Using status messages in the distributed test architecture

If the system under test has multiple interfaces/ports and these are physically distributed then in testing we place a tester at each port. If these testers cannot directly communicate with one another and there is no global clock then we are testing in the distributed test architecture. If the distributed test architecture is used then there may be input sequences that cannot be applied in testing without introducing controllability problems. Additionally, observability problems can allow fault masking. In this paper we consider the situation in which the testers can apply a status message: an input that causes the system under test to identify its current state. We show how such a status message can be used in order to overcome controllability and observability problems.     

A temporal approach for testing distributed systems

This paper deals with testing distributed software systems. In the past, two important problems have been determined for executing tests using a distributed test architecture: controllability and observability problems. A coordinated test method has subsequently been proposed to solve these two problems. In the present article: 1) we show that controllability and observability are indeed resolved if and only if the test system respects timing constraints, even when the system under test is non-real-time; 2) we determine these timing constraints; 3) we determine other timing constraints which optimize the duration of test execution; 4) we show that the communication medium used by the test system does not necessarily have to be FIFO; and 5) we show that the centralized test method can be considered just as a particular case of the proposed coordinated test method.     

A temporal agent based approach for testing open distributed systems

The development of distributed testing frameworks is more complex, where the implementation process must consider the mechanisms and functions required to support interaction as long as the communication and the coordination between distributed testing components. The typical reactions of such systems are the generation of errors‘set: time outs, locks, observability, controllability and synchronization problems. In other side, the distributed testing process must not only check if the output events have been observed, but also the dates when these events have been occurred. In this paper, we show how to cope with these problems by using a distributed testing method including timing constraints. Afterwards, a multi-agent architecture is proposed in the design process to describe the behavior of testing a distributed chat group application on high level of abstraction.     

实时分布式系统性能测试技术研究

实时分布式系统的性能是关注核心,对其进行评估和测试关系着系统的应用前景。基于实时分布式系统的性能测试需求,对系统关键的处理性能、存储性能、传输性能以及实时恢复性能这四种性能测试方法进行了研究和探讨,同时分别利用实时分布式系统中e600架构的处理器、flash存储器、FC网络以及分区调度策略针对这些方法开展了测试,并对获得的测试结果进行了分析。分析结果表明,性能测试结果可信,方法可行,可作为实时分布式系统评测依据。     

Coordination Algorithm for Distributed Testing

With the emergence of new models, architectures and middleware such as ODP, TINA and CORBA, for developing open distributed systems, testing technology requires adaptation for use within conformance assessment in such systems. All these frameworks are object-based and aim at creating open distributed environments supporting interworking, interoperability, and portability, in spite of heterogeneity and autonomy of the related systems. In this context, an open distributed system may be viewed as a system providing standardized distributed interfaces for interacting with other systems. Conformance of such a system can be assessed by attaching a related tester at each provided interface. However, many problems of controllability and observability influencing fault detection during the testing process, arise if there is no coordination between the testers. In this paper, we show how to cope with these problems by using test coordination procedures in a distributed testing architecture.     

一个面向分布式程序的测试系统框架

提出了一个面向分布式程序的测试系统框架TFDS(test system framework for distributed software system),并介绍了它在异构网络中的一个实现原型PSET*(distributed progra m structure and event trace, revised version).框架的主要功能是对分布式程序进行单 元测试和集成测试.包括面向规约设计和源码分析的静态部分和面向程序执行和事件序列分 析的动态部分.在构件的基础上,PSET*的功能可以较容易     

A flexible time-triggered service for real-time CORBA

This paper presents a new service for CORBA applications that orchestrates the timely execution of the tasks of a distributed real-time system in a flexible way. It follows the CORBA philosophy of complementing the CORBA standard with additional services that solve specific problems and facilitate using CORBA in complex applications. The service has been designed for highly coupled applications that execute over LANs. It provides a synchronous framework to synchronize distributed applications that is open to accepting and removing components on-line, with reduced impact on the application timing. It also provides the flexibility to use different distributed scheduling policies that can override the local operating systems schedulers. This paper describes the service architecture and implementation as well as its best-case performance on low computing power hardware with the QNX OS and connected to a switched Ethernet network. Finally the usage and of the service is illustrated with one case study: the synchronization of several robots in a welding process.     

