基于日志的系统任务模型推理工具及其应用

分布式系统成为Internet应用的关键组成部分,理解其运行时行为成为验证系统设计、解决系统逻辑与性能错误的关键.已有工作需要程序员手工标注代码或网络数据包,提供描述请求处理和任务执行的相关信息,以抽取系统运行时路径.工作创新性地从系统日志中提取系统任务信息,推断出系统的层次结构任务模型,利用任务模型将系统运行时行为分解为有层次结构的任务实例.实际应用经验表明,利用日志提取的任务模型能够帮助理解系统运行时行为,并解决系统的性能问题.     

基于改进的动态因果图推理算法的复杂工业过程运行状态在线评价

复杂工业生产中,为获得优质产品和更高经济效益,需保证生产过程运行于"正常"且"优"的状态.针对定量信息与定性信息同时存在的生产过程,提出一种基于改进的动态因果图(dynamic causality diagram,DCD)的过程运行状态评价方法.该方法以因果图理论为基础,扩充了定量分析和定性分析结合描述的动态因果图;针对复杂工业生产过程中存在多个相互关联的事件联合作用导致一个事件发生的特点,提出用联合因果强度来描述事件间关系的方法.最后以金湿法冶金氰化浸出过程为应用背景,分别利用传统DCD与改进DCD两种方法建立评价模型,对比分析评价结果,验证了文中提出方法的有效性和先进性.     

基于动态任务模型的LBS架构的研究

建立良好的任务模型是提高LBS系统智能性的途径.LBS的任务模型用于建立用户的行为与环境(上下文)和服务之间的关系,它描述在特定的条件下,如何为用户特定的活动提供适当的服务.为了克服任务模型在使用的方便性和灵活性方面的不足,DAMo模型使用任务本体描述任务的静态属性,而使用任务实现策略控制任务的实际执行,同时使用任务协调策略支持多任务的融合.通过模型结构分析和应用实例,说明该模型可以较好地应用于LBS系统.     

动态二进制翻译系统的调试器框架

传统的动态二进制翻译系统缺少调试器支持或者调试功能有限,随着开发规模的扩大,调试手段成为制约设计开发进度的瓶颈。该文提出一种针对动态二进制翻译系统的调试器框架,引入观察点、回退执行与调试脚本3个功能,通过在Crossbit平台上的验证,证明该技术能够高效地帮助程序员发现错误,提高系统的开发进度。     

基于图文法的并发系统状态测试方法及其实现

在并发系统的研究和开发中，迫切需要一种能正确有效地描述并发系统的动态进程互联结构、动态进程通信和进程演化行为的形式化方法以及基于这种形式化方法的并发系统动态状态的测试手段．本文介绍一种基于图文法模型的并发系统状态测试方法，该方法与描述并发系统结构和行为的图文法模型相结合，构成了一个并发系统开发支持环境．这一方法可根据对并发系统的状态测试要求，在并发系统的运行期自动跟踪和记录并发系统的运行状态和通信情况，使并发系统的开发者可以实时地得到并发系统的运行状态，或者在并发系统运行结束后重演并发系统的状态变化过程.     

利用连续两阶段在线剖析优化多线程推测执行

针对当前推测多线程优化中使用的离线剖析受到训练输入集限制的问题,提出一种根据在线剖析结果自动变换推测多线程程序的动态优化方法.该方法在程序运行时执行剖析和优化工作,不需要单独的剖析过程以及通用的训练输入集.该方法也适用于那些运行时行为特征呈阶段性变化的程序.实验表明,在指导事务划分和选择并行循环方面,动态优化方法能够达到和静态优化方法相似的效果,完全可以在离线剖析失效时被使用.     

