Automatic verification of any number of concurrent, communicating processes

The automatic verification of concurrent systems by model-checking is limited due to the inability to generalise results to systems consisting of any number of processes. We use abstraction to prove general results, by model-checking, about feature interaction analysis of a telecommunications service involving any number of processes. The key idea is to model-check a system of constant number (m) of concurrent processes, in parallel with an "abstract" process which represents the product of any number of other processes. The system, for any specified set of selected features, is generated automatically using Perl scripts

Adaptable processes

We propose the concept of adaptable processes as a way of overcoming the limitations that process calculi have for describing patterns of dynamic process evolution. Such patterns rely on direct ways of controlling the behavior and location of running processes, and so they are at the heart of the adaptation capabilities present in many modern concurrent systems. Adaptable processes have a location and are sensible to actions of dynamic update at runtime; this allows to express a wide range of evolvability patterns for concurrent processes. We introduce a core calculus of adaptable processes and propose two verification problems for them: bounded and eventual adaptation. While the former ensures that the number of consecutive erroneous states that can be traversed during a computation is bound by some given number k, the latter ensures that if the system enters into a state with errors then a state without errors will be eventually reached. We study the (un)decidability of these two problems in several variants of the calculus, which result from considering dynamic and static topologies of adaptable processes as well as different evolvability patterns. Rather than a specification language, our calculus intends to be a basis for investigating the fundamental properties of evolvable processes and for developing richer languages with evolvability capabilities

Refinement and verification of concurrent systems specified in Object-Z and CSP

The formal development of large or complex systems can often be facilitated by the use of more than one formal specification language. Such a combination of languages is particularly suited to the specification of concurrent or distributed systems, where both the modelling of processes and state is necessary. This paper presents an approach to refinement and verification of specifications written using a combination of Object-Z and CSP. A common semantic basis for the two languages enables a unified method of refinement to be used, based upon CSP refinement. To enable state-based techniques to be used for the Object-Z components of a specification we develop state-based refinement relations which are sound and complete with respect to CSP refinement. In addition, a verification method for static and dynamic properties is presented. The method allows us to verify properties of the CSP system specification in terms of its component Object-Z classes by using the laws of the CSP operators together with the logic for Object-Z

Monitoring Partially Synchronous Distributed Systems using SMT Solvers

In this paper, we discuss the feasibility of monitoring partially synchronous distributed systems to detect latent bugs, i.e., errors caused by concurrency and race conditions among concurrent processes. We present a monitoring framework where we model both system constraints and latent bugs as Satisfiability Modulo Theories (SMT) formulas, and we detect the presence of latent bugs using an SMT solver. We demonstrate the feasibility of our framework using both synthetic applications where latent bugs occur at any time with random probability and an application involving exclusive access to a shared resource with a subtle timing bug. We illustrate how the time required for verification is affected by parameters such as communication frequency, latency, and clock skew. Our results show that our framework can be used for real-life applications, and because our framework uses SMT solvers, the range of appropriate applications will increase as these solvers become more efficient over time.Comment: Technical Report corresponding to the paper accepted at Runtime Verification (RV) 201

Requirements, Formal Verification and Model transformations of an Agent-based System: A CASE STUDY

One of the most challenging tasks in software specifications engineering for a multi-agent system is to ensure correctness. As these systems have high concurrency, often have dynamic environments, the formal specification and verification of these systems along with step-wise refinement from abstract to concrete concepts play major role in system correctness. Our objectives are the formal specification, analysis with respect to functional as well as non-functional properties by step-wise refinement from abstract to concrete specifications and then formal verification of these specifications. A multi-agent system is concurrent system with processes working in parallel with synchronization between them. We have worked on Gaia multi-agent method along with finite state process based finite automata techniques and as a result we have defined the formal specifications of our system, checked the correctness and verified all possible flow of concurrent executions of these specifications. Our contribution consists in transforming requirement specifications based on organizational abstractions into executable formal verification specifications based on finite automata. We have considered a case study of our multi-agent system to exemplify formal specifications and verification.Comment: 16 pages; Computer Engineering and Intelligent Systems http://www.iiste.org - ISSN 2222-1719 (Paper) ISSN 2222-2863 (Online) - Vol.5, No.3, 201

Business process modeling using petri nets with clocks

Petri Nets are tools for the analysis and design of concurrent systems. There is a formal theory, which supports Petri Nets. We propose Petri Nets with Clocks which has a high expressive power in the concurrent and asynchronous process modeling and gives the possibility to model real time systems. The Petri Nets with Clocks are useful to model systems with temporal requirements via specification of clocks, using temporal invariants for the places and temporal conditions in the transitions. Also, we have developed an algorithm for the analysis of Petri Nets with Clocks. For the Business Processes Modeling, we propose to use Petri Nets with Clocks to formalize models, allowing to study the models through a quantitative and qualitative analysis. Petri Nets with Clocks includes additional temporal elements -clocks-, which are appropriate for the Business Processes Modeling and are not taken into consideration in the literature concerning the extensions of Petri Nets with time. Petri Nets with Clocks allows studying the structural properties of Business Processes Modeling. This study not only allows the simulation but also verifies formally the model. It is oriented to the verification and correction of errors in the modeling of the time variable en Business Processes.Eje: Ingeniería de softwareRed de Universidades con Carreras en Informática (RedUNCI