Software Tools for Technology Transfer manuscript No. (will be inserted by the editor) Oris: a Tool for Modeling and Verification of Real-Time Systems Giacomo Bucci, Laura Carnevali, Lorenzo Ridi, Enrico Vicario Dipartimento di Sistemi e Informatica - Universit`a di Firenze {bucci,carnevali,ridi,vicario}@dsi.unifi.it The date of receipt and acceptance will be inserted by the editor Abstract. Oris is a tool for qualitative verification and quantitative evaluation of reactive timed systems. It sup- ports modeling, simulation, and analysis of various classes of timed extensions of Petri Nets, in particular preemp- tive Time Petri Nets (pTPNs) and stochastic Time Petri Nets (sTPNs). In this paper, we present the current ver- sion of the tool and we illustrate its application to real case studies. Key words: preemptive Time Petri Nets, stochastic Time Petri Nets 1 Introduction Time affects the development of a large class of reactive systems, for either explicit real-time constraints or se- quencing limitations resulting from timed behavior. This calls for models which explicitly address these factors in order to achieve predictability, a requirement for crit- ical applications. Formal methods such as Timed Au- tomata [1][2][3] or Time Petri Nets [4][5][6][7] have been effectively adopted for modeling and validation of time- dependent systems. For all these methods, the semantics of the system is defined in terms of state transition rules driving the evolution of logical locations and of a set of quantitative clocks. While the former are discrete, the latter take values in dense domains. To obtain a dis- crete representation, the state-space is covered through equivalence classes, each characterized by a time domain collecting a dense variety of clock values [1][2][3][4][6]. A number of tools [2][3][8][9][10] have been developed to support the formal verification of real time systems. On the one hand, in the context of Timed Automata, UPPAAL is a well-consolidated tool for validation and verification of real-time systems modeled as networks of timed automata extended with data types [2] [11]. It includes a model checker providing a diagnostic trace that can be simulated to understand why a property is (or is not) satisfied. The application of Timed Au- tomata to scheduling theory is enabled by the Times tool [12][8], which supports modeling, analysis and syn- thesis of schedules and executable code. It allows the treatment of tasks with asynchronous and dense release times, running under the most practiced scheduling dis- ciplines. As a limitation, the underlying analysis rules out nondeterministic computation times taking values within dense intervals. On the other hand, in the con- text of Time Petri Nets, Tina [10] and Romeo [9] are well-established tools supporting the construction of var- ious abstract state-space representations and the model- checking of reachability properties. As a relevant trait, Romeo also supports both approximate and exact enu- meration of the state space for an extension of Time Petri Nets (Scheduling- TPNs) modeling preemption. 1 2 In this paper, we provide a description of the Oris tool. Oris comprises a rich set of modules for building, simulating, analyzing and validating real-time systems described through various TPN formalisms. In partic- ular, Oris is able to deal with Preemptive Time Petri Nets [7], extending the model of Time Petri Nets [4][5] with a mechanism of resource assignment which condi- tions the advancement of timers of enabled transitions. The resulting formalism allows representation of com- plex and densely-timed tasking models running under priority scheduling. Section 3 provides an example of how pTPN models can be analyzed through a symbolic state space enumeration method. The method supports reachability analysis and evaluation of tight bounds on the time elapsed between events along critical execution 1 TBD: Aggiornare letteratura sui tool. 2 TBD: Citare i precedenti lavori su Oris ?