Object-Oriented Technology and Computing Systems Re-Engineering

H. S. M. Zedan, A Cau

• Publisher: Woodhead Publishing
• Year: 1999
• Print ISBN: 9781898563563
• eBook ISBN: 9781782420613
• Topic: Computer Science
• Subtopic: Computer Engineering
• Index: Computer Science

This book delivers the latest developments in object technology and their impact in computing systems re-engineering. Object-oriented programming is here shown to provide support for constructing large scale systems that are cheaply built and with reusable components, adaptable to changing requirements and use efficient and cost-effective techniques.Internationally recognised authorities from Finland, France, Germany, Italy, Poland, Spain, the UK and the USA here record their research and development work on the industrial techniques and structured object-oriented methodologies in forward and reverse engineering of computing systems. This book takes stock of progress of that work showing its promise and feasibility, and how its structured technology can overcome the limitations of forward engineering methods used in industry. Forward methods are focused in the domain of reverse engineering to implement a high level of specification for existing software.The book contains the selected, quintessential content of the first UK Colloquium on Object Technology and Systems Re-Engineering held at Oxford University in 1998. The conference was sponsored by British Telecom Laboratories, EMSI limited and the OOSP Specialised Group of The British Computer Society. - Delivers the latest developments in object technology and their impact in computing systems re-engineering - Provides support for constructing large scale systems that are cheaply built and with reusable components, adaptable to changing requirements and use efficient and cost-effective techniques - Contains the content of the first UK Colloquium on Object Technology and Systems Re-Engineering held at Oxford University in 1998

1

Toward an Object-Oriented Design Methodology for Hybrid Systems

Viktor Friesen[email protected] and André Nordwig[email protected], Technische Universität Berlin, FB 13, Sekr. FR 5-6, Franklinstraße 28/29, D-10587 Berlin, Germany

Matthias Weber[email protected], Daimler-Benz AG, Research and Technology, Alt-Moabit 96a, D-10559 Berlin, Germany

Abstract

In this paper, we present an object-oriented approach to the design of hybrid systems using UML^h, a variant of UML for hybrid systems. We introduce the main concepts of UML^h, describe a support tool, and look at their application for the design of a steam-boiler system.

1.1 INTRODUCTION

Hybrid systems are networks of components with discrete and continuous behavior. Typical examples of hybrid systems are physical processes along with their discrete controllers. As such systems are often involved in safety-critical applications, their analysis plays an important role in current research. Three major analysis strategies can be identified: verification, testing, and simulation. Recently, numerous formalisms have been developed for the precise specification of the behavior of hybrid systems; typical examples are Hybrid Automata [2], Extended Duration Calculus [6], and Hybrid CSP [12]. Most of these formalisms are designed to support formal verification. But there is a fundamental problem with the formal verification of hybrid systems: the majority of such systems are not analytically tractable, only for some special types of (in)equation systems do there exist closed solutions and are algorithms known specifying how these solutions can be found. Hence, formal verification can succeed only for a few special types of problems. On the other hand, systematic testing of a hybrid system using physical prototypes or even a real environment is very expensive. Moreover, errors found during unit or integration testing are very expensive to fix. In the case of safety-critical systems, the resources needed for (regression) testing may account for more than 2/3 of the overall development budget. Simulation is therefore an essential analysis method for hybrid systems, especially if it can help to identify errors at an early stage.

The complexity of applications involving hybrid systems continues to grow rapidly. Powerful structuring means are therefore needed to describe such systems. This is one of the reasons why recently proposed simulation languages like Omola [3], Dymola [7], Smile [13], or Modelica [8] all incorporate object-oriented structuring concepts. Another advantage of the object-oriented paradigm is the adequacy of modeling physical components as objects, which leads to model components that are more reusable. The software engineering group at the TU Berlin has proposed an integrated approach to the development of object-oriented simulations of hybrid systems [4]. The main idea behind this approach is to adapt the conventional software-development process to the simulation development. Here we distinguish three main activities: design, model specification, and implementation (Fig. 1.1). The results of these activities are a set of structure diagrams, a precise and complete description of the behavioral model (ZimOO specification), and a model in an executable simulation language (Smile model description), respectively. For the last two phases, we use the object-oriented specification language ZimOO [9] and the simulation language Smile [13]. The interplay between these last two development phases was described in [4].

Figure 1.1 Structure of object-oriented simulation development

In this paper, we concentrate on the first phase. We describe an object-oriented notation and an accompanying methodology for the design of hybrid systems, which are based on UML (Unified Modeling Language [15]). This notation is called UML^h(hybrid UML). UML is becoming a quasi standard in OOD of discrete systems. It integrates many popular notations of OOD, including class diagrams, use-case diagrams, collaboration diagrams, and statecharts. UML^h is still limited to class diagrams, but it is planned to extend it, adapting and integrating other UML concepts for hybrid systems.

So far, little research has been done on the object-oriented design of hybrid systems, the only relevant work, to our knowledge, being the OHMS approach (Object-oriented Methodology for Hybrid Systems) [16]. There are two main differences between OHMS and UML^h. The first is that OHMS uses hybrid automata as a target language. This is a well-known formalism for hybrid-systems specification, but it is not object-oriented. This is not surprising because the main purpose of OHMS is to verify rather than simulate hybrid systems, and a powerful tool (HyTeX) is available for the symbolic verification of linear hybrid automata. As a target language for UML^h we are here using ZimOO, an object-oriented specification language, which was used as a basis for the development of UML^h. However, UML^h could, in principle, also be used in combination with other object-oriented languages for hybrid system modeling. Thus, the full power of object-oriented simulation languages can be exploited in the third development phase. The second difference between the two approaches is related to the class diagrams. OHMS provides only one general notation for a class. It can then be substituted by a hybrid automaton to describe continuous or hybrid behavior, or by a conventional automaton (a finite state machine) when the object represents purely discrete behavior. As different specification means are needed to de...

Table of contents

• Cover image
• Title page
• Table of Contents
• About the Authors
• Copyright
• Preface
• Chapter 1: Toward an Object-Oriented Design Methodology for Hybrid Systems
• Chapter 2: Design Patterns and their Role in Formal Object-oriented Development
• Chapter 3: Devising Coexistence Strategies for Objects with Legacy Systems
• Chapter 4: Object-Oriented Model for Expert Systems Implementation
• Chapter 5: Re-engineering Requirements Specifications for Reuse: A Synthesis of 3 Years Industrial Experience
• Chapter 6: Object-Oriented Development Of X-Ray Spectrometer Software
• Chapter 7: Pre-processing COBOL Programs for Reverse Engineering in A Software Maintenance Tool
• Chapter 8: Agent Oriented Programming Language LASS
• Chapter 9: Fair Objects
• Chapter 10: Systems of Systems as Communicating Structures
• Chapter 11: Suitability of CORBA as a Heterogeneous Distributed Platform
• Chapter 12: Using OO Design to Enhance Procedural Software
• Chapter 13: Reengineering Procedural Software to Object-Oriented Software Using Design Transformations and Resource Usage Matrix
• Electronics: computer science, pattern recognition