Stefano Marrone

Publications

• Adaptive Monitoring of Marine Disasters with Intelligent Mobile Sensor Networks

  M. Iacono, S. Marrone, E. Romano

  IEEE Workshop on Environmental, Energy, and Structural Monitoring Systems (EESMS), Taranto (Italy); 01/2010

  Accidents and sabotages are kinds of environmental disasters that constitute a growing threat to marine ecosystems. Recent events disclosed to the public audience the importance of developing methodologies and systems that can accurately and continuously monitor such events. Sensor networks have bee... [more] Accidents and sabotages are kinds of environmental disasters that constitute a growing threat to marine ecosystems. Recent events disclosed to the public audience the importance of developing methodologies and systems that can accurately and continuously monitor such events. Sensor networks have been successfully applied to early warning and environmental monitoring both in terrestrial and marine contexts. In this paper we propose an architecture for continuous monitoring of marine disasters. After the detection of suspect substances in a sea area by means of its concentration in water, the first goal of this approach is to follow the contour of actual affected area by means of reconfigurable sensor networks and a centralized intelligent system. Such systems are able to estimate substance concentrations (functions that variate in space and time) by means of advanced geostatistical techniques, mobile sensor devices and evolutionary computing.

• Evaluating availability of composed web services

  M. Iacono, S. Marrone

  Operations Research 2010 Conference, Munich (Germany); 01/2010

  Web services composition is an emerging software development paradigm for the implementation of distributed computing systems. A service integrator can produce added value by delivering more abstract and complex services obtained by composition: but while isolated services availability can be improv... [more] Web services composition is an emerging software development paradigm for the implementation of distributed computing systems. A service integrator can produce added value by delivering more abstract and complex services obtained by composition: but while isolated services availability can be improved by tuning and reconfiguring their hosting servers, in the case of Composed Web Services (CWS) basic services have to be taken as they are; in this case a reasonable measure is to evaluate the effects of the composition. We propose an analysis methodology that allows availability evaluation of CWS by transforming BPEL descriptions into models based on the fault tree formalisms family. BPEL definition of a CWS intrinsically describes the relations by which the availability of component basic services influences the availability of the composed one. Systematic analysis of BPEL language elements allows the definition of equivalent fault tree patterns that represent their effects on the composition. With this premises, it is possible to obtain an evaluation of the availability of a CWS given components availability and the expected execution behaviour of the CWS. When used in a system development cycle, such a tool enables designers to compare alternative BPEL compositions of the same or of different sets of services and to explore the benefits of redundant configurations or of the implementation of different fall back mechanisms. Moreover, this approach guides service integrators in the choice of single component services by unveiling their actual influence on the overall service with usual fault tree based analysis techniques. The proposed paper aims to present translations criteria of BPEL elements into fault tree patterns to apply them to the evaluation of an example CWS.

• Multiformalism and transformation inheritance for dependability analysis of critical systems

  S. Marrone, C. Papa, V. Vittorini

  01/2010: pages 215-228;

  ISBN: 978-3-642-16264-0

• A new modeling approach to the safety evaluation of N-modular redundant computer systems in presence of imperfect maintenance

  F. Flammini, S. Marrone, N. Mazzocca, V. Vittorini

  Journal of Reliability Engineering and System Safety. 01/2009; 94:1422-1432.

  A large number of safety-critical control systems are based on N-modular redundant architectures, using majority voters on the outputs of independent computation units. In order to assess the compliance of these architectures with international safety standards, the frequency of hazardous failures m... [more] A large number of safety-critical control systems are based on N-modular redundant architectures, using majority voters on the outputs of independent computation units. In order to assess the compliance of these architectures with international safety standards, the frequency of hazardous failures must be analyzed by developing and solving proper formal models. Furthermore, the impact of maintenance faults has to be considered, since imperfect maintenance may degrade the safety integrity level of the system. In this paper, we present both a failure model for voting architectures based on Bayesian networks and a maintenance model based on continuous time Markov chains, and we propose to combine them according to a compositional multiformalism modeling approach in order to analyze the impact of imperfect maintenance on the system safety. We also show how the proposed approach promotes the reuse and the interchange of models as well the interchange of solving tools.

