8741871
Living with free type and class union
There are two constructs in the formal specification language Object-Z for modelling polymorphic and recursive structures. One construct, the free type, is adopted from the Z specification language. The other, class-union, facilitates polymorphic class declarations. Free type and class-union constructs are respectively based upon the functional value point of view and the object reference point of view. Consequently, the roles these two constructs perform in system modelling are different. The free type and class-union constructs are compared and discussed through various examples. The aim of this comparison and discussion is to present guidelines on how to appropriately and effectively use these two constructs to specify polymorphic and recursive structures.
207130315
Formal Designs for Embedded and Hybrid Systems
The design of embedded and hybrid systems requires powerful mechanisms for modeling data, state, concurrency and real-time behaviour. The {first} part of this paper illustrates a powerful design notation Timed Communicating Object Z (TCOZ) that has both channel based and sensor/actuator based interfaces. We believe that TCOZ is well suited for presenting more complete and coherent design models for complex embedded and hybrid systems. However, the challenge is how to analyze and check these models with tools support. One effective approach is to project (transform) the design models into multiple domains, then to use existing specialized tools in those domains to perform the checking and analyzing tasks. The second part of this paper demonstrates one particular projection from TCOZ designs to Timed Automata (TA) models so that TA model checkers can be used to check time related properties.
13839820
Relating /spl pi/-calculus to Object-Z
Software systems have become increasingly distributed, dynamic and mobile. The complex state and dynamic interfaces of software components and their concurrent interactions provide challenging research issues in system specification and design. An effective combination of structured state-based formalism and dynamic action-based calculus may be a good solution for modeling complex distributed mobile systems. In this paper, we investigate the semantic links between Object-Z and /spl pi/ calculus and consequently introduce a powerful specification technique PiOZ that brings the strengths of the two together. The operational semantics of PiOZ integrates state transition semantics of Object-Z and /spl pi/-calculus reduction rules. The typing rules of PiOZ are developed and reasoning of a system property is presented.
18649413
Capturing periodic concurrent interactions of mission computer tasks
Safety critical systems, such as aviation systems controlled by software, often have hard real-time requirements. Producing the correct result at the right time is the fundamental goal of such systems. Formally specifying the system functions and the timing requirements is the crucial step towards achieving such a goal. Aviation systems often need to be modified or upgraded on a regular basis, i.e. functionality and timing constraints may be altered. Therefore, the formal specification of such systems needs to be easily reused, maintained and modified. This paper demonstrates how the task scheduling aspects of an aircraft mission computer can be formalised in TCOZ.
18404140
Deep Semantic Links of TCSP and Object-Z: TCOZ Approach
Abstract. Formal methods can be used in effective combination only if the semantic links between individual methods are clearly established. This paper discusses the semantic design of TCOZ, a language blended from Object-Z and TCSP. The semantic model adopted is the infinite timed failures model of TCSP, extended to include initial state and update events for modelling operations on internal state. An infinite trace model has been used so as to ensure proper account is taken of the potentially unbounded non-determinism allowed by Z schemas.
15362726
State, event, time and diagram in system modeling
The design of complex systems requires powerful mechanisms for modeling state, concurrent events, and real-time behavior; as well as for visualising and structuring systems in order to control complexity. Methods integration has become a recent research trend in software specification and design. In the graphical area, many object-oriented methods have merged into one, the Unified Modeling Language (UML) which combines various diagrammatic modeling techniques to model static and dynamic aspects of software systems. Although traditional formal methods have not scale-up well, new integrated formal methods show great promise. This tutorial will present the state of the art in formal modeling techniques (state-based Object-Z and event-based Timed CSP), their integration (TCOZ), and transformation techniques from the integrated formalism to UML diagrams. An XML web environment for projecting integrated formal models to UML diagrams will also be demonstrated.
5576673
A Generative Style-driven Framework for Software Architecture Design
Compared with texts, graphs are more intuitive to express comparative and structural information. Many graphical approaches, however, lack a formal basis for precise specifications in the design. This paper proposes a generative style-driven framework for software architecture specification based on a visual language formalism. In this framework, the designer uses graphical notations to define architectural styles. Given the graphical specifications, a visual language generator, i.e. a meta-tool, can automatically generate a specific design environment, which is suitable for the users without any knowledge of formal methods to directly manipulate software architectures by drawing box-line graphs. The graph transformation engine underlying the design environment can automatically validate structural integrity and reveal the hierarchical structure of a user-defined software architecture
46381930
QVT based model transformation for design pattern evolutions
6734225
Supply chain networks, electronic commerce, and supply side and demand side risk
In this paper, we develop a supply chain network model in which both physical and electronic transactions are allowed and in which supply side risk as well as demand side risk are included in the formulation. The model consists of three tiers of decision-makers: the manufacturers, the distributors, and the retailers, with the demands associated with the retail outlets being random. We model the optimizing behavior of the various decision-makers, with the manufacturers and the distributors being multicriteria decision-makers and concerned with both profit maximization and risk minimization. We derive the equilibrium conditions and establish the finite-dimensional variational inequality formulation. We provide qualitative properties of the equilibrium pattern in terms of existence and uniqueness results and also establish conditions under which the proposed computational procedure is guaranteed to converge. We illustrate the supply chain network model through several numerical examples for which the equilibrium prices and product shipments are computed. This is the first multitiered supply chain network equilibrium model with electronic commerce and with supply side and demand side risk for which modeling, qualitative analysis, and computational results have been obtained.
2938720
Extending UML to Visualize Design Patterns In Class Diagrams
A design pattern describes a general solution to a design problem that recurs repeatedly in many projects. Software designers adapt the pattern solution to their specific project. Design patterns are usually modeled using UML. However, UML does not keep track of pattern-related information when a design pattern is applied or composed with other patterns. Thus, it is hard for a designer to identify design patterns in software system designs. The benefits of design patterns are compromised because the designers cannot communicate with each other in terms of the design patterns they use and their design decisions and tradeoffs. In this paper, we present the essential features of a new member of the UML language family that supports working with object-oriented design patterns. This UML extension allows the explicit representation of design patterns in software designs. We also discuss some of the relevant aspects of the UML profile which is based on standard UML extension mechanisms. A case study shows how it can be used to assist pattern-based software development.
17418612
Visualizing design patterns with a UML profile
In this paper, we present a UML profile which defines new stereotypes, tagged values and constraints for visualizing design patterns in UML diagrams. These new stereotypes and tagged values are attached to a modeling element to explicitly represent the role the modeling element plays in a design pattern so that the user can identify the pattern in a UML diagram.