Barry Boehm University of Southern California Richard Turner OUSD(AT&L)/DS/SE (George Washington University) Balancing Agility and Discipline: Evaluating and Integrating Agile and Plan. Driven Methods Based on Balancing Agility and Discipline: A Guide for the Perplexed, B. Boehm and R. Turner, Addison Wesley, 2004
Outline • Tutorial learning objectives – Survey of assumptions about participants • General software trends and implications – Sources of perplexity about agile, plan-driven methods • Overview of agile and plan-driven methods – XP, TSP “days in the life” – Comparisons of differences, strengths, weaknesses • Risk-based balance of agility and discipline – Small, medium, large examples • Observations and Way Forward – Hands-on exercise • Conclusions; review of learning objectives 4/19/04 2
Tutorial Learning Objectives • Practitioners and managers – Understand agile, plan-driven method strengths, difficulties – Learn risk-based approach to tailor hybrid methods – Practice in formulating organizational strategy • Researchers – Understand research issues, opportunities • Techniques for achieving rapid quality • Empirical analyses • Educators – Understand differences in agile, plan-driven approaches – Understand teaching challenges, opportunities • Survey courses, project courses 4/19/04 3
Assumptions About Participants - Surveyed at Tutorial • Generally familiar with plan-driven methods – Waterfall, incremental, spiral, RUP, PSP/TSP – Software CMM, CMMI, SPICE, ISO I 2207 • Less familiar with agile methods – XP, Scrum, Crystal, DSDM, FDD • Representative of mixed domains – Large/small projects, research, education – Variety of software applications domains • Increasing need for high software dependability • Increasing software complexity, speed of change 4/19/04 4
Information Technology Trends Traditional Development Current/Future Trends • Standalone systems • Everything connected (maybe) • Stable requirements • Rapid requirements change • Rqts. determine capabilities • Control over evolution • COTS capabilities determine rqts. • No control over COTS evolution • Enough time to keep stable • Ever-decreasing cycle times • Stable jobs • Outsourced jobs • Failures noncritical • Failures critical • Reductionist systems • Complex, adaptive, emergent • Repeatability-oriented process, systems of systems maturity models • Adaptive process models 4/19/04 5
Background • Two approaches to software development – Disciplined (SW-CMM, document-based, heavy process) – Agile (XP, tacit knowledge, light process) • Both have strengths and weaknesses • Agile and disciplined proponents are believers • Many of us are perplexed 4/19/04 6
Key Definitions • Agile method – – one which fully adopts the four value propositions and twelve principles in the Agile Manifesto. • Discipline – (per Webster) – control gained by enforcing obedience or order; – orderly or prescribed conduct or pattern of behavior; – self-control. • Plan-driven – – a description for disciplined methods (order is often defined in plans) • Plan – (per Webster) – a method for achieving an end (a process plan); – an orderly arrangement of parts of an overall design (a product plan). – We assume that such plans are documented. 4/19/04 7
The Agile Manifesto We are uncovering better ways of developing software by doing it and helping others do it. Through this work we have come to value: • • Individuals and interactions over processes and tools Working software over comprehensive documentation Customer collaboration over contract negotiation Responding to change over following a plan That is, while there is value in the items on the right, we value the items on the left more. 4/19/04 8
Plan-Driven Methods Are Evolving Too • Evolutionary acquisition and spiral development – U. S. Do. D Directive 5000. 1, Instruction 5000. 2 • Risk-driven level of detail – Of processes: peer reviews vs. Critical Design Reviews – Of products: GUI prototypes vs. specifications – Of heavyweight methods: Team Software Process, Rational Unified Process 4/19/04 9
Sources of Perplexity • Distinguishing method use from method misuse • Citing method misuse vs. intended use – Claiming XP use when simply “not documenting” – “CMM Level 4 Memorial Library” of 99 2 -inch binders • Overgeneralization based on the most visible instances – XP is Agile; CMM is Plan-Driven • Multiple definitions – Quality: customer satisfaction or compliance? • Claims of universality – The pace of IT change is accelerating and Agile methods adapt to change better than disciplined methods therefore Agile methods will take over the IT world. – Software development is uncertain and the SW-CMM improves predictability therefore all software developers should use the SW-CMM 4/19/04 10
