eXtreme Programming ?????????? ?????? ??????? ?????

1
eXtreme Programming?????????? ?????? ???????
?????

• ?"? ????? ???
• ?????? ?????? ?????????? ???????, ???????
• oritha_at_techunix.technion.ac.il

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eXtreme Programming ?????????? ?????? ????????
?????

• What is eXtreme Programming
• Why eXtreme Programming?
• Social analysis
• Cognitive analysis

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eXtreme Programming ?????????? ?????? ????????
?????

• ??-??? ???????? ?? ???? ?????? ?????
• ??? ?????? ???????? ????????? ??????? ??????

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Problems in software development

• Google "problems with software development
• Requirements are complex
• Clients usually do not know all the requirements
  in advance
• Requirements may be changing
• Frequent changes are difficult to manage
• Process bureaucracy (documents over development)
• It takes longer
• The result is not right the first time
• It costs more
• Applying the wrong process for the product

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????? ???????? ?? ???????? ?????

• ????????? ??????? ?????? ????? ????? ?????
  ?????? (??? ?????????)
• ??????, ??"? ???? ???-????? ??, ?????, ???? ??
  ???????, ?????? ??? ???? ????, ??-????? ????,
  ?????????, ...

6
??????? ????? ??????

• 75 ?????? ?????? ??????? ??????? ??????? ??????
  ??????? ?? ????? ?????? ??? ?? ????? ???????
  ??????? ???????.
• Based on Mullet, D. (July, 1999). The
  Software Crisis, Benchmarks Online - a monthly
• publication of Academic Computing Services
  2(7).
• ???? ?????? ?? ????? ?????? ????"? ????? ??? ???
  ?- 59.5 ??????
• The National Institute of Standards and
  Technology (NIST), New Release of June 28, 2002.
• ??? ?????? ?- Q2 ?? 2003 ?????? ????"? ??????
  200 ??????

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What is eXtreme Programming

• ?? ??? ?????? ?? XP?
• (?? Windows XP)

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What is eXtreme Programming

• eXtreme Programming ???? ???????.
• Differences from traditional methodologies
• Emphasis on people vs. development activities
  schedule
• XP specifies how to behave still leaves freedom
• 12 practices
• 4 values feedback, simplicity, communication,
  courage
• The meaning of eXtreme
• Optimum teams up to 12 developers can be
  adjusted to bigger teams.

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Why XP?

• Survey
• 31 XP/Agile-methods early adopter projects
• 14 firms
• Findings
• Cost reduction 5-7 on average
• Time to market compression 25-50 reduction
• This datum will be explained later

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Why XP?

• big companies using XP in at least some capacity
• Ford Motor, Chrysler, IBM, HP
• smaller software houses
• Mayford Technologies
• RoleModel Software
• tutorials Industrial Logic, Object Mentor

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Project Timetable 1 release - 3 iterations (2
months - 9 weeks)
Business Day
Business Day
Week 4, Release 1, Iteration 2 Week 3, Release 1, Iteration 1 Week 2, Release 1, Iteration 1 Week 1, Release 1, Iteration 1
Week 8, Release 1, Iteration 3 Week 7, Release 1, Iteration 3 Week 6, Release 1, Iteration 2 Week 5, Release 1, Iteration 2
Release 2 starts Week 9, Release 1, Iteration 3
Business Day
Business Day
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How eXtreme Programming?

• Two days in
• eXtreme Programming Development Environment

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Business Day

• On-site customer
• Planning game
• Small releases
• Simple design
• Metaphor

Source http//www.rolemodelsoftware.com/
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Business Day Reflection

• 5 practices (out of 12)
• Planning game
• On-site customer
• Small releases
• Simple design
• Metaphor

• Planning game
• All developers participate
• All have the same load
• All developers get an overview of the entire
  development process
• Simple means
• Very detailed
• Levels of abstraction

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Business Day Reflection

• 5 practices (out of 12)
• Planning game
• On-site customer
• Small releases
• Simple design
• Metaphor

• On-site customer
• Customers on-going feedback
• Small releases
• On-going opportunity to update/change
  requirements

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Business Day Reflection

• 5 practices (out of 12)
• Planning game
• On-site customer
• Small releases
• Simple design
• Metaphor

• Simple design
• Develop only what is needed for your development
  task
• Metaphor
• Bridges customers-developers-business gaps

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Development Day
Source http//www.rolemodelsoftware.com/

• Stand-up meeting
• The development environment
• Pair programming
• Test driven development (acceptance, unit-test)
• Code standards
• Refactoring
• Simple design
• Continuous integration (one integration machine)
• Collective ownership
• Sustainable pace (40-hour week)

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Development Day - Reflection

