UML and Dependability Analysis

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UML and Dependability Analysis

• Original slides prepared by Simona Bernardi
• Presented by Jeremy Sproston
• PaCo kick-off meeting, 23/10/08

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UML and dependability analysis

• Two tasks
• Development of a UML profile for dependability
  analysis
• Use of formal models for dependability assessment

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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.

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Motivation and objectives

• The current standard UML profiles (SPT, QoSFT,
  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 quantitative dependability analysis of sw
  systems modeled with UML
• With focus on availability, reliability and
  safety properties

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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

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Methodological approach overview

• Literature review
• UML profiles
• Dependability literature
• Survey on UML dep.analysis

Definition of DAM conceptual model
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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

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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)

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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

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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

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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)

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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.