Performance Testing of Distributed Component Architectures

Performance characteristics, such as response time, throughput andscalability, are key quality attributes of distributed applications. Current practice,however, rarely applies systematic techniques to evaluate performance characteristics.We argue that evaluation of performance is particularly crucial in early developmentstages, when important architectural choices are made. At first glance, thiscontradicts the use of testing techniques, which are usually applied towards the endof a project. In this chapter, we assume that many distributed systems are builtwith middleware technologies, such as the Java 2 Enterprise Edition (J2EE) or theCommon Object Request Broker Architecture (CORBA). These provide servicesand facilities whose implementations are available when architectures are defined.We also note that it is the middleware functionality, such as transaction and persistenceservices, remote communication primitives and threading policy primitives,that dominates distributed system performance. Drawing on these observations, thischapter presents a novel approach to performance testing of distributed applications.We propose to derive application-specific test cases from architecture designs so thatthe performance of a distributed application can be tested based on the middlewaresoftware at early stages of a development process. We report empirical results thatsupport the viability of the approach

병렬 및 분산 임베디드 시스템을 위한 모델 기반 코드 생성 프레임워크

학위논문(박사)--서울대학교 대학원 :공과대학 컴퓨터공학부,2020. 2. 하순회.소프트웨어 설계 생산성 및 유지보수성을 향상시키기 위해 다양한 소프트웨어 개발 방법론이 제안되었지만, 대부분의 연구는 응용 소프트웨어를 하나의 프로세서에서 동작시키는 데에 초점을 맞추고 있다. 또한, 임베디드 시스템을 개발하는 데에 필요한 지연이나 자원 요구 사항에 대한 비기능적 요구 사항을 고려하지 않고 있기 때문에 일반적인 소프트웨어 개발 방법론을 임베디드 소프트웨어를 개발하는 데에 적용하는 것은 적합하지 않다. 이 논문에서는 병렬 및 분산 임베디드 시스템을 대상으로 하는 소프트웨어를 모델로 표현하고, 이를 소프트웨어 분석이나 개발에 활용하는 개발 방법론을 소개한다. 우리의 모델에서 응용 소프트웨어는 계층적으로 표현할 수 있는 여러 개의 태스크로 이루어져 있으며, 하드웨어 플랫폼과 독립적으로 명세한다. 태스크 간의 통신 및 동기화는 모델이 정의한 규약이 정해져 있고, 이러한 규약을 통해 실제 프로그램을 실행하기 전에 소프트웨어 에러를 정적 분석을 통해 확인할 수 있고, 이는 응용의 검증 복잡도를 줄이는 데에 기여한다. 지정한 하드웨어 플랫폼에서 동작하는 프로그램은 태스크들을 프로세서에 매핑한 이후에 자동적으로 합성할 수 있다. 위의 모델 기반 소프트웨어 개발 방법론에서 사용하는 프로그램 합성기를 본 논문에서 제안하였는데, 명세한 플랫폼 요구 사항을 바탕으로 병렬 및 분산 임베디드 시스템을에서 동작하는 코드를 생성한다. 여러 개의 정형적 모델들을 계층적으로 표현하여 응용의 동적 행태를 나타고, 합성기는 여러 모델로 구성된 계층적인 모델로부터 병렬성을 고려하여 태스크를 실행할 수 있다. 또한, 프로그램 합성기에서 다양한 플랫폼이나 네트워크를 지원할 수 있도록 코드를 관리하는 방법도 보여주고 있다. 본 논문에서 제시하는 소프트웨어 개발 방법론은 6개의 하드웨어 플랫폼과 3 종류의 네트워크로 구성되어 있는 실제 감시 소프트웨어 시스템 응용 예제와 이종 멀티 프로세서를 활용하는 원격 딥 러닝 예제를 수행하여 개발 방법론의 적용 가능성을 시험하였다. 또한, 프로그램 합성기가 새로운 플랫폼이나 네트워크를 지원하기 위해 필요로 하는 개발 비용도 실제 측정 및 예측하여 상대적으로 적은 노력으로 새로운 플랫폼을 지원할 수 있음을 확인하였다. 많은 임베디드 시스템에서 예상치 못한 하드웨어 에러에 대해 결함을 감내하는 것을 필요로 하기 때문에 결함 감내에 대한 코드를 자동으로 생성하는 연구도 진행하였다. 본 기법에서 결함 감내 설정에 따라 태스크 그래프를 수정하는 방식을 활용하였으며, 결함 감내의 비기능적 요구 사항을 응용 개발자가 쉽게 적용할 수 있도록 하였다. 