A framework for the specification of test cases for real-time distributed systems

The OSI conformance testing methodology and framework (CTMF) is a well established standard which defines and regulates the conformance testing procedure for protocol implementations. Conformance testing is meant to be functional black-box testing. Besides concepts and terminology, the CTMF standardizes testing architectures and the Tree and Tabular Combined Notation (TTCN) test specification language. As more and more distributed systems such as multimedia, safety-critical and real-time systems rely on the timely availability of information, testing of real-time requirements becomes a serious issue, too. Unfortunately, testing real-time and other non-functional requirements (performance and reliability) are outside the scope of CTMF. In this paper we present an extension of CTMF which allows us to specify test cases for testing real-time requirements. The extension includes a generic testing architecture and a notation for test specification, which is called real-time TTCN.     

Case study of testing a distributed internet‐system

This paper describes the testing strategy, methods and tools used for testing a distributed financial services system on the Internet with CORBA interfaces for handling a high volume of queries to a relational database. The new system architecture was derived by reengineering a previous more limited application. The paper starts with an outline of the software architecture, the testing requirements and the testing strategy. It then goes on to describe the tools used in the project and the results achieved. For the project a generic C++ integration test framework was developed especially for testing distributed components. This tool is described in detail. The paper ends with a discussion of the discovered defects and their distribution. Copyright © 2002 John Wiley & Sons, Ltd.     

Fail-Awareness: An Approach to Construct Fail-Safe Systems

We present a framework for building fail-safe hard real-time applications in timed asynchronous distributed systems subject to communication partitions and performance, omission, and crash failures. Most distributed systems built from commercial-off-the-shelf (COTS) processor and communication services are subject to such partitions because their COTS components do not provide hard real-time guarantees. Also custom designed systems can be subject to partitions due to unmaskable link or router failures. The basic assumption behind our approach is that each processor has a local hardware clock that proceeds within a linear envelope of real-time. This allows one to compute an upper bound on the actual delays incurred by a particular processing sequence or message transmission. Services and applications can use these computed bounds to detect when they cannot guarantee all their standard properties because of excessive delays. This allows an application to be fail-aware, that is, to detect when it cannot guarantee all its safety properties and in particular, to detect when to switch to a fail-safe mode.     

Traffic-aware stress testing of distributed real-time systems based on UML models using genetic algorithms

This paper presents a model-driven, stress test methodology aimed at increasing chances of discovering faults related to network traffic in distributed real-time systems (DRTS). The technique uses the UML 2.0 model of the distributed system under test, augmented with timing information, and is based on an analysis of the control flow in sequence diagrams. It yields stress test requirements that are made of specific control flow paths along with time values indicating when to trigger them. The technique considers different types of arrival patterns (e.g., periodic) for real-time events (common to DRTSs), and generates test requirements which comply with such timing constraints. Though different variants of our stress testing technique already exist (that stress different aspects of a distributed system), they share a large amount of common concepts and we therefore focus here on one variant that is designed to stress test the system at a time instant when data traffic on a network is maximal. Our technique uses genetic algorithms to find test requirements which lead to maximum possible traffic-aware stress in a system under test. Using a real-world DRTS specification, we design and implement a prototype DRTS and describe, for that particular system, how the stress test cases are derived and executed using our methodology. The stress test results indicate that the technique is significantly more effective at detecting network traffic-related faults when compared to test cases based on an operational profile.     

基于J2EE的应用框架技术研究

J2EE作为分布式架构的企业级应用平台,在企业的信息化建设中发挥出越来越重要的作用.一方面作为企业信息化应用系统的开发工具,另一方面又作为企业信息化应用系统的集成平台.但就具体的企业应用而言,直接采用J2EE应用服务器开发企业级应用具有较大的风险和难度,因此基于J2EE的各种应用框架技术应运而生,数据持久化层、业务逻辑层、表示层都有相应的框架技术.对于一个具体的企业应用系统,各层具体采用何种技术实现很难定夺.分析研究了基于J2EE的应用框架目的、应用框架的设计原则及方法,提出了应用框架总体结构,并在应用一些项目中得到了应用.     

