Formal Specification and Verification of Dynamic Parametrized Architectures

Abstract

Abstract. We propose a novel approach to the formal specification and verification of dynamic architectures that are at the core of adaptive systems such as critical infrastructure protection. Key features include run-time reconfiguration based on adding and removing components and connections, resulting in systems with unbounded number of components. We provide a logic-based specification of a Dynamic Parametrized Architecture (DPA), where parameters represent the infinite-state space of possible configurations, and first-order formulas represent the sets of initial configurations and reconfiguration transitions. We encode information flow properties as reachability problems of such DPAs, define a translation into an array-based transition system, and use a Satisfiability Modulo Theories (SMT)-based model checker to tackle a number of case studies.

SMT-based verification of data-aware processes: a model-theoretic approach

“…All in all, the present contribution is deeply rooted in the long-standing tradition of the application of model theory in computer science, as witnessed by notable approaches like the one in Ghilardi (2004), Baader et al (2006), Ghilardi et al (2008b), Ghilardi and van Gool (2017), Nicolini et al (2009aNicolini et al ( ,b, 2010, Sofronie-Stokkermans (2008, 2016, Ghilardi andGianola (2017, 2018). In particular, this paper applies these ideas in a genuinely novel mathematical context and shows how these techniques can be used for the first time to empower algorithmic techniques for the verification of infinite-state systems based on arrays in the style of Ghilardi et al (2008a), Ghilardi and Ranise (2010a,b), Alberti et al (2014aAlberti et al ( ,b, 2017, Conchon et al (2012Conchon et al ( , 2015Conchon et al ( , 2018a, Delzanno (2018), Cimatti et al (2018), so as to make such techniques applicable to the timely, challenging settings of data-aware processes (Calvanese et al 2019d). For an explicit linking between the use of model completeness in computer science and our application to verification, see in particular the survey (Calvanese et al 2019b).…”

Universal Invariant Checking of Parametric Systems with Quantifier-free SMT Reasoning

“…Lambda is written in Python, and uses the SMT-based IC3 with implicit predicate abstraction of [4] as underlying quantifier-free verification engine. 6 Lambda accepts as input array-based systems specified either in the language of MCMT [11] or in VMT format (a light-weight extension of SMT-LIB to model transition systems [25]). In case of successful termination, Lambda generates either a counterexample trace (for violated properties) in a concrete instance of the parametric system, or a quantified inductive invariant that proves the property for any instance of the system.…”

“…We have used all the instances which were available in both input formats, and we have split benchmarks containing multiple properties into different files. DynArch consists of 57 instances of verification problems of dynamic architectures, taken from [6]. These benchmarks make use of arithmetic constraints on Trains consists of 17 instances derived by (a simplified version of) verification problems on railway interlocking logics [1].…”

Architectural Views to the Representation of Dynamic Software Architectures

“…In these languages, "parameters representing the infinite-state space of possible configurations, and first-order formulas represent the sets of initial configurations and reconfiguration transitions." (CIMATTI et al, 2018). Because they are languages based on mathematical formalism, its semantics is well defined, which entails the absence of ambiguities.…”

“…We observed that the highly number of formal approaches for representing dynamic architectures are due the following factors: (i) dynamic software architectures had their inspiration in distributed systems architectures (MAGEE et al, 1995) and these architectures were represented by formal models process-algebras, so it is natural that most authors tend to continue using these approaches, adapting it to the context is being applied. Dynamic Wright (ALLEN et al, 1998), for example, was first proposed to lead with dynamic structures in concurrent and distributed systems and are used in dynamic software architectures; and (ii) the use of formal languages makes possible the automatic validation of the described architectures, and the main validated points are related to availability and reliability (ALLEN et al, 1998;HIRSCH;MONTANARI, 2002;OQUENDO, 2016;CIMATTI et al, 2018;WERMELINGER;FIADEIRO, 2002); Another important aspect related to formal representations is the possibility of architecture simulation, a very important factor while several architectural decisions can only be evaluated at run-time (F. Oquendo, 2008). Allen et al (1998) give an example of reconfiguration that we will consider to explain simulation advantages: consider a client-server system that receives requests for e-mail firing, where the router must be reconfigured in a way that balances the load between two servers, that is, if the demand exceeds the capacity of one server, another server must be inserted in the architecture, and, similarly, when the demand decreases, the server must be removed from the architecture.…”