July 2, 2007 Research at the SW Technologies Lab (Time Petri Nets - PowerPoint PPT Presentation

WIRTES 07 WIRTES - Pisa, July07 Primo Workshop Italiano su Real-Time Embedded Systems July 2, 2007 Research at the SW Technologies Lab (Time Petri Nets nella verifica e valutazione di sistemi real-time) Giacomo Bucci, Laura Carnevali, Luigi Sassoli, Enrico Vicario Sw Technologies Lab, Dept.Sistemi e Informatica, University of Florence vicario@dsi.unifi.it, www.dsi.unifi.it/~vicario 1/12

SW Technologies Lab WIRTES - Pisa, July07 � People � G.Bucci, E.Vicario, A.Fantechi � L.Sassoli,F.Baldini,L.Carnevali,L.Grassi,V.Sandrucci,F.Poli,A.Rugnone,J.Torrini, M.Banci, G.Lombardi, E.Spinicci, G.Falcini � Collaborations � Galileo Avionica, Regione Toscana, GE Transportation Systems, Marelli � I+, Rigel, Planet, Rinascimento Digitale, ITTIG.CNR, ISTI.CNR Polo biotecnologico di unifi, Azienda Ospedaliera Careggi, … 2/12

3 main areas of experitze WIRTES - Pisa, July07 � SW architectures and development practices (Bucci,Vicario) � Enterprise architectures and application interoperability (eGovernment ) � Ontological architectures and applications � Workflow management architectures � OO Testing � Focus on experimentation, development capability, technology transfer � Qualitative verification and quantitative evaluation (Bucci,Vicario) � Nondeterministic/stochastic, timed, reactive systems • Time Petri Nets, preemptiveTPN, stochasticTPN, … • Symbolic state space analysis � Real time testing � Formal modelling of embedded safety critical systems (Fantechi) � Specific focus on railway signaling systems � Model driven development • modeling, model checking, automatic code generation, code deployment on target, system testing � Experimentation with commercial modelling tools • IAR Visualstate, Ilogix Statemate, Matlab Stateflow, Esterel Tech.SCADE 3/12

WIRTES - Pisa, July07 � Verification of reactive, timed, non deterministic systems � Sequencing of events � Min-max time between events 4/12

Time Petri Nets (TPN) WIRTES - Pisa, July07 � Reactive, dense timed, non-deterministic, non-preemptive systems � Symbolic state space analysis � State classes, Difference Bound Matrix, symbolic runs � IEEE TSE01: vicario 5/12

Preemptive Time Petri Nets (pTPN) WIRTES - Pisa, July07 � Represents suspension � breaks DBM encoding � Tight DBM approximation, � Selection of critical paths and clean-up of false behaviors � IEEE TSE04: bucci, fedeli, sassoli, vicario 6/12

Communicating Time Petri Nets (cmTPN) WIRTES - Pisa, July07 � Modular decomposition � TPN without preemption � Separate state space enumeration, required/provided interface � Projection and composition � IEEE TSE95: bucci, vicario 7/12

Real Time testing WIRTES - Pisa, July07 � Exploit theory of pTPN to support design and testing � Integration in process standards � RTCA 178B, V-model, … � architecture design and validation, � disciplined coding, execution time profiling � test case selection, sensitization, oracle, coverage analysis � Collaboration with Galileo Avionica � Experimentation on Linux-RTAI � ECRTS07, ETFA07: carnevali, sassoli, vicario 8/12

WIRTES - Pisa, July07 � Quantitative evaluation of stochastic reactive timed systems � Associate non-determinism with a stochastic characterization • Instantaneous choices • Temporal parameters � Provide a measure of probability for alternative behaviors • Symbolic runs • Run timings 9/12

stochastic preemptive Time Petri Nets WIRTES - Pisa, July07 � Time intervals associated with general distribution � Discrete time � Maximal step semantics, confusion and well definedness � Stochastic state transition system � Embeds a Discrete Time Markov Chain � Joint verification of possible behaviors and evaluation of their probability � E.g. overrun handling policies: correctness and efficiency � IEEE TSE05: bucci, sassoli, vicario 10/12

stochastic Time Petri Nets WIRTES - Pisa, July07 � Dense time, no preemption � Extend state classes with state density � symbolic calculus of density functions � Mathematica API, c++ implementation for exp-polynomial distributions � Stochastic extension of the class graph � regeneration classes and boundedness � Markov renewal theory, Continuous Time Markov Chain � QEST05, QEST06, QEST07: bucci, sassoli, vicario � Main work under revision at IEEE TSE: sassoli, vicario 11/12

Tool support WIRTES - Pisa, July07 � All results implemented in the ORIS tool � Plug-in architecture � C++/Java � http://www.stlab.dsi.unifi.it/oris/index.html 12/12

WIRTES 07 WIRTES - Pisa, July07 Primo Workshop Italiano su Real-Time Embedded Systems July 2, 2007 Research at the SW Technologies Lab (Time Petri Nets nella verifica e valutazione di sistemi real-time) Giacomo Bucci, Laura Carnevali, Luigi Sassoli, Enrico Vicario Sw Technologies Lab, Dept.Sistemi e Informatica, University of Florence vicario@dsi.unifi.it, www.dsi.unifi.it/~vicario 13/12