35,610 research outputs found
Passive Testing of Timed Systems
This paper presents a methodology to perform passive testing based on invariants for systems that present temporal restrictions. Invariants represent the most
relevant expected properties of the implementation under test. Intuitively, an invariant expresses the fact that each time the implementation under test performs a given
sequence of actions, then it must exhibit a behavior in a lapse of time reflected in the invariant. In particular, the algorithm presented in this paper are fully implemente
Passive Testing of Stochastic Timed Systems
In this paper we introduce a formal Methodology to perforin passive testing, based on invariants, for systems where the passing of time is represented in probabilistic terms by means of probability distributions functions. In our approach, invariants express the fact that each time the implementation under test performs a given sequence of actions, then it must exhibit a behavior according to the probability distribution functions reflected it? the invariant. We present algorithms to decide the correctness of the proposed invariants with respect to a given specification. Once we know that an invariant is correct, we check whether the execution traces observed from the implementation respect the invariant. In addition to the theoretical framework we have developed a tool., called PASTE, that helps in the automation of our passive testing approach. We have used the tool to obtain experimental results front the application of our methodology
Formal correctness of a passive testing approach for timed systems
In this paper we extend our previous work on passive
testing of timed systems to establish a formal criterion to determine correctness of an implementation under test. In our framework, an invariant expresses the fact that if the implementation under test performs a given sequence of actions, then it must exhibit a behavior in a lapse of time reflected in the invariant. In a previous paper we gave an algorithm to establish the correctness of an invariant with respect to a specification. In this paper we continue the work by providing an algorithm to check the correctness of a log, recorded form the implementation under test, with respect to an invariant. We show the soundness of our method by relating it to an implementation relation. In addition to the theoretical framework we have developed a tool, called PASTE, that facilitates the automation of our passive testing approach
Markovian Testing Equivalence and Exponentially Timed Internal Actions
In the theory of testing for Markovian processes developed so far,
exponentially timed internal actions are not admitted within processes. When
present, these actions cannot be abstracted away, because their execution takes
a nonzero amount of time and hence can be observed. On the other hand, they
must be carefully taken into account, in order not to equate processes that are
distinguishable from a timing viewpoint. In this paper, we recast the
definition of Markovian testing equivalence in the framework of a Markovian
process calculus including exponentially timed internal actions. Then, we show
that the resulting behavioral equivalence is a congruence, has a sound and
complete axiomatization, has a modal logic characterization, and can be decided
in polynomial time
Runtime Verification Based on Executable Models: On-the-Fly Matching of Timed Traces
Runtime verification is checking whether a system execution satisfies or
violates a given correctness property. A procedure that automatically, and
typically on the fly, verifies conformance of the system's behavior to the
specified property is called a monitor. Nowadays, a variety of formalisms are
used to express properties on observed behavior of computer systems, and a lot
of methods have been proposed to construct monitors. However, it is a frequent
situation when advanced formalisms and methods are not needed, because an
executable model of the system is available. The original purpose and structure
of the model are out of importance; rather what is required is that the system
and its model have similar sets of interfaces. In this case, monitoring is
carried out as follows. Two "black boxes", the system and its reference model,
are executed in parallel and stimulated with the same input sequences; the
monitor dynamically captures their output traces and tries to match them. The
main problem is that a model is usually more abstract than the real system,
both in terms of functionality and timing. Therefore, trace-to-trace matching
is not straightforward and allows the system to produce events in different
order or even miss some of them. The paper studies on-the-fly conformance
relations for timed systems (i.e., systems whose inputs and outputs are
distributed along the time axis). It also suggests a practice-oriented
methodology for creating and configuring monitors for timed systems based on
executable models. The methodology has been successfully applied to a number of
industrial projects of simulation-based hardware verification.Comment: In Proceedings MBT 2013, arXiv:1303.037
Process algebra for performance evaluation
This paper surveys the theoretical developments in the field of stochastic process algebras, process algebras where action occurrences may be subject to a delay that is determined by a random variable. A huge class of resource-sharing systems – like large-scale computers, client–server architectures, networks – can accurately be described using such stochastic specification formalisms. The main emphasis of this paper is the treatment of operational semantics, notions of equivalence, and (sound and complete) axiomatisations of these equivalences for different types of Markovian process algebras, where delays are governed by exponential distributions. Starting from a simple actionless algebra for describing time-homogeneous continuous-time Markov chains, we consider the integration of actions and random delays both as a single entity (like in known Markovian process algebras like TIPP, PEPA and EMPA) and as separate entities (like in the timed process algebras timed CSP and TCCS). In total we consider four related calculi and investigate their relationship to existing Markovian process algebras. We also briefly indicate how one can profit from the separation of time and actions when incorporating more general, non-Markovian distributions
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