• Interfaces and Binding in Component Based Development of Formal Models

  G. Franceschinis, M. Gribaudo, M. Iacono, S. Marrone, F. Moscato, V. Vittorini

  4th International Conference on Performance Evaluation Methodologies and Tools (VALUETOOLS), Pisa (Italy); 01/2009

  Component based modeling is of great importance for building and analyzing models of real systems. It is based on a well known paradigm which makes use of abstraction and composition. In this paper we focus on abstraction, by describing a practical approach to the definition of very simple interface... [more] Component based modeling is of great importance for building and analyzing models of real systems. It is based on a well known paradigm which makes use of abstraction and composition. In this paper we focus on abstraction, by describing a practical approach to the definition of very simple interface models allowing for the substitution of components within composed multiformalism models. The work extends the OsMoSys methodology and relies on meta-modeling. This paper does not discuss formal aspects about interface theory and components interaction, but focuses on the problem of building component models in practice with the ultimate goal of solving them by using (the existing) analysis tools. The paper formally extends the OsMoSys conceptual model in order to introduce model interfaces and to provide some rules for interface compatibility. The paper also describes some steps towards the full definition of mechanisms for interface binding and their implementation.

• Testing Complex Safety-Critical Systems in SOA Context

  R. Donini, S. Marrone, N. Mazzocca, A. Orazzo, D. Papa, S. Venticinque

  Complex, Intelligent and Software Intensive Systems, 2008. CISIS 2008. International Conference on; 04/2008

  Due to its simplicity and ease of application, testing is the main technique by which complex safety-critical systems can be verified in order to find both omission and commission bugs. Strict requirements on such systems, joined to the necessity to re-execute the test set in the regression testing ... [more] Due to its simplicity and ease of application, testing is the main technique by which complex safety-critical systems can be verified in order to find both omission and commission bugs. Strict requirements on such systems, joined to the necessity to re-execute the test set in the regression testing campaign, provokes a test case set and testing time explosion that can be tackled only by means of the use of parallel independent testing environments. Parallelism in such environments is not easy to accomplish due to the heterogeneity of processes, methodologies and tools. Service Oriented Architecture (SOA) is a key factor in the development of an organic modelling and execution methodology in order to build a heterogeneous and distributed environment that supports a system testing. In this paper we propose an adoption of a classical SOA reference architecture in order to address the build of such an environment for safety-critical control systems. Moreover we provide indications on the integration of SOA specific architecture components with existing centralized testing environments providing an example in signalling railway control systems.

• A Performance Driven Modelling Approach for SOA Based Application

  M. Iacono, S. Marrone

  European Simulation and Modelling Conference (ESMc), Le-Havre (France); 01/2008

  Service Oriented Architectures are assuming a more and more relevant importance in integrating distributed systems by means of atomic services, allowing a coarse-grain reuse of existing solutions. Compositional systematic modeling approaches can improve the quality of applications built with this lo... [more] Service Oriented Architectures are assuming a more and more relevant importance in integrating distributed systems by means of atomic services, allowing a coarse-grain reuse of existing solutions. Compositional systematic modeling approaches can improve the quality of applications built with this logic: many open issues still drive research on this topic, including the need for methodologies enabling the assessment of both functional requirements (such as correctness) and non functional requirements (such as performances and reliability) in the early phases of design. Since literature deeply analyzes the first kind of requirements, in this paper we try and address the second kind, and introduce a modeling framework that supports the of performance analysis of coarse-grain SOA based applications in the early phases of the design process. This is made by exploiting formal methods (in particular by means of Generalized Stochastic Petri Nets) to anticipate performance requirements compliance verification when possible, given a basic statistical characterization of the services to be integrated.

