Hybrid MARTE statecharts

The specification of modeling and analysis of real-time and embedded systems (MARTE) is an extension of the unified modeling language (UML) in the domain of real-time and embedded systems. Even though MARTE time model offers a support to describe both discrete and dense clocks, the biggest effort has been put so far on the specification and analysis of discrete MARTE models. To address hybrid real-time and embedded systems, we propose to extend statecharts using both MARTE and the theory of hybrid automata. We call this extension hybrid MARTE statecharts. It provides an improvement over the hybrid automata in that: the logical time variables and the chronometric time variables are unified. The formal syntax and semantics of hybrid MARTE statecharts are given based on labeled transition systems and live transition systems. As a case study, we model the behavior of a train control system with hybrid MARTE statecharts to demonstrate the benefit.     

Automatic layout of statecharts

Graphical notations are widely used for system specification. The usefulness of these notations depends primarily on their readability. Hence, automatic methods are needed to obtain efficient and understandable graphical representations of requirements. In this paper, we present an algorithm that automatically generates layouts of statecharts. We assume that relevant information is stored in a structure that we call a decomposition tree, and we draw the graph that models a statechart in a hierarchical fashion. Our approach excludes diagrams with inter‐level transitions. Copyright © 2001 John Wiley & Sons, Ltd.     

Hypercharts: extended statecharts to support hypermediaspecification

Introduces hypercharts, a novel and effective notation that extends the well-known statechart formalism to make it suitable for the specification of temporal and information synchronization requirements of hypermedia applications. Three new definitions are added: timed history, timed transitions, and a set of synchronization mechanisms. The proposed extensions are based on the major characteristics of some Petri net-based multimedia models, and have their semantics described in terms of conventional statechart models. Therefore, any hyperchart construction can be transformed into a statechart that exhibits the desired behavior, giving hyperchart models the same semantic behavior as statecharts. The new constructs are illustrated using a case study based on a hypermedia-modeling example     

Extending statecharts with temporal logic

The task of designing large real-time reactive systems, which interact continuously with their environment and exhibit concurrency properties, is a challenging one. The authors explore the utility of a combination of behavior and function specification languages in specifying such systems and verifying their properties. An existing specification language, statecharts, is used to specify the behavior of real-time reactive systems, while a new logic-based language called FNLOG (based on first-order predicate calculus and temporal logic) is designed to express the system functions over real time. Two types of system properties, intrinsic and structural, are proposed. It is shown that both types of system properties are expressible in FNLOG and may be verified by logical deduction, and also hold for the corresponding behavior specification     

Executable object modeling with statecharts

Statecharts, popular for modeling system behavior in the structural analysis paradigm, are part of a fully executable language set for modeling object-oriented systems. The languages form the core of the emerging Unified Modeling Language. The authors embarked on an effort to develop an integrated set of diagrammatic languages for object modeling, built around statecharts, and to construct a supporting tool that produces a fully executable model and allows automatic code synthesis. The language set includes two constructive modeling languages (languages containing the information needed to execute the model or translate it into executable code)     

Extending statecharts with process algebra operators

This paper describes an adaptation of statecharts to take advantage of process algebra operators like those found in CSP and EB³. The resulting notation is called algebraic state transition diagrams (ASTDs). The process algebra operators considered include sequence, iteration, parallel composition, and quantified synchronization. Quantification is one of the salient features of ASTDs, because it provides a powerful mechanism to precisely and explicitly define cardinalities in a dynamic model. The formal semantics of ASTDs is expressed using the operational style typically used in process algebras. The target application domain is the specification and implementation of information systems.     

Optimizing symbolic model checking for statecharts

Symbolic model checking based on binary decision diagrams is a powerful formal verification technique for reactive systems. In this paper, we present various optimizations for improving the time and space efficiency of symbolic modal checking for systems specified as statecharts. We used these techniques in our analyses of the models of a collision avoidance system and a fault-tolerant electrical power distribution (EPD) system, both used on commercial aircraft. The techniques together reduce the time and space requirements by orders of magnitude, making feasible some analysis that was previously intractable. We also elaborate on the results of verifying the EPD model. The analysis disclosed subtle modeling and logical flaws not found by simulation     

状态图中可同步测试序列生成策略

对于由通信有限状态机构成的状态图的可同步测试序列的生成策略,一种现有的方法是由状态图生成相应的积自动机,然后采用有限状态机的测试序列生成策略。这种方法存在组合空间爆炸问题和测试序列的同步问题。在定义了测试序列的两类同步问题的基础上,提出了基于多测试驱动的测试模型MTM和基于该模型的测试序列生成策略,该策略在不生成积自动机的情况下,通过同步锁和相应的策略解决两种类型的同步问题,避免了组合空间爆炸问题。     