또한, 결함 감내 지원하는 것과 관련하여 실제 수동으로 구현했을 경우와 비교하였고, 결함 주입 도구를 이용하여 결함 발생 시나리오를 재현하거나, 임의로 결함을 주입하는 실험을 수행하였다. 마지막으로 결함 감내를 실험할 때에 활용한 결함 주입 도구는 본 논문의 또 다른 기여 사항 중 하나로 리눅스 환경으로 대상으로 응용 영역 및 커널 영역에 결함을 주입하는 도구를 개발하였다. 시스템의 견고성을 검증하기 위해 결함을 주입하여 결함 시나리오를 재현하는 것은 널리 사용되는 방법으로, 본 논문에서 개발된 결함 주입 도구는 시스템이 동작하는 도중에 재현 가능한 결함을 주입할 수 있는 도구이다. 커널 영역에서의 결함 주입을 위해 두 종류의 결함 주입 방법을 제공하며, 하나는 커널 GNU 디버거를 이용한 방법이고, 다른 하나는 ARM 하드웨어 브레이크포인트를 활용한 방법이다. 응용 영역에서 결함을 주입하기 위해 GDB 기반 결함 주입 방법을 이용하여 동일 시스템 혹은 원격 시스템의 응용에 결함을 주입할 수 있다. 결함 주입 도구에 대한 실험은 ODROID-XU4 보드에서 진행하였다.While various software development methodologies have been proposed to increase the design productivity and maintainability of software, they usually focus on the development of application software running on a single processing element, without concern about the non-functional requirements of an embedded system such as latency and resource requirements. In this thesis, we present a model-based software development method for parallel and distributed embedded systems. An application is specified as a set of tasks that follow a set of given rules for communication and synchronization in a hierarchical fashion, independently of the hardware platform. Having such rules enables us to perform static analysis to check some software errors at compile time to reduce the verification difficulty. Platform-specific program is synthesized automatically after mapping of tasks onto processing elements is determined. The program synthesizer is also proposed to generate codes which satisfies platform requirements for parallel and distributed embedded systems. As multiple models which can express dynamic behaviors can be depicted hierarchically, the synthesizer supports to manage multiple task graphs with a different hierarchy to run tasks with parallelism. Also, the synthesizer shows methods of managing codes for heterogeneous platforms and generating various communication methods. The viability of the proposed software development method is verified with a real-life surveillance application that runs on six processing elements with three remote communication methods, and remote deep learning example is conducted to use heterogeneous multiprocessing components on distributed systems. Also, supporting a new platform and network requires a small effort by measuring and estimating development costs. Since tolerance to unexpected errors is a required feature of many embedded systems, we also support an automatic fault-tolerant code generation. Fault tolerance can be applied by modifying the task graph based on the selected fault tolerance configurations, so the non-functional requirement of fault tolerance can be easily adopted by an application developer. To compare the effort of supporting fault tolerance, manual implementation of fault tolerance is performed. Also, the