• Evaluating the Hazardous Failure Rate of majority voting computer architectures by means of Bayesian Network models

  F. Flammini, S. Marrone, N. Mazzocca, V. Vittorini

  18th European Safety and Reliability Conference (ESREL), Stavanger (Norway); 01/2007

  Safety-critical control systems are usually based on majority voters. In order to assess the compliance of these architectures with international safety standards, the probability of the occurrence of unsafe events should be evaluated by developing and analyzing proper formal models. In this paper w... [more] Safety-critical control systems are usually based on majority voters. In order to assess the compliance of these architectures with international safety standards, the probability of the occurrence of unsafe events should be evaluated by developing and analyzing proper formal models. In this paper we demonstrate that a Bayesian Network (BN) model can be used to evaluate the Mean Time Between Hazardous Events (MTBHE) of voting architectures. The proposed modeling approach is applied to a “2 out of 2” (“2002”) voter consisting of independent computing units. The results obtained from the analysis of the BN model of the “2002” voter can be easily extended to evaluate the hazardous failure rate of more complex voting architectures (e.g. Triple Modular Redundant architectures, based on a 2003 voting). Within this context, BNs have several advantages over other traditional approaches (e.g. Petri Nets or Markov Chains): the model can be directly derived from the analysis of the flow-chart describing the dynamic of hazardous failures and its evaluation is much more efficient, as BN solving algorithms are non state-based; moreover, sensitivity analyses can be automatically performed by using the available user friendly BN tools . Finally, the proposed BN model is quite general and can be easily adapted and/or extended to suit specific computing architectures and fault models.

• Combining Genetic Algorithm and Fault Tree Analysis in Reliability/Cost Optimization for Critical Complex Systems

  F. De Carlo, M. Iacono, S. Marrone

  Modern Information Technology in the Innovation Processes of the Industrial Enterprises (MITIP), Florence (Italy); 01/2007

  The early evaluation of dependability requirements for complex critical systems is a hard task which is usually accomplished by means of well-established formal modeling techniques, as requested by most international reliability standards. On the other hand early product cost optimization is also ne... [more] The early evaluation of dependability requirements for complex critical systems is a hard task which is usually accomplished by means of well-established formal modeling techniques, as requested by most international reliability standards. On the other hand early product cost optimization is also necessary due to well-known difficulty to perform modifications in a stable and assessed system architecture. In this paper we propose a new methodology aiming at the integration of optimization techniques with formal methods in order to provide an efficient search of optimal reliability/cost trade-offs for complex and critical systems. The proposed approach is based on Multi-Objective Genetic Algorithms which are widespread for optimization of complex functions. Genetic Algorithms have been shown to be capable to find global sub-optimum solution overriding the problem of local minima; they also suit to constrained search domains. At best of our knowledge all past research works dealing with reliability/cost optimization by means of Genetic Algorithms are based on simulative approaches. The proposed methodology is instead based on a formal reliability evaluation allowing for better accuracy and reuse of existing models. The approach is based on the formalization of reliability aspects of the system by means of a Fault Tree model and on the exploration, by means of a Genetic Algorithm, of model parameters state space in order to evaluate the optimal combination of component costs and reliability. A customizable framework has been designed and developed in order to automate the proposed methodology: in particular the framework works with any formal language (e.g. Bayesian Networks, Fault Trees, etc…) and can interface with different existing model solvers. The methodology and framework have been applied on a generic Programmable Logic Controller reliability model based on the use of an assessed Fault Tree model, showing their effectiveness and ease of use.

• The software architecture of the OsMoSys Multisolution Framework

  G. Di Lorenzo, F. Flammini, M. Iacono, S. Marrone, F. Moscato, V. Vittorini

  2nd International Conference on Performance Evaluation Methodologies and Tools (VALUETOOLS), Nantes (France); 01/2007

  The use of multi-formalism techniques is very appealing in modeling complex systems since they allow to built complex models by integrating or composing sub-models specified by different formalisms. Hence, the most suitable formalism may be used according to the evaluation objectives, the level of ... [more] The use of multi-formalism techniques is very appealing in modeling complex systems since they allow to built complex models by integrating or composing sub-models specified by different formalisms. Hence, the most suitable formalism may be used according to the evaluation objectives, the level of abstraction of the sub-models and the nature of the subsystems. Each formalism is usually coupled with efficient solution methods, thus multi-solution approaches are needed to solve a multi-formalism model whose analysis involves different techniques and tools. In this paper the software architecture of the OsMoSys Multi-solution Framework (OMF) is presented. OMF was born to provide the support needed to a loosely coupled cooperation among heterogeneous analysis techniques and tools, and automates the tasks that must be performed to solve complex multi-formalism models. OMF does not require that heterogeneous models are translated into a common formalism in order to be solved, nor that the available tools are modified to be integrated in the framework, but it achieves multi-solution by orchestration.