Barriers to continuance use of cloud computing: Evidence from two case studies

Continuous use of cloud computing and cloud sourcing has received limited research attention compared to cloud adoption. There are indications that cloud sourcing benefits are not easy to reap in continuous use for companies, calling for more research on the continuance use of cloud computing. The current study is one of the first studies of the continuance use of cloud computing processes at the organizational level, contributing to the management and business research literature on cloud computing. In particular, the present study has contributed with two case studies verifying the existence of barriers and more importantly identifying an additional type of barrier: management process barriers (MP), i.e., lack of objectives and strategies for cloud sourcing and lack of organizing cloud vendor communication. Overcoming or reducing management process barriers guides the continuance use of cloud computing process in a strategic direction for the company and enables cloud-related innovation. As a contribution, our research builds on and extends extant research by providing a TOMPE framework of barriers to the continuance use of cloud computing (based and modified from the technology–organization–environment (TOE) framework, by complementing it with the identified management process barriers).     

Industry case studies in the use of immersive virtual assembly

In this paper, we report on two engineering case studies that have been conducted as part of a Virtual Assembly Technology Consortium. The objectives of the case studies were to determine if immersive virtual assembly capabilities allow industry assembly situations to be modelled and studied realistically, and to demonstrate the downstream value of the virtual assembly capabilities in areas such as ergonomics, assembly installation, process planning, installation, and serviceability. What is of special significance is that instead of modelling simplified problems or perceived representative situations, the case studies were constructed from actual assembly floor projects and situations encountered at industry member sites and with considerable participation from industry engineers and manufacturing shop floor personnel. Based on the success of the case studies, the consortium members inferred that virtual assembly methods are poised to move out of the realm of special projects and test scenarios to deployment in the actual design and manufacturing cycle. However, in order to be truly accepted in industry, there are still issues to be addressed in terms of ease of use, portability of the applications, and preparation of the models for the evaluations. Thus, the case studies added a new dimension to the exploration and understanding of how this new technology could be of practical value in industry.     

合成状态图中非预期状态转换路径的确认

利用Scenario进行需求建模能够反映从用户角度观察到的系统行为,而利用状态图能够从对象角度对系统行为进行精确描述.从Scenario到状态图的自动转换指软件开发过程中,从UML需求模型自动生成行为模型的过程.在分析已有的自动转换算法存在的不足的基础上,提出了从语法角度出发,对用例进行分析,提取合适的状态向量;利用在算法中增加Scenario的相关信息,确定非预期状态转换路径.     

Unified architecture for network measurement: The case of available bandwidth

In the field of network monitoring and measurement, the efficiency and accuracy of the adopted tools is strongly dependent on (i) structural and dynamic characteristics of the network scenario under measurement and (ii) on manual fine tuning of the involved parameters. This is, for example, the case of the end-to-end available bandwidth estimation, in which the constraints of the measurement stage vary according to the use of the final results. In this work, we present UANM (unified architecture for network measurement), a novel measurement infrastructure for the automatic management of measurement stages, tailored to the end-to-end available bandwidth estimation tools. We describe in detail its architecture, illustrating the features we introduced to mitigate the problems affecting available bandwidth estimation in heterogeneous scenarios. To provide evidences of UANM benefits, we present an experimental validation in three selected scenarios deployed over a real network testbed to (i) quantify the overhead introduced by the use of UANM, (ii) show how UANM is able to alleviate the interferences among concurrent measurements, and (iii) illustrate how UANM is capable to provide more accurate results thanks to the knowledge of the network environment. Finally, for the first time in literature, we provide a “fair comparison” of eight available bandwidth estimations tools in terms of accuracy, probing time, and intrusiveness.     