fault tolerance method is tested with the fault injection tool to emulate fault scenarios and inject faults randomly. Our fault injection tool, which has used for testing our fault-tolerance method, is another work of this thesis. Emulating fault scenarios by intentionally injecting faults is commonly used to test and verify the robustness of a system. To emulate faults on an embedded system, we present a run-time fault injection framework that can inject a fault on both a kernel and application layer of Linux-based systems. For injecting faults on a kernel layer, two complementary fault injection techniques are used. One is based on Kernel GNU Debugger, and the other is using a hardware breakpoint supported by the ARM architecture. For application-level fault injection, the GDB-based fault injection method is used to inject a fault on a remote application. The viability of the proposed fault injection tool is proved by real-life experiments with an ODROID-XU4 system.Chapter 1 Introduction 1 1.1 Motivation 1 1.2 Contribution 6 1.3 Dissertation Organization 8 Chapter 2 Background 9 2.1 HOPES: Hope of Parallel Embedded Software 9 2.1.1 Software Development Procedure 9 2.1.2 Components of HOPES 12 2.2 Universal Execution Model 13 2.2.1 Task Graph Specification 13 2.2.2 Dataflow specification of an Application 15 2.2.3 Task Code Specification and Generic APIs 21 2.2.4 Meta-data Specification 23 Chapter 3 Program Synthesis for Parallel and Distributed Embedded Systems 24 3.1 Motivational Example 24 3.2 Program Synthesis Overview 26 3.3 Program Synthesis from Hierarchically-mixed Models 30 3.4 Platform Code Synthesis 33 3.5 Communication Code Synthesis 36 3.6 Experiments 40 3.6.1 Development Cost of Supporting New Platforms and Networks 40 3.6.2 Program Synthesis for the Surveillance System Example 44 3.6.3 Remote GPU-accelerated Deep Learning Example 46 3.7 Document Generation 48 3.8 Related Works 49 Chapter 4 Model Transformation for Fault-tolerant Code Synthesis 56 4.1 Fault-tolerant Code Synthesis Techniques 56 4.2 Applying Fault Tolerance Techniques in HOPES 61 4.3 Experiments 62 4.3.1 Development Cost of Applying Fault Tolerance 62 4.3.2 Fault Tolerance Experiments 62 4.4 Random Fault Injection Experiments 65 4.5 Related Works 68 Chapter 5 Fault Injection Framework for Linux-based Embedded Systems 70 5.1 Background 70 5.1.1 Fault Injection Techniques 70 5.1.2 Kernel GNU Debugger 71 5.1.3 ARM Hardware Breakpoint 72 5.2 Fault Injection Framework 74 5.2.1 Overview 74 5.2.2 Architecture 75 5.2.3 Fault Injection Techniques 79 5.2.4 Implementation 83 5.3 Experiments 90 5.3.1 Experiment Setup 90 5.3.2 Performance Comparison of Two Fault Injection Methods 90 5.3.3 Bit-flip Fault Experiments 92 5.3.4 eMMC Controller Fault Experiments 94 Chapter 6 Conclusion 97 Bibliography 99 요 약 108Docto

