The importance of assessing software non-functional properties (NFP) beside the functional ones is well accepted in the software engineering community. In particular, dependability is a NFP that should be assessed early in the software life-cycle by evaluating the system behaviour under different fault assumptions. Dependability-specific modeling and analysis techniques include for example Failure Mode and Effect Analysis for qualitative evaluation, stochastic Petri nets for quantitative evaluation, and fault trees for both forms of evaluation. Unified Modeling Language (UML) may be specialized for different domains by using the profile mechanism. For example, the MARTE profile extends UML with concepts for modeling and quantitative analysis of real-time and embedded systems (more specifically, for schedulability and performance analysis). This paper proposes to add to MARTE a profile for dependability analysis and modeling (DAM). A case study of an intrusion-tolerant message service will offer insight on how the MARTE-DAM profile can be used to derive a stochastic Petri net model for performance and dependability assessment.

In this paper we study the use of Sequence Diagrams and Statecharts of the Unified Modeling Language (UML) for the validation and the performance evaluation of systems. We assume that the system is specified as a set of Statecharts and that Sequence Diagrams are used to represent "executions of interest". UML lacks a formal semantics and hence it is not possible to apply, directly, mathematical techniques on UML models for system validation. To reach this goal we propose an automatic translation of Statecharts and Sequence Diagrams into Generalized Stochastic Petri Nets, and a composition of the resulting net models suitable for reaching a given analysis goal. The translation into Petri nets is based on the abstract syntax of the UML Collaborations and of the State Machines packages (from which Sequence Diagrams and Statecharts are derived) and the construction of the complete model heavily uses compositionality.

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The goal is to survey dependability modeling and analysis of software and systems specified with UML, with focus on reliability, availability, maintainability and safety (RAMS). From the literature published in the last decade, 33 approaches presented in 43 papers were identified. They are evaluated according to three sets of criteria regarding UML modeling issues, addressed dependability characteristics and quality assessment of the surveyed approaches. The survey shows that more works are devoted to reliability and safety, fewer to availability and maintainability and none to integrity. Many methods support early life-cycle phases (from requirements to design). More research is needed for tool development to automate the derivation of analysis models and to give feedback to designers.