• The development environment
• All see all fosters communication
• Stand-up meeting
• All know what all do
• Pair programming
• Each task is thought on two levels of abstraction
  
• Unit test (automatic test first)
• First improves understanding Automatic testing
  is easy
• Developers program and test
• Testing becomes manageable
• Success vs. failure

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Development Day - Reflection

• Continuous integration
• Reduces integration risks in later stages
• Collective ownership
• Important in companies with high turnover
• Coding standards
• Refactoring and simple design
• Code improvement is part of the methodology
  (though it doesn't produce code), gradual process
  
• Sustainable pace (40-hour week)
• Intense and productive work, developers are not
  tired

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Development and Business Days Reflection
Human/Social Perspective Code/Technical Perspective
Collective ownership Pair programming Sustainable pace On-site customer Planning game Metaphor Refactoring Simple design Coding standards Testing Continuous integration Small releases
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The 12 XP practices
Note nothing is new gathering the practices
together is XP uniqueness
Source Beck, K. (2000). eXtreme Programming
explained, Addison Wesley.
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What is eXtreme Programming

• Differences from traditional methodologies
• All developers are involved with
  requirements-design-code-testing
• Emphasis on people vs. development activities
  schedule
• XP specifies how to behave still leaves freedom
  and place for creativity
• The meaning of eXtreme
• 12 practices
• 4 values feedback, simplicity, communication,
  courage

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What is eXtreme Programming

• Agile Software Development Methodology
• Other agile methods SCRUM, Feature Driven
  Development, DSDM
• All acknowledge that the main issue of software
  development is people customers, communication
• Manifesto for Agile Software Development
  http//agilemanifesto.org/
• eXtreme Programming Kent Beck, 1996, Chrysler

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Why XP?

• You do not do XP to save money However, XP
  shortens time to market
• XP is a mature software development method

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Why XP?

• Survey
• 31 XP/Agile-methods early adopter projects, 14
  firms
• Findings
• Cost reduction 5-7 on average
• Time to market compression 25-50 reduction in
  time

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Why XP? Analysis

• Shorter development period
• Code is easy-to-work with
• less bugs unit tests
• code is more readable workable (invest now to
  gain benefits later)pair programming,
  refactoring, coding standards
• Development is manageable and controlled
• accurate estimation small releases
• meets customer needs customer on-site, planning
  game, acceptance tests

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Why XP? Analysis

• Shorter development period (cont)
• Knowledge sharing, if one leaves everything
  continues as usual pair programming, collective
  ownership
• Production is increased pair programming (work
  all the time), sustainable pace
• Cost for requirements change/update/elaboration
  is CONSTANT simple design, planning game
  (redundant features are not added by customer and
  developers)

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Why XP?

• Barry W. Boehm (1981). Software Engineering
  Economics, Englewood Cliffs, N.J. Prentice Hall.
  
• 63 software development projects in corporations
  such as IBM.
• Phase of requirement change Cost Ratio
• Requirements  1
•   Design 3-6
• Coding 10
•   Development testing 15-40
•   Acceptance testing 30-70
•   Operation 40-1000

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Why XP?

• Under the assumption that the later a
  requirements is introduced the more expensive it
  is, customers (and developers) try to make a
  complete list of requirements.
• Under the assumption that cost for introducing
  an update in the requirements is constant,
  customers (and developers) do not assume what the
  customer will need and develop exactly and only
  what is needed.

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Why XP?

• You do not use XP to save money However, XP
  shortens time to market
• XP is a mature software development method (at
  least CMM level 3)

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XP in Practice Conceptual Changes

• XP encourages
• Cooperation (vs. knowledge-is-power)
• Simplicity (vs. habit-of-high-complexity)
• Change in work habits

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Why XP? Cognitive and Social Analysis

• ????? XP ?????? ??? ?????????? ???????.
• Game Theory Prisoners Dilemma
• Learning Theory Constructivism

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Social analysis
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Game Theory

• ????? ??????? ????? ?????? ???? ?????? ???????
  ??????? ?? ?? ??? ????????? ?"????" ??????
  ??????? ?? ???????? ??????.

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The Prisoners Dilemma As perspective
B competes ????? B cooperates ?? ?????
-10 ?? ???? ?????? ?? ???? ?- A, B ?????? 5 ??? ???? ?????? A cooperates ?? ?????
0 ?? ???? ??????, ????? ????? ???? ?????? 10 ?? ???? ?????? ?? ???? ?- B, A ?????? A competes ?????
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The Prisoners Dilemma The case of software
engineering As perspective, Bonus
B competes B cooperates
20 50 A cooperates
0 80 A competes
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The Prisoners Dilemma The case of software
engineering As perspective
B competes B cooperates
-10 5 A cooperates
-20 10 A competes
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The Prisoners Dilemma The case of software
engineering

• ??"? ????? ????? ??????? ???? ????? ?? ???????.
• ?????? ?????? ??? ?????? ????? ?????? ?????? ????
  ???? ????.
• ??? ????? ????? ?? ???? ????? ?????? ????? (??
  ???? ?????).
• ??????? ??? ?????? ????? ????? ??????? ???????
  ????? ??? ???? ?????.