An open extensible tool environment for Event-B

Abstract. We consider modelling indispensable for the development of complex systems. Modelling must be carried out in a formal notation to reason and make meaningful conjectures about a model. But formal modelling of complex systems is a difficult task. Even when theorem provers improve further and get more powerful, modelling will remain difficult. The reason for this that modelling is an exploratory activity that requires ingenuity in order to arrive at a meaningful model. We are aware that automated theorem provers can discharge most of the onerous trivial proof obligations that appear when modelling systems. In this article we present a modelling tool that seamlessly integrates modelling and proving similar to what is offered today in modern integrated development environments for programming. The tool is extensible and configurable so that it can be adapted more easily to different application domains and development methods.

Quality-aware model-driven service engineering

Service engineering and service-oriented architecture as an integration and platform technology is a recent approach to software systems integration. Quality aspects ranging from interoperability to maintainability to performance are of central importance for the integration of heterogeneous, distributed service-based systems. Architecture models can substantially influence quality attributes of the implemented software systems. Besides the benefits of explicit architectures on maintainability and reuse, architectural constraints such as styles, reference architectures and architectural patterns can influence observable software properties such as performance. Empirical performance evaluation is a process of measuring and evaluating the performance of implemented software. We present an approach for addressing the quality of services and service-based systems at the model-level in the context of model-driven service engineering. The focus on architecture-level models is a consequence of the black-box character of services

OCL Tools Report based on the IDE4OCL Feature Model

Previously we have developed the idea of an Integrated Development Environment for OCL (IDE4OCL). Based on the OCL community's feedback we have also designed and published an IDE4OCL feature model. Here we present a report on selected OCL tools developed by the authors and their teams. Each author gives an overview of their OCL tool, provides a top level architecture, and gives an evaluation of the tool features in a web framework. The framework can also be used by other potential OCL users and tool developers. For users it may serve as an aid to choose a suitable tool for their OCL use scenarios. For tool developers it provides a comparative view for further development of the OCL tools. Our plans are to maintain the collected data and extend this web framework by further OCL tools. Additionally, we would like to encourage sharing of OCL development resources

Enhancing Formal Modelling Tool Support with Increased Automation

Progress report for the qualification exam report for PhD Student Kenneth Lausdahl. Initial work on enhancing tool support for the formal method VDM and the concept of unifying a abstract syntax tree with the ability for isolated extensions is described. The tool support includes a connection to UML and a test automation principle based on traces written as a kind of regular expressions

Implementing a Debugger for Dresden OCL

Although originally designed as an extension for the Unifi ed Modeling Language (UML), today, the Object Constraint Language (OCL) has been broadly adopted in the context of both UML and other modeling and domain-specifi c languages. However, appropriate tooling, supporting modelers and software developers on using OCL is still scarce and lacks important features such as debugging support. As OCL constraints are likely to become rather complex for real world examples, it is hard to comprehend the in uence of single OCL expressions and subexpressions on the result of a completely evaluated OCL constraint in the context of speci fic constrained objects. Therefore, debugging is of topmost importance for both constraint comprehension and maintenance. Thus, the major task of this work is to develop a graphical debugger integrated into Dresden OCL and the Eclipse Integrated Development Environment (IDE) to fill this gap.:1 Introduction 2 The Dresden OCL Toolkit 2.1 The Dresden OCL Toolkit 2.2 The Dresden OCL2 Toolkit 2.3 Dresden OCL2 for Eclipse 2.4 Dresden OCL 3 The Eclipse Debugging Framework 3.1 The Debug Model 3.2 Interacting with the Debug Model 3.3 The Execution Control Commands 4 Requirements Analysis and Related Work 4.1 Requirements Analysis 4.2 Related Work 5 Design and Structure 5.1 Architecture 5.1.1 Package Structure 5.1.2 Class Structure 5.2 The OCL Debug Model 5.3 The Mapping from ASM to AST 5.4 The OCL Debugger 5.4.1 The Implementation of the Debugger 5.4.2 Testing the Debugger 6 Graphical User Interface Implementation 6.1 The Dresden OCL Debug Perspective 6.2 Using the Debugger 6.2.1 Selecting a Model 6.2.2 Selecting a Model Instance 6.2.3 Debugging 6.3 Summary 7 Evaluation and Future Work 33 7.1 Evaluation 7.2 Future Work 8 Summary and Conclusio

UML as a system level design methodology with application to software radio

Master'sMASTER OF SCIENC

Model-based specification of the flight software of an autonomous satellite

International audienceIn the framework of the AGATA program, we applied a model-based development process founded on a living UML specification to produce the RT-Java code of the AGATA onboard software. Derived from classical V-shaped production cycle, our development process benefited from several model-based engineering methods, such as model-debugging and automated code generation. Our resulting Y-shaped production cycle enabled an incremental development process that allowed us to start software validation early in the process. Despite the complexity of the AGATA onboard software we thereby manage to achieve its functional validation and were able to evaluate RT-Java (Real-Time Java Specification-RTSJ) for real-time space applications