基于命名变量的全景数据在线实时调试模型

随着嵌入式系统硬件架构和应用软件复杂度的提高,已有的与处理器配套的集成开发调试环境已不能很好地满足对系统的调试需求。本文介绍了一种能够按名称实时在线查看和修改系统中所有变量的调试模型,对其架构结构进行了描述,并分析了实现该模型的关键技术:结构体偏移地址的生成、调试代理动态注册机制。文中还将该模型的调试方式以可视化形式展现。该模型适用于由多个CPU组成的分布式嵌入式系统,能够在不影响系统运行的情况下,读写各CPU中动态对象的成员变量信息和内存区域信息;同时整个嵌入式系统只需要提供一个接口,节省了硬件资源。     

FoxPro下动态帮助信息的设计

在FoxPro系统中,提供了动态帮助功能,即通过按F1功能键来随时获取当前操作状态的帮助信息。若在自己编制的程序中,也能实现动态显示帮助信息,则将给使用者提供很大的方便。下面介绍一种在FoxPro for DOS下的编程方法,供大家参考。 动态显示帮助信息的设计思想是: ①设计动态帮助信息数据库。 ②编制新的动态帮助信息显示程序,能够显示出动态帮助信息数据库中的相应的动态帮助信息内容。 ③在主程序运行一开始,重新定义F1功能热键,使之能够随时执行新的动态帮助信息显示程序。 1.设计动态帮助信息数据库(SYSHELP.DBF) 动态帮助信息数据库包括两个文件:SYSHELP.DEF和SYSHELP.FPT。 SYSHELP.DBF数据库的库结构如下:     

基于层次策略的虚拟专用网管理模型的研究

针对虚拟专用网的管理问题,提出了一种基于层次策略的管理模型。模型定义了两级管理策略:全局组策略和局部的设备执行策略。其中,组策略以抽象方式定义通信保护目标,执行策略则描述了具体设备所关联的安全隧道和数据处理行为。针对特定设备,相应的执行策略通过对组策略的扩展自动生成,并可在运行中动态调整以适应网络变化。管理策略的层次结构使得模型可以通过简洁的高层策略对全网VPN设备实施统一管理,从而有效减轻了VPN网络的管理负担,也使系统具备了良好的扩展能力。     

软件DSM系统中的全局断点技术

软件DSM系统的并行调试环境已经成为制约其广泛应用的一个重要因素。全局断点技术是用户调试程序的一种基本方法。该文通过定义软件DSM程序执行的HB1序来描述程序的执行,并以此定义因果分布式断点。并使用重放方法和向量时间戳技术来获得因果分布式断点。应用测试结果表明,该方法产生很小的空间和时间开销。     

SM@RT: Applying Architecture-Based Runtime Management into Internetware Systems

Architecture-based runtime management (ARM) is a promising approach for Internetware systems. The key enablement of ARM is runtime architecture infrastructure(RAI) that maintains the causal connection between runtime systems and architectural mod-els. An RAI is uneasy to implement and, more importantly, specific to the given system and model. In this paper, we propose a model-driven approach for automated generation of RAI implementation. Developers only need to define three MOF models for their preferred archi-tecture model and the target system (these models are reusable independently for di?erent pairs of the model and system), and one QVT transformation for the causal connection. Our Eclipse-based toolset, called SM@RT, will automatically generate the RAI implementation code without any modification on the source code of the target system, and automatically and properly deploy the generated RAI into the distributed systems. This approach is exper-imented on several runtime systems and architectural models, including ABC architectural models on Eclipse GUI and Android, C2 architectural models on JOnAS, Rainbow C/S style on PLASTIC and UML models on POJO.     