Automated support for deriving test requirements from UML statecharts

Many statechart-based testing strategies result in specifying a set of paths to be executed through a (flattened) statechart. These techniques can usually be easily automated so that the tester does not have to go through the tedious procedure of deriving paths manually to comply with a coverage criterion. The next step is then to take each test path individually and derive test requirements leading to fully specified test cases. This requires that we determine the system state required for each event/transition that is part of the path to be tested and the input parameter values for all events and actions associated with the transitions. We propose here a methodology towards the automation of this procedure, which is based on a careful normalization and analysis of operation contracts and transition guards written with the Object Constraint Language (OCL). It is illustrated by one case study that exemplifies the steps of our methodology and provides a first evaluation of its applicability. The scope of the testing activity depends on what is modeled by the statechart. If the statechart models the behavior of a single class, then it can be used to support unit testing. If the behavior of a class-cluster, a subsystem or a component is modeled, then we are concerned with integration testing. If the whole system is modeled, then the focus of statechart-based testing is system testing. Lionel C. Briand is on the faculty of the Department of Systems and Computer Engineering, Carleton University, Ottawa, Canada, where he founded and leads the Software Quality Engineering Laboratory (http://www.sce.carleton.ca/Squall/ Squall.htm). He has been granted the Canada Research Chair in Software Quality Engineering and is also a visiting professor at the Simula laboratories, University of Oslo, Norway. Before that he was the software quality engineering department head at the Fraunhofer Institute for Experimental Software Engineering, Germany. Dr. Lionel also worked as a research scientist for the Software Engineering Laboratory, a consortium of the NASA Goddard Space Flight Center, CSC, and the University of Maryland. He has been on the program, steering, or organization committees of many international, IEEE conferences such as ICSE, ICSM, ISSRE, and METRICS. He is the coeditor-in-chief of Empirical Software Engineering (Springer) and is a member of the editorial board of Systems and Software Modeling (Springer). He was on the board of IEEE Transactions on Software Engineering from 2000 to 2004. His research interests include: object-oriented analysis and design, inspections and testing in the context of object-oriented development, quality assurance and control, project planning and risk analysis, and technology evaluation. Lionel received the BSc and MSc degrees in geophysics and computer systems engineering from the University of Paris VI, France. He received the PhD degree in computer science, with high honors, from the University of Paris XI, France. Yvan Labiche received the BSc in Computer System Engineering, from the graduate school of engineering: CUST (Centre Universitaire des Science et Techniques, Clermont-Ferrand), France. He completed a Master of fundamental computer science and production systems in 1995 (Université Blaise Pascal, Clermont Ferrand, France). While doing his Ph.D. in Software Engineering, completed in 2000 at LAAS/CNRS in Toulouse, France, Yvan worked with Aerospatiale Matra Airbus (now EADS Airbus) on the definition of testing strategies for safety-critical, on-board software, developed using object-oriented technologies. In January 2001, Dr. Yvan Labiche joined the Department of Systems and Computer Engineering at Carleton University, as an Assistant Professor. His research interests include: object-oriented analysis and design, software testing in the context of object-oriented development, and technology evaluation. He is a member of the IEEE. Jim (Jingfeng) Cui completed his BSc in Industrial Automation Control, from the School of Information and Engineering, Northeastern University, China. He received a Master of Applied Science (specialization in Software Engineering) in 2004 from the Ottawa-Carleton Institute of Electrical and Computer Engineering, Ottawa, Canada. While in his graduate study, he was awarded the Ontario Graduate Scholarship of Science and Technology. He is now a senior Software Architect in Sunyard System & Engineering Co.Ltd., China. His interest includes Object-Oriented Software Development, Quality Assurance, and Content Management System.     

Unified model-based fault diagnosis for three industrial application studies

This paper proposes a unified scheme for fault detection and isolation (FDI) that integrates model-based and multivariate statistical methods. For creating suitable models, subspace model identification is utilized together with state-observers to track the measured process operation. To describe and analyze the impact of fault conditions, the scheme utilizes input reconstruction and unknown input estimation to generate multivariate residual-based statistics. In contrast to existing work, the paper presents three industrial application studies involving sensor faults, as well as process and actuator faults which result from measured and unmeasured disturbances.     

Experimenting statecharts for multiple experts knowledge elicitation in agriculture

Statecharts were experimented as a mediation tool between multiple experts and a knowledge engineer. After a short survey of knowledge elicitation methods for multiple experts, we present our method for assessing the quality of the elicited model and give critiques on the basis of our case study in vineyards crop protection management.     

UML vs. classical vs. rhapsody statecharts: not all models are created equal

State machines, represented by statecharts or state machine diagrams, are an important formalism for behavioural modelling. According to the research literature, the most popular statechart formalisms appear to be Classical, UML, and that implemented by Rhapsody. These three formalisms seem to be very similar; however, there are several key syntactic and semantic differences. These differences are enough that a model written in one formalism could be ill-formed in another formalism. Worse, a model from one formalism might actually be well-formed in another, but be interpreted differently due to the semantic differences. This paper summarizes the results of an informal comparative study of these three formalisms with the help of several illustrative examples. We present a classification of the differences according to the nature of potential problems caused by each difference. In addition, for each difference we discuss how translation between formalisms can be achieved, if at all.     

Explicit modeling of semantics associated with composite states in UML statecharts

UML statecharts are used for describing dynamic aspects of system behavior. The work presented here extends a general Petri net-based methodology to support formal modeling of UML statecharts. The approach focuses on the specific task of generating explicit transition models associated with the hierarchical structure of statechart. We introduce a state-transition notation to serve as an intermediate model for conversion of UML statecharts, and in particular, the complexity of composite states, to other target specifications. By defining a process for deriving, from UML statecharts, a state-transition notation that can serve as an intermediate state machine model, we seek to deepen understanding of modeling practices and help bridge the gap between model development and model analysis. This work covers all of the primary issues associated with the hierarchical structure of composite states, including entry and exit transitions, transition priorities, history states, and event dispatching. Thus, the results provide an important step forward toward the goal of modeling increasingly complex semantics of UML statecharts. This material is based upon work supported by the U.S. Army Research Office under grant number DAAD19-01-1-1-0672, and the U.S. National Science Foundation under grant number CCR-9988168.