A logic-based approach for the verification of UML timed models

This article presents a novel technique to formally verify models of real-time systems captured through a set of heterogeneous UML diagrams. The technique is based on the following key elements: (i) a subset of Unified Modeling Language (UML) diagrams, called Coretto UML (C-UML), which allows designers to describe the components of the system and their behavior through several kinds of diagrams (e.g., state machine diagrams, sequence diagrams, activity diagrams, interaction overview diagrams), and stereotypes taken from the UML Profile for Modeling and Analysis of Real-Time and Embedded Systems; (ii) a formal semantics of C-UML diagrams, defined through formulae of the metric temporal logic Tempo Reale ImplicitO (TRIO); and (iii) a tool, called Corretto, which implements the aforementioned semantics and allows users to carry out formal verification tasks on modeled systems. We validate the feasibility of our approach through a set of different case studies, taken from both the academic and the industrial domain

Sampling and Timing: A Task for the Environmetal Process

Sampling and timing is considered a responsibility of the environment of controller software. In this paper we will illustrate a concept whereby an environmental process and multi-way events play an important role in applying timing for untimed CSP software architectures. We use this timing concept for building our control applications based on CSP concepts and with our CSP for C++ (CTC++) library. We present a concept of sampling of control applications that is orthogonal to the application. This implies global timing on the basis of timed events. We also support traditional local timing on the based of timed processes

STAIRS - Understanding and Developing Specifications Expressed as UML Interaction Diagrams

STAIRS is a method for the step-wise, compositional development of interactions in the setting of UML 2.x. UML 2.x interactions, such as sequence diagrams and interaction overview diagrams, are seen as intuitive ways of describing communication between different parts of a system, and between a system and its users. STAIRS addresses the challenges of harmonizing intuition and formal reasoning by providing a precise understanding of the partial nature of interactions, and of how this kind of incomplete specifications may be consistently refined into more complete specifications. For understanding individual interaction diagrams, STAIRS defines a denotational trace semantics for the main constructs of UML 2.x interactions. The semantic model takes into account the partiality of interactions, and the formal semantics of STAIRS is faithful to the informal semantics given in the UML 2.x standard. For developing UML 2.x interactions, STAIRS defines a number of refinement relations corresponding to basic system development steps. STAIRS also defines matching compliance relations, for relating interactions to real computer systems. An important feature of STAIRS is the distinction between underspecification and inherent nondeterminism. Underspecification means that there are several possible behaviours serving the same overall purpose, and that it is sufficient for a computer system to perform only one of these. On the other hand, inherent nondeterminism is used to capture alternative behaviours that must all be possible for an implementation. A typical example is the tossing of a coin, where both heads and tails should be possible outcomes. In some cases, using inherent nondeterminism may also be essential for ensuring the necessary security properties of a system

The Impact of Petri Nets on System-of-Systems Engineering

The successful engineering of a large-scale system-of-systems project towards deterministic behaviour depends on integrating autonomous components using international communications standards in accordance with dynamic requirements. To-date, their engineering has been unsuccessful: no combination of top-down and bottom-up engineering perspectives is adopted, and information exchange protocol and interfaces between components are not being precisely specified. Various approaches such as modelling, and architecture frameworks make positive contributions to system-of-systems specification but their successful implementation is still a problem. One of the most popular modelling notations available for specifying systems, UML, is intuitive and graphical but also ambiguous and imprecise. Supplying a range of diagrams to represent a system under development, UML lacks simulation and exhaustive verification capability. This shortfall in UML has received little attention in the context of system-of-systems and there are two major research issues: 1. Where the dynamic, behavioural diagrams of UML can and cannot be used to model and analyse system-of-systems 2. Determining how Petri nets can be used to improve the specification and analysis of the dynamic model of a system-of-systems specified using UML This thesis presents the strengths and weaknesses of Petri nets in relation to the specification of system-of-systems and shows how Petri net models can be used instead of conventional UML Activity Diagrams. The model of the system-of-systems can then be analysed and verified using Petri net theory. The Petri net formalism of behaviour is demonstrated using two case studies from the military domain. The first case study uses Petri nets to specify and analyse a close air support mission. This case study concludes by indicating the strengths, weaknesses, and shortfalls of the proposed formalism in system-of-systems specification. The second case study considers specification of a military exchange network parameters problem and the results are compared with the strengths and weaknesses identified in the first case study. Finally, the results of the research are formulated in the form of a Petri net enhancement to UML (mapping existing activity diagram elements to Petri net elements) to meet the needs of system-of-systems specification, verification and validation

Petri nets for systems and synthetic biology

We give a description of a Petri net-based framework for modelling and analysing biochemical pathways, which uni¯es the qualita- tive, stochastic and continuous paradigms. Each perspective adds its con- tribution to the understanding of the system, thus the three approaches do not compete, but complement each other. We illustrate our approach by applying it to an extended model of the three stage cascade, which forms the core of the ERK signal transduction pathway. Consequently our focus is on transient behaviour analysis. We demonstrate how quali- tative descriptions are abstractions over stochastic or continuous descrip- tions, and show that the stochastic and continuous models approximate each other. Although our framework is based on Petri nets, it can be applied more widely to other formalisms which are used to model and analyse biochemical networks

Towards a Formal Semantics for UML/MARTE State Machines Based on Hierarchical Timed Automata

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A model driven approach to analysis and synthesis of sequence diagrams

Software design is a vital phase in a software development life cycle as it creates a blueprint for the implementation of the software. It is crucial that software designs are error-free since any unresolved design-errors could lead to costly implementation errors. To minimize these errors, the software community adopted the concept of modelling from various other engineering disciplines. Modelling provides a platform to create and share abstract or conceptual representations of the software system – leading to various modelling languages, among them Unified Modelling Language (UML) and Petri Nets. While Petri Nets strong mathematical capability allows various formal analyses to be performed on the models, UMLs user-friendly nature presented a more appealing platform for system designers. Using Multi Paradigm Modelling, this thesis presents an approach where system designers may have the best of both worlds; SD2PN, a model transformation that maps UML Sequence Diagrams into Petri Nets allows system designers to perform modelling in UML while still using Petri Nets to perform the analysis. Multi Paradigm Modelling also provided a platform for a well-established theory in Petri Nets – synthesis to be adopted into Sequence Diagram as a method of putting-together different Sequence Diagrams based on a set of techniques and algorithms