种基于自治对象的移动交换中心建模方法(AOMSCM),将前台进程进行对象化改造,从移动交换中心网络服务对象中抽象出自治对象,并给出其形式化定义。AOMSCM的研究为移动交换中心整个前台全面转向面向服务的开发积累了经验。     

基于CORBA的分布式MVC软件体系结构

MVC作为一种经典的软件模式,在界面程序设计和B/S系统中得到广泛应用,但对于分布式实时交互应用而言,其高效性和可扩展性等仍有待提高。本文深入分析了MVC软件模式的结构特点,提出一种基于CORBA的分布式MVC软件体系结构SEV。SEV将动态数据处理从模型中分离出来,并采用CORBA分布对象机制提高系统可扩展性,为面向分布式实时交互式系统的设计提供了高效可扩展的软件参考模型。     

Code generators

Code generators, which take a programmer's inputs in the form of some abstraction, design, or direct interaction with the system and write out a source program that implements the details of the application, are reviewed. After a brief overview, four separate presentations cover examples of such systems from four domains. The Tags tools uses abstraction to specify real-time control systems. In this tool, the details of synchronization code are hidden from the designer, but some functionality must still be provided in detail. Microstep is a similar kind of tool for data-processing applications. One can view both Tags and Microstep as high-level specification languages. PSG generates programming environments, i.e. one gives it a nonprocedural specification of a language's syntax and it generates an integrated programming environment for that language. While one must specify the environment in detailed form, the actual code generation is hidden. Escort is a similar system specialized for telecommunications applications. It lets one build, execute, and test specifications for telecommunication systems. Both PSG and Escort illustrate the power of domain-specific tools     

Synchronization through Communication in a Massively Parallel Processor Array

Programming MPPAs for complex real-time embedded applications is difficult with conventional multiprogramming models, which usually treat communication and synchronization separately. Based on a programming model for massively parallel embedded computing that is reasonable and productive for software developers, we developed a scalable MPPA chip architecture that delivers tera-ops performance with very good energy efficiency in an ordinary 130-nm ASIC. This MPPA's architecture is based on the structural object programming model, which composes strictly encapsulated processing and memory objects in a structure of self-synchronizing channels. Small RISC CPUs and memories execute the objects.     

Effective multicast programming in large scale distributed systems

Many distributed applications have a strong requirement for efficient dissemination of large amounts of information to widely spread consumers in large networks. These include applications in e‐commerce and telecommunication. Publish/subscribe is considered one of the most important interaction styles with which to model communication on a large scale. Producers publish information on a topic and consumers subscribe to the topics they wish to be informed of. The decoupling of producers and consumers in time, space, and flow makes the publish/subscribe paradigm very attractive for large scale distribution, especially in environments like the Internet. This paper describes the architecture and implementation of DACE (Distributed Asynchronous Computing Environment), a framework for publish/subscribe communication based on an object‐oriented programming abstraction in the form of Distributed Asynchronous Collection (DAC). DACs capture the variants of publish/subscribe, without blurring their respective advantages. The architecture we present is tolerant of network partitions and crash failures. The underlying model is based on the notion of Topic Membership: a weak membership for the parties involved in a topic. We present how Topic Membership enables the realization of a robust and efficient reliable multicast on a large scale. The protocol ensures that, inside a topic, even a subscriber who is temporarily partitioned away eventually receives a published message. Copyright © 2001 John Wiley & Sons, Ltd.     

实时多任务执行模型到VxWorks的代码映射

基于对实时多任务软件的抽象执行体的研究分析以及对VxWorks平台的分析,提出了实时多任务执行模型到VxWorks平台下C语言程序框架的系统调用的映射规则及代码。给出了实时对象之间的通信原理及映射方法。给出了实时时间管理的映射代码。     

Remote rendezvous

BNR Pascal is a systems programming language intended for the implementation of the systems software of distributed computing systems. It supports the Ada Rendezvous model of tasking and communication, uniformly extended to support communications between tasks distributed over the computing nodes of a system. BNR Pascal was designed and implemented in 1980, and has since been used to implement the operating systems and real-time applications software for Northern Telecom's Meridian family of products. In total, more than 2 million lines of BNR Pascal exist. This paper describes the BNR Pascal remote rendezvous: the extension of rendezvous to interprocessor communication. It discusses the implementation of remote rendezvous, describing the advantages and disadvantages of several options. Finally, it details BNR's experience in using remote rendezvous in building substantial, practical distributed systems used in products.     

Dynamically negotiated resource management for data intensiveapplication suites

In contemporary computers and networks of computers, various application domains are making increasing demands on the system to move data from one place to another, particularly under some form of soft real-time constraint. A brute force technique for implementing applications in this type of domain demands excessive system resources, even though the actual requirements by different parts of the application vary according to the way it is being used at the moment. A more sophisticated approach is to provide applications with the ability to dynamically adjust resource requirements according to their precise needs, as well as the availability of system resources. This paper describes a set of principles for designing systems to provide support for soft real-time applications using dynamic negotiation. Next, the execution level abstraction is introduced as a specific mechanism for implementing the principles. The utility of the principles and the execution level abstraction is then shown in the design of three resource managers that facilitate dynamic application adaptation: Gryphon, EPA/RT-PCIP, and the DQM architectures     

Temporal modelling of real-time communication protocols based on a process/channel approach

The design of temporally-predictable real-time software is a major issue in a wide range of computer applications. This paper focuses on the temporal modelling of communication protocols in real-time OSI-based computer networks, and discusses a method which can form the foundation of a tool which gives true temporal representations of such systems. The proposed approach, implemented using the power of a concurrent object-oriented programming language (STRAND), utilises a modelling methodology based on an advanced process/channel model. The paper suggests that the techniques can be applied to a range of problems, illustrated here by an example of an OSI protocol.     

