Simona Bernardi

Dependability Analysis Techniques

An overview of the techniques traditionally used in dependability analysis that are compliant with current industrial standards (i.e., the International Electrotechnical Commission standards) is provided. In particular, the focus is on those techniques that are chosen as target formalism of model transformations (described in Chap. 7), that is Fault Tree analysis and Petri Net analysis.

Dependability Modeling and Assessment in UML-Based Software Development

Assessment of software nonfunctional properties (NFP) is an important problem in software development. In the context of model-driven development, an emerging approach for the analysis of different NFPs consists of the following steps: (a) to extend the software models with annotations describing the NFP of interest; (b) to transform automatically the annotated software model to the formalism chosen for NFP analysis; (c) to analyze the formal model using existing solvers; (d) to assess the software based on the results and give feedback to designers. Such a modeling→analysis→assessment approach can be applied to any software modeling language, be it general purpose or domain specific. In this paper, we focus on UML-based development and on the dependability NFP, which encompasses reliability, availability, safety, integrity, and maintainability. The paper presents the profile used to extend UML with dependability information, the model transformation to generate a DSPN formal model, and the assessment of the system properties based on the DSPN results.

A systematic approach for performance evaluation using process mining: the POSIDONIA operations case study

Modelling plays an important role in the development of software applications, in particular for the assessment of non functional requirements such as performance. The value of a model depends on the level of alignment with the reality. In this paper, we propose a systematic approach to get a performance model that is a good representation of the system under analysis. From an UML-based system design we get automatically a normative Petri net model, which formally represents the system supposed behaviour, by applying model-to-model (M2M) transformation techniques. Then, a conformance checking technique is iteratively applied to align -from the qualitative point of view- the normative model and the data log until the required fitness threshold is not reached. Finally, a trace-driven simulation technique is used to enrich the aligned model with timing specification from the data log, then obtaining the performance Generalized Stochastic Petri Net (GSPN) model. The proposed approach has been applied to a customizable Integrated Port Operations Management System, POSIDONIA Operations, where the performance model has been used to analyse the scalability of the product considering different deployment configurations.

A systematic approach for performance assessment using process mining

Software performance engineering is a mature field that offers methods to assess system performance. Process mining is a promising research field applied to gain insight on system processes. The interplay of these two fields opens promising applications in the industry. In this work, we report our experience applying a methodology, based on process mining techniques, for the performance assessment of a commercial data-intensive software application. The methodology has successfully assessed the scalability of future versions of this system. Moreover, it has identified bottlenecks components and replication needs for fulfilling business rules. The system, an integrated port operations management system, has been developed by Prodevelop, a medium-sized software enterprise with high expertise in geospatial technologies. The performance assessment has been carried out by a team composed by practitioners and researchers. Finally, the paper offers a deep discussion on the lessons learned during the experience, that will be useful for practitioners to adopt the methodology and for researcher to find new routes.

Towards a model-driven engineering approach for the assessment of non-functional properties using multi-formalism

Model-driven techniques can be used to automatically produce formal models from different views of a system realised by using several modelling languages and notations. Specifications are transformed into formal models so facilitating the analysis of complex system for design, validation or verification purposes. However, no single formalism suits for representing all system’s views. In particular, the assessment of non-functional properties often requires integrated modelling approaches. The ultimate goal of the research work described in this paper is to develop a comprehensive, theoretical and practical framework able to support the development and the integration of new or existing model-driven approaches for the automatic generation of multi-formalism models. This paper defines the core theoretical ideas on which the framework is based and demonstrates their concrete applicability to the development of a multi-formalism approach for performability assessment.

Dependability Assessment and Software Life Cycle

This introductory chapter describes the need, importance, and benefits of assessing dependability of software systems. It also establishes the approach followed in the book for dependability assessment.

Dependability Modeling and Analysis Profile

This chapter presents a UML profile as an example of mapping the dependability domain model ( Chap. 4) to UML, by using the standard UML extension mechanisms. The DAM profile relies on the standard OMG MARTE profile (Appendix A) and it consists of a set of UML extensions (i.e., stereotypes, tags, and constraints) that enable to annotate a UML model with dependability requirements, input parameters, and metrics for dependability analysis purposes. The chapter explains how to apply DAM extensions in UML-based system models. Two case studies, coming from different application domains, are presented.

Dependability Domain Model

This chapter introduces a domain model for the dependability. The model describes core concepts of dependability while provides a vocabulary for it. The domain model bridges the gap between dependability concepts, introduced in Chap. 2, and the dependability profile, described in Chap. 5 The domain model defines information needed to create modeling constructs for dependability-specific modeling languages.

From Software Models to Dependability Analysis Models

The objective of this chapter is to describe some proposals, of interest for practitioners, from those in Chap. 7 The focus of interest is how these proposals address the translation of a D-DSML into models for analysis. Concretely, the chapter focuses on availability and reliability proposals. We selected one from Bernardi et al., addressing availability and the other from Pai and Dugan, addressing reliability. These two approaches are applied to the case studies developed in Chap. 5 Availability analysis is then applied to the secure distributed system case study, while reliability models are obtained for the mission avionics one.

Proposals for Dependability Assessment

During the last two decades, several dependability domain-specific modeling languages (D-DSML) have been proposed. This chapter surveys 36 proposals of D-DSML in literature. Most of the proposals are based on UML and a good number also accomplish the transformation of the D-DSML into proper dependability analysis models, as those presented in Chap. 6 DAM, presented in Chap. 5, is an example of D-DSML developed as a UML profile.