运行时软件体系结构的建模与维护

运行时体系结构是系统运行时刻的一个动态、结构化的抽象,描述系统当前的组成成分、各成分的状态和配置以及不同成分之间的关系.运行时体系结构与目标系统间具有动态的因果关联,即系统的变化及时体现在体系结构上,而对体系结构的修改及时影响当前系统.运行时体系结构允许开发者以读写体系结构的方式实现系统的监测和调整,是体系结构层次系统动态适应与在线演化的基础.构造运行时体系结构的关键是针对不同的目标系统和体系结构风格实现合适的基础设施,以维护二者之间的因果关联.由于目标系统和体系结构的多样性以及因果关联维护逻辑的复杂性,这一构造过程往往过于繁琐、易错、难以复用和维护.提出一种模型驱动的运行时体系结构构造方法.开发者只需针对目标系统、体系结构以及两者之间的关系分别进行建模,根据这些模型,支撑框架自动构造合法而高效的运行时体系结构基础设施.基于MOF 和QVT 标准建模语言定义了一组运行时体系结构建模语言,并基于通用的模型与系统间同步技术实现了相应的支撑框架.一系列实例研究表明,该方法具有广泛的适用性,并显著提高了运行时体系结构构造过程的效率与可复用性.     

An event-based approach for formally verifying runtime adaptive real-time systems

Real-time and embedded systems are required to adapt their behavior and structure to runtime unpredicted changes in order to maintain their feasibility and usefulness. These systems are generally more difficult to specify and verify owning to their execution complexity. Hence, ensuring the high-level design and the early verification of system adaptation at runtime is very crucial. However, existing runtime model-based approaches for adaptive real-time and embedded systems suffer from shortcoming linked to efficiently and correctly managing the adaptive system behavior, especially that a formal verification is not allowed by modeling languages such as UML and MARTE profile. Moreover, reasoning about the correctness and the precision of high-level models is a complex task without the appropriate tool support. In this work, we propose an MDE-based framework for the specification and the verification of runtime adaptive real-time and embedded systems. Our approach stands for Event-B method to formally verify resources behavior and real-time constraints. In fact, thanks to MDE M2T transformations, our proposal translates runtime models into Event-B specifications to ensure the correctness of runtime adaptive system properties, temporal constrains and nonfunctional properties using Rodin platform. A flood prediction system case study is adopted for the validation of our proposal.

     

Detecting component changes at run time with behavior models

Modern software systems are composed of several services which may be developed and maintained by third parties and thus they can change independently and without notice during the system’s runtime execution. In such systems, changes may possibly be a threat to system functional correctness, and thus to its reliability. Hence, it is important to detect them as soon as they happen to enable proper reaction. Change detection can be done by monitoring system execution and comparing the observed execution traces against models of the services composing the application. Unfortunately, formal specifications for services are not usually provided and developers have to infer them. In this paper we propose a methodology which exactly addresses these issues by using software behavior models to monitor component execution and detect changes. In particular, we describe a technique to infer behavior model specifications with a dynamic black box approach, keep them up-to-date with run time observations and detect behavior changes. Finally, we present a case study to validate the effectiveness of the approach in component change detection for a component that implements a complex, real communication protocol.     

Integrated static code analysis and runtime verification

Static code analysis tools automatically generate alerts for potential software faults that can lead to failures. However, these tools usually generate a very large number of alerts, some of which are subject to false positives. Because of limited resources, it is usually hard to inspect all the alerts. As a complementary approach, runtime verification techniques verify dynamic system behavior with respect to a set of specifications. However, these specifications are usually created manually based on system requirements and constraints. In this paper, we introduce a noval approach and a toolchain for integrated static code analysis and runtime verification. Alerts that are generated by static code analysis tools are utilized for automatically generating runtime verification specifications. On the other hand, runtime verification results are used for automatically generating filters for static code analysis tools to eliminate false positives. The approach is illustrated for the static analysis and runtime verification of an open‐source bibliography reference manager software. Copyright © 2014 John Wiley & Sons, Ltd.     

Models@ run.time

Runtime adaptation mechanisms that leverage software models extend the applicability of model-driven engineering techniques to the runtime environment. Contemporary mission-critical software systems are often expected to safely adapt to changes in their execution environment. Given the critical roles these systems play, it is often inconvenient to take them offline to adapt their functionality. Consequently, these systems are required, when feasible, to adapt their behavior at runtime with little or no human intervention. A promising approach to managing complexity in runtime environments is to develop adaptation mechanisms that leverage software models, referred to as models@run. time. Work on models@run.time seeks to extend the applicability of models produced in model-driven engineering (MDE) approaches to the runtime environment. Models@run. time is a causally connected self-representation of the associated system that emphasizes the structure, behavior, or goals of the system from a problem space perspective.     