Aspectual Feature Modules

Two programming paradigms are gaining attention in the overlapping fields of software product lines (SPLs) and incremental software development (ISD). Feature-oriented programming (FOP) aims at large-scale compositional programming and feature modularity in SPLs using ISD. Aspect-oriented programming (AOP) focuses on the modularization of crosscutting concerns in complex software. Although feature modules, the main abstraction mechanisms of FOP, perform well in implementing large-scale software building blocks, they are incapable of modularizing certain kinds of crosscutting concerns. This weakness is exactly the strength of aspects, the main abstraction mechanisms of AOP. We contribute a systematic evaluation and comparison of FOP and AOP. It reveals that aspects and feature modules are complementary techniques. Consequently, we propose the symbiosis of FOP and AOP and aspectual feature modules (AFMs), a programming technique that integrates feature modules and aspects. We provide a set of tools that support implementing AFMs on top of Java and C++. We apply AFMs to a nontrivial case study demonstrating their practical applicability and to justify our design choices.     

Colony: An Artificial Life Model for Active Autonomous Objects

Appropriate aids on top of the primitive object-oriented model will help promote better understanding of the semantics of applications and allow us to focus better on the various aspects of given problems. This study focuses on the exploration of a design model and the corresponding programming framework for the modelling and implementation of applications involving active autonomous objects based on the object technology. The proposed design model is an artificial life model based on the colony phenomenon in nature. This model can naturally be mapped onto an object-oriented implementation. The colony model favours a predicate-based object communication/coordination pattern as opposed to the navigational message-passing paradigm seen in programming languages such as C+ +. The proposed model is particularly appealing to us, for it presents a unifying conceptual design model and programming framework for a wide class of applications including neural networks, genetic algorithms and fuzzy expert systems. The ideas presented are illustrated through a genetic algorithm problem.     

Measuring the complexity of domain-specific languages developed using MDD

The standard ISO/IEC 25010 (SQuaRE) defines appropriateness as one of the three components of functional suitability, the other two components being completeness and correctness. As users of domain-specific language (DSL) are quite often domain experts with limited programming skills, a DSL might be considered appropriate if the resulting domain-specific programs do not contain an excessive amount of nondomain-related programming elements. This paper describes a metric for measuring the appropriateness of DSLs that are developed using model-driven development (MDD), its evaluation and use. The metric measures the depth of the deepest domain-specific command within abstract syntax trees generated by a DSL. It is aimed at being used during the development of a new DSL and for comparing different DSLs defined over the same domain. It is assumed that during MDD, the metamodel describes the domain-independent part of the DSL, while the model supplies the domain-specific part. This resembles the implementation of DSLs using existing metaprogramming tools that provide off-the-shelf implementations of programming constructs but require manual implementation of the domain-specific language elements.     

应用RTOS的TD-LTE无线综测仪的实现

针对通信软件设计中实时性和可靠性两大难题,提出了一种第三代合作伙伴(3GPP)长期演进(LTE)网络端协议栈通信软件的实现方案,即基于Nucleus PLUS实时操作系统的新一代宽带无线通信软件的设计。重点介绍了Nucleus PLUS实时多任务操作系统的主要组件及其相关功能,并论述了在Nucleus PLUS操作系统下对通信软件进行设计和实现的方法。实际测试表明,采用NucleusPLUS操作系统的终端测试仪确保了通信的可靠性和实时性,可应用于其他通信软件的开发过程中。     

SCA中间件技术浅析

针对软件通信体系结构规范(SCA),研究了SCA中间件技术.以SCA软件体系结构为基础,描述了公共对象请求代理(CORGBA)中间件技术在SCA中的作用和优势,探讨了SCA体系中中间件对硬件平台模块化的技术支持,分析了为确保SCA架构下软硬件独立性对硬件组件进行抽象所采用的硬件抽象层(HAL)和实时C0RBA技术方法,...     

基于B/S模式的Rockwell实验室网络监控系统

应用OPC通信技术和Web开发技术,设计并开发了基于B/S模式的Rockwell实验室网络监控系统。OPC的应用多是基于C/S模式的,这导致在传统B/S模式网络监控系统下,数据通信过程要通过OPC服务器、OPC客户端和实时/历史数据库多层通信,存在一定的实时性问题。针对这一问题,提出了新的开发框架,实现了与控制对象的实时通信。用户通过浏览器可以实时监视设备的运行状况,并且可脱离Rockwell的编程软件对设备进行控制。     

The distributed programming language SR—Mechanisms,design and implementation

SR is a new language for programming software containing many processes that execute in parallel. The language allows an entire software system that controls a potentially large collection of processors to be programmed as an integrated set of software modules. The key language mechanisms are resources, operations and input statements. The language supports separate compilation, type abstraction, and dynamic communication links; it also contains novel treatments of arrays and procedures. This paper gives an overview of the language mechanisms, discusses some of the major design decisions and describes one implementation.     

Promondia: a Java-based framework for real-time group communication in the Web

The World Wide Web has evolved from a distributed hypertext system to a platform-independent graphical user interface that integrates many network services. So far, its technology has restricted it mainly to applications for information retrieval.As networks become ubiquitious and more and more users have a permanent connection, there is an increasing demand for other network services, such as real-time data feeds, group communication, and teleconferencing. So far, these services have been provided by various proprietary software systems, which were hard to set up and use, and thus not very successful.Integrating real-time group communication services into the World Wide Web is a natural way to make them more accessible and will take the Web a step further on its way to becoming the universal network application.In this paper, we describe functionalities required for these services and present an implementation based on Sun Microsystem's Java² programming language. We focus on the high-level functionalities and abstractions, but also describe an object-oriented programming model for group communication systems.