330 research outputs found
Modelling and Simulation of Asynchronous Real-Time Systems using Timed Rebeca
In this paper we propose an extension of the Rebeca language that can be used
to model distributed and asynchronous systems with timing constraints. We
provide the formal semantics of the language using Structural Operational
Semantics, and show its expressiveness by means of examples. We developed a
tool for automated translation from timed Rebeca to the Erlang language, which
provides a first implementation of timed Rebeca. We can use the tool to set the
parameters of timed Rebeca models, which represent the environment and
component variables, and use McErlang to run multiple simulations for different
settings. Timed Rebeca restricts the modeller to a pure asynchronous
actor-based paradigm, where the structure of the model represents the service
oriented architecture, while the computational model matches the network
infrastructure. Simulation is shown to be an effective analysis support,
specially where model checking faces almost immediate state explosion in an
asynchronous setting.Comment: In Proceedings FOCLASA 2011, arXiv:1107.584
Specification and Verification of Timing Properties in Interoperable Medical Systems
To support the dynamic composition of various devices/apps into a medical
system at point-of-care, a set of communication patterns to describe the
communication needs of devices has been proposed. To address timing
requirements, each pattern breaks common timing properties into finer ones that
can be enforced locally by the components. Common timing requirements for the
underlying communication substrate are derived from these local properties. The
local properties of devices are assured by the vendors at the development time.
Although organizations procure devices that are compatible in terms of their
local properties and middleware, they may not operate as desired. The latency
of the organization network interacts with the local properties of devices. To
validate the interaction among the timing properties of components and the
network, we formally specify such systems in Timed Rebeca. We use model
checking to verify the derived timing requirements of the communication
substrate in terms of the network and device models. We provide a set of
templates as a guideline to specify medical systems in terms of the formal
model of patterns. A composite medical system using several devices is subject
to state-space explosion. We extend the reduction technique of Timed Rebeca
based on the static properties of patterns. We prove that our reduction is
sound and show the applicability of our approach in reducing the state space by
modeling two clinical scenarios made of several instances of patterns
Extending Rebeca with synchronous messages and reusable components
In this paper, we propose extended Rebeca as a tool-supported actor-based language for modeling and verifying of concurrent and distributed systems. We enrich Rebeca with a formal concept of components which integrates the message-driven computational model of actor-based languages with synchronous message passing. Components are used to encapsulate a set of internal active objects which react asynchronously to messages by means of methods and which additionally interact via a synchronous message passing mechanism. Components themselves interact only via asynchronous and anonymous messages. We present our compositional verification approach and abstraction techniques, and the theory corresponding to it, based on formal semantics of Rebeca. These techniques are exploited to overcome state explosion problem in model checkin
Functional and Performance Analysis of Network-on-Chips Using Actor-based Modeling and Formal Verification
Network on Chip (NoC) has emerged as a promising architecture paradigmfor todays many-core systems. As complexity grows in NoCs, functional verificationand performance prediction in the early stages of the design process are suggestedas ways to reduce the fabrication cost. Formal methods have gained moreattention as alternative ways for analyzing NoC designs. In this paper we propose amethod to model different characteristics of the system, and also verify various functionaland performance properties by generating the full state space of the model fordifferent scenarios. We present a formal model for two-dimensional mesh GloballyAsynchronous Locally Synchronous (GALS) NoCs with four-phase handshakecommunication protocol, using the actor-based modeling language Rebeca. Functionaland timing behaviors, routing algorithm and communication protocol are capturedin the model. Deadlock freedom, message arrival, and end-to-end packet latencyare checked. In order to analyze large NoCs we propose a scalable approachbased on compositional verification for estimating maximum end-to-end packet latency.The compositional approach is specific for the XY-routing algorithm. Resultsof verification are compared and matched to simulation results of HSPICE using32nm technology
Timed Actors and Their Formal Verification
In this paper we review the actor-based language, Timed Rebeca, with a focus
on its formal semantics and formal verification techniques. Timed Rebeca can be
used to model systems consisting of encapsulated components which communicate
by asynchronous message passing. Messages are put in the message buffer of the
receiver actor and can be seen as events. Components react to these
messages/events and execute the corresponding message/event handler. Real-time
features, like computation delay, network delay and periodic behavior, can be
modeled in the language. We explain how both Floating-Time Transition System
(FTTS) and common Timed Transition System (TTS) can be used as the semantics of
such models and the basis for model checking. We use FTTS when we are
interested in event-based properties, and it helps in state space reduction.
For checking the properties based on the value of variables at certain point in
time, we use the TTS semantics. The model checking toolset supports
schedulability analysis, deadlock and queue-overflow check, and assertion based
verification of Timed Rebeca models. TCTL model checking based on TTS is also
possible but is not integrated in the tool.Comment: In Proceedings EXPRESS/SOS2023, arXiv:2309.0578
Symmetry and partial order reduction techniques in model checking Rebeca
Rebeca is an actor-based language with formal semantics that can be used in modeling concurrent and distributed software and protocols. In this paper, we study the application of partial order and symmetry reduction techniques to model checking dynamic Rebeca models. Finding symmetry based equivalence classes of states is in general a difficult problem known to be as hard as graph isomorphism. We show how, for Rebeca models, we can tackle this problem with a polynomial-time solution. Moreover, the coarse-grained interleaving semantics of Rebeca causes considerable reductions when partial order reduction is applied. We have also developed a tool that can make use of both techniques in combination or separately. The evaluation results show significant improvements in model size and model-checking time
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