Animation-based validation of reactive software systems using behavioural models

Tese de doutoramento em InformáticaDuring the development of software systems, validation is a crucial activity to guarantee that the software system ful lls the users' needs and expectations. A key issue to have a successful validation consists in adopting a process where users and clients can actively discuss the requirements of the system under development. A reactive system is expected to continuously interact with its environment. Usually, the interaction of a reactive system with its environment is supported by a set of nonterminating processes that operate in parallel. During the interaction, the reactive system must answer to high-priority events, even when the system is executing something else. Due to above characteristics, the behaviour of reactive systems can be very complex. The approach suggested in this thesis assumes that the requirements of reactive software systems are partially described by use case diagrams, and each use case is detailed by a collection of scenario descriptions. Within this approach, one can obtain, from a set of behavioural scenarios of a given system, an executable behavioural model that can support, when complemented with animation- and domain-speci c elements, a graphical animation for reproducing that set of scenarios for validation purposes. Animating the scenarios using graphical elements from the application domain ensures an e ective involvement of the users in the system's validation. The Coloured Petri nets (CPNs) modelling language is used as the notation to obtain the behavioural models, due to its natural support for mechanisms like concurrency, synchronisation, and resource sharing and its tool support. The obtained CPN model is guaranteed to be (1) parametric, allowing an easy modi cation of the initial conditions of the scenarios, (2) environment-descriptive, meaning that it includes the state of the relevant elements of the environment, and (3) animation-separated, implying that the elements related to the animation are separated from the other ones. We validate our approach based on its application to three case studies of reactive systems.Durante o desenvolvimento de sistemas de software, a validação é uma actividade crucial para garantir que o sistema de software satisfaz as necessidades e expectativas do utilizador. O sucesso na validação consiste na utilização de um processo onde os utilizadores e os clientes possam discutir de uma forma activa os requisitos do sistema que está a ser desenvolvido. Um sistema reactivo está continuamente em interacção com o seu ambiente, que é geralmente suportada por um conjunto de processos intermináveis que operam em paralelo. Durante a interacção, o sistema reactivo dever a responder aos eventos com alta prioridade, mesmo quando o sistema está a executar algo diferente. Devido às características anteriores, o comportamento dos sistemas reactivos pode ser muito complexo. A abordagem sugerida nesta tese assume que os requisitos de sistemas reactivos são em parte descritos por diagramas de casos de uso e que cada caso de uso é detalhado por uma colecção de descrições de cenários. Nesta abordagem, é possível obter, a partir de um conjunto de cenários de um dado sistema, um modelo comportamental que seja executável e que suporte, quando complementado com elementos específicos, uma animação gráfica que reproduza aquele conjunto de cenários para fins de validação. A animação dos cenários utilizando elementos gráficos do domínio da aplicação garante um envolvimento efectivo dos utilizadores na validação do sistema. A linguagem de modelação redes de Petri coloridas (CPNs) é usada como a notação para obter os modelos comportamentais, devido ao seu suporte natural a mecanismos como a concorrência, sincronização e partilha de recursos, e às suas ferramentas de suporte. Se as recomendações da abordagem proposta foram seguidas, temos a garantia que o modelo CPN: (1) parametriza as condições iniciais dos cenários, (2) contém uma descrição do ambiente, incluindo o estado dos seus elementos, e (3) separa os elementos relacionados com a animação dos outros elementos do modelo. A validação da nossa abordagem tem por base a sua aplicação a três casos de estudo de sistemas reactivos.Fundação para a Ciência e a Tecnologia (FCT) SFRH/BD/19718/200

Proceedings of The Multi-Agent Logics, Languages, and Organisations Federated Workshops (MALLOW 2010)

http://ceur-ws.org/Vol-627/allproceedings.pdfInternational audienceMALLOW-2010 is a third edition of a series initiated in 2007 in Durham, and pursued in 2009 in Turin. The objective, as initially stated, is to "provide a venue where: the cost of participation was minimum; participants were able to attend various workshops, so fostering collaboration and cross-fertilization; there was a friendly atmosphere and plenty of time for networking, by maximizing the time participants spent together"

Computers for learning : an empirical modelling perspective

In this thesis, we explore the extent to which computers can provide support for domain learning. Computer support for domain learning is prominent in two main areas: in education, through model building and the use of educational software; and in the workplace, where models such as spreadsheets and prototypes are constructed. We shall argue that computerbased learning has only realised a fraction of its full potential due to the limited scope for combining domain learning with conventional computer programming. In this thesis, we identify some of the limitations in the current support that computers offer for learning, and propose Empirical Modelling (EM) as a way of overcoming them. We shall argue that, if computers are to be successfully used for learning, they must support the widest possible range of learning activities. We introduce an Experiential Framework for Learning (EFL) within which to characterise learning activities that range from the private to the public, from the empirical to the theoretical, and from the concrete to the abstract. The term ‘experiential’ reflects a view of knowledge as rooted in personal experience. We discuss the merits of computer-based modelling methods with reference to a broad constructionist perspective on learning that encompasses bricolage and situated learning. We conclude that traditional programming practice is not well-suited to supporting bricolage and situated learning since the principles of program development inhibit the essential cognitive model building activity that informs domain learning. In contrast, the EM approach to model construction directly targets the semantic relation between the computer model and its domain referent and exploits principles that are closely related to the modeller’s emerging understanding or construal. In this way, EM serves as a uniform modelling approach to support and integrate learning activities across the entire spectrum of the EFL. This quality makes EM a particularly suitable approach for computer-based model construction to support domain learning. In the concluding chapters of the thesis, we demonstrate the qualities of EM for educational technology with reference to practical case studies. These include: a range of EM models that have advantages over conventional educational software due to their particularly open-ended and adaptable nature and that serve to illustrate a variety of ways in which learning activities across the EFL can be supported and scaffolded

