MODELING SOFTWARE PROCESSES WITH SYSTEM DYNAMICS: CURRENT DEVELOPMENTS

Raymond J. Madachy

USC Center for Software Engineering

Litton Data Systems

1996 International System Dynamics Conference

July 22-25, 1996

Outline

• Introduction and brief history
• Process improvement initiatives
• Software process applications and current work
• Research issues and future work
• References

Software Development and Systems Thinking

• Competitive advantage is increasingly dependent on software development in many industrial sectors.
• Software development, a dynamic and complex process, requires systems thinking in order to improve in current environment.
  • Software process: a set of activities, methods, practices and transformations used by people to develop software.
• Models can be used to quantitatively evaluate the software process
  • can experiment with changed processes before committing project resources
  • interactive training for software managers; "process flight simulation"
  • implement process re-engineering and benchmark process improvement

Brief History

Software Process Initiatives

Comparison of Modeling Paradigms

• Software engineers already employ a host of models
  • predictive static cost models
    • these are being extended with dynamic modeling
  • discrete event approaches for low-level process descriptions
    • generally lack feedback
    • comparison study underway

Discipline Comparison

• Software engineers are particularly well-suited for the system dynamics modeling process
  • systems view and programming experience
  • comfortable with levels of abstraction
  • similar heuristics and incremental development process used
• Model validation involves problems unique to system dynamics simulation

Software Process Level Instances

• Work artifacts (requirements, tasks, lines of code, function points, documentation pages, others)
• Defect levels
• Personnel levels
• Effort expenditure
• Schedule date
• Others

Basic Flow Processes and Infrastructures

• Software product transformations
• Error co-flows
• Error detection and rework
• Personnel experience pools and effort expenditures
• Cost/quality tradeoffs enabled

Model Validation

• Controversial issue in the software community
• Multi-perspective validation with quantitative and qualitative criteria needs to be "sold" and accepted
• Often confusion between point prediction and "understanding"
• Aided by improvements in metrics collection

Model Implementations

• Industry/government: AT&T, Bellcore, Draper Labs, Litton, Mitre, NASA, Siemens, others
• Academic: ASU, Imperial College, Stanford, MIT, Naval Postgraduate School, USC, others
• Tool vendors/workshops: Bartz Associates, Dynamica, Rubin Systems
• Many other companies are evaluating system dynamics for process improvement
• Several academic research projects in proposal stage

Process Evaluation

• Investigating the dynamic effects of inspections [Madachy 94], [Tvedt 95]
• Incremental development [Tvedt 95]
• Unit testing phase [Collafello et al. 96]
• Requirements phase (several)
• Investigating software reuse from a macro-inventory perspective [Abdel-Hamid 93a]
• Process model tradeoffs

Process Evaluation (continued)

• Other process improvement investments
  • staffing policies
  • work environment investments
  • computer aided tool investments
  • staff training investments
  • metrics, reuse, risk management and others
• Global software process feedback, stability and product evolution [Lehman et al. 96]

Flight Simulators

• Personnel training
  • graduate software project management (ASU)
  • vendor tools (Rubin et al.)
• Navigating new skies
  • process maturity initiatives
• Stimulate dialogues for shared mental models
• Virtual reality for court cases

Other Applications

• Integration with cost estimation models
  • improving on static assumptions [Madachy 95], [Rubin et al. 95]
  • calibrations between [Madachy 95]
  • deriving static parameters with dynamic experiments [Madachy 95]
• Knowledge-based assistance
  • heuristic project risk analysis and input checking [Madachy 94]
  • input evaluation and change recommendation [Lin et al. 92]
  • QA expert simulator
• Examining heuristics
  • Brookes' Law (several)
  • cost estimation correction processes [Abdel-Hamid 93]
  • others

Sample Insights

Inspection policy tradeoff analysis - diminishing returns from inspections as a function of error generation rates [Madachy 94]

• QA policy tradeoff analysis - finding the optimal QA effort [Abdel-Hamid/Madnick 91]
• Rework staffing allocation [Tvedt 95]
• Organizational process improvement transition requires temporary productivity setbacks [Rubin, Johnson, Yourdon 95]

Sample Insights (continued)

• Leverage of experienced staff (several)
• Internal workings of Brookes' Law - training and communication losses [Abdel-Hamid 93]
• Schedule compression not a static decision [Abdel-Hamid 90]
• Anchor-dragging in project control [Abdel-Hamid 93]
• Competing feedback loops in software reuse factory [Abdel-Hamid 93b]
• Many others

Directions for Future Work

• Model structures
• Common models and component reusability
• Usability
• Process model selection
• Knowledge-based techniques
• Object orientation
• Related simulation research
• Industrial data analysis

