Independent Verification and Validation (IV&V) Techniques for Object Oriented Software Systems

Executive Level Briefing SAS meeting July 2004

Outline Problem Approach Importance/benefits Relevance to NASA Accomplishments Next steps

COMPANY PROPRIETARY

2 APC0342

Problem Statement

NASA has considerable experience applying IV&V to traditional function-based software systems Emerging use of OO brings unique challenges and risks There is a need to develop IV&V techniques for addressing these risks COMPANY PROPRIETARY

3 APC0342

Approach

Risks identified

– Management, technical, process

Developed base set of IV&V Techniques

– Use cases, class diagrams, state transition diagrams

Applied & evaluated techniques on the use cases based on a NASA example

– Data for BBN, A set of use cases processed using the proposed approach Scope Boundary Domain / Context Clarity # Interactions Regular Activity Exception Activity Edge Guard Condition Activity Completeness Complexity Understandabilit y UCP Metric Complete Design Notation Pre Condition Post Condition P&PC Formalism_ Consistence Use Case Modeling Rules Actor Identification User Agrees Consistence Use Case Names Scenario Walkthrough Node Coverage Correct Edge Coverage Expected result/ OP matches RAM System constraints CPU cycles SWFootprint

COMPANY PROPRIETARY

4 APC0342

Importance / Benefits

Improved analysis of UML artifacts

– Framework for use cases, classes, state transition diagrams • Method for prioritization of UML artifacts • Analysis techniques for the artifacts (consistency, completeness, traceability)

Better maturity estimate during SSR, PDR, CDR

– At present maturity estimate is based on “expert opinion” – BBN will allow for the use statistical methods to measure the completeness level of inputs to the milestone reviews

COMPANY PROPRIETARY

5 APC0342

Relevance to NASA

More NASA systems are using object oriented approach

– JWST, HDS, ….

NASA IV&V needs better techniques to support milestone reviews

– Use of BBN – Improved process model

COMPANY PROPRIETARY

6 APC0342

Accomplishments

Techniques for OO models

– – – – – Evaluated current & emerging OO IV&V techniques Identified Risks with OO development Investigated framework for OO IV&V Developing base set of IV&V techniques for Use cases, Class diagrams, State diagrams ISSRE 2003 “IV&V of OO software systems”

BBN based maturity estimate during SSR

– ISSRE 2004 “A Probabilistic Framework to Support Independent Assessment of Use-Case Based Requirements Specifications”

NASA project example analysis COMPANY PROPRIETARY

7 APC0342

Next Steps

Process model

– Developing Use case IV&V process model • Use case IV&V workflow • Need to refine further the IV&V steps for use case analysis

Improved BBN models

– Basic BBN model is ready and submitted to a conference

Extend the IV&V models to other phases

– – Near term-process model for the analysis of class diagram, state transition diagrams Longer term- BBN models for the class diagram, state transition diagrams

COMPANY PROPRIETARY

8 APC0342