Securing open multi-agent systems governed by electronic institutions

One way to build large-scale autonomous systems is to develop an open multi-agent system using peer-to-peer architectures in which agents are not pre-engineered to work together and in which agents themselves determine the social norms that govern collective behaviour. The social norms and the agent interaction models can be described by Electronic Institutions such as those expressed in the Lightweight Coordination Calculus (LCC), a compact executable specification language based on logic programming and pi-calculus. Open multi-agent systems have experienced growing popularity in the multi-agent community and are expected to have many applications in the near future as large scale distributed systems become more widespread, e.g. in emergency response, electronic commerce and cloud computing. A major practical limitation to such systems is security, because the very openness of such systems opens the doors to adversaries for exploit existing vulnerabilities. This thesis addresses the security of open multi-agent systems governed by electronic institutions. First, the main forms of attack on open multi-agent systems are introduced and classified in the proposed attack taxonomy. Then, various security techniques from the literature are surveyed and analysed. These techniques are categorised as either prevention or detection approaches. Appropriate countermeasures to each class of attack are also suggested. A fundamental limitation of conventional security mechanisms (e.g. access control and encryption) is the inability to prevent information from being propagated. Focusing on information leakage in choreography systems using LCC, we then suggest two frameworks to detect insecure information flows: conceptual modeling of interaction models and language-based information flow analysis. A novel security-typed LCC language is proposed to address the latter approach. Both static (design-time) and dynamic (run-time) security type checking are employed to guarantee no information leakage can occur in annotated LCC interaction models. The proposed security type system is then formally evaluated by proving its properties. A limitation of both conceptual modeling and language-based frameworks is difficulty of formalising realistic policies using annotations. Finally, the proposed security-typed LCC is applied to a cloud computing configuration case study, in which virtual machine migration is managed. The secrecy of LCC interaction models for virtual machine management is analysed and information leaks are discussed

Multi-Agent Systems

A multi-agent system (MAS) is a system composed of multiple interacting intelligent agents. Multi-agent systems can be used to solve problems which are difficult or impossible for an individual agent or monolithic system to solve. Agent systems are open and extensible systems that allow for the deployment of autonomous and proactive software components. Multi-agent systems have been brought up and used in several application domains

Computers for learning : an empirical modelling perspective

In this thesis, we explore the extent to which computers can provide support for domain learning. Computer support for domain learning is prominent in two main areas: in education, through model building and the use of educational software; and in the workplace, where models such as spreadsheets and prototypes are constructed. We shall argue that computerbased learning has only realised a fraction of its full potential due to the limited scope for combining domain learning with conventional computer programming. In this thesis, we identify some of the limitations in the current support that computers offer for learning, and propose Empirical Modelling (EM) as a way of overcoming them. We shall argue that, if computers are to be successfully used for learning, they must support the widest possible range of learning activities. We introduce an Experiential Framework for Learning (EFL) within which to characterise learning activities that range from the private to the public, from the empirical to the theoretical, and from the concrete to the abstract. The term ‘experiential’ reflects a view of knowledge as rooted in personal experience. We discuss the merits of computer-based modelling methods with reference to a broad constructionist perspective on learning that encompasses bricolage and situated learning. We conclude that traditional programming practice is not well-suited to supporting bricolage and situated learning since the principles of program development inhibit the essential cognitive model building activity that informs domain learning. In contrast, the EM approach to model construction directly targets the semantic relation between the computer model and its domain referent and exploits principles that are closely related to the modeller’s emerging understanding or construal. In this way, EM serves as a uniform modelling approach to support and integrate learning activities across the entire spectrum of the EFL. This quality makes EM a particularly suitable approach for computer-based model construction to support domain learning. In the concluding chapters of the thesis, we demonstrate the qualities of EM for educational technology with reference to practical case studies. These include: a range of EM models that have advantages over conventional educational software due to their particularly open-ended and adaptable nature and that serve to illustrate a variety of ways in which learning activities across the EFL can be supported and scaffolded.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Combining SOA and BPM Technologies for Cross-System Process Automation

This paper summarizes the results of an industry case study that introduced a cross-system business process automation solution based on a combination of SOA and BPM standard technologies (i.e., BPMN, BPEL, WSDL). Besides discussing major weaknesses of the existing, custom-built, solution and comparing them against experiences with the developed prototype, the paper presents a course of action for transforming the current solution into the proposed solution. This includes a general approach, consisting of four distinct steps, as well as specific action items that are to be performed for every step. The discussion also covers language and tool support and challenges arising from the transformation