References

• BOOKS
  • Abdel-Hamid T, Madnick S, Software Project Dynamics, Englewood Cliffs, NJ, Prentice-Hall, 1991
  • Madachy R, Software Process Modeling with System Dynamics, IEEE Computer Society Press, Washington, D.C., 1997 (current plan)
• JOURNAL ARTICLES, CONFERENCE PROCEEDINGS AND OTHERS

Abdel-Hamid T, The dynamics of software project staffing: A system dynamics based simulation approach, IEEE Transactions on Software Engineering, February 1989

• Abdel-Hamid T, Lessons learned from modeling the dynamics of software development, Communications of the ACM, December 1989
• Abdel-Hamid T, Investigating the cost/schedule trade-off in software development, IEEE Software, January 1990
• Abdel-Hamid T, Adapting, correcting, and perfecting software estimates: a maintenance metaphor, IEEE Computer, March 1993
• Abdel-Hamid T, Thinking in circles, American Programmer, May 1993

References (continued)

• JOURNAL ARTICLES, CONFERENCE PROCEEDINGS AND OTHERS (continued)

Abdel-Hamid T, Modeling the dynamics of software reuse: an integrating system dynamics perspective, Presented at the Sixth Annual Workshop on Software Reuse, Owego, NY, November 1993

Aranda R, Fiddaman T, Oliva R, Quality microworlds: Modeling the impact of quality initiatives over the software product life cycle, American Programmer, May 1993

Chichakly K, The bifocal vantage point: Managing software projects from a systems thinking perspective, American Programmer, May 1993

Collofello J, Yang Z, Tvedt J, Merrill D, Rus I, Modeling Software Testing Processes, Submitted to the International Phoenix Conference on Computers and Communications, 1996

Cooper K, Mullen T, Swords and plowshares: The rework cycles of defense and commercial software development projects, American Programmer, May 1993

• Diehl E, The analytical lens: Strategy-support software to enhance executive dialog and debate, American Programmer, May 1993

References (continued)

• JOURNAL ARTICLES, CONFERENCE PROCEEDINGS AND OTHERS (continued)

Glickman S, The Bellcore-CSELT collaborative project, Proceedings of the Ninth International Forum on COCOMO and Software Cost Modeling, USC, Los Angeles, CA, 1994

• Johnson M: Dynamic Systems Modeling: The Software Management Process, Bartz Associates, 1995
• Lehman M,, Process Improvement - The way forward, Proceedings of CAiSE 95, Jyvaskyla, June 1995
• Lin C, Levary R: Computer-aided software development process design, IEEE Transactions on Software Engineering, September 1989

Lin C, Abdel-Hamid T, Sherif J: Software-engineering process simulation model. TDA Progress Report 42-108, Jet Propulsion Laboratories, February 1992

• Lin C, Walking on battlefields: Tools for strategic software management, American Programmer, May 1993

Madachy R, A software project dynamics model for process cost, schedule and risk assessment, Ph.D. dissertation, Department of Industrial and Systems Engineering, USC, December 1994

References (continued)

• JOURNAL ARTICLES, CONFERENCE PROCEEDINGS AND OTHERS (continued)

Madachy R, Knowledge-based risk assessment and cost estimation, Automated Software Engineering, Kluwer Academic Publishers, September 1995

Madachy R, Process improvement analysis of a corporate inspection program, Proceedings of the Seventh Software Engineering Process Group Conference, May 1995

Madachy R, System Dynamics and COCOMO; Complementary Modeling Paradigms, Proceedings of the Tenth International Forum on COCOMO and Software Cost Modeling, SEI, Pittsburgh, PA, 1995

Madachy R, System Dynamics Modeling of an Inspection-Based Process, Proceedings of the Eighteenth International Conference on Software Engineering, IEEE Computer Society Press, Berlin, Germany, March 1996

Rubin H, Johnson M, Yourdon E, Software process flight simulation: dynamic modeling tools and metrics, Information Systems Management, Summer 1995

References (continued)

• JOURNAL ARTICLES, CONFERENCE PROCEEDINGS AND OTHERS (continued)

Smith B, Nguyen N, Vidale R, Death of a software manager: How to avoid career suicide through dynamic process modeling, American Programmer, May 1993

Tvedt J, Collofello J, Evaluating the effectiveness of process improvements on software development cycle time via system dynamics modeling, Proceedings of the Computer Software and Applications Conference, 1995

• WORLD WIDE WEB
  • My system dynamics site, including updates on forthcoming book:

http:07/22/96/www-rcf.usc.edu/~madachy/sd

• rizona State University Process Modeling Group :

http:07/22/96/www.eas.asu.edu/~sdm/