Adaptive Workload Management through Elastic Scheduling

In real-time computing systems, timing constraints imposed on application tasks are typically guaranteed off line using schedulability tests based on fixed parameters and worst-case execution times. However, a precise estimation of tasks' computation times is very hard to achieve, due to the non-deterministic behavior of several low-level processor mechanisms, such as caching, prefetching, and DMA data transfer. The disadvantage of relying the guarantee test on a priori estimates is that an underestimation of computation times may jeopardize the correct behavior of the system, whereas an overestimation will certainly waste system resources and causes a performance degradation. In this paper, we propose a new methodology for automatically adapting the rates of a periodic task set without forcing the programmer to provide a priori estimates of tasks' computation times. Actual executions are monitored by a runtime mechanism and used as feedback signals for predicting the actual load and achieving rate adaptation. Load balancing is performed using an elastic task model, according to which tasks utilizations are treated as springs with given elastic coefficients.     

A transactional runtime system for the Cell/BE architecture

Single-core architectures have hit the end of the road and industry and academia are currently exploiting new multicore design alternatives. In special, heterogeneous multicore architectures have attracted a lot of attention but developing applications for such architectures is not an easy task due to the lack of appropriate tools and programming models. We present the design of a runtime system for the Cell/BE architecture that works with memory transactions. Transactional programs are automatically instrumented by the compiler, shortening development time and avoiding synchronization mistakes usually present in lock-based approaches (such as deadlock). Experimental results conducted with a prototype implementation and the STAMP benchmark show good scalability for applications with moderate to low contention levels, and whose transactions are not too small. For those cases in which a small performance loss is admissible, we believe that the ease of programming provided by transactions greatly pays off.     

适用于不确定环境中的DVS软实时调度算法

为了解决嵌入式软实时系统的节能问题,提出了一种DVS调度算法。它的特点是克服了任务执行时间不确定所带来的干扰,在运行时动态地寻找最优电压调节方案。实验表明：该调度算法可以很好地保证软实时系统的效率和稳定性,即使在处理器超载的情况下,也能自动调节,超过99%的作业可以在时间期限之前完成。对多种随机任务集的评测显示,该调度算法使得系统能耗平均减少15%以上。     

Verification and analysis of domain-specific models of physical characteristics in embedded control software

ContextA considerable portion of the software systems today are adopted in the embedded control domain. Embedded control software deals with controlling a physical system, and as such models of physical characteristics become part of the embedded control software.ObjectiveDue to the evolution of system properties and increasing complexity, faults can be left undetected in these models of physical characteristics. Therefore, their accuracy must be verified at runtime. Traditional runtime verification techniques that are based on states/events in software execution are inadequate in this case. The behavior suggested by models of physical characteristics cannot be mapped to behavioral properties of software. Moreover, implementation in a general-purpose programming language makes these models hard to locate and verify. Therefore, this paper proposes a novel approach to perform runtime verification of models of physical characteristics in embedded control software.MethodThe development of an approach for runtime verification of models of physical characteristics and the application of the approach to two industrial case studies from the printing systems domain.ResultsThis paper presents a novel approach to specify models of physical characteristics using a domain-specific language, to define monitors that detect inconsistencies by exploiting redundancy in these models, and to realize these monitors using an aspect-oriented approach. We complement runtime verification with static analysis to verify the composition of domain-specific models with the control software written in a general-purpose language.ConclusionsThe presented approach enables runtime verification of implemented models of physical characteristics to detect inconsistencies in these models, as well as broken hardware components and wear and tear of hardware in the physical system. The application of declarative aspect-oriented techniques to realize runtime verification monitors increases modularity and provides the ability to statically verify this realization. The complementary static and runtime verification techniques increase the reliability of embedded control software.