Sources of Perplexity (2) • Early success stories – Chrysler project that successfully birthed XP was later cancelled – Cleanroom has never made it into the mainstream • Purist interpretations (and internal disagreements) – “Don't start by incrementally adopting parts of XP. Its pieces fit together like a fine Swiss watch“ – "An advantage of agile methods is that you can apply them selectively and generatively. " – "If you aren't 100% compliant with SW CMM Level 3, don't bother to bid" – "With the CMMI continuous interpretation, you can improve your processes in any order you feel is best. " 4/19/04 11
Outline • Tutorial learning objectives – Survey of assumptions about participants • General software trends and implications – Sources of perplexity about agile, plan-driven methods • Overview of agile and plan-driven methods – XP, TSP “days in the life” – Comparisons of differences, strengths, weaknesses • Risk-based balance of agility and discipline – Small, medium, large examples • Observations and Way Forward – Hands-on exercise • Conclusions; review of learning objectives 4/19/04 12
Various Agile Methods Available • • * • • • Adaptive Software Development (ASD) Agile Modeling Crystal methods Dynamic System Development Methodology (DSDM) e. Xtreme Programming (XP) Feature Driven Development Lean Development Scrum 4/19/04 13
XP Principles – I • Philosophy: Take known good practices and push them to extremes • “If code reviews are good, we’ll review code all the time” • “If testing is good, we’ll test all the time” • “If design is good, we’ll make it part of everybody’s daily business” 4/19/04 14
XP Principles – II • “If simplicity is good, we’ll always leave the system with the simplest design that supports its current functionality” • “If architecture is important, everybody will work defining and refining the architecture all the time” • “If integration testing is important, then we’ll integrate and test several times a day” 4/19/04 15
XP Principles – III • “If short iterations are good, we’ll make the iterations really, really short – seconds and minutes and hours, not weeks and months and years” • “If customer involvement is good, we’ll make them full-time participants” 4/19/04 16
XP: The 12 Practices -Kent Beck, Extreme Programming Explained, Addison Wesley, 1999 • • • The Planning Game Small Releases Metaphor Simple Design Testing Refactoring • • • Pair Programming Collective Ownership Continuous Integration 40 -hour Week On-site Customer Coding Standards -Used generatively, not imperatively 4/19/04 17
XP Characteristics 4/19/04 18
The Team Software Process (TSP) -Watts Humphrey, Introduction to the ISP, Addison Wesley, 2000 • Scale-up of Personal Software Process (PSP) – To about 20 -person teams • Strong emphasis on planning and control – 21 scripts, 5 roles/activities, 21 forms • Risk-driven tailoring can make process more agile 4/19/04 19
Example TSP Role Script 4/19/04 20
TSP Characteristics 4/19/04 21
Days In The Life: XP and TSP • Comparison of two development teams • Product: – Tool to process complex sales report generated by legacy system – Prototype delivered – Task is to enhance and port prototype – 8 month projected schedule – Estimated size: 20, 000 SLOC 4/19/04 22
Background Information TSP/PSP • Training XP • Training • Tools and environment • Project planning – Each member has 125 -hour PSP for Engineers – 2 Members 5 -day launch coach training – Web-based TSP data collection tool – OO tools – Individual offices and conference room – 4 -day launch session – Develop/tailored all processes – 180 tasks identified and plan accepted by stakeholders 4/19/04 – 2 members attended 40 -hour XP workshop – In-house presentations and mentoring – Automated test suite development tool – OO tools – Bullpen and Conference room/lounge – 1 -day customer exploration – 2 -day follow-up to prioritize – Agreed on 2 -week iteration length, 3 -iteration release length, and release schedule 23
Normal and Crisis Days • Used Friday as common day • Crisis days are plan-breakers – New requirements – Short schedule • Please read the handouts and we’ll discuss 4/19/04 24
Comparison • Differences – – Depth and scope of metrics Specificity of process Level and scope of reporting Customer interface – – – Collaborative teams Well-defined roles Spiral, risk- and increment-driven process Measurement Test first (test-driven) approach • Similarities • Bottom Line – Both were able to confidently push-back when necessary 4/19/04 25
Outline • Tutorial learning objectives – Survey of assumptions about participants • General software trends and implications – Sources of perplexity about agile, plan-driven methods • Overview of agile and plan-driven methods – XP, TSP “days in the life” – Comparisons of differences, strengths, weaknesses • Risk-based balance of agility and discipline – Small, medium, large examples • Observations and Way Forward – Hands-on exercise • Conclusions; review of learning objectives 4/19/04 26
