From Temporal Models to Property-Based Testing

This paper presents a framework to apply property-based testing (PBT) on top of temporal formal models. The aim of this work is to help software engineers to understand temporal models that are presented formally and to make use of the advantages of formal methods: the core time-based constructs of a formal method are schematically translated to the BeSpaceD extension of the Scala programming language. This allows us to have an executable Scala code that corresponds to the formal model, as well as to perform PBT of the models functionality. To model temporal properties of the systems, in the current work we focus on two formal languages, TLA+ and FocusST.Comment: Preprint. Accepted to the 12th International Conference on Evaluation of Novel Approaches to Software Engineering (ENASE 2017). Final version published by SCITEPRESS, http://www.scitepress.or

Symbolic Reachability Analysis of B through ProB and LTSmin

We present a symbolic reachability analysis approach for B that can provide a significant speedup over traditional explicit state model checking. The symbolic analysis is implemented by linking ProB to LTSmin, a high-performance language independent model checker. The link is achieved via LTSmin's PINS interface, allowing ProB to benefit from LTSmin's analysis algorithms, while only writing a few hundred lines of glue-code, along with a bridge between ProB and C using ZeroMQ. ProB supports model checking of several formal specification languages such as B, Event-B, Z and TLA. Our experiments are based on a wide variety of B-Method and Event-B models to demonstrate the efficiency of the new link. Among the tested categories are state space generation and deadlock detection; but action detection and invariant checking are also feasible in principle. In many cases we observe speedups of several orders of magnitude. We also compare the results with other approaches for improving model checking, such as partial order reduction or symmetry reduction. We thus provide a new scalable, symbolic analysis algorithm for the B-Method and Event-B, along with a platform to integrate other model checking improvements via LTSmin in the future

Integrating formal methods into medical software development : the ASM approach

Medical devices are safety-critical systems since their malfunctions can seriously compromise human safety. Correct operation of a medical device depends upon the controlling software, whose development should adhere to certification standards. However, these standards provide general descriptions of common software engineering activities without any indication regarding particular methods and techniques to assure safety and reliability. This paper discusses how to integrate the use of a formal approach into the current normative for the medical software development. The rigorous process is based on the Abstract State Machine (ASM) formal method, its refinement principle, and model analysis approaches the method supports. The hemodialysis machine case study is used to show how the ASM-based design process covers most of the engineering activities required by the related standards, and provides rigorous approaches for medical software validation and verification

Rigorous development process of a safety-critical system: from ASM models to Java code

The paper presents an approach for rigorous development of safety-critical systems based on the Abstract State Machine formal method. The development process starts from a high level formal view of the system and, through refinement, derives more detailed models till the desired level of specification. Along the process, different validation and verification activities are available, as simulation, model review, and model checking. Moreover, each refinement step can be proved correct using an SMT-based approach. As last step of the refinement process, a Java implementation can be developed and linked to the formal specification. The correctness of the implementation w.r.t. its formal specification can be proved by means of model-based testing and runtime verification. The process is exemplified by using a Landing Gear System as case study

From AADL to Timed Abstract State Machines: A Verified Model Transformation

International audienceArchitecture Analysis and Design Language (AADL) is an architecture description language standard for embedded real-time systems widely used in the avionics and aerospace industry to model safety-critical applications. To verify and analyze the AADL models, model transformation technologies are often used to automatically extract a formal specification suitable for analysis and verification. In this process, it remains a challenge to prove that the model transformation preserves the semantics of the initial AADL model or, at least, some of the specific properties or requirements it needs to satisfy. This paper presents a machine checked semantics-preserving transformation of a subset of AADL (including periodic threads, data port communications, mode changes, and the AADL behavior annex) into Timed Abstract State Machines (TASM). The AADL standard itself lacks at present a formal semantics to make this translation validation possible. Our contribution is to bridge this gap by providing two formal semantics for the subset of AADL. The execution semantics provided by the AADL standard is formalized as Timed Transition Systems (TTS). This formalization gives a reference expression of AADL semantics which can be compared with the TASM-based translation (for verification purpose). Finally, the verified transformation is mechanized in the theorem prover Coq

Foundations of the B method

B is a method for specifying, designing and coding software systems. It is based on Zermelo-Fraenkel set theory with the axiom of choice, the concept of generalized substitution and on structuring mechanisms (machine, refinement, implementation). The concept of refinement is the key notion for developing B models of (software) systems in an incremental way. B models are accompanied by mathematical proofs that justify them. Proofs of B models convince the user (designer or specifier) that the (software) system is effectively correct. We provide a survey of the underlying logic of the B method and the semantic concepts related to the B method; we detail the B development process partially supported by the mechanical engine of the prover

Exploring AADL verification tool through model transformation

International audienceArchitecture Analysis and Design Language (AADL) is often used to model safety-critical real-time systems. Model transformation is widely used to extract a formal specification so that AADL models can be verified and analyzed by existing tools. Timed Abstract State Machine (TASM) is a formalism not only able to specify behavior and communication but also timing and resource aspects of the system. To verify functional and nonfunctional properties of AADL models, this paper presents a methodology for translating AADL to TASM. Our main contribution is to formally define the translation rules from an adequate subset of AADL (including thread component, port communication, behavior annex and mode change) into TASM. Based on these rules, a tool called AADL2TASM is implemented using Atlas Transformation Language (ATL). Finally, a case study from an actual data processing unit of a satellite is provided to validate the transformation and illustrate the practicality of the approach