51 research outputs found
Variability Abstraction and Refinement for Game-Based Lifted Model Checking of Full CTL
One of the most promising approaches to fighting the configuration space explosion problem in lifted model checking are variability abstractions. In this work, we define a novel game-based approach for variability-specific abstraction and refinement for lifted model checking of the full CTL, interpreted over 3-valued semantics. We propose a direct algorithm for solving a 3-valued (abstract) lifted model checking game. In case the result of model checking an abstract variability model is indefinite, we suggest a new notion of refinement, which eliminates indefinite results. This provides an iterative incremental variability-specific abstraction and refinement framework, where refinement is applied only where indefinite results exist and definite results from previous iterations are reused. The practicality of this approach is demonstrated on several variability models
Composing Families of Timed Automata
Featured Timed Automata (FTA) is a formalism that enables the verification of an entire Software Product Line (SPL), by capturing its behavior in a single model instead of product-by-product. However, it disregards compositional aspects inherent to SPL development. This paper introduces Interface FTA (IFTA), which extends FTA with variable interfaces that restrict the way automata can be composed, and with support for transitions with atomic multiple actions, simplifying the design. To support modular composition, a set of Reo connectors are modelled as IFTA. This separation of concerns increases reusability of functionality across products, and simplifies modelling, maintainability, and extension of SPLs. We show how IFTA can be easily translated into FTA and into networks of Timed Automata supported by UPPAAL. We illustrate this with a case study from the electronic government domain.POCI-01-0145-FEDER-016826. NORTE-01-0145-FEDER-00003
Model-checking Timed Temporal Logics
AbstractIn this paper, we present several timed extensions of temporal logics, that can be used for model-checking real-time systems. We give different formalisms and the corresponding decidability/complexity results. We also give intuition to explain these results
Fundamental Approaches to Software Engineering
computer software maintenance; computer software selection and evaluation; formal logic; formal methods; formal specification; programming languages; semantics; software engineering; specifications; verificatio
Generalized abstraction-refinement for game-based CTL lifted model checking
cation areas ranging from embedded system domains to system-level software and communication protocols. Software Product Line methods and architectures allow effective building many custom variants of a software system in these domains. In many of the applications, their rigorous verification and quality assurance are of paramount importance. Lifted model checking for system families is capable of verifying all their variants simultaneously in a single run by exploiting the similarities between the variants. The computational cost of lifted model checking still greatly depends on the number of variants (the size of configuration space), which is often huge. Variability abstractions have successfully addressed this configuration space explosion problem, giving rise to smaller abstract variability models with fewer abstract configurations. Abstract variability models are given as modal transition systems, which contain may (over-approximating) and must (under-approximating) transitions. Thus, they preserve both universal and existential CTL properties. In this work, we bring two main contributions. First, we define a novel game-based approach for variability-specific abstraction and refinement for lifted model checking of the full CTL, interpreted over 3-valued semantics. We propose a direct algorithm for solving a 3-valued (abstract) lifted model checking game. In case the result of model checking an abstract variability model is indefinite, we suggest a new notion of refinement, which eliminates indefinite results. This provides an iterative incremental variability-specific abstraction and refinement framework, where refinement is applied only where indefinite results exist and definite results from previous iterations are reused. Second, we propose a new generalized definition of abstract variability models, given as so-called generalized modal transition systems, by introducing the notion of (must) hyper-transitions. This results in more precise abstract models in which more CTL formulae can be proved or disproved. We integrate the newly defined generalized abstract variability models in the existing abstraction-refinement framework for game-based lifted model checking of CTL. Finally, we evaluate the practicality of this approach on several system families
A virtual factory for smart city service integration
Tese de Doutoramento em Informática (MAP-i)In the context of smart cities, governments are investing efforts on creating public
value through the development of digital public services (DPS) focusing on specific
policy areas, such as transport. Main motivations to deliver DPS include reducing
administrative burdens and costs, increasing effectiveness and efficiency of government
processes, and improving citizens’ quality of life through enhanced services and simplified
interactions with governments.
