. In this paper we present a structure-oriented decomposition method for stochastic process algebra specications. The derived components are modied such that the inuence of other components is incorporated. This inuence is described by delays which correspond to waiting times of the components before they can synchronise with other components. Is is shown that the waiting times can be expressed by random variables, which are derived by means of stochastic bundle event structures. It turns out that the derivation of mean values associated with the waiting time random variables could be performed exactly, but is a much too complex task, in time as well as in space, to be actually carried out. Some proposals are given to overcome these problems. 1 Introduction Formal verication and the evaluation of performance models have been proven to be important stages in the design of computer and communication systems. Stochastic process algebras (SPA) are an attempt to integrate t...

Today’s software systems are becoming increasingly configurable and designed for deployment on a plethora of architectures, ranging from sequential machines via multicore and distributed architectures to the cloud. Examples of such systems are found in, e.g., software product lines, service-oriented computing, information systems, embedded systems, operating systems, and telephony. To model and analyze systems without a fixed architecture, the models need to naturally capture and range over relevant deployment scenarios. For this purpose, it is interesting to lift aspects of low-level deployment concerns to the abstraction level of the modeling language. In this paper, the objectoriented modeling language Creol is extended with a notion of dynamic deployment components with parametric processing resources, such that processor resources may be explicitly reallocated. The approach is compositional in the sense that functional models and reallocation strategies are both expressed in Creol, and functional models can be run alone or in combination with different reallocation strategies. The formal semantics of deployment components is given in rewriting logic, extending the semantics of Creol, and executes on Maude, which allows simulations and test suites to be applied to models which vary in their available resources as well as in their resource reallocation strategies.

Abstract. In concurrent real-time processes, the speed of individual components has a double impact: on the one hand, the overall latency of a compound process is affected by the latency of its components. But, if the composition has race conditions, the very outcome of the process will also depend on the latency of component processes. Using stochastic Petri nets, we investigate the probability of a transition occurrence being critical for the entire process, i.e. such that a small increase or decrease of the duration of the occurrence entails an increase or decrease of the total duration of the process. The first stage of the analysis focuses on occurrence nets, as obtained by partial order unfoldings, to determine criticality of events; we then lift to workflow nets to investigate criticality of transitions inside a workflow. 1