Probabilistic verification of architectural software models using SoftArc and Prism

In this paper we will describe the SoftArc approach. With the SoftArc approach it is possible to model and analyse safety-critical embedded and distributed systems that consist of both hardand software. We are going to present the SoftArc modelling language, its syntax and semantics. The semantics of the SoftArc modelling language is defined in terms of stochastic reactive modules. We will show how important measures of interest for probabilistic dependability analysis like availability, unavailability, and survivability, can be analysed. We will demonstrate the feasibility of our approach by means of two case studies, that involve hardand software elements. First, we are presenting two industrial case studies from the automotive industry. We will analyse the non volatile random access manager (NVRAM) from the AUTOSAR open system architecture, Second, we are going to present the survivability analysis of a simplified version of the Google replicated file system. rigor (details will follow) with applicability and openness with respect to true design tools. In this paper, we propose a new XML-based modelling language for architectural models called SoftArc (for “Software-oriented Arcade” (Boudali, Crouzen, Haverkort, Kuntz, and Stoelinga 2008)). SoftArc has the following properties: (i) fully XML-based, so that interfacing to design tools and other analysis tools is easily achieved; (ii) an underlying formal semantics in terms of reactive modules (Alur and Henzinger 1999); (iii) integrated support for dependability (reliability and availability) evaluation, performability evaluation (where a notion of costs/rewards is used), and survivability evaluation (to study “performance” after the occurrence of failures); (iv) full support for the inclusion of component repair strategies. Related work. There is a vast body on literature on approaches, that have been developed for evaluating system dependability, we refer the reader to (Boudali, Crouzen, Haverkort, Kuntz, and Stoelinga 2008) for an extensive overview. In (Boudali, Crouzen, Haverkort, Kuntz, and Stoelinga 2008), we have introduced Arcade on which SoftArc is based. The differences between Arcade and SoftArc can be summarised as follows: (i) We have extended