UML and Dependability Analysis

1. UML and Dependability Analysis Original slides prepared by Simona Bernardi Presented by Jeremy Sproston PaCo kick-off meeting, 23/10/08

2. UML and dependability analysis • Two tasks: • Development of a UML profile for dependability analysis • Use of formal models for dependability assessment

3. A UML profile for dependability analysis • Recently completed work: • S.Bernardi, J. Merseguer, D.C. Petriu, Adding Dependability Analysis capabilities to the MARTE profile.MODELS08, October 2008. • S. Bernardi, J. Merseguer, D.C. Petriu, An UML profile for dependability analysis and modeling of software systems, Tech.Rep. no. RR-08-05, DIIS, Universidad de Zaragoza, Spain, May, 2008.

4. Motivation and objectives • The current standard UML profiles (SPT, QoS&FT, MARTE) do not provide concrete capabilities for dependability analysis in a light-weight fashion • Several proposals on deriving dependability models from UML-based models • The main objective is to propose a UML profile for quantitativedependability analysis of sw systems modeled with UML • With focus on availability, reliability and safety properties

5. Profile requirements • Reuse best-practices reported in the literature • Unify the terminology and concepts for different dependability aspects under a common dependability domain model • MARTE compliance

6. Assessment of the DAM conceptual model Reqs checklist Complete? no yes no Definition of the DAM profile DAM profile assessment with the checklist DAM extensions (stereotypes, tags) yes All reqs satisfied? DAM library Methodological approach overview • Literature review: • UML profiles • Dependability literature • Survey on UML dep.analysis Definition of DAM conceptual model

7. Mapping approach • The mapping process from the conceptual model elements to the DAM profile has been an iterative one • Approach • General guidelines from Selic to extend UML metamodel • Patterns from Lagarde et al. that enable a consistent mapping • Best practice of MARTE to trace the mapping • Specialization of MARTE-GQAM stereotypes to reuse already defined concepts

8. Mapping of conceptual classes • Conceptual classes are good candidates to become stereotypes, but eventually only a subset of them have been mapped to a stereotype • Objective: provide a “small” set of stereotypes • Abstract classes: not considered • Threat/Maintenance concepts: complex dependability types of the DAM Library • E/F/H Step classes become enumeration type values (“subsuming taxonomic concept” pattern)

9. Current activity/open issues • MODELS08 paper: proposed an “open” profile to support the dependability quantitative analysis of UML design • MARTE compliant • Considers the current standards in dependability • Current activity • DAM profile assessment • Application of the DAM profile to examples from literature and to case studies • Both quantitative and qualitative assessment of dependability

10. Current activity/open issues • Open issues • New requirements regarding other dependability attributes (i.e., integrity, confidentiality, maintainability) • Relationship between dependability and performance NFP (possible collaboration with UNIAQ) • Fault tolerance domain: specification of QoS metrics as functions of dependability NFP and performance NFP

11. Use of formal models for dependability assessment (I) • Current activity • Literature review on deriving dependability models from UML system specifications • Future work • Definition of criteria for the selection of a set of formalisms for dependability • Qualitative assessment (e.g., HAZOP,FFA) • Quantitative assessment (e.g., Stochastic Petri Nets, Fault Trees, CSL, Performance Trees)

12. Use of formal models for dependability assessment (II) • Dependability model derivation techniques from UML-DAM annotated models • Customization of techniques in the literature • Definition of new transformation techniques • Definition of a methodology for the synergetic use of the aforementioned techniques within the sw development process.