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The Prisoners Dilemma The case of eXtreme
Programming

• ???????? ???? ????? ????? ??-?? XP ?????? ???
  ???? ????? ????? ??-?? ?????????? ?? XP.
• ?? ???(?) ???? ????(?) ??? ??? ???? ????? ???????
  ????? ??? ???? ?????????.
• ???? ???-?????? (?????? ?? ????? ?????? ?????) ??
  ????.
• ???? ????? ????? ?????? ?? ??????? ???.

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The Prisoners Dilemma The case of Extreme
Programming As perspective
B cooperates
5 A cooperates
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In what follows

• ???? ?-2 ????? ?- 4 ????????? ?? XP
• ??? ??????? ?? ????? ????? ?????? ???.
• ??????? ??? ????? ????? ????? ??-?? XP ???? ???
  ??? ???? ????? ????? ???? ?????? ???? ?????? ???
  ???? ????? (????? ???? ????? ????? ?? ????????).
• ?? ???? ????? ?????? ????? ????????? ???????
  ????? ????? ??? ?? ???????.
• ?? ?????? ?????? ???? ?????? ????? ??.

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The Prisoners Dilemma The value of courage

• ????? ?????
• ?? ???? ????? ??????? ???? ?? ????.
• ?? ???? ????? ???? ???????? ?????? ???? ??? ???
  ???.
• ?? ???? ????? ???? ?????? ????? ??? ?? ???????.
• ?????? ?????? ?????? ??? XP, ?? ???(?) ????(?)
  ??? ?? ??????? ??????? courage ???? ?? ?? ??????
  ???? ?????? ??? ???? ?????.
• ??????? ????? ????? ???????? ???? ??.

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Kent Beck

• Kent Beck explains when XP is not appropriate
• "it's more the social or business environment.
  If your organization punishes honest
  communications and you start to communicate
  honestly, you'll be destroyed."
• An interview with Kent Beck, June 17, 2003,
  Working smarter, not harder, IBM website
  http//www-106.ibm.com/developerworks/library/j-be
  ck/

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The Prisoners Dilemma The value of simplicity

• ????? ?????
• ????? ?? ??????? ??????? ?????? ?????? ?????
  ?????? ?????.
• ????, ?? ?????? ???.
• ???? ??????? ????? ??-??XP ???? ??????? ?? ????
  ???.
• ?? ?????? ???? ?????? ??? ???? ?????.
• ???? ?????? ????? ????? ????????.

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The Prisoners Dilemma Collective Ownership

• In practice anyone can change any code
  anywhere in the system at any time. (Beck,
  2000).
• ????? ????? ????? ????. ????? ????? ???.
• ???? ?????? ??-?? XP ???? ?? ??-?? ??????? ??.
• ?? ?????? ???? ?????? ??? ???? ?????.
• ???? ?????? ?????, ???? ???? ??????? ?????
  ?????? ????? ?????? ??????.

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The Prisoners Dilemma Coding Standards

• ????? ????? ????? ??? ????????? ??????.
• ????? ????? ?? ??-?? ????????? ??????.
• ?? ???? ????? ??????? ????? ??-?? XP ???? ???-??
  ??????? ?? ????.
• ???? ????? ???? ??????? ??? ???? ?????.
• ?? ???? ????? ?????? ????? ????????? ?????????
  ??????? ??? ?? ?? ????????.

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The Prisoners Dilemma Simple Design

• ???? ????? Simplicity
• ????? ????? ????? ???? ??? ????? ????? ?????
  ????? ????? ?????? ?? ????.
• ???? ??????? ????? ??-?? XP ???? ?? ??-?? ???????
  ??.
• ???? ????? ???? ??????? ??? ???? ?????.
• ???? ?????? ????? ????????? ????????? ??????? ???
  ???? ??? ?????.

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The Prisoners Dilemma Sustainable Pace

• ???? ???? ?? 40 ????, ???? ????? ??????.
• ??????? ?????? ?????? ???? ??????? ??? ??????.
• ????????? ????? (e.g., Pair Programming) ???????
  ????? ???? ?? ??? ??.
• ????? ????? ?????? 8-9 ???? ????? ????? ????
  ???? ???? ???? (????, ?? ??? ??????).
• ?? ???? ????? ??????? ????? ??? XP ???? ?? ???
  ??????? ??.
• ???? ????? ???? ??????? ??? ???? ?????.
• ???? ?????? ????? ????????? ????????? ??????? ???
  ???? ????? ????? ??.