Finding Middle Ground • • • A pragmatic view Both approaches have “home grounds” A broad range of environments and needs Trends require better handling of rapid change Processes should be the right weight for the job We believe risk-based analysis is the key to finding middle ground 4/19/04 27
Contrasts and Home Grounds • Comparison is difficult, but we found 4 areas where there are clear differences • Application – Project goals, size, environment; velocity • Management – Customer relations, planning and control, communications • Technical – How the software is developed • Personnel – The type and competency of developers and stakeholders 4/19/04 28
Application Characteristics • Primary goals – A: Rapid value, responsiveness to change – P: Predictability, stability, high assurance • Size – A: Small to medium – P: Large • Environment – A: Turbulent, high change – P: Stable, requirements defined • Project velocity – A: Code, learn, and fix – P: Architect for parallel, incremental development 4/19/04 29
Management Characteristics • Customer Relations – – A: Dedicated, collocated; where feasible P: Contractual; increasingly evolutionary A: Trust through working software and participation P: Trust through process maturity evaluations • Planning and Control – A: Means to an end – P: Anchor processes, communication • Project Communications – A: Tacit, interpersonal knowledge – P: Explicit, documented knowledge 4/19/04 30
Technical Characteristics • Requirements – A: Adjustable, informal stories – P: Formally baselined, complete, consistent specifications • Development – A: Simple Design – P: Architecture-based design • Testing – A: Automated, test-driven – P: Planned, requirements-driven 4/19/04 31
Technical Characteristics (2) Cost of Change: Beck, Li Beck Li 4/19/04 Li 32
Technical Characteristics (3) Cost of change: Poppendieck • At least two cost-escalation curves • Lean development: Architect to defer highstakes decisions – e. g. COTS • Easier to change an unmade decision Cost of Changes in High-stakes Constraints Most Changes 4/19/04 Time 33
Technical Characteristics (4) Cost of Change: TRW Beck Li 4/19/04 34
Technical Characteristics (5) How Much Architecting? Beck 10, 000 KSLOC Sweet spot 100 KSLOC Liu 10 KSLOC 4/19/04 35
Personnel Characteristics • Customers – A: CRACK customers throughout development – P: CRACK customers early • CRACK: Collaborative, Representative, Authorized, Committed, and Knowledgeable • Developers – A: Heavy mix of high caliber throughout – P: Heavy mix early with lower capability later • Culture – A: Many degrees of freedom (Thrives on chaos) – P: Clear policies and procedures (Thrives on order) • Collocated customers are difficult to find/keep current on either side 4/19/04 36
Personnel Characteristics (2) Modified Cockburn Levels Level Characteristics 3 Able to revise a method (break its rules) to fit an unprecedented new situation 2 Able to tailor a method to fit a precedented new situation 1 A With training, able to perform discretionary method steps (e. g. , sizing stories to fit increments, composing patterns, compound refactoring, complex COTS integration). With experience can become Level 2. 1 B With training, able to perform procedural method steps (e. g. coding a simple method, simple refactoring, following coding standards and CM procedures, running tests). With experience can master some Level 1 A skills. -1 May have technical skills, but unable or unwilling to collaborate or follow shared methods. 4/19/04 37
Summary of Home Grounds Characteristics Agile Plan-driven Primary Goals Rapid value; responding to change Predictability, stability, high assurance Size Smaller teams and projects Larger teams and projects Environment Turbulent; high change; project-focused Stable; low-change; project/organization focused Customer Relations Dedicated on-site customers, where feasible; focused on prioritized increments As-needed customer interactions; focused on contract provisions; increasingly evolutionary Planning/Control Internalized plans; qualitative control Documented plans, quantitative control Communications Tacit interpersonal knowledge Explicit documented knowledge Requirements Prioritized informal stories and test cases; undergoing unforseeable change Formalized project, capability, interface, quality, forseeable evolution requirements Development Simple design; short increments; refactoring assumed inexpensive Architect for parallel development; longer increments; refactoring assumed expensive Test Executable test cases define requirements Documented test plans and procedures Customers Dedicated, collocated CRACK* performers, not always collocated Developers At least 30% full-time Cockburn level 2 and 3 experts; no Level 1 B or -1 personnel** 50% Cockburn Level 3 s early; 10% throughout; 30% Level 1 B’s workable; no Level -1 s** Culture Comfort and empowerment via many degrees of freedom (thriving on chaos) Comfort and empowerment via framework of policies and procedures (thriving on order) Application Management Technical Personnel 4/19/04 * Collaborative, Representative, Authorized, Committed, Knowledgeable ** These numbers will particularly vary with the complexity of the application 38
