Best Practices and Supporting ToolsModels

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Best Practices and Supporting Tools/Models

• Jesse Hsia
• Kaman Cheung

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Topics of Discussion

• Definition
• Common best practice software lifecycle
  guidelines/principles
• Hewlett Packard Example
• Best practice tools and models
• COCOMO/COCOMO II
• COCOTS
• PSP
• Lessons Learned

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Definition What is Best Practice?

• Best practice refers to accomplishing a task in
  the best way.
• Best practice can be guidelines or principles in
  accomplishing a task.

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Advantages of Improving Software Process

• Greater efficiency
• Better value for money
• Better quality
• Greater Customer satisfaction
• Competitive advantage

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Guidelines

• Best practice guidelines can be identified in
  each software lifecycle phase
• Some general/managerial guidelines
• Assign a project manager for each project
• Have a separate quality assurance manager
• Constant customer input throughout the phases
• Train all newly appointed managers
• Maintain awareness of latest software engineering
  technology
• Ensure availability of non-software resources
• Have procedures for controlling changes to code,
  requirements, design, etc.

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Planning

• Using a formal cost estimation model
• Using formal methods to estimate software size
  and schedule
• Conduct risk assessment
• Evaluate alternatives

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Requirements/Design

• Use prototyping methods to capture requirements
  elements
• Allow only project managers to produce estimates
  and control changes
• Use a data dictionary for systems design and
  development

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• Implementation
• Establish coding standards
• Keep records which would allow quick and accurate
  reconstruction of all current versions
• Testing
• Plan testing before coding
• Log implementation problems and track their
  solution
• Gather statistics on sources of errors for
  analysis
• Ensure that every function is tested
• Validation and Verification
• Conduct periodic reviews of the status of the
  project
• Conduct inspection and walkthroughs at each stage

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Hewlett Packard

• Best practices are utilized by HP in developing
  large software systems consisting of multiple
  components.
• Some of the practices are
• Set list of criteria for all systems
  (interoperability)
• Specified reliability
• Remaining defect density
• Depth of code testing
• Scheduled software inspections (defect
  prevention)
• Requiring documentation and clarification
• Use of tools to test code coverage
• Standardize types of defects to allow failure
  analysis

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USC Computer Science

• WinWin approach with WinWin Lifecycle process
• Used in USC computer science department
• Students developed application for USC library
• Win-win situation for students
• Win-win situation for faculty
• Win-win situation for client (library)

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Tools and Models COCOMO II

• COCOMO (1981) COCOMO II (1995)
• Developed by Barry Boehm and colleagues in USC
• Three main goals of COCOMO II
• Develop a software cost estimation model that is
  tailored to software processes and practices of
  the 21st century
• Develop software cost database to help improve
  cost estimation
• To provide analysis and tools to software systems
  to improve their software lifecycle costs and
  schedule
• COCOMO II determines cost of software projects
  by
• Source Lines of Code
• Function Points
• Effort Multipliers
• Scale Factors

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Tools and Models (cont)

• COCOTS (Boehm) cost estimation model based on
  todays commercial-off-the-shelf (COTS) software
  packages.
• Cost determined by
• Assessment
• Tailoring
• Glue Code
• Volatility
• Still in experimental phase
• Complementary to COCOMO II

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Personal Software Process (PSP)

• What is PSP?
• Why should anyone use PSP?
• How does PSP work? Benefits? Disadvantages?
• What qualities does it effect?
• Why doesnt anyone use it?

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What is PSP?

• PSP was introduced in 1995 by Watts S. Humphrey
  in the book A Discipline for Software
  Engineering
• Supported by SEI
• Supported by Department of Defense

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Why should anyone use PSP?

• Software Crisis
• Quality software, where is it?
• What deadline?
• How much was it again?
• Examples that show a need for best practices like
  PSP
• Ariane 5
• Therac-25

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How does PSP work?

• Introduction of the Personal Software Process
• Features
• Hands-on intro to basic disciplines needed for
  good software engineering.
• Helps students develop habits they will need for
  professional work
• Focuses on habits needed for time management and
  quality assurance
• Essentially its documentation and the analysis of
  data
• Disciplines in PSP

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PSP

• Time Management
• Time Log
• Engineering Worksheet
• Weekly Time Budget
• Period and Product Planning
• Weekly Activity Summary
• Job Number Log

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PSP

• Making Commitments and Schedules
• Commitments List
• Gantt Chart
• Handling Defects
• Defect Recording Log
• PSP Project Plan Summary

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Gantt Chart
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Benefits of PSP

• Estimation accuracy increased considerable
• Number of defects introduced per 1000 lines of
  code (KLOC) decreased by a factor of two
• Number of defects per (KLOC) to be found late
  during the development decreases by a factor of
  three or more
• EASY TO LEARN!

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Challenges to Results

• Using a defined and measured personal software
  process by Watts Humphrey??
• Case Studies have showed that results stated are
  lower then published
• although the realistic improvements are smaller
  than many may expect, it does indeed produce the
  benefits it claims to produce

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Disadvantages of PSP

• Results not Guaranteed
• Labor intensive
• Tedious Task
• Lack of Support Tools

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What qualities does it effect?

• Reuseability
• Safety
• Many other qualities

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Why doesnt anyone use it?

• Businesses arent willing to spend the time and
  the money
• Self Discipline
• People dont like change
• Learning Curve
• But are these good enough reason?!

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Is it Worth it?

• Legal Benefits
• Cost Benefits
• Productivity Benefits
• Cost of Human life
• Software is everywhere now, is it worth it to you?

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Lessons learned

• There are managerial and technical best practices
• It is best practice to cost estimation models and
  code testing tools
• Software quality can be achieved by following
  best practices
• Importance of software quality