To ensure effective planning and design of DPS in a given domain, governments face
several challenges, like the need of specialized tools to facilitate the effective planning
and the rapid development of DPS, as well as, tools for service integration, affording
high development costs, and ensuring DPS conform with laws and regulations.
These challenges are exacerbated by the fact that many public administrations develop
tailored DPS, disregarding the fact that services share common functionality
and business processes.
To address the above challenges, this thesis focuses on leveraging the similarities of
DPS and on applying a Software Product Line (SPL) approach combined with formal
methods techniques for specifying service models and verifying their behavioural properties.
In particular, the proposed solution introduces the concept of a virtual factory
for the planning and rapid development of DPS in a given smart city domain. The
virtual factory comprises a framework including software tools, guidelines, practices,
models, and other artefacts to assist engineers to automate and make more efficient
the development of a family of DPS.
In this work the virtual factory is populated with tools for government officials and
software developers to plan and design smart mobility services, and to rapidly model
DPS relying on SPLs and components-base development techniques.
Specific contributions of the thesis include: 1) the concept of virtual factory; 2)
a taxonomy for planning and designing smart mobility services; 3) an ontology to fix
a common vocabulary for a specific family of DPS; 4) a compositional formalism to
model SPLs, to serve as a specification language for DPS; and 5) a variable semantics
for a coordination language to simplify coordination of services in the context of SPLs.No contexto das cidades inteligentes, os governos investem esforços na criação de valor
público através do desenvolvimento de serviços públicos digitais (DPS), concentrandose
em áreas políticas específicas, como os transportes. As principais motivações para
entregar o DPS incluem a redução de custos administrativos, o aumento da eficácia
dos processos do governo e a melhoria da qualidade de vida dos cidadãos através de
serviços melhorados e interações simplificadas com os governos.
Para garantir um planeamento efetivo do DPS num determinado domínio, os governos
enfrentam vários desafios, como a necessidade de ferramentas especializadas para
facilitar o planeamento eficaz e o rápido desenvolvimento do DPS, bem como ferramentas
para integração de DPS, reduzindo altos custos de desenvolvimento e garantindo
que os DPS estejam em conformidade com as leis e regulamentos.
Esses desafios são exacerbados pelo fato de que muitas administrações públicas
desenvolvem o DPS sob medida, desconsiderando o fato de que os serviços compartilham
funcionalidade e processos de negócios comuns.
Para enfrentar os desafios, esta tese concentra-se em aproveitar as semelhanças dos
DPS aplicando uma abordagem de Software Product Lines (SPL) combinada com métodos
formais para especificar modelos de DPS e verificar propriedades. Em particular,
introduz o conceito de uma fábrica virtual (VF) para o planeamento e desenvolvimento
rápido de DPS num domínio de cidade inteligente. A VF compreende ferramentas de
software, diretrizes, modelos e outros artefatos para auxiliar os engenheiros a automatizar
e tornar mais eficiente o desenvolvimento de uma família de DPS.
Neste trabalho, a VF é preenchida com ferramentas para várias partes para planear
e projetar serviços de mobilidade inteligente (MI), e modelar rapidamente o DPS com
base em SPLs e técnicas de desenvolvimento baseadas em componentes.
Contribuições específicas da tese incluem: 1) o conceito de VF; 2) uma taxonomia
para planear serviços de MI; 3) uma ontologia para fixar um vocabulário comum para
uma família específica de DPS; 4) um formalismo composicional para modelar SPLs,
e servir como uma linguagem de especificação para DPS; e 5) uma semântica variável
para uma linguagem de coordenação para simplificar a coordenação.This work was funded by FCT – Foundation for Science and Technology, the Portuguese Ministry of Science, Technology and Higher Education, through the Operational Programme for Human Capital (POCH). Grant reference: PD/BD/52238/201
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