Two Case Studies • Show that agile and plan-driven methods can be extended • Provide examples of success and lessons learned • Thought. Works Lease Management – Agile extended with plan-driven • CCPDS-R – Plan-driven overlaid with agile concepts 4/19/04 39
Thoughtworks Lease Management • XP replaced ineffective traditional development • Problems when project moved beyond XP assumptions – The effort to develop or modify a story really does not increase with time and story number – Trusting people to get everything done on time is compatible with fixed schedules and diseconomies of scale – Simple design and YAGNI scale up easily to large projects – • Disciplined practices enabled XP to scale up – High-level architectural plans to provide essential big-picture information – More careful definition of milestone completion criteria to avoid “finishing” but not finishing – Use of design patterns and architectural solutions rather than simple design to handle foreseeable change 4/19/04 40
CCPDS-R • USAF Command Center Processing and Display System Replacement for early missile warning • Government contract environment required plandriven approach, project needed agility • Practices implemented to provide agility mapped well to the Agile Manifesto – Individuals and Interactions over Processes and Tools • Milestone content was redefined • Architecture was organized around the performers’ skill levels – Working Software over Comprehensive Documentation • Later PDR demonstrated working software for high-risk areas – Customer Collaboration Over Contract Negotiation • Used COCOMO for cost and schedule negotiations – Responding to Change Over Following a Plan • Automated plans • Architecture for re-use saved effort 4/19/04 41
CCPDS-R (2) Cost of Change Beck 4/19/04 42
Five Critical Decision Factors • Size, Criticality, Dynamism, Personnel, Culture 4/19/04 43
Comparing the Case Study Projects 4/19/04 44
Misconceptions 4/19/04 45
Outline • Tutorial learning objectives – Survey of assumptions about participants • General software trends and implications – Sources of perplexity about agile, plan-driven methods • Overview of agile and plan-driven methods – XP, TSP “days in the life” – Comparisons of differences, strengths, weaknesses • Risk-based balance of agility and discipline – Small, medium, large examples • Observations and Way Forward – Hands-on exercise • Conclusions; review of learning objectives 4/19/04 46
Using Risk to Balance Discipline and Agility - Overview 4/19/04 47
Risks Used in Risk Comparison • Environmental risks – – Technology uncertainties Many stakeholders Complex system-of-systems Legacy compatibility – – – Scalability Use of simple design Personnel turnover Too-frequent releases Not enough agile-capable people – – Rapid change Need for rapid results Emergent requirements Not enough discipline-capable people • Agility risks • Plan-driven risks 4/19/04 48
Three Examples • Agent-based systems • Small – Event Managers application • Medium – Supply. Chain. com application • Large – National Information System for Crisis Management (NISCM) application • Each example results in a development strategy based on risk analyses 4/19/04 49
Event Managers Project • Small startup company • Diverse set of smaller agent-based planning applications • This project: support for managing the infrastructure and operations of conferences and conventions • Widening variety of options and interdependencies, makes an agent-based approach highly attractive 4/19/04 50
Event Managers Profile 4/19/04 51
Event Managers Strategy LCA 4/19/04 52
Supply. Chain. com Profile • Turnkey agent-based supply chain management systems • Distributed, multi-organization teams of about 50 people • Parts of applications are relatively stable, while others are highly volatile • Architectures are driven by a few key COTS packages that are also continually evolving 4/19/04 53
Supply. Chain. com Profile 4/19/04 54
Supply. Chain. com Strategy 4/19/04 LCO LCA 55
NISCM Profile • Broad coalition of government agencies and critical private-sector organizations • Support cross-agency and public-private sector coordination of crisis management activities • Adaptive mobile network, virtual collaboration, information assurance, and information integration technology • Private-sector system-of-systems integration contractor 4/19/04 56
NISCM Profile 4/19/04 57