基于三层体系结构的单元测试框架研究与实现

单元测试是整个测试流程中的基础也是最重要的环节,通过深入研究三层体系结构特点,提出了一种基于该体系结构下的单元测试框架,该框架采用流行的面向接口编程技术,同时将设计模式灵活应用其中,有效指导了整个测试过程。目前整套框架已投入实际项目的运行,并且经过实践证明是切实可行的,不仅能及时发现软件开发过程中潜藏的问题,更有效保证Web应用程序的质量, 节省了后期维护费用的开销。     

基于1553B总线架构的测试设备设计与实现

随着1553B总线在航空系统和地面车辆系统中分布式从属设备连接方式的广泛应用,提高武器装备保障体系中的测试设备的设计灵活性、可靠性以及可确定性显得尤为重要;因此,提出了一种基于1553B总线架构思想的PXI总线测试设备的设计方法与实现方式,经过工程实际应用表明,能够满足装备的测试需求,具有良好的可扩展性、实时性和可靠性等特点,对武器装备测试领域的设备研制有一定的参考价值。     

矿区分布式网络视频录像系统设计

针对传统集中式网络视频录像系统在多通道、大容量存储与多终端并发访问时,存在存储设备硬件处理能力不足和网络带宽局部拥塞现象,设计了一种分布式网络视频录像系统。该系统采用分布式IP架构,可实现视频数据的分布式物理存储和集中式逻辑管理;应用基于Socket的设备通信控制技术及基于应用层组播的回放控制技术,实现了设备管理和权限管理控制数据的交互及视频流的高效网络传输控制。测试结果表明,该系统较好地解决了矿区多通道、大容量的视频数据实时存储和远程回放问题。     

ConClass: a framework for real-time distributed knowledge-basedprocessing

We have developed a problem-solving framework, called ConClass, that is capable of classifying continuous real-time problems dynamically and concurrently on a distributed system. ConClass provides an efficient development environment for describing and decomposing a classification problem and synthesizing solutions. In ConClass, decomposed concurrent subproblems specified by the application developer effectively correspond to the actual distributed hardware elements. This scheme is useful for designing and implementing efficient distributed processing, making it easier to anticipate and evaluate system behavior. The ConClass system provides an object replication feature that prevents any particular object from being overloaded. In order to deal with an indeterminate amount of problem data, ConClass dynamically creates object networks that justify hypothesized solutions, and thus achieves a dynamic load distribution. A number of efficient execution mechanisms that manage a variety of asynchronous aspects of distributed processing have been implemented without using schedulers or synchronization schemes that are liable to develop bottlenecks. We have confirmed the efficiency of parallel distributed processing and load balancing of ConClass with an experimental application     

An architecture for real-time distributed artificial intelligent systems

This paper introduces a new architecture for a real-time distributed artificial intelligence system: DENIS—a Dynamic Embedded Noticeboard Information System. The fundamental idea underlying the architecture draws heavily upon a distributed human system analogy, as seen, for example, in the workplace. The aim of DENIS is to provide a simple, meaningful means by which autonomous intelligent agents can cooperate and coordinate their actions in order to enhance the reliability and effectiveness of a real-time distributed control system. Based on a human paradigm, the architecture inherently allows for the control of an intelligent agent to be taken over by a human operator, yet still to maintain consistency in the distributed system. The key to the thinking in this new approach is to try to model how humans work together, and to implement this in a distributed architecture. One of the main issues raised is that humans owe much of their flexibility to their ability to reason, not only logically, but also in terms of time.     

A Scalable Testing Framework for Location-Based Services

A novel testing framework for location based services is introduced. In particular, the paper showcases a novel architecture for such a framework. The implementation of the framework illustrates both the functionality and the feasibility of the framework proposed and the utility of the architecture. The new framework is evaluated through comparison to several other methodologies currently available for the testing of location-based applications. A case study is presented in which the testing framework was applied to a typical mobile service tracking system. It is concluded that the proposed testing framework achieves the best coverage of the entire location based service testing problem of the currently available methodologies; being equipped to test the widest array of application attributes and allowing for the automation of testing activities.     

A search-based framework for automatic testing of MATLAB/Simulink models

Search-based test-data generation has proved successful for code-level testing but almost no search-based work has been carried out at higher levels of abstraction. In this paper the application of such approaches at the higher levels of abstraction offered by MATLAB/Simulink models is investigated and a wide-ranging framework for test-data generation and management is presented. Model-level analogues of code-level structural coverage criteria are presented and search-based approaches to achieving them are described. The paper also describes the first search-based approach to the generation of mutant-killing test data, addressing a fundamental limitation of mutation testing. Some problems remain whatever the level of abstraction considered. In particular, complexity introduced by the presence of persistent state when generating test sequences is as much a challenge at the Simulink model level as it has been found to be at the code level. The framework addresses this problem. Finally, a flexible approach to test sub-set extraction is presented, allowing testing resources to be deployed effectively and efficiently.