Proceedings of the IEEE January 2003 The paper describes a model-integrated approach for embedded software development that is based on domain-specific, multiple view models used in all phases of the development process. Models explicitly represent the embedded software and the environment it operates in, and capture the requirements and the design of the application, simultaneously. Models are descriptive, in the sense that they allow the formal analysis, verification and validation of the embedded system at design time. Models are also generative, in the sense that they carry enough information for automatically generating embedded systems using the techniques of program generators. Because of the widely varying nature of embedded systems, a single modeling language may not be suitable for all domains, thus modeling languages are often domain-specific. To decrease the cost of defining and integrating domain-specific modeling languages and corresponding analysis and synthesis tools, the model-integrated approach is applied in a metamodeling architecture, where formal models of domain-specific modeling languages – called metamodels – play a key role in customizing and connecting components of tool chains. The paper will discuss the principles and techniques of model-integrated embedded software development in detail, as well as the capabilities of the tools supporting the process. Examples in terms of real systems will be given that illustrate how the model-integrated approach addresses the physical nature, the assurance issues, and the dynamic structure of embedded software.

Abstract. The Uni ed Modeling Language (UML) is rapidly emerging as a de-facto standard for modelling OO systems. Given this role, it is imperative that the UML needs a well-de ned, fully explored semantics. Such semantics is required in order to ensure that UML concepts are precisely stated and de ned. In this paper we motivate an approach to formalizing UML in which formal speci cation techniques are used to gain insight into the semantics of UML notations and diagrams and describe a roadmap for this approach. The authors initiated the Precise UML (PUML) group in order to develop a precise semantic model for UML diagrams. The semantic model is to be used as the basis for a set of diagrammatical transformation rules, which enable formal deductions to be made about UML diagrams. A small example shows how these rules can be used to verify whether one class diagram is a valid deduction of another. Because these rules are presented at the diagrammatical level, it will be argued that UML can be successfully used as a formal modelling tool without the notational complexities that are commonly found in textual speci cation techniques. 1

Software architecture descriptions are high-level models of software systems. Some researchers have proposed special-purpose architectural notations that have a great deal of expressive power but are not well integrated with common development methods. Others have used mainstream development methods that are accessible to developers, but lack semantics needed for extensive analysis. We describe an approach to combining the advantages of these two ways of modeling architectures. We present two examples of extending UML, an emerging standard design notation, for use with two architecture description languages, C2 and Wright. Our approach suggests a practical strategy for bringing architectural modeling into wider use, namely by incorporating substantial elements of architectural models into a standard design method. Keywords Software architecture, object-oriented design, architecture description languages, constraint languages, incremental development 1

UML is the de-facto standard formalism for software design and analysis. To support the design of large-scale industrial applications, sophisticated CASE tools are available on the market, that provide a user-friendly environment for editing, storing, and accessing multiple UML diagrams. It would be highly desirable to equip such CASE tools with automated reasoning capabilities in order to detect relevant formal properties of UML diagrams, such as inconsistencies or redundancies. With regard to this issue, we consider UML class diagrams, which are one of the most important components of UML, and we address the problem of reasoning on such diagrams. We resort to several results developed in the eld of Description Logics (DLs), a family of logics that admit decidable reasoning procedures.

We present a formal semantics for the Object Constraint Language (OCL) which is part of the Unified Modeling Language (UML) -- an emerging standard language and notation for object-oriented analysis and design. In context of information systems modeling, UML class diagrams can be utilized for describing the overall structure, whereas additional integrity constraints and queries are specified with OCL expressions. By using OCL, constraints and queries can be specified in a formal yet comprehensible way. However, the OCL itself is currently defined only in a semi-formal way. Thus the semantics of constraints is in general not precisely defined. Our approach gives precise meaning to OCL concepts and to some central aspects of UML class models. A formal semantics facilitates verification, validation and simulation of models and helps to improve the quality of models and software designs.

Object-oriented analysis and design is an increasingly popular software development method. The Unified Modeling Language (UML) has recently been proposed as a standard language for expressing object-oriented designs. Unfortunately, in its present form the UML lacks precisely defined semantics. This means that it is difficult to determine whether a design is consistent, whether a design modification is correct and whether a program correctly implements a design. Formal methods provide the rigor which is lacking in object-oriented design notations. This provision is often at the expense of clarity of exposition for the non-expert. Formal methods aim to use mathematical techniques in order to allow software development activities to be precisely defined, checked and ultimately automated. This paper aims to present an overview of work being undertaken to provide (a sub-set of) the UML with formal semantics. The semantics will facilitate the use of the UML in the software developm...

The Unified Modeling Language (UML) is rapidly emerging as a de-facto standard for modelling OO systems. Given this role, it is imperative that the UML have a welldefined, fully explored semantics. Such semantics is required in order to ensure that UML concepts are precisely stated and defined. In this paper we describe and motivate an approach to formalizing UML in which formal specification techniques are used to gain insight into the semantics of UML notations and diagrams. We present work carried out by the Precise UML (PUML) group on the development of a precise semantic model for UML class diagrams. The semantic model is used as the basis for a set of diagrammatical transformation rules, which enable formal deductions to be made about UML class diagrams. It is also shown how these rules can be used to verify whether one class diagram is a valid refinement (design) of another. Because these rules are presented at the diagrammatical level, it will be argued that UML can be successfully used as a formal modelling tool without the notational complexities that are commonly found in formal specification techniques.

Introduction Shorter product cycles, lower prices of products, and higher customer demands have created big challenges for the product development process. A successful approach to master these challenges is to employ knowledge-based systems with domain specific, high level, formal description languages which allow a clear separation between domain knowledge and inference knowledge. These techniques can be exploited to (partially) automate the generation of software solutions. Unfortunately, in many cases, such high level, formal description languages are not integrated in the industrial software development process. In addition, these descriptions are di#cult to communicate to domain experts for reviewing purposes. This makes it demanding for software development departments to incorporate such technologies into their standard development process. Therefore, our goal is to make 449 450 A. Felfernig, G. E. Friedrich & D. Jannach such descriptions more accessible b

We show how to transform UML (Unified Modeling Language) state diagrams into graphs by making explicit the intended semantics of the diagram. The process of state expansion in nested state diagrams is explained by graph transformations in three steps: (1) adding boundary nodes introducing a precise interface for the state to be expanded, (2) expanding the state, and (3) removing the boundary nodes. The general idea of approaching the semantics of UML diagrams by graph transformations is applicable to other forms of UML diagrams as well. The main advantage of the graph transformation approach is the closeness between the (mathematical) graph representation and the (UML) diagram representation.

. The object Constraint Language (OCL), which forms part of the UML set of modelling notations, is a precise, textual language for expressing constraints that cannot be shown diagrammatically in UML. This paper reflects on a number of aspects of the syntax and semantics of the OCL, and makes proposals for clarification or extension. Specifically, the paper suggests that: the concept of flattening collections of collections is unnecessary, state models should be connectable to class models, defining object creation should be made more convenient, OCL should be based on a 2-valued logic, set subtraction should be covered more fully, and a "let" feature should be introduced. 1 Introduction The Object Constraint Language [12] is a precise, textual language designed to complement the largely graphical UML [11]. Specifically, OCL supports the expression of invariants, preconditions and postconditions, allowing the modeller to define precise constraints on the behaviour of a model, ...