On the generation of equational dynamic logics for weighted imperative programs

Dynamic logic is a powerful framework for reasoning about imperative programs. This paper extends previous work [9] on the systematic generation of dynamic logics from the propositional to the equational case, to capture `full- edged' imperative programs. The generation process is parametric on a structure specifying a notion of `weight' assigned to programs. The paper introduces also a notion of bisimilarity on models of the generated logics, which is shown to entail modal equivalence with respect to the latter.POCI-01-0145-FEDER-030947. ERDF—European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation - COMPETE 2020 Programme and by National Funds through the Portuguese funding agency, FCT - Fundação para a Ciência e a Tecnologia, within project POCI-01-0145-FEDER-030947. The second author is supported in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Portuguese Law 57/2017, of July 19 and by UID/MAT/04106/2019 at CIDM

Generalising Projection in Asynchronous Multiparty Session Types

Multiparty session types (MSTs) provide an efficient methodology for specifying and verifying message passing software systems. In the theory of MSTs, a global type specifies the interaction among the roles at the global level. A local specification for each role is generated by projecting from the global type on to the message exchanges it participates in. Whenever a global type can be projected on to each role, the composition of the projections is deadlock free and has exactly the behaviours specified by the global type. The key to the usability of MSTs is the projection operation: a more expressive projection allows more systems to be type-checked but requires a more difficult soundness argument. In this paper, we generalise the standard projection operation in MSTs. This allows us to model and type-check many design patterns in distributed systems, such as load balancing, that are rejected by the standard projection. The key to the new projection is an analysis that tracks causality between messages. Our soundness proof uses novel graph-theoretic techniques from the theory of message-sequence charts. We demonstrate the efficacy of the new projection operation by showing many global types for common patterns that can be projected under our projection but not under the standard projection operation

Hacia la construccion de drivers eficientes en bounded model checking mediante deteccion automatica de builders

Las técnicas que permiten mejorar la calidad del software producido son de vital importancia, sobre todo en sistemas críticos. Entre ellas, contamos con técnicas de verificación acotada de software, como el model checking de software, que permiten explorar exhaustivamente todas las ejecuciones posibles del software con entradas de tamaño acotado, y reportar fallas encontradas durante el proceso. Para llevar a cabo la verificación acotada, los model checkers de software se basan en la definición de drivers: combinaciones de métodos que permiten construir las entradas con las que se ejecutará el programa. En este trabajo se observa que la selección de los métodos empleados en la definición del driver es de vital importancia para la verificación. Intuitivamente, es deseable seleccionar un conjunto de métodos tan pequeño como sea posible (para mayor eficiencia en el análisis), cuyas combinaciones permitan construir todas las estructuras acotadas para el módulo (para analizar el software con todas las entradas posibles). Esta selección de métodos, que usualmente se lleva a cabo de forma manual, no es una tarea fácil: requiere un análisis exhaustivo de las rutinas disponibles en el módulo y una comprensión profunda de la semántica de las mismas. En este trabajo se propone utilizar una herramienta automática para seleccionar un subconjunto de métodos relevantes de un módulo para la construcción de drivers eficientes para bounded model checking. Además, se evalúa el enfoque propuesto en el análisis de una propiedad particular del modulo Apache NodeCachingLinkedList, empleando el model checker Java PathFinder (JPF). Los resultados muestran que el enfoque de construcción de drivers presentado permite incrementar la eficiencia y la escalabilidad a estructuras de mayor tamaño en el análisis usando JPF.XVI Workshop Ingeniería de Software.Red de Universidades con Carreras en Informátic

White-box validation of quantitative product lines by statistical model checking and process mining

We propose a novel methodology for validating software product line (PL) models by integrating Statistical Model Checking (SMC) with Process Mining (PM). Our approach focuses on the feature-oriented language QFLan in the PL engineering domain, allowing modeling of PLs with rich cross-tree and quantitative constraints, as well as aspects of dynamic PLs like staged configurations. This richness leads to models with infinite state-space, requiring simulation-based analysis techniques like SMC. For instance, we illustrate with a running example involving infinite state space. SMC involves generating samples of system dynamics to estimate properties such as event probabilities or expected values. On the other hand, PM uses data-driven techniques on execution logs to identify and reason about the underlying execution process. In this paper, we propose, for the first time, applying PM techniques to SMC simulations' byproducts to enhance the utility of SMC analyses. Typically, when SMC results are unexpected, modelers must determine whether they stem from actual system characteristics or model bugs in a black-box manner. We improve on this by using PM to provide a white-box perspective on the observed system dynamics. Samples from SMC are fed into PM tools, producing a compact graphical representation of observed dynamics. The mined PM model is then transformed into a QFLan model, accessible to PL engineers. Using two well-known PL models, we demonstrate the effectiveness and scalability of our methodology in pinpointing issues and suggesting fixes. Additionally, we show its generality by applying it to the security domain.Comment: Pre-print Special Issue on Managing Variability in Complex Software-Intensive Systems of the Journal of Systems and Softwar

A Framework for Resource Dependent EDSLs in a Dependently Typed Language (Pearl)

Idris' Effects library demonstrates how to embed resource dependent algebraic effect handlers into a dependently typed host language, providing run-time and compile-time based reasoning on type-level resources. Building upon this work, Resources is a framework for realising Embedded Domain Specific Languages (EDSLs) with type systems that contain domain specific substructural properties. Differing from Effects, Resources allows a language’s substructural properties to be encoded within type-level resources that are associated with language variables. Such an association allows for multiple effect instances to be reasoned about autonomically and without explicit type-level declaration. Type-level predicates are used as proof that the language’s substructural properties hold. Several exemplar EDSLs are presented that illustrates our framework’s operation and how dependent types provide correctness-by-construction guarantees that substructural properties of written programs hold