A stochastic extension of a behavioural subset of UML statechart diagrams

We present a stochastically timed extension of UML statechart diagrams. The extension is rather simple both from a notational point of view and from a semantics point of view. In particular we enrich a state/transition formal operational semantics we proposed in (Latella et al., 1999) with random clocks for expressing time values. We do this in an orthogonal way, which means that the enriched semantics preserves all the properties of the untimed one. We show, by means of a simple example, how the enriched notation and its semantics can be used for performing quantitative analysis of stochastic UML statechart diagram models