NISCM Strategy 58 4/19/04 LCO LCA
Risk Profiles Across Examples 4/19/04 59
Outline • Tutorial learning objectives – Survey of assumptions about participants • General software trends and implications – Sources of perplexity about agile, plan-driven methods • Overview of agile and plan-driven methods – XP, TSP “days in the life” – Comparisons of differences, strengths, weaknesses • Risk-based balance of agility and discipline – Small, medium, large examples • Observations and Way Forward – Hands-on exercise • Conclusions; review of learning objectives 4/19/04 60
Summary of Observations • No silver bullet • Clear agile and plandriven home grounds • Increased demands for agility, velocity, quality • Balanced methods are emerging 4/19/04 • Build methods up vs. tailor down • Methods are important; people more so – Values – Communications – Expectations management 61
No Silver Bullet • Brooks’ werewolf concerns – Complexity, conformity, changeability, invisibility • Agile methods – Handle changeability and invisibility – Miss on complexity and conformity • Plan-driven methods – Handle conformity and invisibility – Miss on changeability and complexity 4/19/04 62
Future Applications Need Both • Historically – Many small, non-critical, well-skilled, agile culture, rapidly evolving projects – Many large, critical, mixedskill, ordered culture, stable projects • In the future – Large projects are no longer stable – Maintenance of extensive process and product plans will become too expensive – Complexity and conformity werewolves are waiting for agile projects – Attributes of both approaches will be needed 4/19/04 63
Balanced Methods are Emerging • Agile methods – – Crystal Orange DSDM FDD Lean Development • Plan-Driven methods – Rational Unified Process – CMMI • Hybrid – Boehm-Turner Risk-based – Code Science/Agile Plus 4/19/04 64
Build up – Don’t Tailor Down • Plan-driven methods traditionally – Define heavyweight process guidelines – Advocate tailoring – Treat mass of processes as security blanket • Agilists traditionally – Begin with the minimum – Add as needed (and justified by cost-benefit) – Start small; extend only where necessary 4/19/04 65
Maybe its not the methods! • Agile movement has echoed a long line of warning calls • Success of agile may be due as much to people factors as to technology • Valuing people over processes is the most important factor in the manifesto 4/19/04 I know I saw something about that in the process somewhere… 66
People • Of the people, by the people, for the people • Separation of concerns is increasingly harmful • A few quotes… – The notion of “user” cannot be precisely defined, and therefore it has no place in computer science or software engineering. Dijkstra – Analysis and allocation of the system requirements is not the responsibility of the software engineering group, but it is a prerequisite for their work. The Capability Maturity Model for Software. – Software engineering is not project management. Tucker 4/19/04 67
Values • Reconciling values is a critical people-oriented task • Stakeholders value different things • Software engineering is usually value-neutral – Every requirement, object, test case, defect equally important • Process improvement and plan-driven methods are inwardly-focused – Aimed at productivity improvement – Not higher value to customer • Agilists attention to prioritization and negotiation are promising 4/19/04 68
Communications • Face it, most engineers can’t talk, much less write • Need to bridge the customerdeveloper communications gap • IKIWISI* reigns • Rapid change increases need for solid communication • Few sources of guidance – Cockburn’s Agile Software Development is a good starting place 4/19/04 *I’ll know It When I See It 69
Expectations Management • Differences between successful and troubled projects is often expectations management • SW developers have problems with EM – Strong desire to please – Little confidence in prediction – Over confidence in abilities • Most significant common factor in highly effective plan-driven or agile teams • EM means not setting up unrealistic expectations Developers seem to like Sisyphean tasks… 4/19/04 – Process mastery – Preparation – Courage 70
Research Challenges and Opportunities • Techniques for achieving rapid quality – – – Risk/value-driven process lightening Agile with lightweight V&V overlay Capitalizing on domain knowledge Reuse, component-based approaches Automating quality enhancement • Empirical analyses – – 4/19/04 Distributed agile methods Hybrid agile/plan-driven methods Effects of individual practices Effects of scale, personnel turnover 71
Size Distribution • 60% of projects in agile home ground 4/19/04 • 60% of effort in plan-driven home ground 72
Development Methods 4/19/04 73
