In this paper we propose a methodology for the modelling, verification and performance evaluation of communication components of software for enterprise information systems. The methodology is centered upon model-driven development using a subset of UML 2.0 diagrams. It is supported by the proSPEX model processing tool which offers a simulation-based executable verification environment. The mod...

We review high-level speciication formalisms for Markovian performability models, thereby emphasising the role of structuring concepts as realised par excellence by stochastic process algebras. Symbolic representations based on decision diagrams are presented, and it is shown that they quite ideally support compositional model construction and analysis.

The paper “Performability Analysis: A New Algorithm” describes an algorithm for computing the complementary distribution of the accumulated reward over an interval of time in a homogeneous Markov process. In this comment, we show that in two particular cases, one of which is quite frequent, small modifications of the algorithm may reduce significantly its storage complexity.

Web analytics is the measurement, collection, analysis and summarizing of internet data for purposes of understanding and optimizing web usage. To check the web analytics the website IJCT is considered. This paper is the first step to analyze the availability and performability of the site. Availability depicts that for how much time the system is up i.e. check the utilization of the system on ...

Analytical and simulative modeling for dependability and performance evaluation has been proven to be a useful and versatile approach in all the phases of the system life cycle. Indeed, a widely used approach in performability modeling is to describe the system by state space models (like Markov models). However, for large systems, the state space of the system model may result extremely large,...

This paper deals with the performance analysis of multiple server retrial queueing systems with a finite number of homogeneous sources of calls, where the heterogeneous servers are subject to random breakdowns and repairs. The requests are serviced according to Random Selection and Fastest Free Server disciplines. The novelty of this investigation is the introduction of different service rates ...

Markovian modeling of systems is a promising technique used to gauge the performance, dependability, and performability of systems. It can be used to aid design decisions by evaluating a range of design options for a range of environments, and it can be used to increase understanding of operational systems. Unfortunately, Markovian modeling is limited by the “state-space explosion,” or the expo...

We describe a novel model checking algorithm for analysing the behaviour of stochastic systems with respect to their performability. Systems are modelled as actionlabelled CTMCs, and the properties to be veri ed are speci ed with the help of the action-based temporal logic aCSL. The technique is currently being implemented in our freely available prototype tool ETMCC.

Performability modelling has been most successfully applied for gracefully degradable computer systems by using Markov reward models [2]. In this approach the relation of the performability model with the underlying performance and dependability model is exploited. For many systems and for many measures of interest this type of modelling is not suited, so another performability modelling approa...