• Modeling system reliability aspects of ERTMS/ETCS by Fault Trees and Bayesian Networks

  F. Flammini, S. Marrone, N. Mazzocca, V. Vittorini

  17th European Safety and Reliability Conference (ESREL), Estoril (Portugal); 01/2006

  Critical control systems require proper techniques to predict their failure rate since early design stages, in order to fulfil dependability requirements and minimize development costs. Bayesian Networks have been shown to be suitable to model system reliability aspects, extending the modeling power... [more] Critical control systems require proper techniques to predict their failure rate since early design stages, in order to fulfil dependability requirements and minimize development costs. Bayesian Networks have been shown to be suitable to model system reliability aspects, extending the modeling power of Fault Trees and featuring a better solving efficiency with respect to Petri Nets. In this paper we exploit the Fault Tree and Bayesian Network formalisms in order to perform a hardware reliability analysis of a complex real world case study: the European Railway Traffic Management System/European Train Control System (ERTMS/ETCS). ERTMS/ETCS is a recent standard specification aimed at improving interoperability, performances and depend- ability of modern railways. An implementation of ERTMS/ETCS is a distributed heterogeneous system with strict reliability requirements. Starting from such requirements and from a reference hardware architecture, we studied system reliability by instantiating models with realistic parameters and performing a series of sensitivity analyses in order to highlight design trade-offs. By evaluating and integrating sub-models using a compositional approach we both obtained several interesting results and showed the effectiveness of a combined use of Fault Trees and Bayesian Networks in dealing with system reliability analyses of train control systems.

• A Model Analysis of a Distributed Monitoring System Using a Multi-formalism Approach

  M. Iacono, S. Marrone, N. Mazzocca, F. Moscato, V. Vittorini

  01/2006: pages 499-508;

  ISBN: 3-540-29067-2, 2006

• Using Repairable Fault Trees for the evaluation of design choices for critical repairable systems

  F. Flammini, M. Iacono, S. Marrone, N. Mazzocca

  High Assurance Systems Engineering (HASE), Heidelberg, Germany; 01/2005

  Critical repairable systems are characterized by complex architecture and requirements. The evaluation of benefits produced by repair policies on the overall system availability is not straightforward, as policies can be very articulated and different. In order to support this evaluation process, th... [more] Critical repairable systems are characterized by complex architecture and requirements. The evaluation of benefits produced by repair policies on the overall system availability is not straightforward, as policies can be very articulated and different. In order to support this evaluation process, the Repairable Fault Tree (RFT) formalism revealed to be useful and suitable to represent complex repair policies by extending the existing Fault Tree formalism. In this paper we show how to exploit RFT advantages by evaluating the effects of different repair policies on the availability of the most critical component of ERTMS/ETCS (an European railway standard) systems: the Radio Block Centre (RBC).

• Compositional modeling of complex systems: contact center scenarios in OsMoSys

  G. Franceschinis, M. Gribaudo, M. Iacono, S. Marrone, N. Mazzocca, V. Vittorini

  01/2004: pages 177-196;

  ISBN: 3-540-22236-7

• Modeling Distributed Supervisory Systems using Modular Multi-formalism Methodology

  M. Iacono, S. Marrone, N. Mazzocca, F. Moscato

  European Simulation and Modelling Conference, Paris (France); 01/2004

• SWN client-server composition operators in the OsMoSys framework

  G. Franceschinis, V. Vittorini, S. Marrone, N. Mazzocca

  Petri Nets and Performance Models, 2003. Proceedings. 10th International Workshop on; 10/2003

  Not Available