Do Both Assure Success? • TSP and agile methods are indeed silver bullets and always succeed spectacularly well. • People tend to report success more than they do failures. • The pioneer projects are being done by highcapability early adopters of new methods. • The pioneer projects are experiencing some Hawthorne effects of performing extra well while being in the spotlight. • The projects are being compared to particularly poorly performing past projects. • High improvement numbers make options worth exploring 4/19/04 74
Reifer Scorecard for XP 4/19/04 75
Pair Programming Results 4/19/04 • Short studies are suspect; pairs take about 10 hours to jell 76
Educational Approaches • Survey courses – Materials here plus excursions into practice – Try, compare inspections and pair programming – Try, compare refactoring vs. use of design patterns • Project courses – Some practices need tailoring to student constraints – Steep learning curve; precede with survey course 4/19/04 77
Experimental XP-Like Course • Goals: – Create an improved version of Agile COCOMOII – Use XP practices; supplement where needed – Gather software process data • Characteristics: – Part-time, non-collocated student team – Part-time customer – Personnel with moderate platform/applications experience 4/19/04 78
4/19/04 79
XP + situational common sense => Lightweight method • Planning variants – Brainstorming +modified win-win -> e-Story/Task cards – Bi-weekly meetings – Stories prioritized -> iteration requirements • Design variants – – – 4/19/04 Brainstorming: : group input: : team buy-in Architecture determined from shortfalls of previous arch. Top level design : : iteration designs Iteration design : : fulfills iteration requirements Prototype GUI, draft class design: pair-work 80
Electronic Story/Task Cards 4/19/04 81
XP + situational common sense => Lightweight method • Coding variants: – Coding standards: : drafted, team consensus, will evolve as needed – Customer available bi-weekly for feedback/report – Tests are being written before any code, all code is unit & integration tested • Quality guidelines: – Digital archives of artifacts – Simple, short, risk-based documentation 4/19/04 82
Organizational Way Forward • Convene key stakeholders to determine organizational goals and strategies • Rebalance agility and discipline in this organizational context 4/19/04 83
Determining Organizational Goals and Strategies • • • Current software organization’s status and needs Key stakeholders’ needs and trends How to cope with future trends The increased pace of change and need for agility The increased concern with software dependability and need for discipline • Your ability to satisfy your stakeholders’ evolving value propositions and to keep up with your toughest competitors • The increasing gap between supply and demand for Cockburn Levels 2 and 3 people • Your ability to cope with existing and emerging challenges – COTS integration, evolving Internet/Web capabilities, distributed and mobile operations, agent coordination, multimode virtual collaboration, and outsourcing jobs 4/19/04 84
Collins’ Good to Great - Harper. Business, 2001 High Hierarchical Organization Great Organization Culture of Discipline Bureaucratic Organization Start-up Organization Low 4/19/04 Ethic of Entrepreneurship High 85
Rebalancing Agility and Discipline Graph “typical project” on 5 D chart -Now; 5 years ahead In agile or plan-driven home ground In home ground with some anomalies Develop best home ground continuous process improvement strategy Treat anomalies as risks to be managed Highly mixed agile/plan driven profile Develop incremental mixed strategy. Try on pilot project Integrate, execute process, people, technology plans. Monitor and control using Balanced Scorecard. 4/19/04 86
Hands-on Exercise • Graph your organization’s “typical project” on 5 D charts – Now; 5 years from now • Identify major needs for organizational change – With respect to balancing agility and discipline – With respect to future trends, environmental risks • Identify most critical first steps for improvement • Identify pilot project for applying first steps – Application, staffing – Needs for education, teambuilding, culture change • Summarize in bulleted strategic plan 4/19/04 87
Now 4/19/04 88
In 5 Years 4/19/04 89
Conclusions • Plan-driven and agile methods both aim to – Satisfy customers – Meet cost and schedule parameters • Home grounds exist, but the need/opportunity for integration is expanding • We recommend a self-assessment of your organization and business – Locate your place in the home ground space – Identify areas of change and how they might move your location – Look for ways to integrate methods to better respond to change • People concerns dominate method concerns 4/19/04 90
Скачать презентацию Barry Boehm University of Southern California Richard Turner
5c434bc32802a6e5e26084ec77831c2e.ppt