Lom Messan Hillah

New features in CPN-AMI 3: focusing on the analysis of complex distributed systems

Due to the state-space size explosion problem, behavioral analysis techniques are difficult to scale up to industrial size problems. Our group couples research on analysis tools with an introspection on modeling and software engineering techniques. CPN-AMI is an integrated development and analysis environment dedicated to Petri nets. The numerous services it offers are built by a homogeneous integration of tools developed internally, and third-party tools from partner universities. These tools include state of the art algorithms and data-structures. This third major release offers better support for modeling and analysis of very large systems

UML behavioral consistency checking using instantiable Petri nets

Model-driven engineering (MDE) development methods are gaining increasing attention from industry. In MDE, the model is the primary artifact and serves several goals, including code generation, requirements traceability, and model-based testing. MDE thus enables cost-effective building of models versus direct coding of an application. Thus model-based formal verification of behavioral consistency is desirable as it helps improve model quality. Our approach is based on translation of a UML model to instantiable Petri nets (IPN). This formalism is based on the semantics of Petri nets, but introduces the concepts of type and instance. This allows one to accurately capture these concepts in UML models. IPN support hierarchical descriptions natively, and use the notion of transition synchronization for composition of behaviors. This is a general and powerful mechanism borrowed from process algebra. We show that IPN allow one to adequately address the challenges of translation from UML for analysis purposes. The approach has been implemented and experimental results are presented.

CosyVerif: An Open Source Extensible Verification Environment

CosyVerif aims at gathering within a common framework various existing tools for specification and verification. It has been designed in order to 1) support different formalisms with the ability to easily create new ones, 2) provide a graphical user interface for every formalism, 3) include verification tools called via the graphical interface or via an API as a Web service, and 4) offer the possibility for a developer to integrate his/her own tool without much effort, also allowing it to interact with the other tools. Several tools have already been integrated for the formal verification of (extensions of) Petri nets and timed automata.

A Modular Approach for Reusing Formalisms in Verification Tools of Concurrent Systems

Over the past two decades, numerous verification tools have been successfully used for verifying complex concurrent systems, modelled using various formalisms. However, it is still hard to coordinate these tools since they rely on such a large number of formalisms. Having a proper syntactical mechanism to interrelate them through variability would increase the capability of effective integrated formal methods. In this paper, we propose a modular approach for defining new formalisms by reusing existing ones and adding new features and/or constraints. Our approach relies on standard XML technologies; their use provides the capability of rapidly and automatically obtaining tools for representing and validating models. It thus enables fast iterations in developing and testing complex formalisms. As a case study, we applied our modular definition approach on families of Petri nets and timed automata.

CARE: A Platform for Reliable Comparison and Analysis of Reverse-Engineering Techniques

Reverse engineering of behavior models has received a lot of attention over the last few years. However, no standard benchmark exists for the comparison and analysis of published miners. Evaluation is usually performed on few case studies, which fails to demonstrate effectiveness in a broad context. This paper proposes a general, approach-independent, platform for the intensive evaluation of behavior miners. Its goals are essentially: provide a benchmark mechanism for reverse engineering; allow analysis of miners w.r.t. a class of programs and/or behaviors; help users in choosing the best suited approach for their objective.

Extending pnml Scope: A Framework to Combine Petri Nets Types

The Petri net standard ISO/IEC 15909 comprises 3 parts. The first one defines the most used net types, the second an interchange format for these – both are published. The third part deals with Petri net extensions, in particular structuring mechanisms and the introduction of additional, more elaborate net types within the standard.

Automation and intelligent scheduling of distributed system functional testing

This paper presents the approach to functional test automation of services (black-box testing) and service architectures (grey-box testing) that has been developed within the MIDAS project and is accessible on the MIDAS SaaS. In particular, the algorithms and techniques adopted for addressing input and oracle generation, dynamic scheduling, and session planning issues supporting service functional test automation are illustrated. More specifically, the paper details: (i) the test input generation based on formal methods and temporal logic specifications, (ii) the test oracle generation based on service formal specifications, (iii) the dynamic scheduling of test cases based on probabilistic graphical reasoning, and (iv) the reactive, evidence-based planning of test sessions with on-the-fly generation of new test cases. Finally, the utilisation of the MIDAS prototype for the functional test of operational services and service architectures in the healthcare industry is reported and assessed. A planned evolution of the technology deals with the testing and troubleshooting of distributed systems that integrate connected objects.

Exact and Efficient Temporal Steering of Software Behavioral Model Inference

Behavior Model Inference techniques aim at mining behavior models from execution traces. While most of approaches usually ground on local similarities in traces, recent work, referred to as behavior mining with temporal steering, propose to include long term dependencies in the mining process. Such dependencies correspond to temporal implications between events in execution traces, whose consideration allows to ensure a better consistency of the extracted model. Nevertheless, the existing approaches are usually limited by their high computational complexity and the approximations to reduce the cost of temporal rules checking. This paper revisits behavior mining with temporal steering by defining an efficient algorithm that performs an exact consideration of the observed dependencies: in our experiments, greatly reduced processing times (from exponential to quasi-linear) for exact mining with temporal steering have been observed. Furthermore, beyond highlighting the great benefits of considering temporal dependencies, this paper also proposes new key extensions to the existing work that allow to include more complex dependencies in the mining process. Intensive evaluation finally demonstrates the great performances of the proposed approach.

Service functional testing automation with intelligent scheduling and planning

This paper presents the intelligent automation of functional test of services (unit testing) and services architectures (end-to-end testing) that has been developed by the MIDAS project, and is accessible on the MIDAS SaaS. In particular, the paper illustrates how the extreme automation implemented in the MIDAS prototype includes the solutions of tough problems such as: (i) the configuration of the automated test execution engine against large and complex services architectures, (ii) the test input generation based on formal methods and constraint propagation, (iii) the test oracle generation based on state machine execution, (iv) the dynamic scheduling of test cases and the reactive, evidence-based planning of test campaigns with on the fly generation of new test cases, both based on based on probabilistic graphical inference. This paper reports some feedback from real-world case studies in the health-care and in the logistics sectors.

Extreme symmetries in complex distributed systems: the bag-oriented approach

Model checking is widely used as an automatic exhaustive verification technique to check properties of complex systems. However, it is difficult to operate in the context of todays emerging systems that combine distribution (and asynchronous communications) together with a large size (and a hierarchical composition of components --- and thus, of specifications). This paper combines existing techniques tackling the known combinatorial explosion of model checking. To achieve this, we exploit the structure of such distributed systems (symmetries and hierarchical composition), thus allowing a better compression factor and calculus factorization in favorable cases. We present these techniques and assess their impact on some benchmark examples.