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Cognitive analysis
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Why XP?

• ???? ???? ????? ????? ????? ??? ????? ????? XP
  ????? ?????? ???? ??.
• ?????????????
• ??????? ??????? ?????? ?????.
• ??? ??? ???? ?????? ?? ???? ?????? ??????, ?"?
  ????? ?????? ????? ???????? ??????.
• ????? ?????? ?????? ?????? ????? ???? ??????
  ??????.

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????? ????????? ?? XP

• ????? 4 ???? 12 ?????????? ?? XP ??? ???????
  ?????????????????.
• ????????? ??? ?????? ????? ??????? ?? ?????
  ??????.
• ?????? Communication ?- Feedback ?? ?? ??????.

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XP practices - Cognitive analysis

• Small releases
• Gradual process of knowledge construction re
  requirements
• Refactoring
• Gradual process of knowledge construction re
  code's structure and readability
• Test driven development
• Metaphor

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Cognitive and Social Analysis of XP practices
Social analysis Cognitive analysis
Collective ownership Sustainable pace Simple design Coding standards Refactoring Metaphor Test-first Small releases
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Summary

• eXtreme programming
• What?
• Why? Cognitive and Social analysis
• How?

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References

• Beck, K. (2000). Extreme Programming Explained
  Embrace Change, Addison Wesley.
• Ron Jeffries, What is Extreme Programming?
  http//www.xprogramming.com/xpmag/whatisxp.htm
• eXtreme Programming at the Technion
• RoleModelhttp//www.rolemodelsoftware.com/process
  /whatIsXp.php

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• Questions

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Appendices

• XP and the CMM
• XP conception of failure and success

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Why XP? XP is a Mature Method

• The Capability Maturity Model for Software (CMM
  or SW-CMM) a model for judging the maturity of
  the software processes of an organization and for
  identifying the key practices that are required
  to increase the maturity of these processes.
• The Software CMM has become a de facto standard
  for assessing and improving software processes.

59
Why XP? XP is a Mature Method

• The SW-CMM has been developed by the software
  community with stewardship by the SEI.
• past experiences in process improvement such as
  TQM
• academic business theories
• practical experiences of successful projects
  gained from companies such as IBM
• The CMM has five levels of process capability
  maturity. 

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Why XP? XP is a Mature Method

• The first undisciplined
• processes may be loosely defined and rarely
  understood.
• estimates of cost and schedule are poor and
  consequently projects have serious problems
  meeting deadlines and functionality requirements
  within budgets. 
• management generally is unaware that processes
  exist and often makes decisions that hurt more
  than help.

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Why XP? XP is a Mature Method

• Level 2 - Repeatable
• puts project management practices such as
  requirements definition, configuration
  management, and quality assurance in place that
  are documented and can be repeated. 
• Level 3 - Defined
• graduates the best practices of individual
  projects to an organizational process. 
• adds concepts of organizational training, process
  management, and program management.

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Why XP? XP is a Mature Method

• Levels 4 and 5
• use information and measurements defined in
  levels 2 and 3 to understand why the process
  behaves the way it does so it can be improved. 
• Level 5
• the process is mature enough to prevent defects
  instead of reacting to them and to insert new
  technology and process improvements knowing
  exactly how the organizational process will be
  affected.

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Why XP? XP is a Mature Method

• The CMM has become popular around the world
  because of its ability to be applied practically
  to any software environment. 
• It describes what process components should be in
  place (such as recording requirements, planning
  and tracking activities, estimating, etc.), but
  not how to implement them. 
• eXtreme Programming fits as a framework for how
  to implement the processes.

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XP in practice Success and failure

• 3 Sep, 2002 XP - An interview with Kent Beck
• Q What are the issues you see your clients
  struggling with?
• KB One of the issues is redefining failure or
  redefining success. For example, you think that
  you have a great idea for a project, and it's
  going to take you nine months to really have it
  ready for the market. You may discover after
  four weeks that you are going one-tenth the speed
  that you thought you would, and you cancel the
  project. Is that a failure or success? In many
  organizations, this is perceived as a failure.

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XP in practice Success and failure

• 3 Sep, 2002 XP An interview with Kent Beck
• KB (cont) In the XP world, providing
  information that allows you to constantly make
  that decision after four or eight weeks (out of a
  nine-month development cycle) is what you're
  there for. In the XP world, you call that a
  dramatic success. Now you have this cultural
  mismatch between how outsiders are going to view
  your outcome and how you view it inside the team.
  A lot of people clients struggle with that.
  They think that canceling a project is a bad
  thing, but I think that canceling a project is a
  good thing -- as long as you cancel the right one.